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  • Cataluminescence sensing of carbon disulfide based on CeO 2 hierarchical hollow microspheres
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-06-25
    Pingyang Cai, Xiaofeng Yi, Hongjie Song, Yi Lv

    Material morphology-dependent cataluminescence (CTL) sensing characteristic and application are presented in this work. Hierarchical hollow microspheres CeO2 were synthesized via the hydrothermal reaction of glucose and N, N-dimethyl-formamide (Glu-DMF). SEM, XRD, TEM, HRTEM and BET were used to characterize the prepared CeO2 materials. Compared with CeO2 cubics (CeO2 Cubs), CeO2 hierarchical hollow microspheres (CeO2 HMs) show an enhanced CTL response to carbon disulfide. The response and recovery times of CeO2 HMs-based CTL sensor towards carbon disulfide are about 8 s and 20 s, respectively. CeO2 HMs exhibits a linear CTL response to carbon disulfide in the concentration range of 0.50~10 μg•mL-1 with an excellent sensitivity and selectivity. These results suggest that CeO2 HMs will be a highly promising CTL sensing material for the detection and monitoring carbon disulfide.

    更新日期:2018-07-18
  • A colorimetric assay of DNA methyltransferase activity based on peroxidase mimicking of DNA template Ag/Pt bimetallic nanoclusters
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-06-22
    Hanie Ahmadzade Kermani, Morteza Hosseini, Andrea Miti, Mehdi Dadmehr, Giampaolo Zuccheri, Saman Hosseinkhani, Mohammad Reza Ganjali

    DNA methylation catalyzed by DNA methyl transferase (MTase) is a significant epigenetic process for modulating gene expression. Abnormal levels of DNA MTase enzyme have been regarded as a cancer biomarker or a sign of bacterial diseases. We developed a novel colorimetric method to assay M.SssI MTase activity employing peroxidase-like activity of DNA template Ag/Pt NCs without using restriction enzymes. Based on inhibiting the peroxidase reaction that occurred in the TMB-H2O2 system, in the presence of MTase, a highly sensitive and selective colorimetric biosensor was fabricated with a detection limit (LOD) of 0.05 U/mL and a linear range from 0.5 to 10 U/mL. The changes in absorption intensity were monitored to quantify the M.SssI activity. This strategy had a high selectivity over other proteins. Furthermore, it is also demonstrated that this method can be used for the evaluation and screening of inhibitors for DNA MTase.

    更新日期:2018-07-12
  • Hydrophilic interaction liquid chromatography in the separation of glycopeptides and their isomers
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-05-28
    Petr Kozlik, Radoslav Goldman, Miloslav Sanda

    The analysis of intact glycopeptides is a challenge because of the structural variety of the complex conjugates. In this work, we used separation involving hydrophilic interaction liquid chromatography using a superficially porous particle HALO® penta-HILIC column with tandem mass spectrometric detection for the analysis of N-glycopeptides of hemopexin. We tested the effect of the mobile phase composition on retention and separation of the glycopeptides. The results indicated that the retention of the glycopeptides was the combination of partitioning and adsorption processes. Under the optimized conditions, our HILIC method showed the ability to efficiently separate the glycoforms of the same peptide backbone including separation of the isobaric glycoforms. We achieved efficient separation of core and outer arm linked fucose of bi-antennary and tri-antennary glycoforms of the SWPAVGNCSSALR peptide and bi-antennary glycoform of the ALPQPQNVTSLLGCTH peptide, respectively. Moreover, we demonstrated the separation of antennary position of sialic acid linked via α2-6 linkage of the monosialylated glycopeptides. Glycopeptide isomers are often differentially associated with various biological processes. Therefore, chromatographic separation of the species without the need for an extensive sample preparation appears attractive for their identification, characterization, and reliable quantification.

    更新日期:2018-07-12
  • Proteins and antibodies in serum, plasma, and whole blood—size characterization using asymmetrical flow field-flow fractionation (AF4)
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-05-29
    Mats Leeman, Jaeyeong Choi, Sebastian Hansson, Matilda Ulmius Storm, Lars Nilsson

    The analysis of aggregates of therapeutic proteins is crucial in order to ensure efficacy and patient safety. Typically, the analysis is performed in the finished formulation to ensure that aggregates are not present. An important question is, however, what happens to therapeutic proteins, with regard to oligomerization and aggregation, after they have been administrated (i.e., in the blood). In this paper, the separation of whole blood, plasma, and serum is shown using asymmetric flow field-flow fractionation (AF4) with a minimum of sample pre-treatment. Furthermore, the analysis and size characterization of a fluorescent antibody in blood plasma using AF4 are demonstrated. The results show the suitability and strength of AF4 for blood analysis and open new important routes for the analysis and characterization of therapeutic proteins in the blood.

    更新日期:2018-07-12
  • LC/MS analysis of vitamin D metabolites by dielectric barrier discharge ionization and a comparison with electrospray ionization and atmospheric pressure chemical ionization
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-05-26
    Sebastian Hagenhoff, Heiko Hayen

    Serum vitamin D metabolite levels are of interest as biomarkers for vitamin D status, which has influence on numerous body functions and pathologies. The determination of vitamin D metabolite levels by liquid chromatography/mass spectrometry (LC/MS) is challenging due to their low concentrations and relatively low ionization efficiencies. Three ionization sources, dielectric barrier discharge ionization (DBDI), atmospheric pressure chemical ionization (APCI), and electrospray ionization (ESI), were compared regarding achievable limits of detection and occurring matrix effects. The latter were mainly caused by phospholipids. Therefore, in addition to a conventional solid phase extraction (SPE) stationary phase, a material for selective removal of phospholipids was examined. The selective removal of phospholipids significantly reduced observed matrix effects, especially when ESI was applied. Achievable limits of detection and observed matrix effects were lowest for APCI and with some limitations, also for DBDI.

    更新日期:2018-07-12
  • Highly selective and ratiometric fluorescent nanoprobe for the detection of cysteine and its application in test strips
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-05-11
    Fengyang Wang, Yingying Zhu, Jie Xu, Zhiai Xu, Guiying Cheng, Wen Zhang

    Cysteine (Cys) is a bithiol that plays a vital role in many physiological processes. However, it is difficult to discriminate Cys from homocysteine (Hcy) and glutathione (GSH), due to their similar chemical structures and reactivity. Herein, we have developed a polymeric nanoprobe, nanoHFA, for ratiometric, highly selective, and sensitive detection of Cys based on 7-hydroxycoumarin-3-carboxylic acid (HC) and fluorescein isothiocyanate (FITC)-acrylate (FITC-A) group-functionalized lipopolymer DSPE-PEG. The probe nanoHFA showed a strong fluorescence emission peak centered at 450 nm attributed to HC and a weak fluorescence emission peak centered at 520 nm due to the photoinduced electron transfer (PET) process of FITC induced by acrylate group. In the presence of Cys, the fluorescence signal at 520 nm could be lit up and the ratio of F520nm/F450nm showed a good linear relationship in the range of 5–60 μM with a low detection limit of 0.37 μM. The probe also displayed excellent water solubility and high selectivity to Cys over other biothiols such as Hcy and GSH. Moreover, we further used probe nanoHFA to detect Cu2+ ions in the range of 100–550 nM with a detection limit of 77 nM. The nanoprobe was successfully applied for the quantitative detection of Cys in fetal bovine serum, and fluorescent strips were developed for facile and visual detection of Cys and Cu2+ ions.

    更新日期:2018-07-12
  • An enzyme-free homogenous electrochemical assay for sensitive detection of the plasmid-mediated colistin resistance gene mcr-1
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-05-22
    Bo Li, Zhixin Chai, Xiaohui Yan, Chunchen Liu, Bo Situ, Ye Zhang, Weilun Pan, Shihua Luo, Jianhua Liu, Lei Zheng

    Antibiotic resistance associated with the mcr-1 gene of Gram-negative bacteria, which confers resistance to drugs of last resort and has the potential to spread via plasmids, is one of the most pressing issues facing global health today. Point-of-care testing for the mcr-1 gene is needed to aid in the identification of colistin resistance in the field and to control its horizontal transmission. Here, we report the successful development of an enzyme-free homogenous electrochemical strategy for sensitive detection of the antibiotic resistance gene mcr-1 using the hybridization chain reaction and mcr-1-specific toehold probe. The long double-stranded DNA polymer produced using this strategy could be detected by assessing the diffusion of methylene blue towards the surface of a screen-printed gold electrode. Under optimized conditions, a linear relationship was observed between the variation of peak current and the natural logarithm of the mcr-1 gene concentration in the range of 1 nM to 1 μM with a detection limit of 0.78 nM (S/N = 3). This enzyme-free, isothermal platform is a rapid, portable, disposable, and sensitive method for detection of plasmid-mediated colistin resistance.

    更新日期:2018-07-12
  • Solid-phase extraction of phospholipids using mesoporous silica nanoparticles: application to human milk samples
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-05-11
    Héctor Martínez Pérez-Cejuela, Isabel Ten-Doménech, Jamal El Haskouri, Pedro Amorós, Ernesto F. Simó-Alfonso, José Manuel Herrero-Martínez

    In this study, mesoporous silica materials (MSMs) with bimodal pore systems (namely, UVM-7), MCM-41 silica, and a commercial silica-based material were evaluated as solid-phase extraction (SPE) sorbents for the isolation of phospholipids (PLs) using phosphatidylcholine as a test compound. Morphological characterization (including TEM, surface, and size pore measurements) of these materials was carried out. The mechanism of interaction of the target analyte with the MSMs was also studied. With regard to the SPE process, several experimental parameters that affect the extraction performance (e.g., loading and elution solvent, breakthrough volume, loading capacity, and reusability) were investigated. The recommended protocol was applied to the extraction of PLs in human milk fat samples. The extracted PLs were then determined by hydrophilic interaction liquid chromatography (HILIC) using evaporative light scattering detection (ELSD). This work reports the first application of silica-based mesoporous materials to preconcentrate PLs in these complex matrices.

    更新日期:2018-07-12
  • Chiral capillary electrophoresis with UV-excited fluorescence detection for the enantioselective analysis of 9-fluorenylmethoxycarbonyl-derivatized amino acids
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-05-29
    Amir Prior, Giulia Coliva, Gerhardus J. de Jong, Govert W. Somsen

    The potential of capillary electrophoresis (CE) with ultraviolet (UV)-excited fluorescence detection for sensitive chiral analysis of amino acids (AAs) was investigated. dl-AAs were derivatized with 9-fluorenylmethoxycarbonyl chloride (FMOC)-Cl to allow their fluorescence detection and enhance enantioseparation. Fluorescence detection was achieved employing optical fibers, leading UV excitation light (< 300 nm) from a Xe-Hg lamp to the capillary window, and fluorescence emission to a spectrograph equipped with a charge-coupled device (CCD). Signal averaging over time and emission wavelength intervals was carried out to improve the signal-to-noise ratio of the FMOC-AAs. A background electrolyte (BGE) of 40 mM sodium tetraborate (pH 9.5), containing 15% isopropanol (v/v), 30 mM sodium dodecyl sulfate (SDS), and 30 mM β-cyclodextrin (β-CD), was found optimal for AA chemo- and enantioseparation. Enantioresolutions of 1.0 or higher were achieved for 16 proteinogenic dl-AAs. Limits of detection (LODs) were in the 10–100-nM range (injected concentration) for the d-AA enantiomers, except for FMOC-d-tryptophan (536 nM) which showed intramolecular fluorescence quenching. Linearity (R2 > 0.997) and repeatability for peak height (relative standard deviations (RSDs) < 7.0%; n = 5) and electrophoretic mobility (RSDs < 0.6%; n = 5) of individual AA enantiomers were established for chiral analysis of dl-AA mixtures. The applicability of the method was investigated by the analysis of cerebrospinal fluid (CSF). Next to l-AAs, endogenous levels of d-glutamine and d-aspartic acid could be measured in CSF revealing enantiomeric ratios of 0.35 and 19.6%, respectively. This indicates the method’s potential for the analysis of low concentrations of d-AAs in presence of abundant l-AAs.

    更新日期:2018-07-12
  • Systematic investigations of endogenous cortisol and cortisone in nails by LC-MS/MS and correlation to hair
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-05-17
    Tina M. Binz, Franziska Gaehler, Clarissa D. Voegel, Mathias Hofmann, Markus R. Baumgartner, Thomas Kraemer

    Hair samples are increasingly used for measuring the long-term stress mediator cortisol. However, hair is not always available and nails (finger or toe), as a keratinized matrix, may be an alternative to hair. In order to measure cortisol and cortisone in the nail matrix, an LC-MS/MS method has been developed and validated using 13C3-labeled surrogate analytes. Both analytes were measured in ESI negative mode as formic acid adducts. Different sample preparation techniques were assessed, and single-step extraction in methanol was established for determination of cortisone and cortisol in the nail matrix. The method was successfully validated with limits of detection (LOD) and limits of quantification (LOQ) of 0.5 and 1.0 pg/mg for cortisol and cortisone, respectively. The calibration curve was linear up to a concentration of 500 pg/mg. Recovery was good for both analytes and showed values over 50%. Matrix effects with ion suppression occurred for both substances but could be corrected by the use of internal standard. Accuracy and precision were in the accepted range of ± 20% for both substances. The method was successfully applied to determine cortisol and cortisone concentrations in authentic nail samples. Cortisol and cortisone concentrations varied significantly among different fingernails, being highest in the little fingernails and lowest in the thumbnails. It could be shown that even in only 1 mg nail sample cortisol and cortisone can be reliably quantified. No correlation between hair and nail cortisol and cortisone concentrations could be found. Furthermore, cortisol and cortisone concentrations were significantly higher in hair.

    更新日期:2018-07-12
  • Compensation for matrix effects in GC analysis of pesticides by using cucumber extract
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-09
    Hyeyoung Kwon, Michelangelo Anastassiades, Daniela Dörk, Su-Myoung Hong, Byeong-Chul Moon

    Matrix effects (MEs) can adversely affect quantification in pesticide residue analysis using GC. Analyte protectants (APs) can effectively interact with and mask active sites in the GC system, and are added individually or in combination to sample extracts and calibration solutions to minimize errors related to MEs. Unfortunately, APs cannot sufficiently compensate for MEs in all cases. Plant extracts, containing a broad range of natural compounds with AP properties, can also be used for this purpose. In this study, the applicability of cucumber extract as a natural AP mixture was investigated both alone and in combination with traditional APs. Extracts of two selected difficult matrices (onion and garlic) were prepared according to the citrate-buffered QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure. ME values of 40 representative GC-amenable pesticides were compared when calibrating against standards in pure solvent and in cucumber extract, with and without the addition of APs. Using a GC system with a contaminated inlet liner, the use of a cucumber-based calibration solution decreased MEs remarkably. The combination of APs with cucumber raw extract further decreased MEs, resulting in more than 85% of the tested pesticides showing ≤ 10% ME in onion and ≤ 20% ME in garlic. These results demonstrate that the preparation of calibration standards based on cucumber extracts (with or without the addition of APs) is a very useful and practical approach to compensate for MEs in pesticide residue analysis using QuEChERS and GC-MS/MS. The use of various internal standards is furthermore critically discussed.

    更新日期:2018-07-09
  • Development of immunosorbents for the analysis of forchlorfenuron in fruit juices by ion mobility spectrometry
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-07
    Alejandro Orellana-Silla, Sergio Armenta, Miguel de la Guardia, Josep V. Mercader, Francesc A. Esteve-Turrillas

    The advantages of using smart materials as immunosorbents in the analysis of complex matrices by ion mobility spectrometry (IMS) have been highlighted in this study. A novel analytical method has been proposed for the sensitive, selective, and fast determination of residues of the plant growth regulator forchlorfenuron in fruit juices. Three different monoclonal antibodies (s3#22, p2#21, and p6#41) were employed for the production of immunosorbents, based on Sepharose gel beads, which were characterized in terms of loading capacity, solvent resistance, and repeatability for its use in solid-phase extraction (SPE). Immunosorbents that were prepared with antibody p6#44 provided the best performance, with a loading capacity of 0.97 μg, a 10% (v/v) 2-propanol tolerance, and a reusability of at least eight uses. The SPE procedure involved the use of a column with 0.15 g Sepharose beads, containing 0.5 mg antibody, which was loaded to 20 mL of the sample, washed with 2 mL of water plus 2 mL of 10% (v/v) 2-propanol, and eluted with 2 mL of 2-propanol. The cleaned extract was directly analyzed by IMS, giving a limit of detection of 2 μg L−1 with a relative standard deviation of 7.6%. Trueness was assessed by the analysis of blank grape and kiwifruit juice samples spiked with forchlorfenuron concentrations from 10 to 400 μg L−1, with recoveries from 80 to 115%. The analytical performance of the proposed immunosorbent was compared with conventional extraction and cleanup methods, such as QuEChERS and C18-based SPE, giving the cleanest extracts for accurate determinations of forchlorfenuron by IMS.

    更新日期:2018-07-08
  • Isolation of transferrin by imprinted nanoparticles with magnetic deep eutectic solvents as monomer
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-07
    Yida Zhang, Huawei Cao, Qiangwei Huang, Xiaoyan Liu, Haixia Zhang

    Transferrin (TrF) is a very important human body glycoprotein and a clinical biomarker which controls the body’s iron ion channels and iron ion balance. Any change in TrF concentration and isoform also reflects the emergence of some diseases. In this work, we prepared magnetic molecularly imprinted nanoparticles (deep eutectic solvent-molecular imprinting polymers [DES-MIPs]) with a deep eutectic solvent (DES) as a functional monomer to separate TrF in human serum. The DES dosage for MIP, pH value, and time for adsorption have been optimized, and these materials show special adsorption properties for TrF. The maximum adsorption capacity (Qmax) and dissociation constant KL of the MIP by the Langmuir adsorption curve (R2 = 0.9949) were 37.5 mg/g and 0.015 g/L, respectively. The imprinting factor of the MIP is 3.50 with relative standard deviation (5.63%). In summary, the use of DES as a functional monomer in molecular imprinting technology provides a novel, efficient, and biocompatible method for the isolation and purification of proteins.

    更新日期:2018-07-08
  • Chiral and molecular recognition of monosaccharides by photoexcited tryptophan in cold gas-phase noncovalent complexes as a model for chemical evolution in interstellar molecular clouds
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-07
    Akimasa Fujihara, Yusuke Okawa

    Chiral and molecular recognition between amino acid and sugar molecules and their implications for chemical evolution were investigated using a tandem mass spectrometer equipped with an electrospray ionization source and a cold ion trap. Ultraviolet photodissociation of mass-selected and temperature-controlled gas-phase noncovalent complexes of protonated tryptophan (Trp) and monosaccharide enantiomers, such as aldohexose, aldopentose, and deoxyhexose, was examined as a model for chemical evolution in interstellar molecular clouds. Upon photoexcitation of noncovalent heterochiral H+(l-Trp)(d-aldohexose) complexes, NH2CHCOOH loss from protonated Trp via Cα–Cβ bond cleavage occurred. Conversely, in homochiral H+(l-Trp)(l-aldohexose), the energy absorbed by Trp was released through the detachment of aldohexose, and dissociation of the amino acid was suppressed. In the photodissociation mass spectra of protonated Trp with aldopentose and deoxyhexose, which lacks the OH group of aldohexose, no dissociation of the molecules in the complexes or differences between enantiomers were observed. These results indicate that the OH groups in monosaccharides contribute to enantiomer-selective photodissociation in molecular clouds. The differences observed between enantiomers in the photodissociation mass spectra were applied to distinguishing and quantifying aldohexose enantiomers in solution using l-Trp as a chiral probe. The enantiomeric excesses of aldohexoses in solution could be determined from a single photodissociation mass spectrum by reference to the relative ion intensities for the NH2CHCOOH-elimination product and H+(l-Trp) formed via detachment of aldohexose. This analysis method could also distinguish and quantify two d-aldohexose mixtures, where l-Trp was employed as an isomer probe.

    更新日期:2018-07-08
  • Immunoassay and amperometric biosensor approaches for the detection of deltamethrin in seawater
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-07
    Philipp Fruhmann, Ana Sanchis, Lisa Mayerhuber, Tünde Vanka, Christoph Kleber, J.-Pablo Salvador, M.-Pilar Marco

    The study of an enzyme-linked immunosorbent assay (ELISA) and an amperometric biosensor for the detection of the pyrethroid deltamethrin in seawater is reported. The preparation of specific polyclonal antibodies is addressed using two immunizing haptens based on deltamethrin and cypermethrin compounds, with a spacer arm placed at the cyano residue in the pyrethroid structure. Different conjugates based on bovine serum albumin and aminodextran are prepared depending on the lipophilic profile of the competitor haptens studied. A reproducible and sensitive indirect competitive ELISA is developed, reaching a limit of detection of 1.2 ± 0.04 μg L−1 and an IC50 value of 21.4 ± 0.3 μg L−1 (both n = 3). For validation of the assays described, artificial seawater samples fortified with deltamethrin are analyzed. For the ELISA assay, these accuracy studies reported a slope of 0.904. An amperometric immunosensor is developed using the same immunoreagents and achieving a comparable detectability in terms of LOD of 4.7 μg L−1, measuring seawater without any pretreatment. These results suggest that both techniques can be used as rapid and simple analytical methods for deltamethrin quantification in seawater samples, which are great candidates for initial environmental screening programs.

    更新日期:2018-07-08
  • Issues with analyzing noble gases using gas chromatography with thermal conductivity detection
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-06
    George C. Rhoderick, Michael E. Kelley, Lyn Gameson, Kimberly J. Harris, Joseph T. Hodges

    The noble gases, namely neon, argon, krypton and xenon, have many uses including in incandescent and gas discharge lighting, in plasma televisions, shielding gas in welding, in lasers for surgery and semiconductors, and in magnetic resonance imaging (MRI) of the lungs. When incorporating these noble gases in industries, especially the medical field, it is important to know accurately the composition of the noble gas mixture. Therefore, there is a need for accurate gas standards that can be used to determine the noble gas amount-of-substance fraction in the appropriate mixture application. A recent comparison of mixtures containing four noble gases in a helium balance showed mixed results among National Metrology Institutes. Significant differences, 0.7 to 3.8% relative, were seen in the analytical amount-of-substance assignments versus the gravimetric value of the noble gases in the comparison mixture when using “binary standards”, i.e. neon in helium, argon in helium and krypton in helium, as applied by the National Institute of Standards and Technology. Post-comparison studies showed that when all four noble gases were included in the standards, the agreement between analytical and gravimetric values was within 0.05% relative. Further research revealed that different carrier gases (hydrogen, helium and nitrogen) resulted in varying differences between the analytical and gravimetric values assignments. This paper will discuss the findings of these analytical comparisons.

    更新日期:2018-07-08
  • Reference database design for the automated analysis of microplastic samples based on Fourier transform infrared (FTIR) spectroscopy
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-06
    Sebastian Primpke, Marisa Wirth, Claudia Lorenz, Gunnar Gerdts

    The identification of microplastics becomes increasingly challenging with decreasing particle size and increasing sample heterogeneity. The analysis of microplastic samples by Fourier transform infrared (FTIR) spectroscopy is a versatile, bias-free tool to succeed at this task. In this study, we provide an adaptable reference database, which can be applied to single-particle identification as well as methods like chemical imaging based on FTIR microscopy. The large datasets generated by chemical imaging can be further investigated by automated analysis, which does, however, require a carefully designed database. The novel database design is based on the hierarchical cluster analysis of reference spectra in the spectral range from 3600 to 1250 cm−1. The hereby generated database entries were optimized for the automated analysis software with defined reference datasets. The design was further tested for its customizability with additional entries. The final reference database was extensively tested on reference datasets and environmental samples. Data quality by means of correct particle identification and depiction significantly increased compared to that of previous databases, proving the applicability of the concept and highlighting the importance of this work. Our novel database provides a reference point for data comparison with future and previous microplastic studies that are based on different databases.

    更新日期:2018-07-08
  • Interactions between elastin-like peptides and an insulating poly( ortho -aminophenol) membrane investigated by AFM and XPS
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-06
    Maria Elvira Carbone, Rosanna Ciriello, Pasquale Moscarelli, Federica Boraldi, Giuliana Bianco, Antonio Guerrieri, Brigida Bochicchio, Antonietta Pepe, Daniela Quaglino, Anna Maria Salvi

    This investigation was undertaken to explore the mutual recognition of the pentapeptide (ValGlyGlyValGly)n, a hydrophobic elastin-like peptide (ELP), suspended in deionized water in monomer (n = 1) and trimer (n = 3) forms and the outer surface of a very thin, insulating polymer, poly(ortho-aminophenol) (PoAP), electrochemically grown on a platinum foil by cyclic voltammetry in a neutral medium (phosphate-buffered saline, I = 0.1M) immersed in the suspension. As a prior task, the proved propensity of the ValGlyGlyValGly sequence, at the given minimal length (three or more repeats), to self-assemble into amyloid-like fibrils when solubilized in an aqueous environment was considered within the framework of testing PoAP surfaces for the specific detection of amyloid precursors. From our knowledge of the chemical structure and physical properties of both biomacromolecule families obtained in previous studies, we focused on the efficacy of the binding sites offered to ELP fibrils by PoAP in its as-prepared form or properly modified either by postsynthesis oxidation or by adsorption/entrapping of ELP monomer(s) with or without protecting terminal groups. Consistent with all methods of preparation, the best surfaces, recognizable by the trimer fibrils, are those modified to carry a larger number of carbonyls, particularly by entrapment of ELP monomer(s) during PoAP electrosynthesis using an imprinting-inspired method. The degree of attachment of fibrillar aggregates, detected by atomic force microscopy and X-ray photoelectron spectroscopy, provides unequivocal evidence of the cooperative forces involving PoAP–ELP interactions. The results obtained suggest the prospect of using the proposed Pt/PoAP/ELP systems as biodetectors in Alzheimer disease.

    更新日期:2018-07-08
  • Correction to: Monitoring dynamic release of intracellular hydrogen peroxide through a microelectrode based enzymatic biosensor
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-05
    Hang Zhang, Jun Ruan, Weiwei Liu, Xuerui Jiang, Tianyu Du, Hui Jiang, Alberto Pasquarelli, Kay-Eberhard Gottschalk, Xuemei Wang

    The authors would like to call the reader’s attention to the fact that unfortunately Alberto Pasquarelli’s and Kay-Eberhard Gottschalk’s affiliations were wrong in the original publication.

    更新日期:2018-07-08
  • Ionic liquids on optical sensors for gaseous carbon dioxide
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-05
    M. D. Fernández-Ramos, M. L. Aguayo-López, I. Pérez de Vargas-Sansalvador, L. F. Capitán-Vallvey

    This work presents a study on the influence of eight different ionic liquids (ILs) in the composition of dry membranes used for gaseous CO2 optical sensing. The presence of CO2 causes a displacement of a colorimetric pH indicator toward its acid form that increases the emission intensity of the luminophore by an inner filter process. The influence of ILs in the membrane on the stability and dynamic behavior—usually the main drawbacks of these sensors—of the membranes is studied. The characterization of the different membranes prepared was carried out and the discussion of the results is presented. In all cases, the response and recovery times improved considerably, with the best case being response times of only 10 s and recovery times of 48 s, compared to response and recovery times of 41 and 100 s, respectively, for membranes without IL. The useful life of the detection membranes is also considerably longer than that of membranes that do not include IL, at least 292 days in the best case. The sensing membrane without luminophore and only containing the pH indicator is proposed for the color-based measurement of CO2 using a digital camera for possible use in food-packaging technology.

    更新日期:2018-07-08
  • Feasibility study of a candidate reference material for ions in PM 2.5 : does commutability matter also for inorganic matrices?
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-04
    G. Emma, J. Snell, J. Charoud-Got, A. Held, H. Emons

    The existing Air Quality Directive 2008/50/EC establishes within the European Union (EU) member states limit values for fine air particulate matter (PM2.5) including the possibility to discount natural sources of pollution when assessing compliance with the legislation. In proving this, EU member states shall determine, amongst others, the rural background concentration of some anions (Cl−, NO3− and SO42−) and cations (Na+, NH4+, K+, Ca2+ and Mg2+). To deliver reliable data and to comply with the data quality objectives of the legislation, environmental control laboratories should use certified reference materials (CRMs) to validate or verify the performance of their analytical methods. Since no CRMs for anions and cations in PM2.5 are presently available, we present the commutability issues encountered during the first attempt to develop such a material. We demonstrate that a dust, collected in a road tunnel and previously used for the production of two CRMs of a PM10-like material, does not behave as an authentic fine particulate matter collected according to EN12341:2014 when measured by an established method proposed by the European Committee for Standardization (CEN/TR 16269:2011). The water-soluble fractions of SO42−, NH4+, K+, Ca2+ and Mg2+ in a PM2.5-like candidate CRM produced from that road tunnel dust are only fully extracted after 3 h of sonication and not after 30 min, as stated in the method. Moreover, we found that the particle size of the test material influenced the extraction yield of K+, Ca2+ and Mg2+, suggesting that these ionic species were incorporated in the core of the particles and inaccessible to the extraction procedure. These particular features make the material unsuitable for the measurements of ions with the CEN method. The difference in the extraction time can be seen as a commutability issue and the candidate CRM should be considered as not commutable with routine samples. This demonstrates that commutability studies should not only be considered for clinical CRMs, but also for inorganic CRMs when they are intended to be used to quantify operationally defined analytes.

    更新日期:2018-07-05
  • Determination of the β-glycosylate fraction of contaminants of emerging concern in lettuce ( Lactuca sativa L.) grown under controlled conditions
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-04
    Carlos Hurtado, Carmen Domínguez, Pere Clapés, Josep M. Bayona

    The uptake of a large variety of contaminants of emerging concern (CECs) by crops has already been reported, and the occurrence of phase II metabolites or conjugates has only been detected in plant cell cultures. However, the extent of their formation under cropping conditions is largely unknown. In this study, an analytical strategy to assess the conjugation of 11 CECs in lettuce (Lactuca sativa L.) irrigated with different concentrations (0, 0.05, 0.5, 5, and 50 μg L−1) of CECs was developed. The methodology involved enzymatic digestion with β-glucosidase to obtain the total fraction (free form + conjugates) of CECs. The conjugation fraction was then obtained based on the difference. The highest extent of conjugation (i.e., 27 to 83%) was found with the most hydrophobic compounds, such as bisphenol A, carbamazepine, methyl paraben, and triclosan. So, the CEC conjugate fraction cannot be neglected in the estimate of human daily intake.

    更新日期:2018-07-05
  • Sheathless coupling of microchip electrophoresis to ESI-MS utilising an integrated photo polymerised membrane for electric contacting
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-04
    T. Scholl, C. Dietze, M. Schmidt, S. Ohla, D. Belder

    In this article, we present a novel approach for the sheathless coupling of microchip electrophoresis (MCE) with electrospray mass spectrometry (ESI-MS). The key element is an ion-conductive hydrogel membrane, placed between the separation channel and an adjacent microfluidic supporting channel, contacted via platinum electrodes. This solves the persistent challenge in hyphenation of mass spectrometry to chip electrophoresis, to ensure a reliable electrical connection at the end of the electrophoresis channel without sacrificing separation performance and sensitivity. Stable electric contacting is achieved via a Y-shaped supporting channel structure, separated from the main channel by a photo polymerised, ion permeable hydrogel membrane. Thus, the potential gradient required for performing electrophoretic separations can be generated while simultaneously preventing gas formation due to electrolysis. In contrast to conventional make-up or sheathflow approaches, sample dilution is also avoided. Rapid prototyping allowed the study of different chip-based approaches, i.e. sheathless, open sheathflow and electrode support channel designs, for coupling MCE to ESI-MS. The performance was evaluated with fluorescence microscopy and mass spectrometric detection. The obtained results revealed that the detection sensitivity obtained in such Y-channel chips with integrated hydrogel membranes was superior because sample dilution or loss was prevented. Furthermore, band broadening is reduced compared to similar open structures without a membrane.

    更新日期:2018-07-05
  • Employing proteomics to understand the effects of nutritional intervention in cancer treatment
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-04
    Monica M. Schroll, Amanda B. Hummon

    Lifestyle optimizations are implementable changes that can have an impact on health and disease. Nutrition is a lifestyle optimization that has been shown to be of great importance in cancer initiation, progression, and metastasis. Dozens of clinical trials are currently in progress that focus on the nutritional modifications that cancer patients can make prior to and during medical care that increase the efficacy of treatment. In this review, we discuss various nutritional inventions for cancer patients and the analytical approaches to characterize the downstream molecular effects. We first begin by briefly explaining the many different forms of nutritional intervention currently being used in cancer treatment as well as their motivating biology. The forms of nutrient modulation described in this review include calorie restriction, the different practices of fasting, and carbohydrate restriction. The review then shifts to explain how proteomics is used to determine biomarkers of cancer and how it can be utilized in the future to determine the metabolic phenotype of a tumor, and inform physicians if nutritional intervention should be recommended for a cancer patient. Nutrigenomics aims to understand the relationship of nutrients and gene expression and can be used to understand the downstream molecular effects of nutrition restriction, partially through proteomic analysis. Proteomics is just beginning to be used as cancer diagnostic and predictive tools. However, these approaches have not been used to their full potential to understand nutritional intervention in cancer.

    更新日期:2018-07-05
  • Headspace analysis for screening of volatile organic compound profiles of electronic juice bulk material
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-04
    Ryan F. LeBouf, Dru A. Burns, Anand Ranpara, Kathleen Attfield, Leonard Zwack, Aleksandr B. Stefaniak

    The use of electronic nicotine delivery systems continues to gain popularity, and there is concern for potential health risks from inhalation of aerosol and vapor produced by these devices. An analytical method was developed that provided quantitative and qualitative chemical information for characterizing the volatile constituents of bulk electronic cigarette liquids (e-liquids) using a static headspace technique. Volatile organic compounds (VOCs) were screened from a convenience sample of 146 e-liquids by equilibrating 1 g of each e-liquid in amber vials for 24 h at room temperature. Headspace was transferred to an evacuated canister and quantitatively analyzed for 20 VOCs as well as tentatively identified compounds using a preconcentrator/gas chromatography/mass spectrometer system. The e-liquids were classified into flavor categories including brown, fruit, hybrid dairy, menthol, mint, none, tobacco, and other. 2,3-Butanedione was found at the highest concentration in brown flavor types, but was also found in fruit, hybrid dairy, and menthol flavor types. Benzene was observed at concentrations that are concerning given the carcinogenicity of this compound (max 1.6 ppm in a fruit flavor type). The proposed headspace analysis technique coupled with partition coefficients allows for a rapid and sensitive prediction of the volatile content in the liquid. The technique does not require onerous sample preparation, dilution with organic solvents, or sampling at elevated temperatures. Static headspace screening of e-liquids allows for the identification of volatile chemical constituents which is critical for identifying and controlling emission of potentially hazardous constituents in the workplace.

    更新日期:2018-07-05
  • Preparation and evaluation of surface-bonded phenylglycine zwitterionic stationary phase
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-03
    Huanjun Peng, Xiang Wang, Jingdong Peng, Yan He, Yu Chen, Fang Chen, Shiyu Li

    4-Hydroxy-d-phenylglycine was modified with methacrylic anhydride and then immobilized on silica through thiol-initiated surface polymerization; the prepared material was applied as stationary phase for HPLC. The obtained stationary phase was characterized by elemental analysis, infrared spectroscopy, and thermogravimetric analysis. The chromatographic performance of the packed column was evaluated in reversed-phase liquid chromatograph (RPLC) and hydrophilic interaction liquid chromatograph (HILIC) mode; this column has shown excellent selectivity to both the hydrophobic and hydrophilic solutes. The selectivity towards polycyclic aromatic hydrocarbons relative to that towards alkylbenzenes exhibited by the prepared column was higher than the corresponding selectivity exhibited by commercial C18 column, which could be explained by electronic π-π interaction between phenylglycine and electron-rich aromatic rings. On the other hand, the prepared column has also shown better selectivity for polar compounds, which was based on the multiple interaction and retention mechanisms. It was also used to separate sulfonamides and organic acid compared with a commercial C18 and HILIC column; the results show its great chromatographic performance with distinctive selectivity. All the results indicated the prepared column had potential application in a wide range.

    更新日期:2018-07-03
  • Round robin study of formalin-fixed paraffin-embedded tissues in mass spectrometry imaging
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-03
    Achim Buck, Bram Heijs, Birte Beine, Jan Schepers, Alberto Cassese, Ron M. A. Heeren, Liam A. McDonnell, Corinna Henkel, Axel Walch, Benjamin Balluff

    Mass spectrometry imaging (MSI) has provided many results with translational character, which still have to be proven robust in large patient cohorts and across different centers. Although formalin-fixed paraffin-embedded (FFPE) specimens are most common in clinical practice, no MSI multicenter study has been reported for FFPE samples. Here, we report the results of the first round robin MSI study on FFPE tissues with the goal to investigate the consequences of inter- and intracenter technical variation on masking biological effects. A total of four centers were involved with similar MSI instrumentation and sample preparation equipment. A FFPE multi-organ tissue microarray containing eight different types of tissue was analyzed on a peptide and metabolite level, which enabled investigating different molecular and biological differences. Statistical analyses revealed that peptide intercenter variation was significantly lower and metabolite intercenter variation was significantly higher than the respective intracenter variations. When looking at relative univariate effects of mass signals with statistical discriminatory power, the metabolite data was more reproducible across centers compared to the peptide data. With respect to absolute effects (cross-center common intensity scale), multivariate classifiers were able to reach on average > 90% accuracy for peptides and > 80% for metabolites if trained with sufficient amount of cross-center data. Overall, our study showed that MSI data from FFPE samples could be reproduced to a high degree across centers. While metabolite data exhibited more reproducibility with respect to relative effects, peptide data-based classifiers were more directly transferable between centers and therefore more robust than expected.

    更新日期:2018-07-03
  • Stepwise frontal affinity chromatography model for drug and protein interaction
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-02
    Xiaoshuang He, Yue Sui, Sicen Wang

    Frontal affinity chromatography is an efficient technique that combines affinity interaction and high-performance liquid chromatography, and frontal analysis has been used in studying the interaction between drugs and proteins. Based on frontal analysis, stepwise frontal analysis has been established. The present study aimed to use the Lineweaver–Burk plot in stepwise frontal analysis by taking the weighted average of time data. Commercial human serum albumin (HSA) and alpha-1-acid glycoprotein (AGP) columns were used as an affinity column. Warfarin and digitoxin were chosen as model drugs for the HSA column, whereas verapamil and tamsulosin were selected as model drugs for the AGP column. The time data obtained by frontal analysis and stepwise frontal analysis were compared, and the results revealed good correlation (r2 = 0.9946–0.9998). Frontal analysis and stepwise frontal analysis were also used to analyze the equilibrium dissociation constants (Kd) of model drugs on the HSA and AGP columns. The Kd values were compared with literature values, which revealed the same order of magnitude. These results illustrate that conversion of the time data is reasonable and feasible. The Lineweaver–Burk plot can be used in the stepwise frontal analysis model to study the characteristics of the interaction between drugs and proteins.

    更新日期:2018-07-02
  • Graphene oxide-based biosensing platform for rapid and sensitive detection of HIV-1 protease
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-02
    Youwen Zhang, Xiaohan Chen, Golbarg M. Roozbahani, Xiyun Guan

    HIV-1 protease is essential for the life cycle of the human immunodeficiency virus (HIV), and is one of the most important clinical targets for antiretroviral therapies. In this work, we developed a graphene oxide (GO)-based fluorescence biosensing platform for the rapid, sensitive, and accurate detection of HIV-1 protease, in which fluorescent-labeled HIV-1 protease substrate peptide molecules were covalently linked to GO. In the absence of HIV-1 protease, fluorescein was effectively quenched by GO. In contrast, in the presence of HIV-1 protease, it would cleave the substrate peptide into short fragments, thus producing fluorescence. Based on this sensing strategy, HIV-1 protease could be detected at as low as 1.18 ng/mL. More importantly, the sensor could successfully detect HIV-1 protease in human serum. Such GO-based fluorescent sensors may find useful applications in many fields, including diagnosis of protease-related diseases, as well as sensitive and high-throughput screening of drug candidates.

    更新日期:2018-07-02
  • Increased optical pathlength through aqueous media for the infrared microanalysis of live cells
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-02
    James Doherty, Zhe Zhang, Katia Wehbe, Gianfelice Cinque, Peter Gardner, Joanna Denbigh

    The study of live cells using Fourier transform infrared spectroscopy (FTIR) and FTIR microspectroscopy (FT-IRMS) intrinsically yields more information about cell metabolism than comparable experiments using dried or chemically fixed samples. There are, however, a number of barriers to obtaining high-quality vibrational spectra of live cells, including correction for the significant contributions of water bands to the spectra, and the physical stresses placed upon cells by compression in short pathlength sample holders. In this study, we present a water correction method that is able to result in good-quality cell spectra from water layers of 10 and 12 μm and demonstrate that sufficient biological detail is retained to separate spectra of live cells based upon their exposure to different novel anti-cancer agents. The IR brilliance of a synchrotron radiation (SR) source overcomes the problem of the strong water absorption and provides cell spectra with good signal-to-noise ratio for further analysis. Supervised multivariate analysis (MVA) and investigation of average spectra have shown significant separation between control cells and cells treated with the DNA cross-linker PL63 on the basis of phosphate and DNA-related signatures. Meanwhile, the same control cells can be significantly distinguished from cells treated with the protein kinase inhibitor YA1 based on changes in the amide II region. Each of these separations can be linked directly to the known biochemical mode of action of each agent.

    更新日期:2018-07-02
  • One- vs two-phase extraction: re-evaluation of sample preparation procedures for untargeted lipidomics in plasma samples
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-07-02
    Andres Gil, Wenxuan Zhang, Justina C. Wolters, Hjalmar Permentier, Theo Boer, Peter Horvatovich, M. Rebecca Heiner-Fokkema, Dirk-Jan Reijngoud, Rainer Bischoff

    Lipidomics is a rapidly developing field in modern biomedical research. While LC-MS systems are able to detect most of the known lipid classes in a biological matrix, there is no single technique able to extract all of them simultaneously. In comparison with two-phase extractions, one-phase extraction systems are of particular interest, since they decrease the complexity of the experimental procedure. By using an untargeted lipidomics approach, we explored the differences/similarities between the most commonly used two-phase extraction systems (Folch, Bligh and Dyer, and MTBE) and one of the more recently introduced one-phase extraction systems for lipid analysis based on the MMC solvent mixture (MeOH/MTBE/CHCl3). The four extraction methods were evaluated and thoroughly compared against a pooled extract that qualitatively and quantitatively represents the average of the combined extractions. Our results show that the lipid profile obtained with the MMC system displayed the highest similarity to the pooled extract, indicating that it was most representative of the lipidome in the original sample. Furthermore, it showed better extraction efficiencies for moderate and highly apolar lipid species in comparison with the Folch, Bligh and Dyer, and MTBE extraction systems. Finally, the technical simplicity of the MMC procedure makes this solvent system highly suitable for automated, untargeted lipidomics analysis.

    更新日期:2018-07-02
  • Ionic liquid inspired alkalinochromic salts based on Reichardt’s dyes for the solution phase and vapochromic detection of amines
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-06-27
    Jeremy B. Essner, Gary A. Baker

    Chromogenic salts based on the negatively solvatochromic pyridinium N-phenolate betaines 2,6-diphenyl-4-(2,4,6-triphenyl-N-pyridino)-phenolate (Reichardt’s dye 30) and 2,6-dichloro-4-(2,4,6-triphenyl-N-pyridino)-phenolate (Reichardt’s dye 33) proved to be promising probes for the colorimetric detection of bases, including hydroxide ion, ammonia, and aliphatic amines. Specifically, the protonated halide forms of these two dyes were ion exchanged to generate lipophilic bis(trifluoromethylsulfonyl)imide derivatives, denoted [ET(30)][Tf2N] and [ET(33)][Tf2N], respectively. When dissolved in 95 vol% EtOH, these essentially colorless solutions displayed dramatic “alkalinochromic” color-on switching due to phenolic deprotonation to generate the zwitterionic form of the dyes with their characteristic charge-transfer absorption. The extent of the colorimetric response varied with the base strength for the aliphatic amines tested (i.e., propylamine, ethanolamine, ethylenediamine, diethylenetriamine, triethylamine, triethanolamine), being loosely correlated with the pKb of the amine. In addition, we demonstrated proof of concept for the vapochromic detection of ammonia and aliphatic amines by dissolution of the chromogenic probes in the ionic liquid 1-propyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide. We also showed that the dyed ionic liquid can be successfully immobilized within silica sol-gel ionogels to generate more practical and robust sensory platforms. This strategy represents a useful addition to existing colorimetric sensor arrays targeting amines and other basic species. In particular, the differential response of the two different probes offers a measure of chemical selectivity which will be of interest for detecting biogenic amines in food safety applications, among other areas.

    更新日期:2018-07-02
  • Ionic liquid phases with comprehensive two-dimensional gas chromatography of fatty acid methyl esters
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-02-17
    Siriluck Pojjanapornpun, Yada Nolvachai, Kornkanok Aryusuk, Chadin Kulsing, Kanit Krisnangkura, Philip J. Marriott

    New generation inert ionic liquid (iIL) GC columns IL60i, IL76i and IL111i, comprising phosphonium or imidazolium cationic species, were investigated for separation of fatty acid methyl esters (FAME). In general, the iIL phases provide comparable retention times to their corresponding conventional columns, with only minor selectivity differences. The average tailing factors and peak widths were noticeably improved (reduced) for IL60i and IL76i, while they were slightly improved for IL111i. Inert IL phase columns were coupled with conventional IL columns in comprehensive two-dimensional GC (GC × GC) with a solid-state modulator which offers variable modulation temperature (TM), programmable TM during analysis and trapping stationary phase material during the trap/release (modulation) process, independent of oven T and column sets. Although IL phases are classified as polar, relative polarity of the two phases comprising individual GC × GC column sets permits combination of less-polar IL/polar IL and polar IL/less-polar IL column sets; it was observed that a polar/less-polar column set provided better separation of FAME. A higher first dimension (1D) phase polarity combined with a lower 2D phase polarity, for instance 1D IL111i with 2D IL59 gave the best result; the greater difference in 1D/2D phase polarity results in increasing occupancy of peak area in the 2D space. The IL111i/IL59 column set was selected for analysis of fatty acids in fat and oil products (butter, margarine, fish oil and canola oil). Compared with the conventional IL111, IL111i showed reduced column bleed which makes this more suited to GC × GC analysis of FAME. The proposed method offers a fast profiling approach with good repeatability of analysis of FAME.

    更新日期:2018-07-02
  • Real-time monitoring of endogenous cysteine levels in living cells using a CD-based ratiometric fluorescent nanoprobe
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-04-30
    Hong Wang, Peisheng Zhang, Yong Tian, Yuan Zhang, Heping Yang, Shu Chen, Rongjin Zeng, Yunfei Long, Jian Chen

    A simple and readily available fluorescent probe is needed for the real-time monitoring of endogenous cysteine (Cys) levels in living cells, as such a probe could be used to study the role of Cys in related diseases. Herein, we report the first fluorescent probe based on carbon dots (CDs-FITA) for the selective and ratiometric imaging of endogenous Cys in live cells. In this ratiometric fluorescent probe, a fluorescein derivative (FITA) that recognizes Cys is covalently linked to the surfaces of carbon dots (CDs); employing CDs greatly improves the water solubility of the probe. Acrylate on FITA is selectively cleaved by Cys in aqueous solution under mild conditions, leading to a dramatic increase in the fluorescence from fluorescein. The probe therefore allows the highly selective ratiometric fluorescent detection of Cys even in the presence of various interferents. The as-prepared CDs-FITA showed excellent performance when applied to detect Cys in blood serum. In addition, due to its negligible cytotoxicity, the CDs-FITA can also be utilized for the real-time monitoring of endogenous cysteine (Cys) levels in living cells.

    更新日期:2018-06-28
  • Development of mRNA-based body fluid identification using reverse transcription loop-mediated isothermal amplification
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-04-25
    Tetsuya Satoh, Seiya Kouroki, Keita Ogawa, Yorika Tanaka, Kazutoshi Matsumura, Susumu Iwase

    Identifying body fluids from forensic samples can provide valuable evidence for criminal investigations. Messenger RNA (mRNA)-based body fluid identification was recently developed, and highly sensitive parallel identification using reverse transcription polymerase chain reaction (RT-PCR) has been described. In this study, we developed reverse transcription loop-mediated isothermal amplification (RT-LAMP) as a simple, rapid assay for identifying three common forensic body fluids, namely blood, semen, and saliva, and evaluated its specificity and sensitivity. Hemoglobin beta (HBB), transglutaminase 4 (TGM4), and statherin (STATH) were selected as marker genes for blood, semen, and saliva, respectively. RT-LAMP could be performed in a single step including both reverse transcription and DNA amplification under an isothermal condition within 60 min, and detection could be conveniently performed via visual fluorescence. Marker-specific amplification was performed in each assay, and no cross-reaction was observed among five representative forensically relevant body fluids. The detection limits of the assays were 0.3 nL, 30 nL, and 0.3 μL for blood, semen, and saliva, respectively, and their sensitivities were comparable with those of RT-PCR. Furthermore, RT-LAMP assays were applicable to forensic casework samples. It is considered that RT-LAMP is useful for body fluid identification.

    更新日期:2018-06-28
  • Monitoring dynamic release of intracellular hydrogen peroxide through a microelectrode based enzymatic biosensor
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-05-24
    Hang Zhang, Jun Ruan, Weiwei Liu, Xuerui Jiang, Tianyu Du, Hui Jiang, Pasquarelli Alberto, Kay-Eberhard Gottschalk, Xuemei Wang

    A high sensitive and selective hydrogen peroxide (H2O2) biosensor was fabricated on the basis of reduced hemoglobin (Hb) and single-walled carbon nanotubes (SWCNTs) for detecting the release of H2O2 from living HepG2 cancer cells in the process of the in situ biosynthesis of ZnO quantum. The modification of carbon fiber microelectrode (CFME) was carried out by physical adsorption. By the scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), the dense cover of surface and successful immobilization were characterized. Electrochemical investigation demonstrates that the as-prepared modified microelectrode showed a quasi-reversible process toward the reduction of H2O2, which exhibited a linear range from 0.51 to 10.6 μM, with a limit of detection of 0.23 μM. This microelectrode biosensor was applied for the quantification of the change of H2O2 concentration released from HepG2 cells through the in situ biosynthesis of ZnO quantum dots, which was further confirmed by the fluorescence staining.

    更新日期:2018-06-28
  • A highly sensitive fluorescent probe based on the Michael addition mechanism with a large Stokes shift for cellular thiols imaging
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-04-23
    Song Chen, Peng Hou, Jing Wang, Shuang Fu, Lei Liu

    A novel fluorescent probe IPY-MAL for thiols was developed based on imidazo[1,5-α]pyridine derivative, which was decorated with a maleimide group. The probe IPY-MAL showed a rapid response (30 s), high sensitivity and selectivity for thiols with a large Stokes shift (140 nm), which was triggered by the Michael addition reaction of thiols toward the C=C double bond of the maleimide group. Moreover, this probe IPY-MAL could quantitatively detect the concentrations of thiols ranging from 0 to 50 μM, and the detection limit was found to be as low as 28 nM. Cell imaging results indicated that the probe IPY-MAL could detect and visualize thiols in the living cells.

    更新日期:2018-06-28
  • Selective detection of copper ion in complex real samples based on nitrogen-doped carbon quantum dots
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-04-30
    Li Zhao, Huiyu Li, Yuan Xu, Haochi Liu, Tianyu Zhou, Ning Huang, Yi Li, Lan Ding

    Highly selective nitrogen-doped carbon quantum dots (ND-CQDs) for copper ion (Cu2+) determination were synthesized by a solvent-free pyrolysis of citric acid and histidine. The resultant ND-CQDs display a stable bright blue fluorescence with a satisfactory product yield of 56% and quantum yield of 16%. The ND-CQDs not only show good photostability under continuous UV irradiation, but are also dramatically stable against extreme ionic strengths. The solid powders of the ND-CQDs re-dispersed in water still maintain a strong blue fluorescence after storing at room temperature for 6 months. The ND-CQDs can be employed to selectively detect Cu2+ in a wide linear range of 0.6–30 μM. The detection limit is as low as 0.19 μM. The ND-CQDs were applied for Cu2+ detection in environmental water samples, fruit juice samples, and urine sample. Satisfactory recoveries of 96–102% with relative standard deviations below 3% were obtained. The research provided a promising prospect for selective detection of Cu2+ in the complex matrix.

    更新日期:2018-06-28
  • Nanospray desorption electrospray ionization mass spectrometry of untreated and treated probiotic Lactobacillus reuteri cells
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-04-28
    Agbo-Oma Uwakweh, Joseph N. Mwangi, Daniel Todd, Zhenquan Jia, Norman H. L. Chiu

    Mass spectrometry has proven to be a useful technique for rapid identification of bacterial cells. Among various ionization techniques in mass spectrometry, matrix-assisted laser desorption/ionization (MALDI) has been commonly used for the identification of bacterial cells. Recently, MALDI mass spectrometry has also been utilized to distinguish cellular responses. Ambient ionization techniques do support whole bacterial cell analysis, which include desorption electrospray ionization (DESI). Nanospray DESI (nDESI) is a new variant of DESI, and its application to whole-cell mass spectrometry is limited. In this project, the use of nDESI mass spectrometry to measure probiotic Lactobacillus reuteri (LR) cells is explored. A unique and reproducible mass spectral pattern of untreated LR cells was obtained by using 50% methanol/water as nDESI solvent. The use of nDESI mass spectrometry is further extended to distinguish untreated LR cells from treated LR cells that have been exposed to low pH. These findings demonstrate the feasibility of using nDESI in whole-cell mass spectrometry.

    更新日期:2018-06-28
  • Correction to: Precise, accurate and user-independent blood collection system for dried blood spot sample preparation
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-04-30
    Ricardo Neto, Andrew Gooley, Michael C. Breadmore, Emily F. Hilder, Florian Lapierre

    The authors would like to call the reader’s attention to the following: The instrument they used to measure the volumetric precision of the dispensing devices is not called “VMS” but “PCS®”.

    更新日期:2018-06-20
  • Online screening of α-amylase inhibitors by capillary electrophoresis
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-04-20
    Ondřej Hodek, Tomáš Křížek, Pavel Coufal, Helena Ryšlavá

    Pancreatic α-amylase plays an important role in dietary starch hydrolysis in the small intestine and participates in enhanced glucose concentration after meals. It seems to be a problem for diabetic patients, who suffer from longer postprandial hyperglycemia after meal consumption than healthy people. There are commercially available drugs that inhibit α-amylase and thus reduce the postprandial hyperglycemia effect. However, these drugs may cause severe side effects. Conversely, some naturally occurring flavonoids were suggested to have an α-amylase-inhibiting effect without any side effects. There had been no rapid, undemanding method in terms of sample and reagent preparation that would enable screening of many potential inhibitors. Therefore, we developed an online capillary electrophoresis method to monitor α-amylase activity in the presence of an inhibitor. Each reaction constituent was introduced separately, directly into a capillary where the reagents were mixed by diffusion, which resulted in a 5-min analysis including conditioning of the capillary. We applied the method to test the inhibitory effect of flavonoid standards and their mixture and we investigated the inhibitory effect of ethanolic extract from Betula pendula bark. The developed method presents a faster and less expensive alternative to previously described offline methods.

    更新日期:2018-06-20
  • Novel and label-free colorimetric detection of radon using AuNPs and lead(II)-induced GR5 DNAzyme-based amplification strategy
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-04-23
    Hongwen Liu, Yating Chen, Chunli Song, Gang Tian, Shiya Li, Guiying Yang, Changyin Lv

    Radioactive radon decays into a stable daughter product, 210Pb, which was used as the detection target to determine the radon radiation dose in a new technique. Pb2+ triggers DNAzyme to cleave a molecular beacon (MB), resulting in the stem–loop structure opening and forming two single DNA strands (ssDNA). The ssDNA binds to unmodified gold nanoparticles and effectively prevents their aggregation in a salt solution. The detached enzyme strands continue to complement the remaining MB to amplify the response signal. The method proposed in this study exhibited a good linear relationship for Pb2+ and radon concentrations in the range of 6.22 × 102–1.02 × 105 Bq h/m3 with a detection limit of 186.48 Bq h/m3 using an ultraviolet–visible spectrometer. In practical applications, this sensitive method can avoid radioactive damage in field testing, and the detection limit meets the national standard in China. Importantly, this simple, highly sensitive strategy uses simple equipment and has a strong anti-interference ability.

    更新日期:2018-06-20
  • Rapid detection of the neonicotinoid insecticide imidacloprid using a quenchbody assay
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-04-28
    Shitao Zhao, Jinhua Dong, Hee-Jin Jeong, Koichi Okumura, Hiroshi Ueda

    Contamination of the land and water by neonicotinoid insecticide residues is currently a severe environmental problem. However, the traditional methods for pesticide residue analysis are time consuming and laborious. To tackle this problem, here we describe a novel quenchbody (Q-body) immunoassay reagent that allows the rapid and sensitive detection of imidacloprid, one of the most frequently used neonicotinoid pesticides, in aqueous solution. A Q-body comprises an antibody Fab fragment that is site-specifically labeled with a fluorescent dye. The Fab fragment quenches the dye with its internal tryptophan residues via photoinduced electron transfer. The subsequent addition of imidacloprid stabilizes the antibody structure and displaces the quenched dye to the outside of the protein, resulting in increased fluorescence. The constructed Q-body assay exhibited a high dynamic range and a low limit of detection (10 ng mL−1), and the entire assay procedure could be completed in a few minutes. The assay showed a low cross-reactivity with possible interfering analogous compounds, indicating that it has a good selectivity. Hence, the developed Q-body assay has excellent potential as a universal technology for monitoring neonicotinoid residues in environmental and food samples.

    更新日期:2018-06-20
  • Preconcentration of DNA using magnetic ionic liquids that are compatible with real-time PCR for rapid nucleic acid quantification
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-04-28
    Miranda N. Emaus, Kevin D. Clark, Paige Hinners, Jared L. Anderson

    Nucleic acid extraction and purification represents a major bottleneck in DNA analysis. Traditional methods for DNA purification often require reagents that may inhibit quantitative polymerase chain reaction (qPCR) if not sufficiently removed from the sample. Approaches that employ magnetic beads may exhibit lower extraction efficiencies due to sedimentation and aggregation. In this study, four hydrophobic magnetic ionic liquids (MILs) were investigated as DNA extraction solvents with the goal of improving DNA enrichment factors and compatibility with downstream bioanalytical techniques. By designing custom qPCR buffers, we directly incorporated DNA-enriched MILs including trihexyl(tetradecyl)phosphonium tris(hexafluoroacetylaceto)nickelate(II) ([P6,6,6,14+][Ni(hfacac)3−]), [P6,6,6,14+] tris(hexafluoroacetylaceto)colbaltate(II) ([Co(hfacac)3−]), [P6,6,6,14+] tris(hexafluoroacetylaceto)manganate(II) ([Mn(hfacac)3−]), or [P6,6,6,14+] tetrakis(hexafluoroacetylaceto)dysprosate(III) ([Dy(hfacac)4−]) into reaction systems, thereby circumventing the need for time-consuming DNA recovery steps. Incorporating MILs into the reaction buffer did not significantly impact the amplification efficiency of the reaction (91.1%). High enrichment factors were achieved using the [P6,6,6,14+][Ni(hfacac)3−] MIL for the extraction of single-stranded and double-stranded DNA with extraction times as short as 2 min. When compared to a commercial magnetic bead-based platform, the [P6,6,6,14+][Ni(hfacac)3−] MIL was capable of producing higher enrichment factors for single-stranded DNA and similar enrichment factors for double-stranded DNA. The MIL-based method was applied for the extraction and direct qPCR amplification of mutation prone-KRAS oncogene fragment in plasma samples.

    更新日期:2018-06-20
  • Development of an online SPE-UHPLC-MS/MS method for the multiresidue analysis of the 17 compounds from the EU “Watch list”
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-04-24
    Lucia Gusmaroli, Sara Insa, Mira Petrovic

    During the last decades, the quality of aquatic ecosystems has been threatened by increasing levels of pollutions, caused by the discharge of man-made chemicals, both via accidental release of pollutants as well as a consequence of the constant outflow of inadequately treated wastewater effluents. For this reason, the European Union is updating its legislations with the aim of limiting the release of emerging contaminants. The Commission Implementing Decision (EU) 2015/495 published in March 2015 drafts a “Watch list” of compounds to be monitored Europe-wide. In this study, a methodology based on online solid-phase extraction (SPE) ultra-high-performance liquid chromatography coupled to a triple-quadrupole mass spectrometer (UHPLC-MS/MS) was developed for the simultaneous determination of the 17 compounds listed therein. The proposed method offers advantages over already available methods, such as versatility (all 17 compounds can be analyzed simultaneously), shorter time required for analysis, robustness, and sensitivity. The employment of online sample preparation minimized sample manipulation and reduced dramatically the sample volume needed and time required, dramatically the sample volume needed and time required, thus making the analysis fast and reliable. The method was successfully validated in surface water and influent and effluent wastewater. Limits of detection ranged from sub- to low-nanogram per liter levels, in compliance with the EU limits, with the only exception of EE2.

    更新日期:2018-06-20
  • Critical assessment of digital PCR for the detection and quantification of genetically modified organisms
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-03-24
    Tigst Demeke, David Dobnik

    The number of genetically modified organisms (GMOs) on the market is steadily increasing. Because of regulation of cultivation and trade of GMOs in several countries, there is pressure for their accurate detection and quantification. Today, DNA-based approaches are more popular for this purpose than protein-based methods, and real-time quantitative PCR (qPCR) is still the gold standard in GMO analytics. However, digital PCR (dPCR) offers several advantages over qPCR, making this new technique appealing also for GMO analysis. This critical review focuses on the use of dPCR for the purpose of GMO quantification and addresses parameters which are important for achieving accurate and reliable results, such as the quality and purity of DNA and reaction optimization. Three critical factors are explored and discussed in more depth: correct classification of partitions as positive, correctly determined partition volume, and dilution factor. This review could serve as a guide for all laboratories implementing dPCR. Most of the parameters discussed are applicable to fields other than purely GMO testing.

    更新日期:2018-06-20
  • Ambient desorption/ionization mass spectrometry: evolution from rapid qualitative screening to accurate quantification tool
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-04-21
    Jacob T. Shelley, Sunil P. Badal, Carsten Engelhard, Heiko Hayen

    In this article, some recent trends and developments in ambient desorption/ionization mass spectrometry (ADI-MS) are reviewed, with a special focus on quantitative analyses with direct, open-air sampling. Accurate quantification with ADI-MS is still not routinely performed, but this aspect is considered of utmost importance for the advancement of the field. In fact, several research groups are devoted to the development of novel and optimized ADI-MS approaches. Some key trends include novel sample introduction strategies for improved reproducibility, tailored sample preparation protocols for removing the matrix and matrix effects, and multimode ionization sources. In addition, there is significant interest in quantitative mass spectrometry imaging.

    更新日期:2018-06-20
  • Metrology for stable isotope reference materials: 13 C/ 12 C and 18 O/ 16 O isotope ratio value assignment of pure carbon dioxide gas samples on the Vienna PeeDee Belemnite-CO 2 scale using dual-inlet mass spectrometry
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-05-25
    Abneesh Srivastava, R. Michael Verkouteren

    Isotope ratio measurements have been conducted on a series of isotopically distinct pure CO2 gas samples using the technique of dual-inlet isotope ratio mass spectrometry (DI-IRMS). The influence of instrumental parameters, data normalization schemes on the metrological traceability and uncertainty of the sample isotope composition have been characterized. Traceability to the Vienna PeeDee Belemnite(VPDB)-CO2 scale was realized using the pure CO2 isotope reference materials(IRMs) 8562, 8563, and 8564. The uncertainty analyses include contributions associated with the values of iRMs and the repeatability and reproducibility of our measurements. Our DI-IRMS measurement system is demonstrated to have high long-term stability, approaching a precision of 0.001 parts-per-thousand for the 45/44 and 46/44 ion signal ratios. The single- and two-point normalization bias for the iRMs were found to be within their published standard uncertainty values. The values of 13C/12C and 18O/16O isotope ratios are expressed relative to VPDB-CO2 using the \( {\delta}^{13}{C}_{VPDB-{CO}_2} \) and \( {\delta}^{18}{O}_{VPDB-{CO}_2} \) notation, respectively, in parts-per-thousand (‰ or per mil). For the samples, value assignments between (−25 to +2) ‰ and (−33 to −1) ‰ with nominal combined standard uncertainties of (0.05, 0.3) ‰ for \( {\delta}^{13}{C}_{VPDB-{CO}_2} \) and \( {\delta}^{18}{O}_{VPDB-{CO}_2} \), respectively were obtained. These samples are used as laboratory reference to provide anchor points for value assignment of isotope ratios (with VPDB traceability) to pure CO2 samples. Additionally, they serve as potential parent isotopic source material required for the development of gravimetric based iRMs of CO2 in CO2-free dry air in high pressure gas cylinder packages at desired abundance levels and isotopic composition values.

    更新日期:2018-06-20
  • A molecularly imprinted sensor with enzymatic enhancement of electrochemiluminescence of quantum dots for ultratrace clopyralid determination
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-06-19
    Qingyu Wang, Shuhuai Li, Jianping Li

    A new molecularly imprinted polymer electrochemiluminescence (ECL) sensor was developed for the detection of clopyralid (CPD) based on enzyme-biocatalyzed amplification. CdTe quantum dots were immobilized on the surface of an electrode by reaction with p-aminothiophenol preadsorbed on the electrode. Then a molecularly imprinted film was formed by electrochemical polymerization of o-phenylenediamine in the presence of CPD on the CdTe-modified gold electrode. During the analytical cycle, horseradish peroxidase (HRP)-labeled CPD was replaced by CPD in the sample. The amount of HRP on the molecularly imprinted polymer electrode decreased, and then less H2O2 was catalytically decomposed. Subsequently, the ECL intensity of the CdTe–H2O2 system was enhanced. There was a good linear relationship between ECL intensity and the concentration of CPD in the range from 2.0 × 10-11 to 2.5 × 10-10 mol/L and in the range from 2.5 × 10-10 to 3.5 × 10-8 mol/L. The detection limit was 4.1 × 10-12 mol/L. The sensor was applied to determine CPD in vegetable samples.

    更新日期:2018-06-19
  • Search of non-ionic surfactants suitable for micellar liquid chromatography
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-06-19
    Ester Peris-García, Jorge Rodríguez-Martínez, Juan J. Baeza-Baeza, María Celia García-Alvarez-Coque, María José Ruiz-Angel

    Most reports in reversed-phase liquid chromatography (RPLC) with micellar mobile phases make use of the anionic sodium dodecyl sulfate. This surfactant masks efficiently the silanol groups that are the origin of the poor efficiencies and tailing peaks observed for basic compounds in conventional RPLC. However, it has the handicap of yielding excessive retention, which forces the addition of an organic solvent to reduce the retention times to practical values. Other surfactants, such as the non-ionic polyoxyethylene(23)lauryl ether (Brij-35), are rarely used. Brij-35 allows the separation of a large range of analytes in adequate retention times, without the need of adding an organic solvent to the mobile phase. However, this non-ionic surfactant shows irreversible adsorption on chromatographic columns and peak shape is poorer. Therefore, the search of non-ionic surfactants with similar properties to Brij-35, but showing reversible adsorption and better peak shape, can be of great interest. In this work, the adequacy of several non-ionic surfactants as modifiers in RPLC has been explored, being polyoxyethylene(10)tridecyl ether particularly attractive. The separation of different types of compounds was checked: sulfonamides (acidic), β-adrenoceptor antagonists and tricyclic antidepressants (basic with diverse polarity), and flavonoids (with and without hydroxyl groups on the aromatic rings). The chromatographic behaviors were examined in terms of retention and peak shape. The results were compared with those obtained with Brij-35.

    更新日期:2018-06-19
  • Cross-reactivity by botanicals used in dietary supplements and spices using the multiplex xMAP food allergen detection assay (xMAP FADA)
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-06-18
    Ronnie O. Pedersen, William L. Nowatzke, Chung Y. Cho, Kerry G. Oliver, Eric A. E. Garber

    Food allergies affect some 15 million Americans. The only treatment for food allergies is a strict avoidance diet. To help ensure the reliability of food labels, analytical methods are employed; the most common being enzyme-linked immunosorbent assays (ELISAs). However, the commonly employed ELISAs are single analyte-specific and cannot distinguish between false positives due to cross-reactive homologous proteins; making the method of questionable utility for regulatory purposes when analyzing for unknown or multiple food allergens. Also, should the need arise to detect additional analytes, extensive research must be undertaken to develop new ELISAs. To address these and other limitations, a multiplex immunoassay, the xMAP® food allergen detection assay (xMAP FADA), was developed using 30 different antibodies against 14 different food allergens plus gluten. Besides incorporating two antibodies for the detection of most analytes, the xMAP FADA also relies on two different extraction protocols; providing multiple confirmatory end-points. Using the xMAP FADA, the cross-reactivities of 45 botanicals used in dietary supplements and spices commercially sold in the USA were assessed. Only a few displayed cross-reactivities with the antibodies in the xMAP FADA at levels exceeding 0.0001%. The utility of the xMAP FADA was exemplified by its ability to detect and distinguish between betel nut, saw palmetto, and acai which are in the same family as coconut. Other botanicals examined included allspice, amchur, anise seed, black pepper, caraway seed, cardamom, cayenne red pepper, sesame seed, poppy seed, white pepper, and wheat grass. The combination of direct antibody detection, multi-antibody profiling, high sensitivity, and a modular design made it possible for the xMAP FADA to distinguish between homologous antigens, provide multiple levels of built-in confirmatory analysis, and optimize the bead set cocktail to address specific needs.

    更新日期:2018-06-18
  • Electrochemical nonenzymatic sensor for cholesterol determination in food
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-06-16
    Ksenia Derina, Elena Korotkova, Yekaterina Taishibekova, Lyazat Salkeeva, Bohumil Kratochvil, Jiri Barek

    The treatment of some inborn metabolism errors requires cholesterol substitution therapy. Cholesterol plays a vital role in the human body. Therefore, the majority of cholesterol determination techniques are targeted to blood and blood serum. Nevertheless, cholesterol determination in food is important as well. In this paper, cholesterol determination using differential pulse voltammetry (DPV) in dairy products (e.g., milk, clotted cream, yogurt, butter, etc.) is reported with a novel nonenzymatic sensor based on diphosphonic acid of 1,4-diacetylglycoluril (DPADGU) as an electrode surface modifier. Stable anodic response was obtained from cholesterol on the modified carbon-based electrode. The sensor has high stability, sensitivity (20 μA mol L−1 cm−2), and a wide linear range from 1 up to 200 μM. The LOD and LOQ values are 1.5 and 5.1 μM, respectively. The developed methods were successfully applied to the above mentioned dairy products.

    更新日期:2018-06-16
  • What about the herb? A new metabolomics approach for synthetic cannabinoid drug testing
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-06-16
    Lubertus Bijlsma, Rubén Gil-Solsona, Félix Hernández, Juan Vicente Sancho

    Synthetic cannabinoids (SCs) are consumed as legal alternative to cannabis and often allow passing drug-screening tests. Their rapid transience on the drug scene, combined with their mostly unknown metabolic profiles, creates a scenario with constantly moving analytical targets, making their monitoring and identification challenging. The development of fast screening strategies for SCs, not directly focused on their chemical structure, as an alternative to the commonly applied target acquisition methods, would be highly appreciated in forensic and public health laboratories. An innovative untargeted metabolomics approach, focused on herbal components commonly used for ‘spice’ products, was applied. Saliva samples of healthy volunteers were collected at pre-dose and after smoking herbal components and analysed by high-resolution mass spectrometry. The data obtained, combined with appropriate statistical analysis, allowed to highlight and elucidate two markers (scopoletin and N,N-bis(2-hydroxyethyl)dodecylamine), which ratio permitted to differentiate herbal smokers from non-smokers. The proposed strategy will allow discriminating potential positives, on the basis of the analysis of two markers identified in the herbal blends. This work is presented as a step forward in SC drug testing, promoting a smart first-line screening approach, which will allow reducing the number of samples to be further investigated by more sophisticated HRMS methods.

    更新日期:2018-06-16
  • Construction of a thermoresponsive magnetic porous polymer membrane enzyme reactor for glutaminase kinetics study
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-06-16
    Liping Zhao, Juan Qiao, Meyong Hee Moon, Li Qi

    Fabrication of polymer membranes with nanopores and a confinement effect toward enzyme immobilization has been an enabling endeavor. In the work reported here, an enzyme reactor based on a thermoresponsive magnetic porous block copolymer membrane was designed and constructed. Reversible addition–fragmentation chain transfer polymerization was used to synthesize the block copolymer, poly(maleic anhydride–styrene–N-isopropylacrylamide), with poly(N-isopropylacrylamide) as the thermoresponsive moiety. The self-assembly property of the block copolymer was used for preparation of magnetic porous thin film matrices with iron oxide nanoparticles. By covalent bonding of glutaminase onto the surface of the membrane matrices and changing the temperature to tune the nanopore size, we observed enhanced enzymolysis efficiency due to the confinement effect. The apparent Michaelis–Menten constant and the maximum rate of the enzyme reactor were determined (Km = 32.3 mM, Vmax = 33.3 mM min−1) by a chiral ligand exchange capillary electrochromatography protocol with l-glutamine as the substrate. Compared with free glutaminase in solution, the proposed enzyme reactor exhibits higher enzymolysis efficiency, greater stability, and greater reusability. Furthermore, the enzyme reactor was applied for a glutaminase kinetics study. The tailored pore sizes and the thermoresponsive property of the block copolymer result in the designed porous membrane based enzyme reactor having great potential for high enzymolysis performance.

    更新日期:2018-06-16
  • In vivo tumor imaging by a γ-glutamyl transpeptidase-activatable near-infrared fluorescent probe
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-06-16
    Lihong Li, Wen Shi, Xiaofeng Wu, Xiaohua Li, Huimin Ma

    γ-Glutamyl transpeptidase (GGT), overexpressed in various cancer cells, has been perceived as a latent tumor biomarker. Thus, developing near-infrared (NIR) fluorescent GGT probes is highly desired for in vivo tumor imaging and studies. To our knowledge, however, such a GGT probe is still rare. Herein, we construct a new GGT-activatable NIR fluorescent probe HCAGlu by incorporating γ-glutamyl group as a recognition unit directly into a NIR hemicyanine fluorophore. HCAGlu exhibits a highly sensitive and selective NIR fluorescence off-on response to GGT. The probe has been applied to cell and histological section imaging, which demonstrates the ability of HCAGlu in distinguishing different GGT-expression levels in situ in biological samples. Notably, in vivo fluorescence imaging in tumor-bearing mice has been performed, verifying that probe HCAGlu can rapidly produce a distinct fluorescence signal in the tumor site via both intravenous and intratumoral injections. The simplicity and excellent performance of HCAGlu make it of high potential in studying the physiological function of GGT in vivo.

    更新日期:2018-06-16
  • Strain-level typing and identification of bacteria – a novel approach for SERS active plasmonic nanostructures
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-06-16
    Evelin Witkowska, Dorota Korsak, Aneta Kowalska, Anna Janeczek, Agnieszka Kamińska

    One of the potential applications of surface-enhanced Raman spectroscopy (SERS) is the detection of biological compounds and microorganisms. Here we demonstrate that SERS coupled with principal component analysis (PCA) serves as a perfect method for determining the taxonomic affiliation of bacteria at the strain level. We demonstrate for the first time that it is possible to distinguish different genoserogroups within a single species, Listeria monocytogenes, which is one of the most virulent foodborne pathogens and in some cases contact with which may be fatal. We also postulate that it is possible to detect additional proteins in the L. monocytogenes cell envelope, which provide resistance to benzalkonium chloride and cadmium. A better understanding of this infectious agent could help in selecting the appropriate pharmaceutical product for enhanced treatment.

    更新日期:2018-06-16
  • Comparison of μ-ATR-FTIR spectroscopy and py-GCMS as identification tools for microplastic particles and fibers isolated from river sediments
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-06-16
    Andrea Käppler, Marten Fischer, Barbara M. Scholz-Böttcher, Sonja Oberbeckmann, Matthias Labrenz, Dieter Fischer, Klaus-Jochen Eichhorn, Brigitte Voit

    In recent years, many studies on the analysis of microplastics (MP) in environmental samples have been published. These studies are hardly comparable due to different sampling, sample preparation, as well as identification and quantification techniques. Here, MP identification is one of the crucial pitfalls. Visual identification approaches using morphological criteria alone often lead to significant errors, being especially true for MP fibers. Reliable, chemical structure-based identification methods are indispensable. In this context, the frequently used vibrational spectroscopic techniques but also thermoanalytical methods are established. However, no critical comparison of these fundamentally different approaches has ever been carried out with regard to analyzing MP in environmental samples. In this blind study, we investigated 27 single MP particles and fibers of unknown material isolated from river sediments. Successively micro-attenuated total reflection Fourier transform infrared spectroscopy (μ-ATR-FTIR) and pyrolysis gas chromatography-mass spectrometry (py-GCMS) in combination with thermochemolysis were applied. Both methods differentiated between plastic vs. non-plastic in the same way in 26 cases, with 19 particles and fibers (22 after re-evaluation) identified as the same polymer type. To illustrate the different approaches and emphasize the complementarity of their information content, we exemplarily provide a detailed comparison of four particles and three fibers and a critical discussion of advantages and disadvantages of both methods.

    更新日期:2018-06-16
  • Analysis of human C24 bile acids metabolome in serum and urine based on enzyme digestion of conjugated bile acids and LC-MS determination of unconjugated bile acids
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-06-16
    Pingping Zhu, Jian Zhang, Yujie Chen, Shanshan Yin, Mingming Su, Guoxiang Xie, Kim L. R. Brouwer, Changxiao Liu, Ke Lan, Wei Jia

    Host-gut microbiota metabolic interactions are closely associated with health and disease. A manifestation of such co-metabolism is the vast structural diversity of bile acids (BAs) involving both oxidative stereochemistry and conjugation. Herein, we describe the development and validation of a LC-MS-based method for the analysis of human C24 BA metabolome in serum and urine. The method has high throughput covering the discrimination of oxidative stereochemistry of unconjugated species in a 15-min analytical cycle. The validated quantitative performance provided an indirect way to ascertain the conjugation patterns of BAs via enzyme-digestion protocols that incorporated the enzymes, sulfatase, β-glucuronidase, and choloylglycine hydrolase. Application of the method has led to the detection of at least 70 unconjugated BAs including 27 known species and 43 newly found species in the post-prandial serum and urine samples from 7 nonalcoholic steatohepatitis patients and 13 healthy volunteers. Newly identified unconjugated BAs included 3α, 12β-dihydroxy-5β-cholan-24-oic acid, 12α-hydroxy-3-oxo-5β-cholan-24-oic acid, and 3α, 7α, 12β-trihydroxy-5β-cholan-24-oic acid. High-definition negative fragment spectra of the other major unknown species were acquired to facilitate future identification endeavors. An extensive conjugation pattern is the major reason for the “invisibility” of the newly found BAs to other common analytical methods. Metabolomic analysis of the total unconjugated BA profile in combination with analysis of their conjugation patterns and urinary excretion tendencies have provided substantial insights into the interconnected roles of host and gut microbiota in maintaining BA homeostasis. It was proposed that the urinary total BA profile may serve as an ideal footprint for the functional status of the host-gut microbial BA co-metabolism. In summary, this work provided a powerful tool for human C24 BA metabolome analysis that bridges the gap between GC-MS techniques in the past age and LC-MS techniques currently prevailing in biomedical researches. Further applications of the present method in clinical, translational research, and other biomedical explorations will continue to boost the construction of a host-gut microbial co-metabolism network of BAs and thus facilitate the decryption of BA-mediated host-gut microbiota crosstalk in health and diseases.

    更新日期:2018-06-16
  • Elucidation of chromatographic peak shifts in complex samples using a chemometrical approach
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-06-14
    Pedro F. M. Sousa, Angela de Waard, K. Magnus Åberg

    Chromatographic retention time peak shifts between consecutive analyses is a well-known fact yet not fully understood. Algorithms have been developed to align peaks between runs, but with no specific studies considering the causes of peak shifts. Here, designed experiments reveal chromatographic shift patterns for a complex peptide mixture that are attributable to the temperature and pH of the mobile phase. These results demonstrate that peak shifts are highly structured and are to a high degree explained by underlying differences in physico-chemical parameters of the chromatographic system and also provide experimental support for the alignment algorithm called the generalized fuzzy Hough transform which exploits this fact. It can be expected that the development of alignment algorithms enters a new phase resulting in increasingly accurate alignment by considering the latent structure of the peak shifts.

    更新日期:2018-06-14
  • Toward continuous amperometric gas sensing in ionic liquids: rationalization of signal drift nature and calibration methods
    Anal. Bioanal. Chem. (IF 3.307) Pub Date : 2018-06-13
    Lu Lin, Xiangqun Zeng

    Sensor signal drift is the key issue for the reliability of continuous gas sensors. In this paper, we characterized the sensing signal drift of an amperometric ionic liquid (IL)-based oxygen sensor to identify the key chemical parameters that contribute to the signal drift. The signal drifts due to the sensing reactions of the analyte oxygen at the electrode/electrolyte interface at a fixed potential and the mass transport of the reactant and product at the electrode/electrolyte interface were systematically studied. Results show that the analyte concentration variation and the platinum electrode surface activity are major factors contributing to sensing signal drift. An amperometric method with a double potential step incorporating a conditioning step was tested and demonstrated to be useful in reducing the sensing signal drift and extending the sensor operation lifetime. Also, a mathematic method was tested to calibrate the baseline drift and sensing signal sensitivity change for continuous sensing. This study provides the understanding of the chemical processes that contribute to the IL electrochemical gas (IL-EG) sensor signal stability and demonstrates some effective strategies for signal drift calibration that can increase the reliability of the continuous amperometric sensing.

    更新日期:2018-06-13
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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