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  • Chiral magnetic-nanobiofluids for rapid electrochemical screening of enantiomers at a magneto nanocomposite graphene-paste electrode
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-12
    J. Muñoz, A. González-Campo, M. Riba-Moliner, M. Baeza, M. Mas-Torrent

    The development of highly sensitive and selective enantiomeric platforms towards the rapid screening of active pharmaceutical ingredients (APIs) is nowadays a crucial challenge in several fields related to pharmacology, biomedicine, biotechnology and (bio)sensors. Herein, it is presented a novel, facile and generic methodology focused on exploiting the synergistically and electrocatalytic properties of chiral magnetic-nanobiofluids (mNBFs) with electrochemical enantiobiosensing at a magneto nanocomposite graphene paste electrode (mNC–GPE). The feasibility of this approach has been validated by chirally recognizing tryptophan (TRP) enantiomers as a proof-of-concept. For this aim, a specific chiral mNBF based on an aqueous dispersion of cobalt ferrite loaded with gold nanoparticles carrying a thiolated β-cyclodextrin (β–CD-SH/Au/CoFe2O4–NPs) has been synthesized and used towards the supramolecular discrimination of TRP enantiomers at an advanced graphene-paste transducer via cyclic voltammetry. This strategy, which is the first demonstration of applicability of chiral mNBFs for electrochemical enantiorecognition, opens up new approaches into enantio(bio)sensing.

    更新日期:2018-01-12
  • Ultrasensitive microfluidic paper-based electrochemical/visual biosensor based on spherical-like cerium dioxide catalyst for miR-21 detection
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-12
    Xiaolu Sun, He Wang, Yannan Jian, Feifei Lan, Lina Zhang, Haiyun Liu, Shenguang Ge, Jinghua Yu

    In this work, an electrochemical biosensor based on Au nanorods (NRs) modified microfluidic paper-based analytical devices (μPADs) were constructed for sensitive detection of microRNA (miRNA) by using cerium dioxide - Au@glucose oxidase (CeO2-Au@GOx) as an electrochemical probe for signal amplification. Au NRs were synthesized by in-situ growth method in μPADs surface to enhance the conductivity and modified hairpin probe through Au-S bonds. The construction of “the signal transducer layer” was carried out by GOx catalyzing glucose to produce H2O2, which was further electrocatalyzed by CeO2. After the biosensor was constructed, an obvious electrochemical signal was observed from the reduction of H2O2. In order to make the detection more convincing, the visual detection was performed based on the oxidation of 3,3',5,5'-tetramethylbenzidine by H2O2 with the help of Exonuclease I. The electrochemical biosensor provided a wide linear range of 1.0 fM to 1000 fM with a relatively low detection limit of 0.434 fM by the electrochemical measurement. Linear range of 10 fM to 1000 fM with a relatively low detection limit of 7.382 fM was obtained by visual detection. The results indicated the proposed platform has potential utility for detection of miRNA.

    更新日期:2018-01-12
  • Caco-2 cell-based electrochemical biosensor for evaluating the antioxidant capacity of Asp-Leu-Glu-Glu isolated from dry-cured Xuanwei ham
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-12
    Lujuan Xing, Qingfeng Ge, Donglei Jiang, Xiaoge Gao, Rui Liu, Songmin Cao, Xinbo Zhuang, Guanghong Zhou, Wangang Zhang

    A cell-based electrochemical biosensor was developed to determine the antioxidant activity of Asp-Leu-Glu-Glu (DLEE) isolated from dry-cured Chinese Xuanwei ham. A platinized gold electrode (Pt NPs/GE) covered with silver nanowires (Ag NWs) was fabricated to detect H2O2 using redox signaling via cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Under optimal condition, the detection limit of the modified electrode was 0.12 μM with a linear relationship from 0.2~2 μM, which showed relatively outstanding catalytic effects towards the reduction of H2O2. Furthermore, the generation of reactive oxygen species (ROS) in the cell can be used to indirectly assess changes in intercellular oxidative stress by detecting variations in electrochemical signals. A 3D cell culture of alginate/graphene oxide (NaAlg/GO) was used to encapsulate and immobilize Caco-2 cells. Based on ROS generation and electrochemical results, we found that DLEE could effectively reduce oxidative stress level in Caco-2 cells under external stimulation. DLEE showed high antioxidant activity with a relative antioxidant capacity (RAC) rate of 88.17% at 1.5 mg/mL. Finally, an efficient electrochemical biosensor was established using the active 3D Caco-2 cell platform. This system is sensitive and simple to operate with the property to evaluate the antioxidant activity of peptides by the detection of H2O2 in cell membrane. In summary, this work describes a new method for assessing antioxidant capacity of peptide DLEE using cell-based electrochemical signaling with a rapid screening pattern.

    更新日期:2018-01-12
  • Fabrication of Sensitive Bioelectrode Based on Atomically Thin CVD Grown Graphene for Cancer Biomarker Detection
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-12
    Vijay K. Singh, Saurabh Kumar, Sumit Kumar Pandey, Saurabh Srivastava, Monu Mishra, Govind Gupta, B.D. Malhotra, R.S. Tiwari, Anchal Srivastava
    更新日期:2018-01-12
  • The field effect transistor DNA biosensor based on ITO nanowires in label-free hepatitis B virus detecting compatible with CMOS technology
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-11
    Mohsen Shariati

    In this paper the field-effect transistor DNA biosensor for detecting hepatitis B virus (HBV) based on indium tin oxide nanowires (ITO NWs) in label free approach has been fabricated. Because of ITO nanowires intensive conductance and functional modified surface, the probe immobilization and target hybridization were increased strongly. The high resolution transmission electron microscopy (HRTEM) measurement showed that ITO nanowires were crystalline and less than 50 nm in diameter. The single-stranded hepatitis B virus DNA (SS-DNA) was immobilized as probe on the Au-modified nanowires. The DNA targets were measured in a linear concentration range from 1fM to 10 µM. The detection limit of the DNA biosensor was about 1fM. The time of the hybridization process for defined single strand was 90 min. The switching ratio of the biosensor between "on" and "off" state was ~ 1.1×105. For sensing the specificity of the biosensor, non-complementary, mismatch and complementary DNA oligonucleotide sequences were clearly discriminated. The HBV biosensor confirmed the highly satisfied specificity for differentiating complementary sequences from non-complementary and the mismatch oligonucleotides. The response time of the DNA sensor was 37 sec with a high reproducibility. The stability and repeatability of the DNA biosensor showed that the peak current of the biosensor retained 98% and 96% of its initial response for measurements after three and five weeks, respectively.

    更新日期:2018-01-12
  • Biosensors for rapid and sensitive detection of Staphylococcus aureus in food
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-11
    Momna Rubab, Hafiz Muhammad Shahbaz, Amin N. Olaimat, Deog-Hwan Oh

    Foodborne illness outbreaks caused by the consumption of food contaminated with harmful bacteria has drastically increased in the past decades. Therefore, detection of harmful bacteria in the food has become an important factor for the recognition and prevention of problems associated with food safety and public health. Staphylococcus aureus is one of the most commonly isolated foodborne pathogen and it is considered as a major cause of foodborne illnesses worldwide. A number of different methods have been developed for the detection and identification of S. aureus in food samples. However, some of these methods are laborious and time-consuming and are not suitable for on-site applications. Therefore, it is highly important to develop rapid and more approachable detection methods. In the last decade, biosensors have gained popularity as an attractive alternative method and now considered as one of most rapid and on-site applicable methods. An overview of the biosensor based methods used for the detection of S. aureus is presented herein. This review focuses on the state-of-the-art biosensor methods towards the detection and quantification of S. aureus, and discusses the most commonly used biosensor methods based on the transducing mode, such as electrochemical, optical, and mass-based biosensors.

    更新日期:2018-01-11
  • One-pot synthesis of the CuNCs/ZIF-8 nanocomposites for sensitively detecting H2O2 and screening of oxidase activity
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-10
    Xue Hu, Xidong Liu, Xiaodan Zhang, Hongxiang Chai, Yuming Huang

    The fluorescent CuNCs/ZIF-8 nanocomposites were facilely prepared by mixing the PEI protected CuNCs with the precursors of ZIF-8, and characterized by UV-vis absorption, fluorescence, FT-IR, TEM, XRD and XPS. The quantum yield of the CuNCs/ZIF-8 is 15 times that of the PEI-CuNCs. Furthermore, the CuNCs/ZIF-8 possesses better stability and higher fluorescence response due to protective and confinement effects of MOFs. It was found that H2O2 could cause much more quenching of fluorescent CuNCs/ZIF-8 than that of PEI-CuNCs, which might result from enriching H2O2 by ZIF-8. The CuNCs/ZIF-8 can be designed as fluorescence probe to selectively and sensitively detect H2O2 with a linear range from 0.01 to 1.5 µM and a LOD of 0.01 µM, while those with PEI-CuNCs are 0.5–30 µM and 0.50 µM, respectively. Through formation of CuNCs/ZIF-8 hybrid, the sensitivity for the detection of H2O2 increases by nearly 50-fold, which makes CuNCs/ZIF-8 a desirable probe to detect H2O2 content in human serum samples. Also, we successfully demonstrated the potential application of the CuNCs/ZIF-8 for screening and evaluating activities of oxidase using glucose oxidase as a model. The glucose oxidase activity can be detected in a range of 0.1 ∼ 10 mU/L with a LOD of 0.1 mU/L.

    更新日期:2018-01-11
  • Facile Electrochemiluminescence Sensing Platform Based on High-Quantum-Yield Gold Nanocluster Probe for Ultrasensitive Glutathione Detection
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-10
    Hua-Ping Peng, Mei-Li Jian, Zhong-Nan Huang, Wen-Jun Wang, Hao-Hua Deng, Wei-Hua Wu, Ai-Lin Liu, Xing-Hua Xia, Wei Chen

    This report outlines a highly sensitive and facile electrochemiluminescence (ECL) sensing platform based on a novel high-quantum-yield Au-nanocluster (AuNC) probe for glutathione (GSH) detection. Owing to the prominent quenching effect of GSH on the ECL of the AuNCs, the proposed ECL nanosensor showed a wide response to GSH in the ranges of 1.0 × 10-9-1.0 × 10-5 M and 1.0 × 10-5-1.0 × 10-1 M and a low detection limit of 3.2 × 10-10 M. In addition, the proposed system exhibited good selectivity for GSH in the presence of other chemical/biological interferences. Moreover, since no further functionalization of AuNC-based sensor interface was necessary, together with the stability, high sensitivity and selectivity of the proposed nanosensor, this convenient approach was able to successfully detect GSH in both of human urine samples and blood samples with excellent recoveries, which indicated its promising application under physiological conditions. Of significant importance is that this study not only helps in gaining a better understanding of the applicability of the ECL properties of AuNCs, but also provides a new avenue for the design and development of ECL sensors based on the novel high-quantum-yield AuNC-based probe and other functional-metal-based NC probes.

    更新日期:2018-01-11
  • Fast and Sensitive Near-Infrared Fluorescent Probes for ALP Detection and 3D Printed Calcium Phosphate Scaffold Imaging In vivo
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-10
    Chul Soon Park, Tai Hwan Ha, Moonil Kim, Naren Raja, Hui-suk Yun, Mi Jeong Sung, Oh Seok Kwon, Hyeonseok Yoon, Chang-Soo Lee

    Alkaline phosphatase (ALP) is a critical biological marker for osteoblast activity during early osteoblast differentiation, but few biologically compatible methods are available for its detection. Here, we describe the discovery of highly sensitive and rapidly responsive novel near-infrared (NIR) fluorescent probes (NIR-Phos-1, NIR-Phos-2) for the fluorescent detection of ALP. ALP cleaves the phosphate group from the NIR skeleton and substantially alters its photophysical properties, therefore generating a large “turn-on” fluorescent signal resulted from the catalytic hydrolysis on fluorogenic moiety. Our assay quantified ALP activity from 0 to1.0 U mL-1 with a 10-5−10-3 U mL-1 limit of detection (LOD), showing a response rate completed within 1.5 min. A potentially powerful approach to probe ALP activity in biological systems demonstrated real-time monitoring using both concentration- and time-dependent variations of endogenous ALP in live cells and animals. Based on high binding affinity to bone tissue of phosphate moiety, bone-like scaffold-based ALP detection in vivo was accessed using NIR probe-labeled three-dimensional (3D) calcium deficient hydroxyapatite (CDHA) scaffolds. They were subcutaneously implanted into mice and monitored ALP signal changes using a confocal imaging system. Our results suggest the possibility of early-stage ALP detection during neo-bone formation inside a bone defect, by in vivo fluorescent evaluation using 3D CDHA scaffolds.

    更新日期:2018-01-11
  • An aptamer nanopore-enabled microsensor for detection of theophylline
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-10
    Silu Feng, Changtian Chen, Wei Wang, Long Que

    This paper reports an aptamer-based nanopore thin film sensor for detecting theophylline in the buffer solution and complex fluids including plant extracts and serum samples. Compared to antibody-based detection, aptamer-based detection offers many advantages such as low cost and high stability at elevated temperatures. Experiments found that this type of sensor can readily detect theophylline at a concentration as low as 0.05 µM, which is much lower than the detection limit of current lab-based equipment such as liquid chromatography (LC). Experiments also found that the aptamer-based sensor has good specificity, selectivity, and reasonable reusability with a significantly improved dynamic detection range. By using the same nanopore thin film sensors as the reference sensors to further mitigate the non-specific binding effect, the theophylline in plant extracts and serum has been detected. Only a small amount (~1 µl) of plant extracts or serum samples is required to measure theophylline. Its low cost and ease-of-operation make this type of sensor suitable for point-of-care application to monitor the theophylline level of patients in real time.

    更新日期:2018-01-10
  • A catalytic and dual recycling amplification ATP sensor based on target-driven allosteric structure switching of aptamer beacons
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-09
    Ying Peng, Daxiu Li, Ruo Yuan, Yun Xiang

    Abnormal concentrations of ATP are associated with many diseases and cancers, and quantitative detection of ATP is thus of great importance for disease diagnosis and prognosis. In the present work, we report a new dual recycling amplification sensor integrated with catalytic hairpin assembly (CHA) to achieve high sensitivity for fluorescent detection of ATP. The association of the target ATP with the aptamer beacons causes the allosteric structure switching of the aptamer beacons to expose the toehold regions, which hybridize with and unfold the fluorescently quenched hairpin signal probes (HP1) to recycle the target ATP and to trigger CHA between HP1 and the secondary hairpin probes (HP2) to form HP1/HP2 duplexes. Due to the recycling amplification, the presence of ATP leads to the formation of many HP1/HP2 duplexes, generating dramatically amplified fluorescent signals for sensitive detection of ATP. Under optimal experimental conditions, our sensor linearly responds to ATP in the range from 25 to 600 nM with a calculated detection limit of 8.2 nM. Furthermore, the sensor shows a high selectivity and can also be used to detect ATP in human serums to realize its application for real samples. With the distinct advantage of significant signal amplification without the involvement of any nanomaterial and enzyme, the developed sensor thus holds great potential for simple and sensitive detection of different small molecules and proteins.

    更新日期:2018-01-10
  • Allosteric Kissing Complex-Based Electrochemical Biosensor for Sensitive, Regenerative and Versatile Detection of Proteins
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-09
    Mingsha Zhao, Shanshan Zhang, Zhiqiang Chen, Changzhi Zhao, Li Wang, Shufeng Liu

    Herein, an allosteric kissing complex-based electrochemical biosensor was ingeniously proposed for the simple, sensitive, regenerative and versatile detection of proteins. Two hairpins (Hp1 and Hp2) were designed and the Hp1 was immobilized on the electrode surface, which could form a kissing complex with Hp2 through the apical loop-loop or kissing interaction of the RNA-RNA base sequences. The Hp2 possesses the appended single-stranded tails on each end, which hybridize with the recognition element-conjugated DNA strands to construct a protein responsive switch of Hp2 scaffold. After kissing complex formation between the Hp2 scaffold and the immobilized Hp1, the streptavidin-labeled alkaline phosphatase (SA-ALP) can be introduced onto the electrode surface for the generation of electrochemical signal. In the presence of target protein, its binding to the recognition elements linked onto the Hp2 scaffold endows the steric strain to open the Hp2 stem, propagated by the disruption of the kissing complex structure, resulting into a decreased electrochemical signal related with the protein quantification. Also, the Hp1 immobilized electrode can be directly regenerated after protein-induced kissing complex dissociation. The current kissing complex-based electrochemical biosensing strategy can be easily extended for the detection toward different protein targets of interest by simply changing the recognition elements conjugated onto the Hp2 scaffold. The sensitive and selective detection toward proteins could be achieved with the detection limits toward Anti-Dig antibody and thrombin of about 1 ng/mL and 10 pM, respectively. The developed kissing complex-based protein biosensing strategy should be a beneficial supplement in current biosensor field, providing a promising means for the applications in bioanalysis, disease diagnostics, and clinical biomedicine.

    更新日期:2018-01-10
  • Ultrasensitive electrochemical immuno-sensing platform based on gold nanoparticles triggering chlorpyrifos detection in fruits and vegetables
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-09
    Sonu Gandhi, Anita Talan, Annu Mishra, Sergei A. Eremin, Jagriti Narang, Ashok Kumar

    Chlorpyrifos (chl) is an organophosphate pesticide extensively used in agriculture and highly toxic for human health. Fluorine doped tin-oxide (FTO) based electrochemical nanosensor was developed for chlorpyrifos detection with gold nanoparticles (AuNPs) and anti-chlorpyrifos antibodies (chl-Ab). AuNPs provides high electrical conductivity and specific resistivity, thus increases the sensitivity of immunoassay. High electrical conductivity of AuNPs reveals that it promotes the redox reaction for better cyclic voltammetry. Based on the intrinsic conductive properties of FTO-AuNPs complex, chl-Ab was immobilized onto AuNPs surface. Under optimized conditions, the proposed FTO based nanosensor exhibited high sensitivity and stable response for the detection of chlorpyrifos, ranging from 1 fM to 1 µM with limit of detection (LOD) up to 10 fM. The FTO-AuNPs sensor was successfully employed for the detection of chlorpyrifos in standard as well in real samples up to 10 nM for apple and cabbage, 50 nM for pomegranate. The proposed FTO-AuNPs nanosensor can be used as a quantitative tool for rapid, on-site detection of chlorpyrifos traces in real samples when miniaturized due to its excellent stability, sensitivity, and simplicity.

    更新日期:2018-01-10
  • Three-dimensional graphene biointerface with extremely high sensitivity to single cancer cell monitoring
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-09
    Xiahua Wang, Aiping Liu, Yun Xing, Hongwei Duan, Weizhong Xu, Qi Zhou, Huaping Wu, Cen Chen, Benyong Chen
    更新日期:2018-01-09
  • Electrosynthesized MIPs for Transferrin: Plastibodies or Nano-Filters?
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-09
    Xiaorong Zhang, Aysu Yarman, Júlia Erdossy, Sagie Katz, Ingo Zebger, Katharina J. Jetzschmann, Zeynep Altintas, Ulla Wollenberger, Róbert E. Gyurcsányi, Frieder W. Scheller

    Molecularly imprinted polymer (MIP) nanofilms for transferrin (Trf) have been synthesized on gold surfaces by electro-polymerizing the functional monomer scopoletin in the presence of the protein target or around pre-adsorbed Trf. As determined by atomic force microscopy (AFM) the film thickness was comparable with the molecular dimension of the target. The target (re)binding properties of the electro-synthesized MIP films was evaluated by cyclic voltammetry (CV) and square wave voltammetry (SWV) through the target-binding induced permeability changes of the MIP nanofilms to the ferricyanide redox marker, as well as by surface plasmon resonance (SPR) and surface enhanced infrared absorption spectroscopy (SEIRAS) of the immobilized protein molecules. For Trf a linear concentration dependence in the lower micromolar range and an imprinting factor of ~5 was obtained by SWV and SPR. Furthermore, non-target proteins including the iron-free apo-Trf were discriminated by pronounced size and shape specificity. Whilst it is generally assumed that the rebinding of the target or of cross-reacting proteins exclusively takes place at the polymer here we considered also the interaction of the protein molecules with the underlying gold transducers. We demonstrate by SWV that adsorption of proteins suppresses the signal of the redox marker even at the bare gold surface and by SEIRAS that the treatment of the MIP with proteinase K or NaOH only partially removes the target protein. Therefore, we conclude that when interpreting binding of proteins to directly MIP-covered gold electrodes the interactions between the protein and the gold surface should also be considered.

    更新日期:2018-01-09
  • Paper-based fluorescent sensor via aggregation induced emission fluorogen for facile and sensitive visual detection of hydrogen peroxide and glucose
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-06
    Jiafu Chang, Haiyin Li, Ting Hou, Wenna Duan, Feng Li

    Hydrogen peroxide (H2O2), an important reactive oxygen species (ROS), is related to the oxidative stress in organisms, and plays important roles in a variety of cellular activities as well. So it is of crucial importance to develop sensitive and accurate sensing strategies to detect H2O2 in biological systems. Herein, by taking advantage of the unique emission characteristics of aggregation induced emission (AIE) fluorogens, we proposed a non-enzymatic fluorescence platform for facile and sensitive detection of H2O2, both in solution state using fluorescence spectrometer and on paper-based sensor via visual inspection. Through the reaction between L-cysteine and H2O2, the fluorescence of TPE-M-L, an AIE fluorogen formed between maleimide-functionalized tetraphenylethene (TPE-M) and L-cysteine, is quenched, and highly sensitive non-enzymatic H2O2 assay is readily carried out. The limit of detection of 10 nM in solution state and 2.5 μM on paper-based sensor were obtained for H2O2 detection, which were superior or comparable to those previously reported in literature. Moreover, by integrating glucose oxidase with the AIE fluorogen of TPE-M-L, highly sensitive and selective glucose detection was also conveniently achieved both in solution state and on paper-based sensor by the as-proposed strategy, with the LODs of 50 nM in solution state and 10 μM via visual observation, much better than those obtained by other fluorescence methods. The as-proposed sensing strategy was also successfully applied to assay glucose in human serum samples. Therefore, the paper-based fluorescence sensor exhibits the advantages of simple fabrication, high sensitivity and portability, and has great potential to be applied in on-site assay of H2O2 and glucose in real samples.

    更新日期:2018-01-06
  • Water-soluble mercury ion sensing based on the thymine-Hg2+-thymine base pair using retroreflective Janus particle as an optical signaling probe
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-06
    Hyeong Jin Chun, Saemi Kim, Yong Duk Han, Dong Woo Kim, Ka Ram Kim, Hyo-Sop Kim, Jae-Ho Kim, Hyun C. Yoon

    Herein, we report an optical sensing platform for mercury ions (Hg2+) in water based on the integration of Hg2+-mediated thymine-thymine (T-T) stabilization, a biotinylated stem-loop DNA probe, and a streptavidin-modified retroreflective Janus particle (SA-RJP). Two oligonucleotide probes, including a stem-loop DNA probe and an assistant DNA probe, were utilized. In the absence of Hg2+, the assistant DNA probe does not hybridize with the stem-loop probe due to their T-T mismatch, so the surface-immobilized stem-loop DNA probe remains a closed hairpin structure. In the presence of Hg2+, the DNA forms a double-stranded structure with the loop region via Hg2+-mediated T-T stabilization. This DNA hybridization induces stretching of the stem-loop DNA probe, exposing biotin. To translate these Hg2+-mediated structural changes in DNA probe into measurable signal, SA-RJP, an optical signaling label, is applied to recognize the exposed biotin. The number of biospecifically bound SA-RJPs is proportional to the concentration of Hg2+, so that the concentration of Hg2+ can be quantitatively analyzed by counting the number of RJPs. Using the system, a highly selective and sensitive measurement of Hg2+ was accomplished with a limit of detection of 0.027 nM. Considering the simplified optical instrumentation required for retroreflection-based RJP counting, RJP-assisted Hg2+ measurement can be accomplished in a much easier and inexpensive manner. Moreover, the detection of Hg2+ in real drinking water samples including tap and commercial bottled water was successfully carried out.

    更新日期:2018-01-06
  • 更新日期:2018-01-06
  • Molecularly imprinted electrochemical sensor, formed on Ag screen-printed electrodes, for the enantioselective recognition of D and L phenylalanine
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-06
    Shin-Hong Ou, Liang-Siou Pan, Jiin-Jiang Jow, Ho-Rei Chen, Tzong-Rong Ling

    In this study, electrochemical sensors for the enantioselective recognition of D and L phenylalanine were prepared using a molecular imprinting technique in which the electro-polymerization of pyrrole was carried out by Chronopotentiometry(CP) with the target molecules being present on a Ag screen printed electrode's (SPE) surface. The sensing performance was evaluated by multi-potential steps at 0 and 2 V(vs. Ag/AgCl) held for 1 sec and 2 sec, respectively, for 20 cycles (with the two enantiomers being present at the same concentration). The individual selectivity's for L and D- phenylalanine on their respective imprinted films were estimated to be L/D = 23.480±2.844/1 and D/L = 19.134±1.870/1 respectively, based on the current change between 0 and 2 V (vs. Ag/AgCl) with the two enantiomers being present at the same concentration (10 mM). Several parameters affecting recognition ability were investigated including: cross-selectivity of D and L- phenylalanine imprinted film, phenylalanine concentration effects, interfering species, deactivation and the storage life of electrode. The phenylalanine imprinted films were also characterized by AC impedance, chronoamperometry, Fourier-transform infrared spectroscopy (FTIR), Scanning Electron Microscope(SEM), and Energy Dispersive X-Ray Spectroscopy (EDS). Finally, a recognition mechanism for the interaction of the polypyrrole film with its template under the influence of applied negative and positive potentials is proposed.

    更新日期:2018-01-06
  • Heating enhanced sensitive and selective electrochemical detection of Hg2+ based on T-Hg2+-T structure and exonuclease III-assisted target recycling amplification strategy at heated gold disk electrode
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-05
    Shao-Hua Wu, Biao Zhang, Fang-Fang Wang, Zhen-Zhen Mi, Jian-Jun Sun

    A sensitive and selective electrochemical Hg2+ sensor was developed based on T-Hg2+-T structure and exonuclease (Exo) III -assisted target recycling amplification at heated gold disk electrode (HAuDE). First, a DNA signal probe P1 was for the first time designed and labeled with ferrocene (Fc) near the attached SH-5′-end, so as to shorten the distance between Fc and the electrode and enhance the initial current of Fc compared with that labeled at the 3′-end far from the electrode. Then the signal amplification was achieved by Exo III-assisted Hg2+ recycling. Briefly, the P1 was complementary to the assistant DNA P2 except the T-T mismatches. In the presence of Hg2+, the P1 self-assembled on the HAuDE could hybridize with P2 and form DNA duplex with blunt end at the 3′- terminus, triggering Exo III to stepwise digest mononucleotides from the 3′-terminus of P1, ultimately liberating Hg2+ and P2, which could be “recycled”, resulting in the digestion of a large amount of P1 and significantly decrease the amount of Fc. The electrochemical signal difference before and after digestion was proportional to the Hg2+ concentration. Furthermore, during the digestion period, the Exo III activity could be significantly increased by elevating the electrode temperature, great improving the sensitivity and efficiency for Hg2+ detection. A detection limit of 6.2 pM (S/N = 3) could be obtained with an electrode temperature of 40 °C during 60 min digestion period, which was lower ca. two magnitudes than that at 0 °C and one magnitude than that at 25 °C.

    更新日期:2018-01-06
  • Ultrasensitive electrochemical sensing of Hg2+ based on thymine-Hg2+-thymine interaction and signal amplification of alkaline phosphatase catalyzed silver deposition
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-05
    Aigui Xu, Long Chao, Hongbo Xiao, Yuyun Sui, Jia Liu, Qingji Xie, Shouzhuo Yao

    We report an ultrasensitive electrochemical sensor for Hg2+ detection, on the basis of two Hg2+-specific oligonucleotide probes (a thiolated capture probe and a biotinated signal probe), “terminal” signal amplification of alkaline phosphatase catalyzed deposition of silver and in situ microliter-droplet anodic stripping voltammetry (ASV). The thiolated capture probe is immobilized on an Au-plated glassy carbon electrode, and the biotinated signal probe is then attached to the electrode surface through the thymine-Hg2+-thymine interaction in the presence of Hg2+. A streptavidin-alkaline phosphatase (ALP) composite is then immobilized on the electrode surface via biotin–streptavidin interaction. The immobilized ALP can catalyze the hydrolyzation of ascorbic acid 2-phosphate trisodium salt to generate ascorbic acid, which can reduce AgNO3 to form silver deposit on the modified electrode. Quantitative analysis of Hg2+ is conducted through microliter-droplet ASV of silver after its simultaneous chemical dissolution and cathodic preconcentration on the modified electrode. The sensor can linearly respond to the common logarithm of Hg2+ concentration from 0.1 nM to 250 μM with a limit of detection of 0.01 nM (2 ppt, S/N=3) and a sensitivity as high as 227 μA dec−1.

    更新日期:2018-01-05
  • Hybrid porous thin films: Opportunities and challenges for sensing applications
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-05
    Pawan Kumar, Ki-Hyun Kim, Kowsalya Vellingiri, Pallabi Samaddar, Parveen Kumar, Akash Deep, Naresh Kumar

    In this paper, the scientific progress in the field of thin film materials and their associated sensing technologies are described comprehensively to address the directions for future research and developments as per modern-day technologies need. To begin with, we briefly discuss the fundamental synthesis approaches of advanced thin films with an emphasis on the properties necessary for controlled fabrication (e.g., the elemental ratio and spatial arrangement). Subsequently, we explore the control, characterization, and optimization of hybrid porous thin films with respect to diverse sensing applications. The application of hybrid porous thin film materials has also been discussed in terms of the mechanisms used for biological, optical, electrical, acoustic, and other advanced sensing techniques (e.g., surface-enhanced Raman scattering (SERS)). Finally, conclusions are drawn to highlight the current state of thin film-based sensing technology along with its opportunities and challenges.

    更新日期:2018-01-05
  • A novel cytosensor based on Pt@Ag nanoflowers and AuNPs/Acetylene black for ultrasensitive and highly specific detection of Circulating Tumor Cells
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-04
    Sitian Tang, Huawei Shen, Yixiong Hao, Zhenglan Huang, Yiyi Tao, Yang Peng, Yongcan Guo, Guoming Xie, Wenli Feng

    Circulating tumor cells (CTCs), as the cellular origin of metastasis, are cancer cells that break away from a primary tumor and circulate in the peripheral blood. And they provide a wealth of information about tumor phenotype. Here, this work reported a novel ultrasensitive immunoassay protocol for the detection of CTCs by using Pt@Ag nanoflowers (Pt@AgNFs) and AuNPs/Acetylene black (AuNPs/AB) nanomaterial. In the established approach, AuNPs/AB nanomaterial was used as substrate material to increase the specific surface area and enhance the conductivity of the gold electrode. Protein G was used for oriented immobilization of capture antibody, which strongly improved the capture efficiency of MCF-7 cells. The innovatively synthesized Pt@AgNFs by our group with high specific surface area and good biocompatibility were not only as the carriers of signal antibodies (Ab2) but also catalyzed the reduction of H2O2, which effectually amplified the current signal. A linear relationship between current signals and the concentrations of CTCs was obtained in the range from 20 to 1×106 cells mL−1 and the detection limit is as low as 3 cells mL−1 on condition of acceptable stability and reproducibility. Furthermore, the as-proposed cytosensor showed excellent performance in the detection of CTCs in human blood samples. These results suggest that the proposed cytosensor will be a promising application for accurately quantitative detection of CTCs.

    更新日期:2018-01-05
  • Poly(3,6-diamino-9-ethylcarbazole) based molecularly imprinted polymer sensor for ultra-sensitive and selective detection of 17-β-estradiol in biological fluids
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-04
    Weilu Liu, Haifeng Li, Shangmin Yu, Jiaxing Zhang, Weihua Zheng, Liting Niu, Gengen Li

    In this work, we reported the synthesis of 3, 6-diamino-9-ethylcarbazole and its application as a new monomer for preparation of molecularly imprinted polymer (MIP) electrochemical sensor. The as prepared MIP sensor exhibited ultrahigh sensitivity and selectivity for the detection of 17-β-estradiol in attomolar levels (1×10–18 mol L−1). The sensor works by detecting the change of the interfacial impedance that is derived from recognition of 17-β-estradiol on the MIP layer. The MIP sensor based on 3, 6-diamino-9-ethylcarbazole monomer revealed better performance than that of unmodified carbazole monomer. The monomer/template ratio, electropolymerization scanning cycles, and the incubation pH values were optimised in order to obtain the best detection efficiency. Under the optimised condition, the MIP sensor exhibits a wide linear range from 1 aM to 10 μM (1 × 10–18 ̶ 1 × 10−5 mol L−1). A low detection limit of 0.36 aM (3.6 × 10–19 mol L−1) and a good selectivity towards structurally similar compounds were obtained. The proposed MIP sensor also exhibits long-term stability and applicability in human serum samples. These advantages enabled this MIP sensor to be a promising alternative of electrochemical sensor and may be extended to detection of other endogenous compounds.

    更新日期:2018-01-05
  • Disposable InkJet-Printed Electrochemical Platform for Detection of Clinically Relevant HER-2 Breast Cancer Biomarker
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2018-01-04
    Susanita Carvajal, Samantha N. Fera, Abby L. Jones, Thaisa A. Baldo, Islam M. Mosa, James F. Rusling, Colleen E. Krause

    Rapidly fabricated, disposable sensor platforms hold tremendous promise for point-of-care detection. Here, we present an inexpensive (< $0.25) fully inkjet printed electrochemical sensor with integrated counter, reference, and working electrodes that is easily scalable for commercial fabrication. The electrochemical sensor platform featured an inkjet printed gold working 8-electrode array (WEA) and counter electrode (CE), along with an inkjet –printed silver electrode that was chlorinated with bleach to produce a Ag/AgCl quasi-reference electrode (RE). As proof of concept, the electrochemical sensor was successfully applied for detection of clinically relevant breast cancer biomarker Human Epidermal Growth Factor Receptor 2 (HER-2). Capture antibodies were bound to a chemically modified surface on the WEA and placed into a microfluidic device. A full sandwich immunoassay was constructed following a simultaneous injection of target protein, biotinylated antibody, and polymerized horseradish peroxide labels into the microfluidic device housing the WEA. With an ultra fast assay time, of only 15 mins a clinically relevant limit of detection of 12 pg mL−1 was achieved. Excellent reproducibility and sensitivity were observed through recovery assays preformed in human serum with recoveries ranging from 76–103%. These easily fabricated and scalable electrochemical sensor platforms can be readily adapted for multiplex detection following this rapid assay protocol for cancer diagnostics.

    更新日期:2018-01-05
  • Proximity Ligation Detection of Lectin Concanavalin A and Fluorescence Imaging Cancer Cells Using Carbohydrate Functionalized DNA-Silver Nanocluster Probes
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-31
    Xiaoru Zhang, Fengting Chen, Xiaojie Song, Peng He, Shusheng Zhang

    A novel method for study the interaction between carbohydrate and lectin was developed in homogenous solution. DNA was introduced to the recognition process of carbohydrate with protein. Due to the versatile detection mode of DNA, the detection efficiency for carbohydrate and protein was highly promoted. Herein, two kinds of mannose-DNA conjugates were synthesized. One of which was used to prepare DNA-templated silver nanocluster (AgNCs) and the other one contained guanine-rich DNA sequences. When the mannose of two conjugates binding to lectin Concanavalin A (Con A), great enhancement on fluorescence intensity was obtained due to the proximity ligation of the DNA-templated Ag NCs with guanine-rich DNA sequences. Hence Con A can be quantified conveniently in homogenous solution using Ag NCs with low toxicity and tunable fluorescence. Moreover, carbohydrate functionalized DNA-templated AgNCs was also utilized for cancer cell imaging based on the recognition of mannose with mannose receptor on cancer cell MDA-MB-231.

    更新日期:2017-12-31
  • Exonuclease III-Boosted Cascade Reactions for Ultrasensitive SERS Detection of Nucleic Acids
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-29
    Yudie Sun, Pai Peng, Ruiyan Guo, Huihui Wang Tao Li

    A variety of nucleic acid amplification techniques have been integrated into different detection methods to promote the development of sensitive and convenient analysis of nucleic acids. However, it is still in urgent need to develop amplified nucleic acid biosensors for the analysis of susceptible gene and even distinguishing single-base mismatched DNA in complex biological samples. Benefiting from the achieved detection strategies, here we boost isothermal nucleic acid amplification by resorting to enzyme amplification, and combine this two-stage amplification method with surface-enhanced Raman spectroscopy (SERS) to develop a signal-on nucleic acid detection platform. Due to the high cleavage efficiency of Exonuclease III (Exo III), a large amount of trigger DNA are produced to initiate multiple hybridization chain reaction circles. The product structure tagged with Tamra is then anchored onto the plasmonic SERS substrate and meanwhile enriched. It is demonstrated that this detection platform is sensitive toward the myocardial infarction disease related gene. A detection limit of 1 fM for the gene analysis in a linear relationship in the wide range from 1 fM to 10 nM is acheived, better than most of previous counterparts. Meanwhile, our developed detection platform exhibits a high selectivity for the target gene over mismatched analogues. Our strategy provides a robust tool for signal amplification of gene detection even in blood samples.

    更新日期:2017-12-31
  • High-performance electrochemical mercury aptasensor based on synergistic amplification of Pt nanotube arrays and Fe3O4/rGO nanoprobes
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-27
    Jingyi Luo, Danfeng Jiang, Tao Liu, Jingmeng Peng, Zhenyu Chu, Wanqin Jin

    In this work, a novel sandwich-type aptasensor was designed for the ultrasensitive recognition of trace mercury ions in water. Numerous oriented platinum nanotube arrays (PtNAs) were in-situ crystallized on a flexible electrode as a sensing interface, while thionine labelled Fe3O4/rGO nanocomposites as signal amplifiers. Both PtNAs/CF and nanocomposites were synthesized by easy hydrothermal processes. With their large surface area, it was favorable for electrochemical performance and immobilization of capture DNAs (cDNA) and report DNAs (rDNA). Upon the existence of Hg2+, partial linker DNAs were tightly bound with cDNAs through thymine-Hg2+-thymine pairing (T-Hg2+-T). Then rDNAs attached Fe3O4/rGO nanoprobes were fixed on the electrode through the match of remaining linker DNAs and rDNAs. Under the optimal conditions, the Hg2+ aptasensor showed a synergistic amplification performance with a wide linear range from 0.1 nM to 100 nM, as well as a low detection limit of 30 pM. Moreover, the as-prepared aptasensor also exhibited reliable performance for assay in real lake water samples.

    更新日期:2017-12-27
  • QCM-D surpassing clinical standard for the dose administration of new oral anticoagulant in the patient of coagulation disorders
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-27
    Munawar Hussain, Hans Peter Wendel, Katrin Schmidt, Elisabeth Langer, Mareike Kristina Körber, Oksana Faul, Hinnak Northoff, Christian von Heymann, Frank K Gehring

    The study focuses the dose administration of dabigatran to avoid the deaths due to hemorrhagic complications and thromboembolic stroke in clinics worldwide. To target the issue, a novel emerging acoustic technology, namely ''Quartz Crystal Microbalance with Dissipation'' (QCM-D) has been applied, while the acoustic assays namely ''activated Partial Thromboplastin Time'' (aPTT) and ''Prothrombinase complex-induced Clotting Test'' (PiCT) have been compared with the standard methods in parallel. Both techniques have been applied to 300 samples, including 220 plasma samples of patients suffering coagulation disorders and 80 plasma samples of non-patients. In comparison, the coagulation times of the acoustic aPTT and PiCT yielded an excellent correlation with the standard methods with in analytical standard deviation limits. Finally, the acoustic aPTT assay is the ''gold standard'' for a dose administration of the new oral anticoagulant, where the Δf / ΔΓ ratio of the acoustic assay demonstrates that dabigatran with FEIBA 50 combination could be a safe remedy to avoid the deaths in clinics.

    更新日期:2017-12-27
  • A novel electrochemiluminescent biosensor based on resonance energy transfer between poly(9,9-di-n-octylfluorenyl-2,7-diyl) and 3,4,9,10-perylenetetracar-boxylic acid for insulin detection
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-27
    Han Zhang, Fumei Zuo, Xingrong Tan, Shenghao Xu, Ruo Yuan, Shihong Chen

    An electrochemiluminescencent (ECL) biosensor was designed for the determination of insulin using a novel ECL resonance energy transfer (ECL-RET) strategy. In this strategy, carboxyl poly(9,9-dioctyfluorenyl-2,7-diyl) dots (PFO dots) were worked as ECL donor and 3,4,9,10-perylenetetracar-boxylic acid (PTCA) exploited as ECL acceptor, and hydrogen peroxide (H2O2) employed as the coreactant. The ECL donor and ECL acceptor were separately labeled with primary antibody (Ab1) and secondary antibody (Ab2), forming a sensing interface to the analyte target, insulin. In this expected sandwich-type ECL biosensor, PFO dots acted as sensing platform and PTCA employed as labels to quench the ECL emission of PFO dots. During the determination process, ECL signal of PFO dots was decreased in a gradual way by the increase of insulin concentration, and the quenching mechanism was also investigated. Under the optimal experimental conditions, the constructed biosensor exhibited an excellent performance, including a wide linear range from 1.0×10-5 ng/mL to 1.0×102 ng/mL, low detection limit of 3.0×10-6 ng/mL, good stability and selectivity for the detection of insulin. This pair of PFO-PTCA, as a new donor-acceptor pair in ECL-RET system, would provide a promising platform for bioanalysis in ECL field.

    更新日期:2017-12-27
  • Microfluidic platform to generate spatial and temporal dynamic stimulations in a single device for real-time single cell analysis
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-27
    Jiyoung Song, Hyunryul Ryu, Minhwan Chung, Youngtaek Kim, Yannick Blum, Sungsik Lee, Olivier Pertz, Noo Li Jeon

    Recent research on cellular responses is changing from static observations in static stimuli to real-time monitoring in a dynamic environment. Since cells sense and interact with their surrounding microenvironment, the dynamically-changing microenvironments must be mimicked in vitro in order to understand cell behavior. However, there has been a lack of microfluidic devices to support the various shapes of stimulation without further modification of channel design. Here, we developed a microfluidic device that generates dynamic temporal stimulation in a single device. This microfluidic device provides at least 12 hours of versatile stimulations, which is suitable for mammalian cell culture. Therefore, combination of our microfluidic device with live-cell imaging techniques facilitates real-time observation of cellular response for a long time at single cell level. Using our device, ERK (Extracellular signal-Regulated Kinase) activities were observed under the pulsatile and ramping stimulations of EGF (Epidermal Growth Factor). We quantified ERK activation even at extremely low EGF concentration, which is hard to be observed in conventional techniques. In addition, the cytoskeleton rearrangement of the 3T3 fibroblast was compared under the abrupt and gradual change in the gradient of the GFs.

    更新日期:2017-12-27
  • Spore-based biosensor to monitor the microbicidal efficacy of gaseous hydrogen peroxide sterilization processes
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-27
    Jan Oberländer, Marlena Mayer, Anton Greeff, Michael Keusgen, Michael J. Schöning

    In this work, a spore-based biosensor is evaluated to monitor the microbicidal efficacy of sterilization processes applying gaseous hydrogen peroxide (H2O2). The sensor is based on interdigitated electrode structures (IDEs) that have been fabricated by means of thin-film technologies. Impedimetric measurements are applied to study the effect of sterilization process on spores of Bacillus atrophaeus. This resilient microorganism is commonly used in industry to proof the sterilization efficiency. The sensor measurements are accompanied by conventional microbiological challenge tests, as well as morphological characterizations with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The sensor measurements are correlated with the microbiological test routines. In both methods, namely the sensor-based and microbiological one, a tailing effect has been observed. The results are evaluated and discussed in a three-dimensional calibration plot demonstrating the sensor's suitability to enable a rapid process decision in terms of a successfully performed sterilization.

    更新日期:2017-12-27
  • A label-free electrochemical immunosensor based on the novel signal amplification system of AuPdCu ternary nanoparticles functionalized polymer nanospheres
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-26
    Qin Yan, Yuying Yang, Zhaoling Tan, Qing Liu, Hui Liu, Ping Wang, Lei Chen, Daopeng Zhang, Yueyun Li, Yunhui Dong

    A sensitive label-free electrochemical immunosensor was designed using a novel signal amplification system for quantitative detecting hepatitis B surface antigen (HBsAg). Nitrogen-doped graphene quantum dots (N-GQDs) supported surfactant-free AuPdCu ternary nanoparticles (AuPdCu/N-GQDs), which featured with good conductivity and excellent catalytic properties for the reduction of hydrogen peroxide (H2O2), was synthesized by a simple and benign hydrothermal procedure. At the same time, the electroactive polymer nanospheres (PS) was synthesized by infinite coordination polymers of ferrocenedicarboxylic acid, which could play as carrier and electronic mediator to load AuPdCu/N-GQDs. The PS not only improved the ability to load antibodies because of the good biocompatibility, but also accelerated electron transport of the electrode interface attribute to plentiful ferrocene unit. Thus, the prepared AuPdCu/N-GQDs@PS has abilities of good biocompatibility, catalytic activity and electrical conductivity to be applied as transducing materials to amplify electrochemical signal in detection of HBsAg. Under optimal conditions, the fabricated immunosensor exhibited high sensitivity and stability in the detection of HBsAg. A linear relationship between current signals and the concentrations of HBsAg was obtained in the range from 10 fg/mL to 50 ng/mL and the detection limit of HBsAg was 3.3 fg/mL (signal-to-noise ratio of 3). Moreover, the designed immunosensor with excellent selectivity, reproducibility and stability shows excellent performance in detection of human serum samples. Furthermore, this label-free electrochemical immunosensor has promising application in clinical diagnosis of HBsAg.

    更新日期:2017-12-27
  • Ultrasensitive detection of lysozyme in droplet-based microfluidic devices
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-26
    Maria Chiara Giuffrida, Giovanni Cigliana, Giuseppe Spoto

    Lysozyme (LYS) is a bacteriolytic enzyme, available in secretions such as saliva, tears and human milk. LYS is an important defence molecule of the innate immune system, and its overexpression can be a consequence of diseases such as leukaemia, kidney disease and sarcoidosis. This paper reports on a digital microfluidic-based approach that combines the gold nanoparticle-enhanced chemiluminescence with aptamer interaction to detect human lysozyme into droplets 20 nanoliters in volume. The described method allows identifying LYS with a 44.6 femtomolar limit of detection, using sample volume as low as1 µL and detection time in the range of 10 minutes.We used luminol to generate the chemiluminescence and demonstrated that the compartmentalization of LYS in droplets also comprising gold nanoparticles provided enhanced luminescence. We functionalized the gold nanoparticles with a thiolated aptamer to achieve the required selectivity that allowed us to detect LYS in human serum.

    更新日期:2017-12-27
  • Low-picomolar, label-free procalcitonin analytical detection with an electrolyte-gated organic field-effect transistor based electronic immunosensor
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-26
    Preethi Seshadri, Kyriaki Manoli, Nicole Schneiderhan-Marra, Uwe Anthes, Piotr Wierzchowiec, Klaus Bonrad, Cinzia Di Franco, Luisa Torsi

    Herein a label-free immunosensor based on electrolyte-gated organic field-effect transistor (EGOFET) was developed for the detection of procalcitonin (PCT), a sepsis marker. Antibodies specific to PCT were immobilized on the poly-3-hexylthiophene (P3HT) organic semiconductor surface through direct physical adsorption followed by a post-treatment with bovine serum albumin (BSA) which served as the blocking agent to prevent non-specific adsorption. Antibodies together with BSA (forming the whole biorecognition layer) served to selectively capture the procalcitonin target analyte. The entire immunosensor fabrication process was fast, requiring overall 45 min to be completed before analyte sensing. The EGOFET immunosensor showed excellent electrical properties, comparable to those of bare P3HT based EGOFET confirming reliable biosensing with bio-functional EGOFET immunosensor. The detection limit of the immunosensor was as low as 2.2 pM and within a range of clinical relevance. The relative standard deviation of the individual calibration data points, measured on immunosensors fabricated on different chips (reproducibility error) was below 7%. The developed immunosensor showed high selectivity to the PCT analyte which was evident through control experiments. This report of PCT detection is first of its kind among the electronic sensors based on EGOFETs. The developed sensor is versatile and compatible with low-cost fabrication techniques.

    更新日期:2017-12-27
  • PEPTIDE NANOPARTICLES (PNPs) MODIFIED DISPOSABLE PLATFORM FOR SENSITIVE ELECTROCHEMICAL CYTOSENSING OF DLD-1 CANCER CELLS
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-25
    Yesim Tugce Yaman, Öznur Akbal, Gulcin Bolat, Betul Bozdogan, Emir Baki Denkbas, Serdar Abaci

    A novel diphenylalaninamid (FFA) based peptide nanoparticles (PNPs) modified pencil graphite electrodes (PGEs) for construction of electrochemical cytosensor was demonstrated for the first time in this study. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images revealed the spherical nanostructure of the synthesized FFA based PNPs while attenuated total reflectance-fourier transform infrared (ATR-FTIR) spectra provided information about the structure and conformation of proteins in their structure. Self-assembly of PNPs on PGE surface and adhesion of DLD-1 cancer cells on this surface was also characterized by electrochemical measurements. PNP/PGEs acted as a sensitive platform for simple and rapid quantification of low concentration of DLD-1 cancer cells in early diagnosis using the electrochemical impedance method (EIS). The offered cytosensor demonstrated outstanding performance for the detection of DLD-1 cells by the EIS method. The impedance of electronic transduction was associated with the amount of the immobilized cells ranging from 2× 102 to 2.0 × 105 cells mL−1 with a limit of detection of 100 cells mL−1. The efficient performance of the cytosensor was attributed to the well-defined nanostructure and biocompability of PNPs on the substrate.

    更新日期:2017-12-27
  • Manganese Porphyrin Decorated on DNA Networks as Quencher and Mimicking Enzyme for Construction of Ultrasensitive Photoelectrochemistry Aptasensor
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-24
    Liaojing Huang, Li Zhang, Liu Yang, Ruo Yuan, Yali Yuan

    In this work, the manganese porphyrin (MnPP) decorated on DNA networks could serve as quencher and mimicking enzyme to efficiently reduce the photocurrent of photoactive material 3,4,9,10-perylene tetracarboxylic acid (PTCA), which was elaborately used to construct a novel label-free aptasensor for ultrasensitive detection of thrombin (TB) in a signal-off manner. The Au-doped PTCA (PTCA-PEI-Au) with outstanding membrane-forming and photoelectric property was modified on electrode to acquire a strong initial photoelectrochemistry (PEC) signal. Afterward, target binding aptamer Ι (TBAΙ) was modified on electrode to specially recognize target TB, which could further combine with TBAII and single-stranded DNA P1-modified platinum nanoparticles (TBAII-PtNPs-P1) for immobilizing DNA networks with abundant MnPP. Ingeniously, the MnPP could not only directly quench the photocurrent of PTCA, but also acted as hydrogen peroxide (HRP) mimicking enzyme to remarkably stimulate the deposition of benzo-4-chlorhexidine (4-CD) on electrode for further decreasing the photocurrent of PTCA, thereby obtaining a definitely low photocurrent for detection of TB. As a result, the proposed PEC aptasensor illustrated excellent sensitivity with a low detection limit down to 3 fM, exploiting a new avenue about intergrating two functions in one substance for ultrasensitive biological monitoring.

    更新日期:2017-12-27
  • A Non-Enzymatic Two Step Catalytic Reduction of Methylglyoxal by Nanostructured V2O5 Modified Electrode
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-23
    Lakshmishri Ramachandra Bhat, Srinivasan Vedantham, Uma Maheswari Krishnan, John Bosco Balaguru Rayappan
    更新日期:2017-12-27
  • Electrochemical sensor and biosensor platforms based on advanced nanomaterials for biological and biomedical applications
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-22
    Govindhan Maduraiveeran, Manickam Sasidharan, Vellaichamy Ganesan

    Introduction of novel functional nanomaterials and analytical technologies signify a foremost possibility for the advance of electrochemical sensor and biosensor platforms/devices for a broad series of applications including biological, biomedical, biotechnological, clinical and medical diagnostics, environmental and health monitoring, and food industries. The design of sensitive and selective electrochemical biological sensor platforms are accomplished conceivably by offering new surface modifications, microfabrication techniques, and diverse nanomaterials with unique properties for in vivo and in vitro medical analysis via relating a sensibly planned electrode/solution interface. The advantageous attributes such as low-cost, miniaturization, energy efficient, easy fabrication, online monitoring, and the simultaneous sensing capability are the driving force towards continued growth of electrochemical biosensing platforms, which have fascinated the interdisciplinary research arenas spanning chemistry, material science, biological science, and medical industries. The electrochemical biosensor platforms have potential applications in the early-stage detection and diagnosis of disease as stout and tunable diagnostic and therapeutic systems. The key aim of this review is to emphasize the newest development in the design of sensing and biosensing platforms based on functional nanomaterials for biological and biomedical applications. High sensitivity and selectivity, fast response, and excellent durability in biological media are all critical aspects which will also be wisely addressed. Potential applications of electrochemical sensor and biosensor platforms based on advanced functional nanomaterials for neuroscience diagnostics, clinical, point-of-care diagnostics and medical industries are also concisely presented.

    更新日期:2017-12-22
  • Ultra-sensitive detection of malathion using quantum dots-polymer based fluorescence aptasensor
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-22
    Rajni Bala, Anuradha Swami, Ilja Tabujew, Kalina Peneva, Nishima Wangoo, Rohit K. Sharma

    A novel detection platform with high malathion specificity has been developed, which operates based on the signal response in the fluorescence of CdTe@CdS quantum dots (QDs). The designed nanoprobe comprises of QDs, poly(N-(3-guanidinopropyl)methacrylamide) homopolymer (PGPMA) and malathion specific aptamer. The interaction of aptamer with malathion results in switching off of the fluorescence signal of the probe due to the availability of the cationic polymer, which causes quenching of the QDs. However, in the absence of malathion, the polymer interacts with the aptamer, via electrostatic interactions thereby rendering the fluorescence of QDs unaffected. The assay exhibited excellent sensitivity towards malathion with a detection limit of 4 pM. A logarithmic correlation was observed in a wide range of malathion concentrations from 0.01 nm to 1 μM, facilitating the potential of proposed assay in the quantitative determination of the analyte of interest. The selectivity of the designed probe was confirmed in the presence of various pesticides, commonly employed in agricultural fields.

    更新日期:2017-12-22
  • Electrochemiluminecence Evaluation for Carbohydrate Antigen 15-3 Based on the Dual-Amplification of Ferrocene Derivative and Pt/BSA Core/Shell Nanospheres
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-21
    Hong Ke, Xin Zhang, Chusen Huang, Nengqin Jia

    Herein, a novel methodology for ultrasensitive and facile breast cancer biomarker carbohydrate antigen 15-3 (CA15-3) evaluation was proposed by fabricating a sandwiched ECL immunosensor. In the protocol, MOCs-Fc and Pt@BSA-luminol nanohybrids were successfully synthesized and further employed to achieve dual-amplification strategy for luminol-H2O2 system. Notably, inherent porous microstructure and large specific surface area from MOCs enabled a high loading of Fc, which succeeded in catalyzing luminol-H2O2 ECL emission and therefore enhancing ECL response. In addition, higher sensitivity could be realized due to the excellent electronic conductivity of MOCs. Furthermore, the as-obtained Pt@BSA- luminol was not only employed as capture probe to recognize CA15-3 after hybridization with Ab2, but also played a crucial role in acting as ECL signal probe due to the presence of massive luminol. It is of vital importance that Pt@BSA core/shell nanospheres showed admirable catalytic effect towards H2O2, which resulted in more excited state luminol and stronger ECL intensity. Therefore, the synergistic amplification strategy of MOCs-Fc and Pt@BSA nanohybrids offered an extremely enhanced ECL signal. The well-established applicable ECL immune- sensing platform displayed favorable analytical performance for CA15-3. In summary, the proposed ECL immunosensor opened a new era for sensitive CA15-3 evaluation and offered a promising platform for clinical breast cancer diagnostics.

    更新日期:2017-12-21
  • Aldehyde functionalized ionic liquid on electrochemically reduced graphene oxide as a versatile platform for covalent immobilization of biomolecules and biosensing
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-21
    Devaraj Manoj, K. Theyagarajan, Duraisamy Saravanakumar, Sellappan Senthilkumar, Kathavarayan Thenmozhi
    更新日期:2017-12-21
  • Mobile phone based ELISA (MELISA)
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-21
    Arsenii Zhdanov, Jordan Keefe, Luis Franco-Waite, Karthik Raj Konnaiyan, Anna Pyayt

    Enzyme-linked immunosorbent assay (ELISA) is one of the most important technologies for biochemical analysis critical for diagnosis and monitoring of many diseases. Traditional systems for ELISA incubation and reading are expensive and bulky, thus cannot be used at point-of-care or in the field. Here, we propose and demonstrate a new miniature mobile phone based system for ELISA (MELISA). This system can be used to complete all steps of the assay, including incubation and reading. It weighs just 1 pound, can be fabricated at low cost, portable, and can transfer test results via mobile phone. We successfully demonstrated how MELISA can be calibrated for accurate measurements of progesterone and demonstrated successful measurements with the calibrated system.

    更新日期:2017-12-21
  • Simultaneous Detection of Dual Biomarkers from Humans Exposed to Organophosphorus Pesticides by Combination of Immunochromatographic Test Strip and Ellman Assay
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-21
    Mingming Yang, Yuting Zhao, Limin Wang, Michael Paulsen, Christopher D. Simpson, Fengquan Liu, Dan Du, Yuehe Lin

    A novel sandwich immunoassay based immunochromatographic test strip (ICTS) has been developed for simultaneously measuring both butyrylcholinesterase (BChE) activity and the total amount of BChE (including inhibited and active enzyme) from 70 μLpost-exposure human plasma sample. The principle of this method is based on the BChE monoclonal antibody (MAb) capable of acting as both capture antibody and detection antibody. The BChE MAb which was immobilized on the test line was able to recognize both organophosphorus BChE adducts (OP-BChE) and BChE and provided equal binding affinity, permitting detection of the total enzyme amount in post-exposure human plasma samples. The formed immunocomplexes on the test line can further be excised from the test-strip for subsequent off-line measurement of BChE activity using the Ellman assay. Therefore, dual biomarkers of BChE activity and phosphorylation (OP-BChE) will be obtained simultaneously. The whole sandwich-immunoassay was performed on one ICTS, greatly reducing analytical time. The ICTS sensor showed excellent linear responses for assaying total amount of BChE and active BChE ranging from 0.22 to 3.58 nM and 0.22 to 7.17 nM, respectively. Both the signal detection limits are 0.10 nM. We validated the practical application of the proposed method to measure 124 human plasma samples from orchard workers and cotton farmers with long-term exposure to organophosphorus pesticides (OPs). The results were in highly agreement with LC/MS/MS which verified our method is extremely accurate. Combining the portability and rapidity of test strip and the compatibility of BChE MAb as both capture antibody and detection antibody, the developed method provides a baseline-free, low-cost and rapid tool for in-field monitoring of OP exposures.

    更新日期:2017-12-21
  • Photoelectrochemical biosensor for HEN1 RNA methyltransferase detection using peroxidase mimics PtCu NFs and poly(U) polymerase-mediated RNA extension
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-21
    Haiyan Wang, Libang Zhu, Junling Duan, Minghui Wang, Huanshun Yin, Po Wang, Shiyun Ai
    更新日期:2017-12-21
  • 更新日期:2017-12-21
  • Optoelectronic Fowl Adenovirus Detection Based on Local Electric Field Enhancement on Graphene Quantum Dots and Gold Nanobundle Hybrid
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-20
    Syed Rahin Ahmed, Jack Mogus, Rohit Chand, Eva Nagy, Suresh Neethirajan
    更新日期:2017-12-21
  • A sandwich-type electrochemical immunosensor based on in situ silver deposition for determination of serum level of HER2 in breast cancer patients
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-20
    Mojtaba Shamsipur, Mahdi Emami, Leila Farzin, Reza Saber

    The sensitive quantification of Human Epidermal growth factor Receptor 2 (HER2), as a key prognostic tumor marker, plays a critical role in screening, early diagnosis and management of breast cancer. This paper describes a sandwich-type immunoassay with silver signal enhancement strategy for highly sensitive detection of HER2. For this purpose, the target capturing step was designed by functionalization of 3-aminopropyltrimethoxysilane coated magnetite nanoparticles with antibody (antiHER2/APTMS-Fe3O4), as a platform bioconjugate (PB), and immobilized at a bare GCE. Then, in the presence of label-free immunosensor, the PB was covered by magnetic gold nanoparticles self-assembled with thiolated antibodies (antiHER2/Hyd@AuNPs-APTMS-Fe3O4) containing chemically reduced silver ions, as a label bioconjugate (LB). Under optimum conditions, a linear relationship between the differential pulse voltammetric (DPV) stripping signal of silver and the logarithm of HER2 concentrations was obtained in the range of 5.0×10-4-50.0 ng mL-1 (R2=0.9906) with a detection limit of 2.0×10-5 ng mL-1. The effectiveness of this protocol was evaluated experimentally through employing of designed immunosensor for detection of the serum level of tumor marker. The good consistency of the results with those obtained by the enzyme-linked immunosorbent assay (ELISA) conventional method (p-value of <0.05) showed that this immunosensor can be applied for the testing of HER2 in clinical samples of breast cancer patients.

    更新日期:2017-12-21
  • Magnetic Biosensors: Modelling and Simulation
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-20
    Vahid Nabaei, Rona Chandrawati, Hadi Heidari

    In the past few years, magnetoelectronics has emerged as a promising new platform technology in various biosensors for detection, identification, localisation and manipulation of a wide spectrum of biological, physical and chemical agents. The methods are based on the exposure of the magnetic field of a magnetically labelled biomolecule interacting with a complementary biomolecule bound to a magnetic field sensor. This Review presents various schemes of magnetic biosensor techniques from both simulation and modelling as well as analytical and numerical analysis points of view, and the performance variations under magnetic fields at steady and nonstationary states. This is followed by magnetic sensors modelling and simulations using advanced Multiphysics modelling software (e.g. Finite Element Method (FEM) etc.) and home-made developed tools. Furthermore, outlook and future directions of modelling and simulations of magnetic biosensors in different technologies and materials are critically discussed.

    更新日期:2017-12-20
  • 更新日期:2017-12-19
  • Ultratrace and Robust Visual Sensor of Cd2+ Ions Based on the Size-dependent Optical Properties of Au@g-CNQDs Nanoparticles in Mice Models
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-18
    Zhuoyue Zhang, Zhen Zhang, Huihui Liu, Xiang Mao, Wei Liu, Shouting Zhang, Zongxiu Nie, Xiaoquan Lu

    Visual inspection is expected as an ideal technique, which can directly and conveniently detect heavy metal ions by observing the color change. Insensitivity of detecting weakly colored heavy transition metal ions and low adsorptivity of metal ions on nanoparticle surface are two main factors hindering the application of visual detection in heavy metal ions detection. Herein, we demonstrated an operational colorimetric sensor based on the color dependence of nanoparticles aggregation to selective and facile detect weakly colored transition heavy metal Cd2+ ions that have been considered as the origin of the “Itai-itai” disease. Uniform colloidal 15 nm graphite-like nitride doped carbon quantum dots-capped gold nanoparticle (Au@g-CNQDs) was successfully prepared, wherein the existence of numerous heptazine, carboxyl and hydroxyl groups on the nanoparticle's surface strengthened adsorption of the Cd2+ ions on the surface of Au@g-CNQDs through the “cooperative effect”. As a consequence, without expensive and intricate exogenous indicators or other special additives, the Cd2+ ions could sensitively and quickly captured to detect at ultra-low concentration within 30 seconds by the naked-eye. Under the optimal conditions, the Cd2+ ions sensor possesses good analytical performances with a wide linear range of 0.01–3.0 μM and a detection limit of 10 nM (S/N=3). Moreover, the biodistribution and aggregation of Cd2+ ions were detected effectively in mice organ tissues suggesting its great potential use for real-word applications.

    更新日期:2017-12-18
  • Highly sensitive electrochemical biosensor for streptavidin detection based on CdSe quantum dots
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-18
    Yu-ping Wei, Xin-Pei Liu, Chang-jie Mao, He-Lin Niu, Ji-Ming Song, Bao-Kang Jin

    An electrochemical biosensor was developed based on a steric hindrance hybridization assay to allow the highly sensitive detection of streptavidin. In the steric hindrance hybridization assay, the signaling strand DNA (sig-DNA) was labeled at the 3’ end with CdSe quantum dots (QDs) and at the 5’ end with biotin, and capturing strand DNA (the complementary strand of sig-DNA) was labeled at the 5’ end with thiol. The steric hindrance effect generated by streptavidin which was bound with the signaling DNA strand. The streptavidin limited the ability of the sig-DNA to hybridize with the cap-DNA, which were linked on the surface of a gold electrode. Therefore, the concentration of streptavidin was detected indirectly based on the concentration of CdSe QDs on the electrode surface. The concentration of CdSe QDs on the electrode surface was detected by differential pulse anodic stripping voltammetry. Under optimal conditions, the streptavidin detection range using the as-prepared biosensor was 1.96 pg/mL to 1.96 µg/mL and the detection limit was 0.65 pg/mL. The experimental results showed that the electrochemical biosensor could detect streptavidin rapidly and accurately.

    更新日期:2017-12-18
  • Label-free sensor for automatic identification of erythrocytes using digital in-line holographic microscopy and machine learning
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-15
    Taesik Go, Hyeokjun Byeon, Sang Joon Lee

    Cell types of erythrocytes should be identified because they are closely related to their functionality and viability. Conventional methods for classifying erythrocytes are time consuming and labor intensive. Therefore, an automatic and accurate erythrocyte classification system is indispensable in healthcare and biomedical fields. In this study, we proposed a new label-free sensor for automatic identification of erythrocyte cell types using a digital in-line holographic microscopy (DIHM) combined with machine learning algorithms. A total of 12 features, including information on intensity distributions, morphological descriptors, and optical focusing characteristics, is quantitatively obtained from numerically reconstructed holographic images. All individual features for discocytes, echinocytes, and spherocytes are statistically different. To improve the performance of cell type identification, we adopted several machine learning algorithms, such as decision tree model, support vector machine, linear discriminant classification, and k-nearest neighbor classification. With the aid of these machine learning algorithms, the extracted features are effectively utilized to distinguish erythrocytes. Among the four tested algorithms, the decision tree model exhibited the best identification performance for the training sets (n = 440, 98.18%) and test sets (n = 190, 97.37%). This proposed methodology, which smartly combined DIHM and machine learning, would be helpful for sensing abnormal erythrocytes and computer-aided diagnosis of hematological diseases in clinic.

    更新日期:2017-12-16
  • Silk provides a new avenue for third generation biosensors: sensitive, selective and stable electrochemical detection of nitric oxide
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-15
    Mustafa M. Musameh, Christopher J. Dunn, Md Hemayet Uddin, Tara D. Sutherland, Trevor D. Rapson

    Using heme entrapped in recombinant silk films, we have produced third generation biosensors, which allow direct electron transfer from the heme center to an electrode avoiding the need for electron mediators. Here, we demonstrate the use of these heme-silk films for the detection of nitric oxide (NO) at nanomolar levels in the presence and absence of oxygen. The sensor was prepared by drop-casting a silk solution on a glassy carbon electrode modified with multiwalled carbon nanotubes (MWCNT) followed by infusion with heme. The sensor was characterized by cyclic voltammetry and showed well defined and reversible Fe2+/Fe3+ redox couple activity, with NO detection by oxidation at potentials above +0.45 V or reduction at potentials below −0.7 V. Evaluation of the effect of pH on the sensor response to NO reduction indicated a maximum response at pH 3. The sensor showed good linearity in the concentration range from 19 – 190 nM (R2= 0.99) with a detection limit of 2 nM. The sensor had excellent selectivity towards NO with no or negligible interference from oxygen, nitrite, nitrate, dopamine and ascorbic acid and retained 86% of response after 2 months of operation and storage at room temperature.

    更新日期:2017-12-15
  • Photonic Crystals on Copolymer Film for Label-Free Detection of DNA Hybridization
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-14
    Han Su, Xin R. Cheng, Tatsuro Endo, Kagan Kerman

    The presence of a single-nucleotide polymorphism in Apolipoprotein E4 gene is implicated with the increased risk of developing Alzheimer's disease (AD). In this study, detection of AD-related DNA oligonucleotide sequence associated with Apolipoprotein E4 gene sequence was achieved using localized-surface plasmon resonance (LSPR) on 2D-Photonic crystal (2D-PC) and Au-coated 2D-PC surfaces. 2D-PC surfaces were fabricated on a flexible copolymer film using nano-imprint lithography (NIL). The film surface was then coated with a dual-functionalized polymer to react with surface immobilized DNA probe. DNA hybridization was detected by monitoring the optical responses of either a Fresnel decrease in reflectance on 2D-PC surfaces or an increase in LSPR on Au-coated 2D-PC surfaces. The change in response due to DNA hybridization on the modified surfaces was also investigated using mismatched and non-complementary oligonucleotides sequences. The proof-of-concept results are promising towards the development of 2D-PC on copolymer film surfaces as miniaturized and wearable biosensors for various diagnostic and defense applications.

    更新日期:2017-12-15
  • Minimizing the Effects of Oxygen Interference on L-lactate Sensors by a Single Amino Acid Mutation in Aerococcus viridans L-lactate Oxidase
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-14
    Kentaro Hiraka, Katsuhiro Kojima, Chi-En Lin, Wakako Tsugawa, Ryutaro Asano, Jeffrey T. LaBelle, Koji Sode

    L-lactate biosensors employing L-lactate oxidase (LOx) have been developed mainly to measure L-lactate concentration for clinical diagnostics, sports medicine, and the food industry. Some L-lactate biosensors employ artificial electron mediators, but these can negatively impact the detection of L-lactate by competing with the primary electron acceptor: molecular oxygen. In this paper, a strategic approach to engineering an AvLOx that minimizes the effects of oxygen interference on sensor strips was reported. First, we predicted an oxygen access pathway in Aerococcus viridans LOx (AvLOx) based on its crystal structure. This was subsequently blocked by a bulky amino acid substitution. The resulting Ala96Leu mutant showed a drastic reduction in oxidase activity using molecular oxygen as the electron acceptor and a small increase in dehydrogenase activity employing an artificial electron acceptor. Secondly, the Ala96Leu mutant was immobilized on a screen-printed carbon electrode using glutaraldehyde cross-linking method. Amperometric analysis was performed with potassium ferricyanide as an electron mediator under argon or atmospheric conditions. Under argon condition, the response current increased linearly from 0.05–0.5 mM L-lactate for both wild-type and Ala96Leu. However, under atmospheric conditions, the response of wild-type AvLOx electrode was suppressed by 9%–12% due to oxygen interference. The Ala96Leu mutant maintained 56%–69% of the response current at the same L-lactate level and minimized the relative bias error to −19% from −49% of wild-type. This study provided significant insight into the enzymatic reaction mechanism of AvLOx and presented a novel approach to minimize oxygen interference in sensor applications, which will enable accurate detection of L-lactate concentrations.

    更新日期:2017-12-15
  • A dual-functional microfluidic chip for on-line detection of interleukin-8 based on rolling circle amplification
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-12
    Wanling Zhang, Ziyi He, Linglu Yi, Sifeng Mao, Haifang Li, Jin-Ming Lin

    Interleukin 8 (IL-8), also known as C-X-C motif ligand 8(CXCL8), is a proinflammatory chemokine functioned in neutrophil chemotaxis and activation. And it plays an important role in the process of glioma stem-like cell vascularization in the latest research. Herein, a dual-function microfluidic biosensor based on rolling circle amplification (RCA) was fabricated for cell culture and online IL-8 detection. A microfluidic chip was designed with two high passages connected by the vertical channels. One of the channels with immobilized capture antibody was prepared for IL-8 detection and another channel for cell culture. Immunoassays were achieved by a sandwich structure consisting of antibodies, IL-8, and aptamers. Signal amplification was mainly due to RCA and biotin-streptavidin linkage. The linear range for IL-8 was 7.5 −120 pg•mL−1 in this assay. Moreover, the developed method was successfully applied to detect the IL-8 in tumor-derived endothelial cells (TDEC) and Human Umbilical Vein Endothelial cells (HUVEC) under chemical hypoxia condition. Semi-quantitative detection of IL-8 consumption in HUVEC cells in low oxygen condition was also achieved. These results were in statistical agreement with those obtained by commercial assay of enzyme-linked immunoassay kit (ELISA). The microfluidic chip based biosensor reported hereby has a large prospect in the basic research and clinical diagnosis of cancer stem cell.

    更新日期:2017-12-13
  • Air bio-battery with a gas/liquid porous diaphragm cell for medical and health care devices
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-11
    Takahiro Arakawa, Rui Xie, Fumiya Seshima, Koji Toma, Kohji Mitsubayashi

    Powering future generations of medical and health care devices mandates the transcutaneous transfer of energy or harvesting energy from the human body fluid. Glucose-driven bio fuel cells (bio-batteries) demonstrate promise as they produce electrical energy from glucose, which is a substrate presents in physiological fluids. Enzymatic biofuel cells can convert chemical energy into electrical energy using enzymes as catalysts. In this study, an air bio-battery was developed for healthcare and medical applications, consisting of a glucose-driven enzymatic biofuel cell using a direct gas-permeable membrane or a gas/liquid porous diaphragm. The power generation characteristics included a maximum current density of 285 μA/cm2 and maximum power density of 70.7 μW/cm2 in the presence of 5 mmol/L of glucose in solution. In addition, high-performance, long-term-stabilized power generation was achieved using the gas/liquid porous diaphragm for the reactions between oxygen and enzyme. This system can be powered using 5 mmol/L of glucose, the value of which is similar to that of the blood sugar range in humans.

    更新日期:2017-12-11
  • In-vitro and in-vivo measurement of the animal's middle ear acoustical response by partially implantable fiber-optic sensing system
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-10
    Zoran Djinović, Robert Pavelka, Miloš Tomić, Georg Sprinzl, Hanns Plenk, Udo Losert, Helga Bergmeister, Roberto Plasenzotti

    The main obstacle in realization of a totally implantable hearing aid is a lack of reliable implantable microphone. In this paper we have described a potentially miniature fiber-optic vibrometer based on a modified Michelson interferometer, designed to serve as a middle-ear microphone for totally implantable cochlear- or middle-ear hearing aids. A model of the sensing system was used for in-vitro and in-vivo investigation of acoustical response of sheep's middle-ear ossicles. Surgical and implantation procedure of introducing the sensing optical fiber into the middle-ear and its aiming at the incus was investigated and described here in detail. The frequency responses of the incus was measured while a cadaver and living sheep was exposed to the sinusoidal acoustical excitation of 40 to 90 dB SPL, in the frequency range from 100 Hz to 10 kHz. The amplitude of the incus vibration was found to be in the range between 10 pm to 100 nm, strongly depending on the frequency, with a lot of resonant peaks, corresponding mainly to the natural outer ear canal gain. The noise floor in the experiments was about 2 pm/Hz1/2, but recently we have decreased it to < 0.5 pm/Hz1/2, which corresponds to a minimal detectable sound level of 31–35 dB(A) SPL for humans. The histological examination of temporal bones of cadaver animals and the intensity of in-vivo optical signal demonstrated that the aiming of the sensing fiber to the target has been preserved for five months after the implantation.

    更新日期:2017-12-10
  • Ultra-narrow surface lattice resonances in plasmonic metamaterial arrays for biosensing applications
    Biosens. Bioelectron. (IF 7.780) Pub Date : 2017-12-09
    Artem Danilov, Gleb Tselikov, Fan Wu, Vasyl G. Kravets, Igor Ozerov, Frederic Bedu, Alexander N. Grigorenko, Andrei V. Kabashin

    When excited over a periodic metamaterial lattice of gold nanoparticles (~ 100 nm), localized plasmon resonances (LPR) can be coupled by a diffraction wave propagating along the array plane, which leads to a drastic narrowing of plasmon resonance lineshapes (down to a few nm full-width-at-half-maximum) and the generation of singularities of phase of reflected light. These phenomena look very promising for the improvement of performance of plasmonic biosensors, but conditions of implementation of such diffractively coupled plasmonic resonances, also referred to as plasmonic surface lattice resonances (PSLR), are not always compatible with biosensing arrangement implying the placement of the nanoparticles between a glass substrate and a sample medium (air, water). Here, we consider conditions of excitation and properties of PSLR over arrays of glass substrate-supported single and double Au nanoparticles (~100–200 nm), arranged in a periodic metamaterial lattice, in direct and Attenuated Total Reflection (ATR) geometries, and assess their sensitivities to variations of refractive index (RI) of the adjacent sample dielectric medium. First, we identify medium (PSLRair, PSLRwat for air and water, respectively) and substrate (PSLRsub) modes corresponding to the coupling of individual plasmon oscillations at medium- and substrate-related diffraction cut-off edges. We show that spectral sensitivity of medium modes to RI variations is determined by the lattice periodicity in both direct and ATR geometries (~ 320 nm per RIU change in our case), while substrate mode demonstrates much lower sensitivity. We also show that phase sensitivity of PSLR can exceed 105 degrees of phase shift per RIU change and thus outperform the relevant parameter for all other plasmonic sensor counterparts. We finally demonstrate the applicability of surface lattice resonances in plasmonic metamaterial arrays to biosensing using standard streptavidin-biotin affinity model. Combining advantages of nanoscale architectures, including drastic concentration of electric field, possibility of manipulation at the nanoscale etc, and high phase and spectral sensitivities, PSLRs promise the advancement of current state-of-the-art plasmonic biosensing technology toward single molecule label-free detection.

    更新日期:2017-12-10
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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