Search

Polysaccharides are widely represented in plants and bacteria, where they are distinguished by their extraordinary structural diversity and the performance of various functions. To study the functions of polysaccharides, their fluorescent labeling is needed. This review discusses methods for introducing fluorescent labels into polysaccharides by chemical modification of certain functional groups of these complex biopolymers, as well as using the so-called bioorthogonal reactions, which allow labeling in a cell without affecting its viability. In addition to modification with organic dyes, the possibility of using quantum dots and coordination compounds of lanthanides is also discussed. [ABSTRACT FROM AUTHOR]

Reliable cell labeling and tracking techniques are imperative for elucidating the intricate and ambiguous interactions between mesenchymal stromal cells (MSCs) and tumors. Here, we explore fluorescent photoconvertible nanoengineered vesicles to study mMSC migration in brain tumors. These 3 μm sized vesicles made of carbon nanoparticles, Rhodamine B (RhB), and polyelectrolytes are readily internalized by cells. The dye undergoes photoconversion under 561 nm laser exposure with a fluorescence blue shift upon demand. The optimal laser irradiation duration for photoconversion was 0.4 ms, which provided a maximal blue shift of the fluorescent signal label without excessive laser exposure on cells. Vesicles modified with an extra polymer layer demonstrated enhanced intracellular uptake without remarkable effects on cell viability, motility, or proliferation. The optimal ratio of 20 vesicles per mMSC was determined. Moreover, the migration of individual mMSCs within 2D and 3D glioblastoma cell (EPNT-5) colonies over 2 days and in vivo tumor settings over 7 days were traced. Our study provides a robust nanocomposite platform for investigating MSC–tumor dynamics and offers insights into envisaged therapeutic strategies. Photoconvertible vesicles also present an indispensable tool for studying complex fundamental processes of cell–cell interactions for a wide range of problems in biomedicine. [ABSTRACT FROM AUTHOR]

Tracing individual cell pathways among the whole population is crucial for understanding their behavior, cell communication, migration dynamics, and fate. Optical labeling is one approach for tracing individual cells, but it typically requires genetic modification to induce the generation of photoconvertible proteins. Nevertheless, this approach has limitations and is not applicable to certain cell types. For instance, genetic modification often leads to the death of macrophages. This study aims to develop an alternative method for labeling macrophages by utilizing photoconvertible micron-sized capsules capable of easy internalization and prolonged retention within cells. Thermal treatment in a polyvinyl alcohol gel medium is employed for the scalable synthesis of capsules with a wide range of fluorescent dyes, including rhodamine 6G, pyronin B, fluorescein, acridine yellow, acridine orange, thiazine red, and previously reported rhodamine B. The fluorescence brightness, photostability, and photoconversion ability of the capsules are evaluated using confocal laser scanning microscopy. Viability, uptake, mobility, and photoconversion studies are conducted on RAW 264.7 and bone marrow-derived macrophages, serving as model cell lines. The production yield of the capsules is increased due to the use of polyvinyl alcohol gel, eliminating the need for conventional filtration steps. Capsules entrapping rhodamine B and rhodamine 6G meet all requirements for intracellular use in individual cell tracking. Mass spectrometry analysis reveals a sequence of deethylation steps that result in blue shifts in the dye spectra upon irradiation. Cellular studies on macrophages demonstrate robust uptake of the capsules. The capsules exhibit minimal cytotoxicity and have a negligible impact on cell motility. The successful photoconversion of RhB-containing capsules within cells highlights their potential as alternatives to photoconvertible proteins for individual cell labeling, with promising applications in personalized medicine.

Reliable cell labeling and tracking techniques are imperative for elucidating the intricate and ambiguous interactions between mesenchymal stromal cells (MSCs) and tumors. Here, we explore fluorescent photoconvertible nanoengineered vesicles to study mMSC migration in brain tumors. These 3 μm sized vesicles made of carbon nanoparticles, Rhodamine B (RhB), and polyelectrolytes are readily internalized by cells. The dye undergoes photoconversion under 561 nm laser exposure with a fluorescence blue shift upon demand. The optimal laser irradiation duration for photoconversion was 0.4 ms, which provided a maximal blue shift of the fluorescent signal label without excessive laser exposure on cells. Vesicles modified with an extra polymer layer demonstrated enhanced intracellular uptake without remarkable effects on cell viability, motility, or proliferation. The optimal ratio of 20 vesicles per mMSC was determined. Moreover, the migration of individual mMSCs within 2D and 3D glioblastoma cell (EPNT-5) colonies over 2 days and in vivo tumor settings over 7 days were traced. Our study provides a robust nanocomposite platform for investigating MSC–tumor dynamics and offers insights into envisaged therapeutic strategies. Photoconvertible vesicles also present an indispensable tool for studying complex fundamental processes of cell–cell interactions for a wide range of problems in biomedicine.

A new method for assessing the quality of fibre coating based on a combination of fluorescence microscopy and electron paramagnetic resonance is presented in this work. An influence of the carboxymethylcellulose/polyvinylamine gel preparation method on the mobility of the spin label was established. The mobility of the spin label changes from 3.5 ns in the case of a polyvinylamine solution to 12.8 ns in the case of a cross-linked gel on the surface of the glass fibre. A qualitative relationship was found between the mobility of the spin label in the gel applied to the glass fibre and the rate of spreading of crude oil over its surface. This method can be used to make membranes for the separation of water-in-oil emulsions.

The semi-synthesis and antibacterial study of penicillin V potassium is primarily an interdisciplinary experiment. Currently, only a few foreign universities such as the Massachusetts Institute of Technology (MIT) allow undergraduate students to conduct this experiment. To incorporate a research-like environment into teaching experiments and enable students to develop scientific thinking, the following improvements were made to the experiment: 1) A circulating condensing device was designed and built, and low-temperature control was introduced to improve the stability of the products and effectively reduce the formation of by-products. 2) Absolute ethyl alcohol was added to remove the by-products based on solubility difference. 3) The minimum inhibitory concentration of penicillin was determined using the microbroth dilution method, and antibiotic sensitivity was determined using the Oxford penicillin cup method. 4) The effects of penicillin on the integrity of bacterial cell walls were characterized via wheat germ agglutinin fluorescent labeling combined with confocal fluorescence microscopy. This comprehensive experiment, which combines several important multidisciplinary concepts, can develop students' skills in integrated analysis and increase their interest in scientific research. [ABSTRACT FROM AUTHOR]

The behavior and migration of human mesenchymal stromal cells (hMSCs) are focal points of research in the biomedical field. One of the major aspects is potential therapy using hMCS, but at present, the safety of their use is still controversial owing to limited data on changes that occur with hMSCs in the long term. Fluorescent photoconvertible proteins are intensively used today as "gold standard" to mark the individual cells and study single-cell interactions, migration processes, and the formation of pure lines. A crucial disadvantage of this method is the need for genetic modification of the primary culture, which casts doubt on the possibility of exploring the resulting clones in personalized medicine. Here we present a new approach for labeling and tracking hMSCs without genetic modification based on the application of cell-internalizable photoconvertible polyelectrolyte microcapsules (size: 2.6 ± 0.5 μm). These capsules were loaded with rhodamine B, and after thermal treatment, exhibited fluorescent photoconversion properties. Photoconvertible capsules demonstrated low cytotoxicity, did not affect the immunophenotype of the hMSCs, and maintained a high level of fluorescent signal for at least seven days. The developed approach was tested for cell tracking for four days and made it possible to trace the destiny of daughter cells without the need for additional labeling. [ABSTRACT FROM AUTHOR]

Fluorescent photoconvertible materials and molecules have been successfully exploited as bioimaging markers and cell trackers. Recently, the novel fluorescent photoconvertible polymer markers have been developed that allow the long‐term tracking of individual labeled cells. However, it is still necessary to study the functionality of this type of fluorescent labels for various operating conditions, in particular for commonly used discrete wavelength lasers. In this article, the photoconversion of fluorescent polymer labels with both pulsed and continuous‐wave lasers with 532 nm‐irradiation wavelength, and under different laser power densities were studied. The photoconversion process was described and its possible mechanism was proposed. The peculiarities of fluorescent polymer capsules performance as an aqueous suspension and as a single capsule were described. We performed the successful nondestructivity marker photoconversion inside RAW 264.7 monocyte/macrophage cells under continuous‐wave laser with 532 nm‐irradiation wavelength, showing prospects of these fluorescent markers for long‐term live cell labeling. [ABSTRACT FROM AUTHOR]

The behavior and migration of human mesenchymal stromal cells (hMSCs) are focal points of research in the biomedical field. One of the major aspects is potential therapy using hMCS, but at present, the safety of their use is still controversial owing to limited data on changes that occur with hMSCs in the long term. Fluorescent photoconvertible proteins are intensively used today as “gold standard” to mark the individual cells and study single-cell interactions, migration processes, and the formation of pure lines. A crucial disadvantage of this method is the need for genetic modification of the primary culture, which casts doubt on the possibility of exploring the resulting clones in personalized medicine. Here we present a new approach for labeling and tracking hMSCs without genetic modification based on the application of cell-internalizable photoconvertible polyelectrolyte microcapsules (size: 2.6 ± 0.5 μm). These capsules were loaded with rhodamine B, and after thermal treatment, exhibited fluorescent photoconversion properties. Photoconvertible capsules demonstrated low cytotoxicity, did not affect the immunophenotype of the hMSCs, and maintained a high level of fluorescent signal for at least seven days. The developed approach was tested for cell tracking for four days and made it possible to trace the destiny of daughter cells without the need for additional labeling.

Metal Organic Frameworks (MOFs) are extensively used for a wide range of applications due to their exceptionally high surface area. MOF particles are conventionally in micron size, but the nanosized MOFs show good transportation/mobility due to their small size, and when combined with the high surface area of MOFs, it makes MOF nanoparticles an ideal candidate to study for environmental remediation. Therefore, it is important to study the ecotoxicological impact of these MOFs. In this study, we developed rhodamine labelled nanoparticles of zinc imidazolate metal organic framework (ZIF-8 MOFs) as a means of in vivo tracing the MOF translocation in C. elegans. Rhodamine B isothiocyanate functionalized ZIF-8 MOFs nanoparticles (RBITC@ZIF-8 MOF nanoparticles; size 44 ± 7 nm) were fed to the worms naturally within a concentration range of 0.16–16.4 μg mg−1. Fluorescence was detected in the pharyngeal and gut lumen regions of the worms after 4 h of treatment, for exposure concentrations >0.163 μg mg−1. A higher intensity of fluorescence was observed at the end of 24 h for all exposure concentrations. Worms treated with RBITC@ZIF-8 MOF concentrations of ≥1.63 μg mg−1 for 24 h showed a bright stable fluorescence signal at the tail region. The uptake of RBITC@ZIF-8 MOF for an exposure concentration of 0.163, 1.63, and 8.2 μg mg−1 was found to be 52.1, 11.4 and 28.6%, respectively. Through this study, we showed that RBITC@ZIF-8 MOFs can be exposed to C. elegans and imaged at low concentrations of ∼0.16 μg mg−1.

Tracing individual cell pathways among the whole population is crucial for understanding their behavior, cell communication, migration dynamics, and fate. Optical labeling is one approach for tracing individual cells, but it typically requires genetic modification to induce the generation of photoconvertible proteins. Nevertheless, this approach has limitations and is not applicable to certain cell types. For instance, genetic modification often leads to the death of macrophages. This study aims to develop an alternative method for labeling macrophages by utilizing photoconvertible micron-sized capsules capable of easy internalization and prolonged retention within cells. Thermal treatment in a polyvinyl alcohol gel medium is employed for the scalable synthesis of capsules with a wide range of fluorescent dyes, including rhodamine 6G, pyronin B, fluorescein, acridine yellow, acridine orange, thiazine red, and previously reported rhodamine B. The fluorescence brightness, photostability, and photoconversion ability of the capsules are evaluated using confocal laser scanning microscopy. Viability, uptake, mobility, and photoconversion studies are conducted on RAW 264.7 and bone marrow-derived macrophages, serving as model cell lines. The production yield of the capsules is increased due to the use of polyvinyl alcohol gel, eliminating the need for conventional filtration steps. Capsules entrapping rhodamine B and rhodamine 6G meet all requirements for intracellular use in individual cell tracking. Mass spectrometry analysis reveals a sequence of deethylation steps that result in blue shifts in the dye spectra upon irradiation. Cellular studies on macrophages demonstrate robust uptake of the capsules. The capsules exhibit minimal cytotoxicity and have a negligible impact on cell motility. The successful photoconversion of RhB-containing capsules within cells highlights their potential as alternatives to photoconvertible proteins for individual cell labeling, with promising applications in personalized medicine., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Determination of the expression level of tumor marker PRAME protein is important both for predicting the course of the disease and for monitoring the effectiveness of anticancer therapy. A fluorescently labeled monoclonal antibody to the PRAME protein was obtained by periodate oxidation of glycans followed by modification with a bifunctional azido-oxyamine reagent and a "click" reaction with alkyne-modified sulfonated cyanine dye Cy3. A new approach to the synthesis of a bifunctional azido-oxyamine reagent using the ethoxyethylidene protecting group for oxyamine is proposed. The labeled antibodies were characterized with UV/Vis absorption spectra and the stoichiometry of the modification was determined. It has been demonstrated that the fluorescent antibodies retain affinity and can be used as a diagnostic tool for detecting the residual marker (the PRAME protein) after anticancer therapy. [ABSTRACT FROM AUTHOR]

To make waterborne painting be applied into metal protection area, the mechanical, water resistant, and anti‐corrosion properties of the dried coating based on it should be improved effectively. Among various methods, self‐crosslinking the latex during its drying process is thought to be an effective way. For example, the latex with DAAM/ADH (diacetoneacrylamide/adipoyl hydrazide) as the self‐crosslinker has attracted a lot of attention due to its excellent stability and coating performance. In this study, a kind of reactable AIEgen was used and taken part in synthesizing the self‐crosslinkable acrylic latex. Based on Aggregation Induced Emission(AIE) phenomenon, it is easy to real‐time trace the preparation and curing process of the obtained latexes. At the same time, the influence of DAAM/ADH on the properties of the cured coating was studied in detail. In addition, as AIEgen is knitted onto the polymer chains via chemical bonds, external stimulus might interfere the coating's fluorescent property. Based on this phenomenon, the cured coating was studied and explored the feasibility to be applied into gas sensing area via its fluorescent property. [ABSTRACT FROM AUTHOR]

Fluorescent dyes absorbing and emitting in the visible and near-IR regions are promising for the development of fluorescent probes for labeling and bio-visualization of body cells. The ability to absorb and emit in the long-wavelength region increases the efficiency of recording the spectral signals of the probes due to the higher permeability of the skin layers. Compared to other fluorescent dyes, BODIPYs are attractive due to their excellent photophysical properties–narrow absorption and emission, intense fluorescence, simple signal modulation for the practical applications. As part of conjugates with biomolecules, BODIPY could act as a biomarker, but as therapeutic agent, which allows solving several problems at once-labeling or bioimaging and treatment based on the suppression of pathogenic microflora and cancer cells, which provides a huge potential for practical application of BODIPY conjugates in medicine. The review is devoted to the discussion of the recent, promising directions of BODIPY application in the field of conjugation with biomolecules. The first direction is associated with the development of BODIPY conjugates with drugs, including compounds of platinum, paclitaxel, chlorambucil, isoxazole, capsaicin, etc. The second direction is devoted to the labeling of vitamins, hormones, lipids, and other biomolecules to control the processes of their transport, localization in target cells, and metabolism. Within the framework of the third direction, the problem of obtaining functional optically active materials by conjugating BODIPY with other colored and fluorescent particles, in particular, phthalocyanines, is being solved.

BACKGROUND: Mesenchymal stem cell transplantation has been proved to be effective for ulcerative colitis, while the effect of endothelial progenitor cells in ulcerative colitis treatment is still unknown. They are both promising cells for tissue engineering, which can be used for cell transplantation. OBJECTIVE: To explore whether co-transplantation of endothelial progenitor cells and adipose mesenchymal stem cells can relieve ulcerative colitis in a mouse model. METHODS: C57BL/6J mice were randomly divided into six groups (n=24 per group): co-transplantation group, mesenchymal stem cell transplantation group, endothelial progenitor cell transplantation group, glucocorticoid treatment group, transplantation control group and normal control group. Murine ulcerative colitis model was established in all groups except for the normal control group. At 7 and 10 days after modeling, transplantation groups were respectively injected via tail vein with adipose mesenchymal stem cells and/or endothelial progenitor cells, glucocorticoid or PBS. Mice were sacrificed at 12 days after modeling. Colon length, disease activity index, histological score and the serum level of tumor necrosis factor-α were compared between groups. RESULTS AND CONCLUSION: Treatment with glucocorticoid was significantly effective for ulcerative colitis relative to the transplantation control group (P < 0.05). Adipose mesenchymal stem cells were proved to have better effects than glucocorticoids in the murine ulcerative colitis model (P < 0.05). No significant differences were found between endothelial progenitor cell transplantation group and transplantation control group (P > 0.05). Co-transplantation of adipose mesenchymal stem cells and endothelial progenitor cells was better than the other treatments, which significantly improved the shortening of the colon, disease activity index, histological score, and serum level of tumor necrosis factor-α. [ABSTRACT FROM AUTHOR]

A portable device for measuring fluorescence signals from a lateral flow test strip was developed. The aim was to build an easy-to-use, affordable reader device for fast, quantitative analysis of point-of-care tests, made mostly of commercial off-the-shelf components. The device is capable of exciting fluorescent labels with 532 nm and 650 nm lasers and collecting the emitted fluorescent light with a camera. Core of the device is a Raspberry Pi Zero W wireless single board computer that controls the Raspberry Pi camera v2 module and lasers. The computer can also perform the image analysis and communicate the results to a mobile phone application acting as a user interface. Sensitivity of the device was characterized by sweeping the imaging parameters and comparing the performance with a high-grade fluorescence reader. Using dummy LFA samples, it was found that the device is able to detect signals from analyte concentrations that are relevant in biological samples. Image exposure time of $500~\mu \text{s}$ was enough to read a distinguishable signal. The manufacturing costs were estimated to be below 100 euros per device in mass production. [ABSTRACT FROM AUTHOR]

Mesoporous silica nanoparticles (MSNs) feature ideal structural properties and surface chemistry for use as nanocarriers of molecules, polymers and biomolecules in cutting-edge applications. One important challenge remaining in their preparation is the ability to tune their diameter in the range of a few tens of nanometers, with narrow size dispersity, preferably using a simple, sustainable and scalable synthetic process. This work presents a fully controllable low-temperature and purely aqueous sol-gel method to prepare MSNs with user-defined diameters from 15 nm to 80 nm and narrow size dispersity. The method also allows modification of the pore structure and offers the possibility of incorporating a luminescent species in the silica network for optical traceability. Control was achieved by tuning the colloidal stability of the assembly of cylindrical micelles that template the MSN synthesis. Using CTAB cylindrical micelles as template and sodium hydroxide (NaOH) as catalyst, precise diameter control was achieved either by changing the pH (that controls micelle surface charge) or by adding salt at constant pH (to tune the ionic strength and charge screening). This new sustainable MSN synthesis method provides full control over the nanoparticle diameters and can be used as a platform for the application of MSNs with user-defined sizes in different fields. [ABSTRACT FROM AUTHOR]

Research on the origin, distribution, detection, identification, and quantification of polymer nanoparticles (NPs) in the environment and their possible impact on animal and human health is surging. For different types of studies in this field, well-defined reference materials or mimics are needed. While isolated reports on the preparation of such materials are available, a simple and broadly applicable method that allows for the production of different NP types with well-defined, tailorable characteristics is still missing. Here, we demonstrate that a confined impinging jet mixing process can be used to prepare colloidally stable NPs based on polystyrene, polyethylene, polypropylene, and poly(ethylene terephthalate) with diameters below < 100 nm. Different fluorophores were incorporated into the NPs, to allow their detection in complex environments. To demonstrate their utility and detectability, fluorescent NPs were exposed to J774A.1 macrophages and visualized using laser scanning microscopy. Furthermore, we modified the NPs in a postfabrication process and changed their shape from spherical to heterogeneous geometries, in order to mimic environmentally relevant morphologies. The methodology used here should be readily applicable to other polymers and payloads and thus a broad range of NPs that enable studies of their behavior, uptake, translocation, and biological end points in different systems.

Graphical abstract Abstract The argyrins are a family of non-ribosomal peptides that exhibits different biological activities through only small structural changes. Ideally, a biologically active molecule can be tracked and observed in a variety of biological and clinical settings in a non-invasive manner. As a step towards this goal, we report here a chemical synthesis of unnatural deep blue amino acid β-(1-azulenyl)- l alanine with different fluorescence and photophysical properties, which allows a spectral separation from the native tryptophan signal. This might be especially useful for cell localization studies and visualizing the targeted proteins. In particular, the synthesis of β-(1-azulenyl)- l alanine was achieved through a Negishi coupling which proved to be a powerful tool for the synthesis of unnatural tryptophan analogs. Upon β-(1-azulenyl)- l alanine incorporation into argyrin C, deep blue octapeptide variant was spectrally and structurally characterized. [ABSTRACT FROM AUTHOR]

Highly luminescent nanophosphors (NPs) containing rare earth (RE) ions were successfully prepared by careful control of nanosynthesis. The YVO4:Eu3+ NPs formed core/shell structures with sizes from 10 nm to 25 nm. The NPs were functionalized with biocompatible groups such as OH, NH2 and SCN. A chemical coupling reaction connected the functionalized YVO4:Eu3+ NPs with Biotin via a direct reaction between the functional groups or an intermediate linker. Under UVIS excitation, YVO4:Eu3+ NPs exhibited strong red luminescence with narrow bands corresponding to the intra 4f transitions of D05–Fj7 (j = 1, 2, 3, 4) Eu3+. The peaks were found at 594 nm (D05–F17), 619 nm (D05–F27), 652 nm (D05–F37) and 702 nm (D05–F47) with the strongest emission at 619 nm. The fluorescence intensity and stability of the functionalized YVO4:Eu3+ NPs have been increased. This is a promising result in sense of using the conjugates of YVO4:Eu3+ and a bioactive molecule, Biotin for the development of a fluorescent label tool in biomedical analysis.

Glucose oxidase (GOx) is an important industrial enzyme that can be optimized for specific applications by mutagenesis and activity-based screening. To increase the efficiency of this approach, we have developed a new ultrahigh-throughput screening platform based on a microfluidic lab-on-chip device that allows the sorting of GOx mutants from a saturation mutagenesis library expressed on the surface of yeast cells. GOx activity was measured by monitoring the fluorescence of water microdroplets dispersed in perfluorinated oil. The signal was generated via a series of coupled enzyme reactions leading to the formation of fluorescein. Using this new method, we were able to enrich the yeast cell population by more than 35-fold for GOx mutants with higher than wild-type activity after two rounds of sorting, almost double the efficiency of our previously described flow cytometry platform. We identified and characterized novel GOx mutants, the most promising of which (M6) contained a combination of six point mutations that increased the catalytic constant kcat by 2.1-fold compared to wild-type GOx and by 1.4-fold compared to a parental GOx variant. The new microfluidic platform for GOx was therefore more sensitive than flow cytometry and supports comprehensive screens of gene libraries containing multiple mutations per gene.

A method for the determination of non-lactose oligosaccharides (NLO) in milk using liquid chromatography has been developed. Oligosaccharides were labelled with a fluorescent tag, 2-aminobenzamide (2AB), and were identified by comparison of their retention times to those of oligosaccharide standards, their mass (as measured by mass spectrometry) and their fragmentation patterns in the mass spectrometer. The concentrations of the NLO in milk have been determined using 2 different approaches: (1) by preparing a calibration curve using genuine standards of each oligosaccharide. (2) by preparing a calibration curve using maltotriose as a universal standard for all NLO, and assuming all 2AB labelled oligosaccharides give an equimolar response in the detector. The accuracy of the method was assessed by spike-recovery experiments. Using genuine NLO standards for calibration, recoveries were in the range 96–114%. Using maltotriose as a universal calibrant, recoveries were in the range 86–120%. Method precision was assessed by determining the relative standard deviation of the results under repeatability (RSD(r)) and intermediate reproducibility (RSD(iR)) conditions. In most cases RSD(r) and RSD(iR) were below 5% irrespective of calibration method, but increased when NLO levels were close to LoQ. [ABSTRACT FROM AUTHOR]

Isoprenoid cytokinins play a number of crucial roles in the regulation of plant growth and development. To study cytokinin receptor properties in plants, we designed and prepared fluorescent derivatives of 6-[(3-methylbut-2-en-1-yl)amino]purine ( N 6 -isopentenyladenine, iP) with several fluorescent labels attached to the C2 or N9 atom of the purine moiety via a 2- or 6-carbon linker. The fluorescent labels included dansyl (DS), fluorescein (FC), 7-nitrobenzofurazan (NBD), rhodamine B (RhoB), coumarin (Cou), 7-(diethylamino)coumarin (DEAC) and cyanine 5 dye (Cy5). All prepared compounds were screened for affinity for the Arabidopsis thaliana cytokinin receptor (CRE1/AHK4). Although the attachment of the fluorescent labels to iP via the linkers mostly disrupted binding to the receptor, several fluorescent derivatives interacted well. For this reason, three derivatives, two rhodamine B and one 4-chloro-7-nitrobenzofurazan labeled iP were tested for their interaction with CRE1/AHK4 and Zea mays cytokinin receptors in detail. We further showed that the three derivatives were able to activate transcription of cytokinin response regulator ARR5 in Arabidopsis seedlings. The activity of fluorescently labeled cytokinins was compared with corresponding 6-dimethylaminopurine fluorescently labeled negative controls. Selected rhodamine B C2-labeled compounds 17 , 18 and 4-chloro-7-nitrobenzofurazan N9-labeled compound 28 and their respective negative controls ( 19 , 20 and 29 , respectively) were used for in planta staining experiments in Arabidopsis thaliana cell suspension culture using live cell confocal microscopy. [ABSTRACT FROM AUTHOR]

Kinetics of DNA condensation with zwitterionic lipid, dipalmitoylphosphatidylcholine, in the presence of calcium and sodium cations was investigated using fluorescence stopped-flow technique. The process was followed from two points of view: the changes on DNA were monitored with ethidium bromide, and fluorescently labelled phospholipid was used to follow the changes in the lipid bilayer. The measurements showed different reaction kinetics. In the case of the DNA side, a consecutive reaction mechanism was found, while two-step first-order reaction mechanism described well the processes on the lipid side. Both, sodium and calcium cations influence significantly the reaction mechanism. Calcium is necessary to condensate DNA with lipid, while sodium modulates the kinetics of the reactions considerably. [ABSTRACT FROM AUTHOR]

λ Exonuclease hydrolyzes a 5′-phosphorylated strand of double-stranded DNA in the 5′-3′ direction. In this paper, the activity of the enzyme with respect to DNA substrates containing Cy3 and Cy5 fluorescent labels at their 5′ ends is studied for the first time. It is demonstrated using the fluorescence procedure for measuring the exonuclease activity that double-stranded DNA, of which both the 5′ ends contain these fluorophores, is not destroyed under the action of λ exonuclease. Using the electrophoretic separation of DNA in polyacrylamide gel, the process of obtaining single-stranded DNA from double-stranded precursors containing different labels at the 5′ ends is studied. It is shown that the introduction of Cy3 and Cy5 fluorophores to the 5′ end of the DNA strand protects this strand from enzyme damage both in the duplex and in single-stranded form, and these labels can be used to produce fluorescently labeled single-stranded DNA. [ABSTRACT FROM AUTHOR]

Lanthanide phosphors have recently been proven as a novel type of fluorescent label that can be extensively used in analytical detection. La 2 (MoO 4 ) 3 :Eu 3+ phosphors with uniform twinned hemispheres morphology have been successfully synthesized via a sodium citrate mediated hydrothermal method. The crystal structure has been determined by X-ray powder diffraction (XRD) and the microstructures were characterized by scanning electron microscopy (SEM). The La 2 (MoO 4 ) 3 :Eu 3+ microcrystals emitted strong emission at 616 nm under the 269 nm excitation. The photoluminescence (PL) emission intensities were enhanced with the increment of Eu 3+ ion concentration and the optimal doping concentration was 15 mol%. The as-prepared La 2 (MoO 4 ) 3 :Eu 3+ was further applied in developing latent fingerprint images, which exhibited clear and well-defined details with high contrast and low background interference under 254 nm excitation. This work shows that La 2 (MoO 4 ) 3 :Eu 3+ powder is a versatile fluorescent label for the detection of LFPs for individual identification in forensic science. [ABSTRACT FROM AUTHOR]

Rotational depolarization of fluorescence from fluorescein covalently linked to oligonucleotides was studied. Fluorescence anisotropy of two nucleic acids was measured as a function of the temperature-to-viscosity ratio in buffer solutions with various glycerin concentrations. It was shown that the experimental results could be satisfactorily explained by a diffusion model of an elongated molecular top with internal rotation. It was found that the coefficient of internal rotational diffusion in all instances was 1.5-2 times greater than that for rotation around the oligonucleotide axis. [ABSTRACT FROM AUTHOR]

A new bioanalytical method for urea determination by using the immobilized urease on the highly luminescent ZnS quantum dots (QDs), which functioned as the pH fluorescent label has been developed. Bioconjugation of ZnS QDs to urease via amide bond was performed to obtain the ZnS QDs-urease bioconjugate. Upon enzymatic hydrolysis of urea by the immobilized urease, a pH change to a more alkaline condition has led to the deprotonation of ZnS QDs, and an increase in the fluorescence intensity can be observed. The fluorescence intensity of the urease conjugated ZnS QDs changed linearly with the urea concentrations between 4 × 10 −9 M and 4 × 10 −3 M (R 2 = 0.992) at pH 6 with a calibration sensitivity of 179.46 intensity/decade. No noticeable influence by the Ca 2+ , Mg 2+ , K + and Na + ions on the response of the fluorescent pH bioprobe. Urea determination in soil sample by using the urea bioprobe was in good agreement with the standard DMAB (p-dimethylaminobenzaldehyde) UV–vis spectrophotometric method. By employing the strategy of ZnS QDs-urease bioconjugation, the stable covalent link between the two substances has appeared to widen the dynamic range and lower the detection limit for urea compared to free enzyme and QDs in solution for bioassay of urea concentration. [ABSTRACT FROM AUTHOR]

In this paper, the NaYF 4 :Yb,Er,Gd fluorescent upconversion nanorods (UCNRs) were successfully employed as a promising fluorescent label for the detection of blood fingerprints with high sensitivity, low background, high efficiency, and low toxicity on a range of substrates including non-infiltrating materials (glass, ceramic tile, aluminium foil, stainless steel sheet, coin and marble), and infiltrating materials (magazine cover and train ticket). To assess the efficiency of this approach, comparisons were performed with Acid Yellow 7 (AY7, an effective blood reagent) on above-mentioned eight substrates. The fingerprints were cut in halves and the halves treated separately with UCNRs and AY7. The results manifested that UCNRs were superior to AY7 on all test substrates. This work shows that UCNRs are a versatile fluorescent label for the detection of blood fingerprints in criminal science for individual identification. [ABSTRACT FROM AUTHOR]

A device is developed for automated immunochromatographic assay, designed for one-time tests at the place of occurrence of a disease. The device comprises a turntable platform for up to five strips placed simultaneously, a unit for sample collection and microdosing to a test strip, a detection unit, and a microprocessor control system. A manual, semiautomatic, or automatic operation mode may be selected. Colloidal quantum dots with a luminescence peak from the visible to near-infrared spectral region (600-800 nm) are used as fluorescent labels. A UV-LED or a laser at 365-480 nm can be used as an excitation system; the detection device is a spectrometer with an operation range of 500-800 nm, based on a CCD series of TCD1304DG sensors (Toshiba). RFID tags of samples can re read and the analysis results can be sent to an external computer. The device is made in a plastic case for carrying. [ABSTRACT FROM AUTHOR]

Microscale thermophoresis (MST) is an emerging technology for studying a broad range of biomolecular interactions with a high sensitivity. The affinity constant can be obtained for a wide range of molecules within minutes based on reactions in microliters. Here we describe the application of MST in quantifying protein-carbohydrate interactions. A CBM3a and a CBM4 are titrated with insoluble substrate (cellulose nanocrystal) and soluble oligosaccharide (xylohexaose), respectively., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

In this report, we are presenting the controlled fabrication results of the strong emission YVO 4 : Eu 3+ nanoparticles and nanowires by microwave which is assisted chemical synthesis. The effects of incorporated synthesis conditions such as microwave irradiated powers, pH values and concentration of chemical composition on properties of nanomaterials are also investigated to obtain the controllable size and homogenous morphology. Morphological and optical properties of YVO 4 : Eu 3+ prepared products which have been characterized by X-ray diffraction (XRD), field emission micrcroscopy (FESEM) and photoluminescence spectroscopy. As based from result of synthesized samples, we found that the changing of pH values, microwave irradiated powers and chemical composition rise to change reform the size and shape of materials from nanoparticles (diameter about 20 nm) to wires shape (with about 500÷800 nm length and 10÷20 nm width). The photoluminescence (PL) spectroscopy measurements of YVO 4 : Eu 3+ nanostructure materials under UV excitation showed that: the strong luminescence in red region with narrow lines corresponding to the intra-4f transitions of 5 D 0 – 7 F j ( j =1, 2, 3, and 4) of Eu 3+ ions with the highest luminescence intensity of 5 D 0 → 7 F 2 transition. [ABSTRACT FROM AUTHOR]

An efficient method for preparation of fluorescently labelled mannan-peptide glycoconjugates has been developed. After selective Dess-Martin periodinane oxidation of mannan, it was conjugated to the fluorescent label alone and a peptide with the label via reductive amination. Prepared glycoconjugates were characterised by HPSEC, FTIR-ATR and UV-VIS spectroscopy. Finally, the fluorescently labelled mannan and mannan-peptide conjugate were used for microscopic visualization of their accumulation in intracellular organelles of RAW 264.7 cells. [ABSTRACT FROM AUTHOR]

Polymeric nanoparticles (NPs) are currently being investigated for various therapeutic, diagnostic and drug delivery applications. The study of their interactions and fate in biological systems is frequently performed via their fluorescent labeling and following them using fluorescent microscopy. Quantum dots are proposed as stable fluorescent label and compared to other organic dyes (Nile red and DiI) in terms of their entrapment, diffusion in different aqueous or lipophilic media and photostability. In vitro transfer to hydrophilic PBS solution showed that after 8 h, 4.2 ± 2.2, 15.5 ± 2.0 and 0.9 ± 0.02% was released from the QDs, NR and DiI nanoparticles, respectively. However, higher diffusion rates were observed in the lipophilic medium chain triglyceride and artificial sebum for all the dyes used. Fluorescent intensity of the three different markers was found to be stable over a period of 24 h. Continuous illumination with laser beam using a confocal laser scanning microscopy indicated the superior stability of quantum dots compared to the other organic dyes. Skin permeation experiments have shown that QDs were the most representative marker for the polymeric nanoparticles skin penetration. [ABSTRACT FROM AUTHOR]

A new Schiff base of N-salicylidene-3-amino-1,2,4-triazole (SAT) was synthesized and its photoluminescent, photochromic and thermochromic properties were characterized and demonstrated. The fluorescence lifetime and quantum yield of SAT were measured and the microcrack bone imaging using SAT as a fluorescent label was observed by laser scanning confocal microscope (LSCM). The absorption spectrum of SAT was demonstrated using DFT/TD-DFT calculation. [ABSTRACT FROM AUTHOR]

Interaction between proteins (as analytes) and de novo designed structured peptides as capture molecules cause structural changes, which are reflected in fluorescent-intensity changes of labeled peptides in a dose dependent manner. In contrast to conventional detection methods our detection system does not involve the detection of specific molecules themselves in a 1:1 manner, but uses the principle of the differences in fluorescent intensity changes of capture peptides upon addition of analytes. Instead of the use of secondary antibodies we have attempted monitoring these structural changes by an array of de novo designed synthetic and structured peptides. In the present study we have focused on a recognition system, 5-fluorouracil, as a low molecular antigen and a monoclonal antibody against 5-FU. The fluorescent intensity changes of fluorescent labeled peptides have been measured after incubation with a monoclonal antibody and again after further incubation with the antigen, 5-FU. Unique intensity changes were found for several peptides in the fluorescent peptide library that allowed the visualization as a color-coded protein fingerprint. The peptide screen used in the present study offers a useful detection system as capture molecules for peptide-based microarrays. [ABSTRACT FROM AUTHOR]

Hydrogels are an increasingly important class of medical device materials that enable diverse and unique function, but can also be subject to significant biofouling and contamination. Although it is challenging to accurately quantify protein biofouling in hydrogels, spectroscopic detection of fluorescently labeled proteins is one method with the potential to provide direct, sensitive quantitation in transparent materials. Therefore, it is important to understand how fluorophores can affect protein-material interactions in hydrogels. This work uses an independent method, native ultraviolet fluorescence (native UV) of proteins, in conjunction with labeled protein fluorescence and the bicinchoninic acid assay (BCA), to assess the effect of fluorescent labels on protein sorption in polymer hydrogels. Bovine serum albumin (BSA) and lysozyme (LY) were labeled with two common but structurally different fluorophores and used as model biofouling proteins in three contact lens hydrogel materials. Native UV was used to directly measure both labeled and unlabeled protein sorption, while orthogonal measurements were performed with extrinsic fluorescence and BCA assay to compare with the native UV results. Sorption of labeled proteins was found to be <2-fold higher than unlabeled proteins on most protein-material combinations, while differences of up to 10-fold were observed for labeled BSA in more hydrophobic hydrogels. Fluorescence recovery after photobleaching (FRAP) also showed that the fluorescent label chemistry can significantly affect surface adsorption of sorbed proteins on the internal surfaces of hydrogels. This study reveals the complex nature of fluorophore-protein-material interactions and shows the potential of native UV for investigating unlabeled protein biofouling in hydrogels. [ABSTRACT FROM AUTHOR]