Enhancement of hydrophilicity and functionalization of CdTe QDs (Quantum Dots) via surface modifications have made them suitable to be used as specific probes for cell imaging. Applications for targeting cell surfaces have been widely demonstrated in vitro but their use in animal models is not trivial. Here, we reported the interaction of mercaptosuccinic-coated (MSA) CdTe QDs with the epidermis of

Photochemical reactions can be designed to convert either irreversibly or reversibly a nonemissive reactant into an emissive product. The irreversible disconnection of a photocleavable group from an emissive chromophore or the reversible interconversion of a photochromic component is generally exploited to implement these operating principles for fluorescence switching. In both instances, the interplay

Quantitative phase imaging (QPI) technique is used to determine various biophysical parameters, such as refractive index, cell thickness, morphology, etc. On the other hand, fluorescence microscopy is used to acquire information regarding molecular specificity of the biological cells and tissues. Conventionally, a fully coherent light source such as laser is used in QPI technique to obtain the interference

Fluorescence technologies have been the preferred method for detection, analytical sensing, medical diagnostics, biotechnology, imaging, and gene expression for many years. Fluorescence becomes essential for studying molecular processes with high specificity and sensitivity through a variety of biological processes. A significant problem for practical fluorescence applications is the apparent non-linearity

Six emissive amphoteric copolymers were prepared and characterized (1H NMR, DSC, steady-state UV-vis, and emission spectroscopy) in the paper. A system of multi-color emitters, composed of P1 (green and yellow), P2 (green), P3 (red), P4 (blue), P5 (yellow) and P6 (green and yellow), were presented. P5 showed multicolor fluorescence that belonged to the color-specially emissive system at different excitation

Single-molecule hybridisation of CY3 dye labelled short oligonucleotides to surface immobilised probes was investigated in zero-mode waveguide nanostructures using a modified DNA sequencer. At longer measuring times, we observed changes of the initial hybridisation fluorescence pulse pattern which we attribute to products created by chemical reactions at the nucleobases. The origin is a charge separated

Multiphoton fluorescence lifetime microscopy has revolutionized studies of pathophysiological and xenobiotic dynamics, enabling temporal quantification of these processes in intact organs in vivo. We have previously used multiphoton fluorescence lifetime microscopy to characterise the morphology and amplitude weighted mean fluorescence lifetime of the endogenous fluorescent metabolic cofactor nicotinamide

Green-emitting water-soluble amino-ketoenole dye AmyGreen is proposed as an efficient fluorescent stain for visualization of bacterial amyloids in biofilms and the detection of pathological amyloids in vitro. This dye is almost non-fluorescent in solution, displays strong green emission in the presence of amyloid fibril of proteins. AmyGreen is also weakly fluorescent in presence to biomolecules that

FRET is both a phenomenon and a spectroscopic technique, capable of measuring one geometric quantity: kappa-squared divided by the sixth power of the donor-acceptor distance. Kappa-squared is often replaced by a constant even though such a replacement may lead to serious errors. Kappaphobia, the fear of kappa or the reluctance to deal with kappa-squared adequately, is a looming presence in the FRET

Fluorescence Lifetime Imaging (FLIM) in life sciences based on ultrashort laser scanning microscopy and time-correlated single photon counting (TCSPC) started 30 years ago in Jena/East-Germany. One decade later, first two-photon FLIM images of a human finger were taken with a lab microscope based on a tunable femtosecond Ti:sapphire laser. In 2002/2003, first clinical non-invasive two-photon FLIM studies

An easy to make organic probe (hereafter called as R) possessing multiple ligating sites have been synthesized and characterized using spectral techniques. The probe exhibits selective and sensitive turn-on fluorescence response with Al(III) in aqueous dimethylformamide (DMF) (1:1 v/v) solution. Fluorescence titration experiment shows that the probe binds with Al(III) with a 1:1 stoichiometry and a

Ba5Zn4Gd8O21:Tb3+ nanorods; synthesized via solution combustion route; were found to crystallize in the tetragonal (I4/m, 87) crystal system. The UV excitation at 290 nm of all Ba5Zn4Gd8O21:Tb3+ samples yielded the characteristics emission corresponding to 5D4 → 7F6,5,4,3 transitions in Tb3+ activator (used for Judd-Ofelt analysis). A detailed investigation of photoluminescence decay curves and emission

The measurement of fluorescence spectra and the determination of fluorescence quantum yields in transparent samples are conceptually simple tasks, but these procedures are subject to several pitfalls that can lead to significant errors. Available technical reports and protocols often assume that the reader possesses a solid theoretical background in spectroscopy and has ample experience with fluorescence

In several cellular systems, the phasor FLIM approach has shown the existence of more than 2 components in the same pixel, a typical example being free and bound NADH. In order to properly quantify the concentrations and the spatial distributions of fluorescence components associated with different molecular species we developed a general method to resolve 3 and 4 components in the same pixel using

Facultative intracellular pathogens are able to live inside and outside host cells. It is highly desirable to differentiate their cellular locations for the purposes of fundamental research and clinical applications. In this work, we developed a novel analysis platform that allows users to choose two analysis models: amplitude weighted lifetime ( τ A ) and intensity weighted lifetime ( τ I ) for fluorescence

Intracellular refractive index (RI) is an essential biophysical parameter, which best represents the mass and the distribution of proteins in the cell interior, including high-density accumulations in membraneless organelles. For RI measurements, a number of sophisticated techniques have been developed; however most of the new approaches are either insufficiently sensitive to intracellular variations

In this paper, a photoluminescent turn off-on switch probe β-cyclodextrin-hydroxyquinoline (β-CD-HQ) was efficiently applied for detection and measurement of Cd2+ ions and detection of tetracycline. The proposed assay has shown an excellent selective fluorescence response toward Cd2+ ions over other ions like Al3+, Pb2+, Zn2+, Co2+, K+, Na+ and Sr2+. The fluorescence emission intensity of the probe

We have implemented polarization-resolved fluorescence lifetime measurement through stimulated emission based pump-probe technique, which promises much higher temporal resolution (~4 ps) than conventional time-correlated single-photon counting. The depolarization of ATTO 647N fluorescent dye is resolved through anisotropy fluorescence lifetime measurements, with variable time delay introduced between

Single molecule localization microscopy (SMLM) allows the imaging of cellular structures with resolutions five to ten times below the diffraction limit of optical microscopy. It was originally introduced as a two-dimensional technique based on the localization of single emitters as projection onto the x-y imaging plane. The determination of the axial position of a fluorescent emitter is only possible

In recent years, luminescence nanothermometers with near infrared light (NIR) emission excited in the NIR range have attracted much attention due to their potential bio applications. Here, we propose a new nanothermometer based on triple doped 1%Ho, 1%Er, 1%Yb - Y2O3that operates in the second and third biological window around 1200 and 1530 nm under pulsed excitation at 905 nm. The NIR emissions were

Despite intracellular molecular dynamics being fundamental to understand pathological, biomechanical or biochemical events, several processes are still not clear because of the difficulty of monitoring and measuring these phenomena. To engineer an effective fluorescent tool useful to improve protein intracellular tracking studies, we fused a supernegative green fluorescent protein, (−30)GFP, to a myogenic

An eco-friendly fluorescence polymer nanoparticle based on carbon quantum dots and poly(methyl methacrylate) nanoparticles is successfully fabricated to detect sulfadiazine. By making use of the abundant functional group of carbon quantum dots and poly(methyl methacrylate) nanoparticles, without any extra modification, the synthetic process of the fluorescence nanoparticles is reduced and the unnecessary

To better understand pH-dependence of endogenous fluorescence of algae, we employed spectroscopy and microscopy methods, including advanced time-resolved fluorescence imaging microscopy (FLIM), using green algae Chlorella sp. as a model system. Absorption spectra confirmed two peaks, at 400-420 nm and 670 nm. Emission was maximal at 680 nm, with smaller peaks between 520 and 540 nm. Acidification led

Upconversion nanoparticles have attracted considerable attention as luminescent markers for bioimaging and sensing due to their capability to convert near-infrared (NIR) excitation into visible or NIR luminescence. However, the wavelength of about 970 nm is commonly used for the upconversion luminescence excitation, where the strong absorption of water is observed, which can lead to laser-induced overheating

Fluorescence Lifetime Imaging Microscopy (FLIM) is a robust tool to measure Förster Resonance Energy Transfer (FRET) between two fluorescent proteins, mainly when using genetically-encoded FRET biosensors. It is then possible to monitor biological processes such as kinase activity with a good spatiotemporal resolution and accuracy. Therefore, it is of interest to improve this methodology for future

In this review, we discuss methods and advancements in fluorescence lifetime imaging microscopy that permit measurements to be performed at faster speed and higher resolution than previously possible. We review fast single-photon timing technologies and the use of parallelized detection schemes to enable high-throughput and high content imaging applications. We appraise different technological implementations

Photochemical stability is one of the most important parameters that determine the usefulness of organic dyes in different applications. This Review addresses key factors that determine the dye photostability. It is shown that photodegradation can follow different oxygen-dependent and oxygen-independent mechanisms and may involve both 1S1-3T1 and higher-energy 1Sn-3Tn excited states. Their involvement

Metal clusters confined inside zeolite materials display remarkable luminescent properties, making them very suitable as potential alternative phosphors in white LED applications. However, up to date, only single-color emitters have been reported for luminescent metal-exchanged zeolites. In this study, we synthesized and characterized white emitting silver-sulfur zeolites, which show a remarkable color

Spatial light modulation using cost efficient digital micromirror devices (DMD) is finding broad applications in fluorescence microscopy due to the reduction of phototoxicity and bleaching and the ability to manipulate proteins in optogenetic experiments. However, precise illumination by DMDs and their application to single-molecule localization microscopy (SMLM) remained a challenge because of non-linear

We describe the performance of a new wide area time-gated single-photon avalanche diode (SPAD) array for phasor-FLIM, exploring the effect of gate length, gate number and signal intensity on the measured lifetime accuracy and precision. We conclude that the detector functions essentially as an ideal shot noise limited sensor and is capable of video rate FLIM measurement. The phasor approach used in

Fluorescent dyes used for single-molecule spectroscopy can undergo millions of excitation-emission cycles before photobleaching. Due to the upconcentration of light in a plasmonic hotspot, the conditions for fluorescent dyes are even more demanding in DNA origami nanoantennas. Here, we briefly review the current state of fluorophore stabilization for single-molecule imaging and reveal additional factors

This paper presents a two-photon phase-resolved fluorescence-lifetime measurement method based on the use of an ultrashort pulse laser. The proposed method also involves the use of a lock-in amplifier to control the phase difference between the reference and fluorescence signals, thereby facilitating the use of an alternative method for determining fluorescence lifetimes. Verification of the fluorescence

2-aminopurine (2AP) is a responsive fluorescent base analogue that is used widely as a probe of the local molecular environment in DNA. The ability of 2AP to report changes in local conformation and base-stacking interactions arises from the efficient quenching of its fluorescence by the natural DNA bases. However, the mechanism of this inter-base quenching remains imperfectly understood. Two previous

In this work we demonstrate a composite material based on silica particles. The particles have been doped with zinc oxide quantum dots which possess long living luminescence. The surface of the particles has been functionalized with phenyl groups using sol-gel process. The new material has been successfully applied for visualization of natural latent fingermarks on several surfaces, in particular,

Increasingly, the auto-fluorescent coenzymes NAD(P)H and FAD are being tracked by multi-photon fluorescence lifetime microscopy (FLIM) and used as versatile markers for changes in mammalian metabolism. The cellular redox state of different cell model systems, organoids and tissue sections is investigated in a range of pathologies where the metabolism is disrupted or reprogrammed; the latter is particularly

Many molecular processes within a cell are carried out by molecular machines built from a large number of proteins organized by their protein-protein interactions (PPIs). Exploring PPIs in their cellular context is critical to better understand the proteins functions. Förster resonance energy transfer measured by fluorescence lifetime imaging (FLIM-FRET) enables to monitor PPIs and to map their spatial

In this paper, a simple and convenient fluorescence method for detection of uric acid (UA) based on Ag-doped carbon quantum dots (Ag-CQDs) is developed. The Ag-CQDs contain Ag species could bond with UA, which promoted the electron and/or energy transfer and produced high quenching extent. Thus, the fluorescence intensity of Ag-CQDs decreased in the presence of UA. Under the optimal condition, the

There is no abstract.

Photon pressure has been used to induce the aggregation from solution of a series of photoluminescent conjugated polyelectrolytes containing tetraphenylethene units. These polymers show steady-state and time-resolved emission properties that are dependent on the local chromophore environment that can be influenced by the degree of intra- and inter-molecular interactions, which enables the photoaggregation

Noble metal nanomaterials have been studied by many researchers for their ultra-small size, excellent photophysical properties and good biocompatibility. Metal nanoclusters are a kind of nanoscale ultrafine particle, which have completely different properties from macroscopic metals. In the visible region, they do not usually show the characteristic surface plasmon resonance absorption but instead

The present manuscript gives a short overview on Förster Resonance Energy Transfer (FRET) of molecular interactions in the nanometre range. First, its principle is described and a short historical overview is given. Subsequently some principal methods and applications of FRET sensing and imaging are described (with some emphasis on fluorescence lifetime imaging, FLIM), and finally two innovative FRET

The oocytes from Xenopus laevis are well known for their polarity, presenting a distinct animal and vegetal pole. Other heterogeneities are less known. To study the heterogeneity of the Xenopus oocyte, we expressed eGFP and analyzed the protein distribution with fluorescence lifetime microscopy. The vegetal pole exhibited higher levels of fluorescence, than the animal pole. However, the fluorescence

Photo-initiated, oxygen-mediated degradation of the molecules in the active layer of organic photovoltaic, OPV, devices currently limits advances in the development of solar cells. To address this problem systematically and at a molecular level, it is informative to quantify the kinetics of the pertinent processes, both in solution phase and in solid films. To this end, we examined the oxygen-dependent

We report a multidimensional luminescence microscope providing hyperspectral imaging and time-resolved (luminescence lifetime) imaging for the study of luminescent diamond defects. The instrument includes crossed-polariser white light transmission microscopy to reveal any birefringence that would indicate strain in the diamond lattice. We demonstrate the application of this new instrument to detect

Exploring metabolism in human tumors at the cellular level remains a challenge. The reduced form of metabolic cofactor NAD(P)H is one of the major intrinsic fluorescent components in tissues and a valuable indicator of cellular metabolic activity. Fluorescence lifetime imaging (FLIM) enables resolution of both the free and protein-bound fractions of this cofactor, and thus, high sensitivity detection

The effect of aminopyridines substituted at different positions on the fluorescence properties deserves to be studied. Since 2-aminopyridyl-based probes have been reported, the effects of 3-aminopyridine and 4-aminopyridine on the performance of fluorescein probes were discussed in here. Two Schiff base fluorescein probes FN-1, FN-2 were designed and synthesized. Among them, since the ligand shows

Biological proteins are understood in terms of five structural levels-primary, secondary, tertiary, quaternary and quinary. The quinary structure is defined as the set of macromolecular interactions that are transient in vivo. This includes non-covalent protein-protein interactions occurring within the crowded intracellular environment. For much of twentieth century science, the canonical approach

A novel label-free fluorescence aptasensor used for the detection of ochratoxin A (OTA) is presented in this study. When aggregated on the surface of DNA aptamer, aggregation-induced emission (AIE) fluorescence probe presents turn-on fluorescence property. The method proposed in this article was based on an AIE probe, 4, 4-(1E,1E)-2, 2-(anthracene-9, 10-diyl) bis (ethene-2, 1-diyl) bis (N, N, N-tr

Viscosity sensitive fluorophores termed 'molecular rotors' represent a convenient and quantitative tool for measuring intracellular viscosity via Fluorescence Lifetime Imaging Microscopy (FLIM). We compare the FLIM performance of two BODIPY-based molecular rotors bound to HaloTag protein expressed in different subcellular locations. While both rotors are able to penetrate live cells and specifically

Autofluorescence based fluorescence lifetime imaging microscopy (AF-FLIM) techniques have come a long way from early studies on cancer characterization and have now been widely employed in several cellular and animal studies covering a wide range of diseases. The majority of research in autofluorescence imaging (AFI) study metabolic fluxes in live biological samples. However, tissues from clinical

Protein-induced fluorescence enhancement (PIFE) is an increasingly used approach to investigate DNA-protein interactions at the single molecule level. The optimal probe for this type of application is highly photostable, has a high absorption extinction coefficient, and has a moderate fluorescence quantum yield that increases significantly when the dye is in close proximity to a large macromolecule

This article focuses on the use of graphene oxide-polyaniline (GO-PANI) nanocomposite as fluorescent probe for sensing of adenine (A) and guanine (G). Swollen liquid crystalline mesophase were used for the synthesis of graphene oxide-polyaniline nanocomposite. GO-PANI nanocomposite showed enhanced fluorescent at 441 nm (ƛ excitation = 361 nm) on interaction of purines viz A and G solutions in dimethyl

The growing demand for tissue engineered vascular grafts (TEVG) motivates the development of optimized fabrication and monitoring procedures. Bioreactors which provide physiologically-relevant conditions are important for improving holistic TEVG properties and performance. Herein we describe a fiber-based intraluminal imaging system that allows for in situ assessment of vascular materials and re-cellularization

Induced pluripotent stem cells (iPSC) are a promising tool for personalized cell therapy, in particular, in the field of dermatology. Metabolic plasticity of iPSC are not completely understood due to the fact that iPSC have a mixed mitochondrial phenotype, which still resembles that of somatic cells. In this study we investigated the metabolic changes in iPSC undergoing differentiation in two directions

Fluorescence lifetime sensing enables researchers to probe the physicochemical environment of a fluorophore providing a window through which we can observe the complex molecular make-up of the cell. Fluorescence lifetime imaging microscopy (FLIM) quantifies and maps cell biochemistry, a complex ensemble of dynamic processes. Unfortunately, typical high-resolution FLIM systems exhibit rather limited

Concentric Förster resonance energy transfer (cFRET) is an emerging concept for single-vector multiplexed bioanalysis and imaging. It features a network of competitive and sequential energy transfer pathways, which, to date, has been assembled with a central semiconductor quantum dot (QD) and biomolecular linkers to multiple copies of multiple types of concentrically-arranged fluorescent dyes. In this

A ratiometric fluorescence method is designed and exploited for the sensitive detection of Hg2+ and Fe3+ ions, which is prepared by simply mixing bovine serum albumin-protected gold/silver nanoclusters (BSA-Au/Ag NCs) with histidine-stabilized gold nanoclusters (His-Au NCs). The as-prepared Au NCs/Au-Ag NCs solution emits pink fluorescence and exhibits two emission peaks around 485 and 660 nm excited

Nearly monodisperse Zinc oxide (ZnO) quantum dots (QDs) displayed yellow fluorescence were synthesized using urea as dispersant. In this paper, urea-ZnO QDs were used as fluorescent probe to detect Cr6+ in solution. The emission from the as-synthesized urea-ZnO QDs is selectively quenched when Cr6+ ions were added. Moreover, there are two linear relationships between the quenching of fluorescence intensity

The Conference and Spring School on Properties, Design and Applications of Upconversion Nanomaterials (UPCON) provides a new forum for all experts and newcomers in the field of upconversion research. On the occasion of the second UPCON 2018 in Valencia (Spain), we are pleased to present a collection of 12 reviews and research articles that reflect recent advances in upconversion materials, their unique

In this work, we report a sensitive and selective turn-on fluorescence detection of cysteine with glutathione protected silver nanoclusters (GSH-Ag NCs). The glutathione stabilized silver nanoclusters were synthesized by the boiling water method. When excited at 380 nm, the GSH-Ag NCs exhibited a weak emission at about 680 nm, which could be enhanced by cysteine. The proposed method allows evaluation