Search

To rapid and efficient detection of TNP in water (TNP=2,4,6‐trinitrophenol), a pyrenyl‐based double‐charged probe PYPN was employed. The bright orange‐red emission of PYPN was seriously quenched upon the addition of TNP. The detection limit of PYPN for TNP is 0.218 μM. In addition, PYPN shows fast response rate (5 s) to TNP, good stability, excellent selectivity and anti‐interference (pH, anion, cation and other nitro compounds). Furthermore, PYPN can be used to rapidly detect TNP in various types of water samples. The rapid and efficient detection of TNP by PYPN may due to the electron and energy transfer as well as electrostatic interactions. [ABSTRACT FROM AUTHOR]

A new sugar based acrylamide, 6‐N‐acrylamido‐D‐galactopyranose (Gal‐acryl) was synthesized from D‐galactose in 6 steps. A solution of Gal‐acryl at basic pH exhibited concentration dependent fractal type assembly formation upon solvent evaporation as revealed by the microscopic images. The fractal dimensions calculated point towards Diffusion Limited Aggregation mode of aggregate formation. The critical aggregation concentration (CAC) of Gal‐acryl in water was found to be 49.3 μM. The increase in fluorescence intensity accompanied by blue shift in emission maxima of coumarin 153 suggests increase in non‐polar environment with Gal‐acryl concentration. The I1/I3ratio of pyrene emission confirmed more non‐polar microenvironment at acidic pH and vice versa at basic pH. Self‐assembly allows Gal‐acryl to exhibit specificity to lectin RCA120 as is demonstrated by fluorescence study further supported by turbidimetric assay. The fluorescence quenching studies with FITC‐RCA120 afforded the Ka value as 6.34×105 M−1, which is much higher than Ka values observed for small galactose derivatives. The present study may help in designing different fractal like glycomaterials with potential applications in drug delivery, bio‐sensing, tissue engineering, and as ligands to asialoglycoprotein receptors that are exclusively expressed by liver cells. [ABSTRACT FROM AUTHOR]

Herein, we have successfully prepared multifunctional nitrogen–boron co-doped carbon quantum dots (N,B-CQDs) with excellent performance by a one-step hydrothermal method and further applied them to the design of highly efficient fluorescent probes and visible light responsive photocatalysts. N,B-CQDs have excellent selectivity and high sensitivity to Fe3+ and Hg2+, with LODs of 1.8 μM and 0.34 μM, respectively. The experimental results show that the fluorescence quenching mechanism of Fe3+ and Hg2+ detected by N,S-CQDs is the result of dynamic quenching and static quenching. Besides, BiOCl modified by N,S-CQDs(BiOCl/N,B-CQDs) was prepared by one-step hydrothermal method, and the morphology of catalysts and the adhesion of N,B-CQDs were observed by several scientific methods. The photocatalytic results showed that the degradation rate of RhB by BiOCl/N,B-CQDs was up to 99.4% under optimal conditions, which was higher than that of BiOCl (80%). Free radical quenching experiments proved that ·OH and ·O2− were the main active substances in the reaction process. Finally, the aim of this study is to offer a novel approach to developing multi-function CQDs as a sensor for metal ions and their modified composites as visible light-induced photocatalysts for the effective detection and degradation of contaminants. [ABSTRACT FROM AUTHOR]

This manuscript provides a comprehensive analysis of the characteristics of unavoidable thermal effects in solid-state lasers and an end-to-end solution for the heat generated inside the gain medium. After a description of the basic physical mechanisms (Quantum defect, Upconversion, and Thermal Quenching of Fluorescence), Total Heat Generation Coefficient is calculated for suitable holder designed used in the practical operating conditions of a cavity to reduce the thermal effects and to increase lasing efficiency. In particular, simulations that have been performed with a finite-element model is used to theoretically simulate thermal lensing in Cr:Nd:GSGG crystals with pumping scenarios. The predicted values for thermally induced strengths are compared with experimentally observed previous results. Finally, necessary calculations for the new crystal holder design were made by the help of the simulation modelling for a 1.5 W Gaussian (TEM00) laser diode double-end-pumped slab geometry Cr:Nd:GSGG crystal. The results were discussed deeply, and it is proven that the new holder design for this gain medium is suitable. [ABSTRACT FROM AUTHOR]

Freshwater contamination is a significant concern due to the increasing pollution by industrial activities. Dyes have a wide range of uses and are introduced at different stages of manufacture, raising the risk of unwanted human and environmental contact. Consequently, the demand for an effective method for removing dyes has become more important than before. In this context, carbon dots have been synthesized by the green synthesis method from coriander leaves (C-CDs) and used as a prospective adsorbent to remove (MB) methylene blue dye from aqueous solution. The as-synthesized C-CDs are characterized by HR-TEM, XRD, XPS, FTIR, Zeta potential, UV–visible, and photoluminescence (PL). Effects of different controlling parameters such as adsorbent dosage, pH, contact time, and initial MB dye concentration were investigated. The highest adsorption efficiency (82.6%) and maximum adsorption capacity (96.05 mg/g) of MB were obtained at optimum conditions (303 K). The adsorption isotherm data could be fitted well by Freundlich model, and the experimental data fitted to the Pseudo-Second-Order kinetic model. It is worth noting that C-CDs exhibited excellent sensitivity and high fluorescence quenching effect on Fe3+ ions. [ABSTRACT FROM AUTHOR]

Aims: Disabling bacterial virulence with small molecules has been proposed as a potential strategy to prevent bacterial pathogenicity. The von Willebrand factor-binding protein of Staphylococcus aureus was identified previously as a key virulence determinant. Our objective was to discover a von Willebrand-factor binding protein (vWbp) inhibitor distinct from the antibiotics used to prevent infections resulting from S. aureus. Methods and results: Using coagulation assays, we found that the sesquiterpene trilactone bilobalide blocks coagulation mediated by vWbp, but has no impact on the growth of S. aureus at a concentration of 128 μg ml−1. Moreover, a mouse model of pneumonia caused by S. aureus indicated that bilobalide could attenuate S. aureus virulence in vivo. This effect is achieved not by interfering with the expression of vWbp but by binding to vWbp, as demonstrated by western blotting, thermal shift assays, and fluorescence quenching assays. Using molecular dynamic simulations and point mutagenesis analysis, we identified that the Q17A and R453A residues are key residues for the binding of bilobalide to vWbp. Conclusions: Overall, we tested the ability of bilobalide to inhibit S. aureus infections by targeting vWbp and explored the potential mechanism of this activity. [ABSTRACT FROM AUTHOR]

In current work, myrrh residue, a special type of natural biomass, was used as the feedstock for carbon dots (CDs) preparation for the first time. The effect of synthesis conditions including ethylenediamine addition, reaction temperature, and reaction time on the CDs fluorescence intensity was investigated to construct a proper synthesis system. Under the suitable condition, CDs with an average particle size of 6.35 ± 1.07 nm and excitation wavelength dependence were prepared, and the CDs yield and the CDs quantum yield were 3.78% and 10.63%, respectively. The CDs obtained were used for the detection of various metal ions, and Fe3+ could be detected most sensitively due to its significant quenching effect. For low Fe3+ concentrations (0.2–1 mM), it had a good linear relationship with F0/F (the relative fluorescence intensity) that a standard curve (y = 0.3553x + 0.926) was built with R2 of 0.997 and the limit of detection (LOD) of 24.62 μM. While for high Fe3+ concentrations (1–15 mM), it also had a good linear relationship with F0/F that a standard curve (y = 0.3232x + 0.7636) was built with R2 of 0.991 and LOD of 27.06 μM. The CDs was used for the real samples detection with the recoveries ranged from 92.71 to 103.84%. The fluorescence quenching mechanism of CDs by Fe3+ was learned and the static quenching was the possible mechanism. In addition, based on the antioxidant properties of myrrh itself, the myrrh residue derived CDs also had antioxidant activities and thus had potential for antioxidant application. On the whole, this work can provide an attractive technology for chemical conversion from low-cost myrrh residue to functional CDs which can be applied for Fe3+ detection and antioxidation. [ABSTRACT FROM AUTHOR]

The interaction of cobalt(II) tetrasulfophthalocyanine (CoPc) with the ORF8 accessory protein of SARS-CoV-2 was studied by spectroscopy and calorimetry. The protein was found to shift the aggregation equilibrium in cobalt tetrasulfophthalocyanine solutions towards dimerization. Most probably, the CoPc dimer binds to ORF8 on the greater β-sheet side, thus causing fluorescence quenching. The protein affinity constant to CoPc dimer is 1.5 × 105. Differential scanning calorimetry data indicate that ORF8 undergoes thermally induced denaturation in the temperature range of 38–67°C. Melting of ORF8 includes two stages, which partly overlap. The complex formation of ORF8 with CoPc leads to thermal stabilization of the protein, thus preventing the second stage of protein unfolding. Denaturation of the complex proceeds between 40 and 77°C as two temperature-separated stages. According to gel electrophoresis and immunoblotting data, visible light photoirradiation of the ORF8 complex with CoPc does not induce photooxidation of the protein. It was shown that water-soluble cobalt sulfo-substituted phthalocyanine can be considered as a potential drug inhibiting the ORF8 accessory protein. [ABSTRACT FROM AUTHOR]

The response performances of the crystalline organic fluorescence probe are highly dependent on the long-range ordered arrangement of crystalline structure. Herein, a novel organic crystalline fluorescent probe with a high quantum yield was established through the rapid self-assembly of 1,2,4,5-Tetrakis (4-carboxyphenyl) benzene (H4TCPB) and DMF molecules. Each H4TCPB, which connects to four DMF molecules through hydrogen bonds, acts as the structural unit. The building units are packed by π–π, lone pair···π, and lone pair···lone pair interactions to form solid-state crystalline materials. H4TCPB·4DMF exhibits distinct blue fluorescent under UV light, while the quantum yield is as high as 89.02% and the fluorescence lifetime is 1.95 ns. The H4TCPB·4DMF nanocrystal exhibits a specific fluorescence quench sensibility to tetracycline (TC), compared with the common chemicals and ions in environmental water. Moreover, the test results can be obtained quickly and are easily visible to the naked eye. The limit of detection for TC is as low as 12 nM in an aqueous solution. Spectral analysis and density functional theory (DFT) theoretical calculations were used to explain the fluorescence quenching mechanism of H4TCPB·4DMF toward TC, which could be attributed to the photoinduced electron transfer occurring from H4TCPB·4DMF to TC. Our work enriches the database of crystalline luminescent materials and provides theoretical support for the design and mechanical studies of organic fluorescent probes. [ABSTRACT FROM AUTHOR]

In this study, we have fabricated a novel platform for sensing of urea using gelatin/carbon dots nanocomposite system. The sensor electrode was created by depositing the nanocomposite gel onto thin glass plates coated with indium tin oxide (ITO) using the drop casting technique. The behavior of these electrodes was investigated against a number of bioanalytes in the concentration range of 2–20 mM by cyclic voltammetry. The system was observed to be highly selective for urea with a sensitivity of 1.65 μA/mM/cm in the experimental linear range of 2–20 mM. Furthermore, the gelatin/CD-ITO electrode were also subjected to 50 KeV N 2 + ion beam irradiation with varying fluence in the range of 1012 to 1016 ions/cm2. Sensing profile of the irradiated samples for urea suggested enhancement in sensitivity to 2 μA/mM cm2, when the ion fluence was 5 × 1015 ions/cm2. This enhancement after irradiation suggests a clear dependence of detection on the fluence of the ion beam. The observed excellent sensitivity of radiation processed nanocomposite material can be used as an enzyme-free platform for urea detection. Additionally, the CDs showed fluorescence quenching on treatment with mere 50 μM urea suggesting the high sensitivity of the platform. • Gelatin/CD nanocomposite based electrochemical sensor for urea. • Sensitivity of 1.65 μA/mM/cm2 was observed. • Irradiation with N 2 + ion (1016 ions/cm2) increased the detection sensitivity. • Promises rapid and high selectivity biocompatible matrix for urea detection. [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) are a type of nanoparticle with excellent optical properties, suitable for many optical-based biomedical applications. However, the potential of quantum dots to be used in clinical settings is limited by their toxicity. As such, much effort has been invested to examine the mechanism of QDs' toxicity. Yet, the current literature mainly focuses on ROS- and apoptosis-mediated cell death induced by QDs, which overlooks other aspects of QDs' toxicity. Thus, our study aimed to provide another way by which QDs negatively impact cellular processes by investigating the possibility of protein structure and function modification upon direct interaction. Through shotgun proteomics, we identified a number of QD-binding proteins, which are functionally associated with essential cellular processes and components, such as transcription, translation, vesicular trafficking, and the actin cytoskeleton. Among these proteins, we chose to closely examine the interaction between quantum dots and actin, as actin is one of the most abundant proteins in cells and plays crucial roles in cellular processes and structural maintenance. We found that CdSe/ZnS QDs spontaneously bind to G-actin in vitro, causing a static quenching of G-actin's intrinsic fluorescence. Furthermore, we found that this interaction favors the formation of a QD–actin complex with a binding ratio of 1:2.5. Finally, we also found that CdSe/ZnS QDs alter the secondary structure of G-actin, which may affect G-actin's function and properties. Overall, our study provides an in-depth mechanistic examination of the impact of CdSe/ZnS QDs on G-actin, proposing that direct interaction is another aspect of QDs' toxicity. [ABSTRACT FROM AUTHOR]

A selective sensing technique for HgII ions has been developed utilizing an amino acid based probe. The design, synthesis and efficacy of the chemosensor have been described. The probe (SALTYR) was successfully synthesized from a naturally occurring amino acid after sequential functional group modifications. Recognition studies were performed against a wide variety of metal cations and anions including real water samples. All the analyses were carried out utilizing UV–vis and fluorescence techniques with micromolar concentrations of the probe in HEPES buffer. The selectivity of the probe was found to be very specific for HgII with quenching of the fluorescence in a turn-off mechanism. The detection limit of the probe SALTYR was calculated and found to be 5.9 × 10−6 M. Quantum chemical calculations demonstrated the stability of the HgII complex in the context of binding energy. Furthermore, the change of the pattern of emission spectra has been rationalized with a logic gate model. A novel chemosensor has been designed and synthesized from a naturally occurring α-amino acid (l-tyrosine). Selective recognition of HgII has been achieved utilizing the chemosensing ability of the probe (SALTYR). The fluorescence intensity has been subsequently quenched showing a turn-off mechanism. [ABSTRACT FROM AUTHOR]

1,10-Phenanthroline monohydrate (1,10-phen) is a fluorescent compound and a chemically versatile ligand that forms complexes with transition metals. The fluorescence quenching study has been done for 1,10-phen in the present study. We have synthesized Zirconium oxide (ZrO2) nanoparticles (NPs) by the modified precipitation method followed by post-hydrothermal synthesis. The synthesized NPs were subjected to x-ray diffraction, Scanning Electron Microscopy, Energy Dispersive x-ray, Ultraviolet-visible, and Fluorimetry characterization techniques. The effect of ZrO2 NPs on absorption and emission spectra of 1,10-phen has been investigated through spectroscopic technique. The excitation and emission wavelengths of 1,10-phen are observed to be 280 and 363 nm, respectively. Temperature studies to differentiate between static and dynamic quenching have been done through the Stern–Volmer plot. The type of fluorescence quenching mechanism is found to be collisional quenching. A study of the Forster resonance energy transfer theory on 1,10-phen was carried out with metal oxide ions. There is a considerable energy transfer between 1,10-phen and metal oxide ions. The present investigation can be aided in various applications, such as fluorescent biosensors and medical diagnosis. [ABSTRACT FROM AUTHOR]

An unsophisticated fluorescence-enabled strategy is brought forward to process the highly sensitive fluorescence detection of Salmonella typhimurium (S. typhimurium) which based on polyethyleneimine (PEI)-templated silver/copper nanoclusters (Ag/CuNCs) (λ excitation = 334 nm and λ emission = 466 nm) with cryonase-assisted target recycling amplification. The Ag/CuNCs nanoclusters are synthesized as fluorescent materials due to their strong and stable fluorescence characteristics and are modified with S. typhimurium aptamers to form aptamer-Ag/CuNCs probes. The probes can be adsorbed on the surface of quenching agents-polydopamine nanospheres (PDANSs), thereby inducing fluorescence quenching of the probes. Once the aptamers are bound to the target, the aptamers/targets complexes are separated from the PDANSs surface, and the Ag/CuNCs recover the fluorescence signal. The released complexes will immediately be transformed into a substrate digested by cryonase (an enzyme that can digest all types of nucleic acids), and the released targets are bound to another aptamers to initiate the next round of cleavage. This reaction will be repeated continuously until all relevant aptamers are consumed and all Ag/CuNCs are released, resulting in a significant amplification of the fluorescence signal and improved sensitivity. Using Ag/CuNCs as fluorescent probes combined with cryonase-assisted amplification strategy, the fluorescence aptasensor is constructed with detection limits as low as 3.8 CFU mL−1, which is tenfold better than without the cryonase assistance. The method developed has been applied to milk, orange juice, chicken, and egg white samples with excellent selectivity and accuracy providing an approach for the early and rapid detection of S. typhimurium in food. [ABSTRACT FROM AUTHOR]

A new strategy integrating the straight synthesis of carbon dots (CDs) and their direct use for the determination of heavy metals by means of fluorescence quenching is presented. The proposal consists of a modular analyzer, which includes a low temperature co-fired ceramics (LTCC) microreactor for the synthesis of CDs and a cyclic olefin copolymer (COC) microfluidic platform, which automatically performs a reverse flow injection analysis (rFIA) protocol for the determination of heavy metal ions in water by CD fluorescence quenching. As a proof of concept, nitrogen-doped CDs were synthesized from acrylic acid and ethylenediamine (ED) with quantum yields (QYs) of up to 44%, which are selective to cobalt. With the described system, we synthesized homogeneous CDs without the need for further purification and with the minimum consumption of reagents, and optimized fluorescence measurements can be performed with freshly obtained luminescent nanomaterials that have not undergone decomposition processes. They have an average hydrodynamic diameter of 4.2 ± 0.9 nm and maximum excitation and emission wavelengths at 358 nm and 452 nm, respectively. The system allows the automatic dilution and buffering of the synthesized CDs and the sample prior to the determination of cobalt. The concentration of cobalt was determined with good sensitivity and a limit of detection of 7 μg·L−1 with a linear range of 0.02–1 mg·L−1 of Co2+. Spiked tap water and river water samples were analyzed, obtaining recovery from 98 to 104%. This demonstrates the potential of the equipment as an efficient on-site control system for heavy metal monitoring in water. [ABSTRACT FROM AUTHOR]

Glyphosate (Glyp) is an organophosphorus herbicide, and its abuse causes potential harm to the environment and human health. Thus, the development of simple and portable methods for rapid and visual detection of glyphosate is of great importance. Herein, we successfully developed a new fluorescent probe L with dansyl fluorophore as a fluorescent dye and tetrapeptide (Ala-Ser-Arg-His-NH2) as a recognition group. According to the design, L exhibited a specific fluorescence quenching response to Cu2+ and formed an L-Cu2+ ensemble with a molecular ratio of 2:1, demonstrating a limit of detection (LOD) as low as 12.04 nM. Interestingly, the L-Cu2+ ensemble as a relay response probe exhibited a specific fluorescence "off–on" response to glyphosate without interference from other pesticides and anions based on the strong complexation of glyphosate and Cu2+. The LOD of the L-Cu2+ ensemble for glyphosate was calculated as 12.59 nM. Additionally, the results of three recovery experiments with real samples showed that L has good practicability and accuracy in detecting glyphosate. Test strips were also fabricated to achieve facile detection of glyphosate to demonstrate the practical application potential of the L-Cu2+ ensemble. The L-Cu2+ ensemble was integrated with a smartphone for semi-quantification of glyphosate in a field environment under a 365 nm UV lamp. [ABSTRACT FROM AUTHOR]

A selective sensing technique for HgII ions has been developed utilizing an amino acid based probe. The design, synthesis and efficacy of the chemosensor have been described. The probe (SALTYR) was successfully synthesized from a naturally occurring amino acid after sequential functional group modifications. Recognition studies were performed against a wide variety of metal cations and anions including real water samples. All the analyses were carried out utilizing UV–vis and fluorescence techniques with micromolar concentrations of the probe in HEPES buffer. The selectivity of the probe was found to be very specific for HgII with quenching of the fluorescence in a turn-off mechanism. The detection limit of the probe SALTYR was calculated and found to be 5.9 × 10−6 M. Quantum chemical calculations demonstrated the stability of the HgII complex in the context of binding energy. Furthermore, the change of the pattern of emission spectra has been rationalized with a logic gate model. A novel chemosensor has been designed and synthesized from a naturally occurring α-amino acid (l-tyrosine). Selective recognition of HgII has been achieved utilizing the chemosensing ability of the probe (SALTYR). The fluorescence intensity has been subsequently quenched showing a turn-off mechanism. [ABSTRACT FROM AUTHOR]

BACKGROUND: Coal‐based carbon quantum dots have better stability compared with other carbon quantum dots prepared from small molecules as carbon sources. Elemental doping can effectively improve the fluorescence performance of carbon quantum dots. However, the electronegativity difference between sulfur and carbon is small and the charge transfer between the two is very weak, so it is very difficult to dope sulfur onto carbon quantum dots by chemical methods. High sulfur content coal can achieve in situ synthesis of sulfur‐containing carbon quantum dots. RESULTS: The results showed that the prepared quantum dots had good stability and which increased with the increase of coal rank. CQDS is well dispersed, with an average particle size between 2.44 and 2.74 nm. It can emit light blue fluorescence under the UV excitation of 365 nm. It was found that trace amount of Cr6+ had a fluorescence quenching effect on CQDS and a good linear relationship was observed in the range of 0–100 μmol·L−1. CONCLUSION: Quantum dots doped with S atoms have better selectivity, interference resistance, and sensitivity in the detection of metal ions. The stability and the particle size of CQDS are increased with the coal rank. The quantum yield of CQDS prepared from high sulfur content coal is higher than low sulfur content coal which has same rank. The addition of Cr6+ to CQDS produces a dynamic fluorescence quenching. This study provides a new idea for the green preparation of coal‐based carbon quantum dots and the ion detection. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Influence of six metal ions viz. Mg2+, K+, Ca2+, Mn2+, Cu2+ and Ba2+ on the binding affinity of human serum albumin (HSA) towards three antimalarial drugs, namely, sulfadoxine (SDN), mefloquine (MEF) and lumefantrine (LUM) was investigated using fluorescence quenching titrations. The effects of metal ions (Mn2+, Cu2+ and Ba 2+) were similar on the affinity of HSA towards SDN, MEF and LUM. Values of the association constant, Ka, for SDN/MEF/LUM ̶HSA interactions in the presence of these metal ions, decreased significantly in the order: Mn2+ > Cu2+ > Ba2+. On the other hand, the presence of Mg2+, K+, and Ca2+ affected the binding affinity for these drugs differently. Whereas a slight increase in the Ka value of the SDN ̶HSA complex was seen in the presence of Mg2+, Ca2+ produced a similar effect on the LUM ̶HSA system. For MEF ̶HSA and LUM ̶HSA systems, effects of K+ and Mg2+ were similar, showing a decrease in the Ka value, being more effective with K+ ; however, this decrease was more significant than Mn2+,Cu2+ and Ba2+. Values of ‘n’ remained approximately equal to 1, hinting at a single binding site for each drug. [ABSTRACT FROM AUTHOR]

A responsive spectrofluorometric method was developed for the determination of sitagliptin phosphate using l‐tyrosine as a fluorescence probe. The fluorescence intensity of l‐tyrosine was quenched with sitagliptin phosphate. The fluorescence intensity was recorded at 307 nm using a 272 nm excitation wavelength. The calibration plot between fluorescence intensity and the concentration of drug was linear in the range of 0.1 to 2.0 mM with a good correlation value of 0.997. The limit of detection and quantification were established to be 3.7 × 10−4 and 1.23 × 10−3 mM, respectively. Commonly used excipients did not interfere with sitagliptin phosphate measurement. The proposed method was used to measure the sitagliptin phosphate in its standard type, dosage form, and biological samples. The percent recovery ranged from 97.41–103.36%. The static quenching was shown to be responsible for quenching as indicated by the Stern–Volmer plot. The method was validated using ICH guidelines and profitably applied for the content uniformity test, resulting in a high percent recovery and small relative standard deviation. The proposed approach is effortless, susceptible, selective, economic, and provides a high precision and accuracy, and can be used to determine sitagliptin phosphate in the pharmaceutical industry. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Xinyang Normal University Natural Science Edition is the property of Journal of Xinyang Normal University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work present a highly sensitive fluorescence method for auramine O (AO) detection in food and drug samples based on carbon nanodots (CDs). The AO can effectively diminish the emission of CDs based on an integrated quenching mechanism of inner filter effect (IFE) and dynamic reaction. The CDs were prepared via a one-step hydrothermal method with citric acid and o-phenylenediamine as precursors. The good selectivity and high sensitivity feature of the proposed method for AO detection were validated. The fluorescence signals were linearly correlated with AO concentration over a range of 0.01‒10.0 µM with a detection limit of 36.3 nM was obtained. The proposed method was finally used for AO determination in traditional Chinese medicine, curry power, bean curb and candy samples with high accuracy. The recoveries ranged from 95.5 to 107.2% and relative standard deviations (RSDs) were less than 3.39%. This work provided a new insight and an operational access to AO detection in food and drug colorants monitoring. Thus, the CDs-based sensor demonstrated feasibility of rapid AO detection considering its appealing simplicity, rapidity and high sensitivity features. [ABSTRACT FROM AUTHOR]

Histamine (HA) plays an important role in many pathological processes including asthma, diarrhea, and anaphylactic shock. Therefore, accurate and rapid detecting HA is of great significance. In this work, we report on a novel turn-on fluorescent aptasensor for HA detection based on a competitive combination process performed by both HA-specific and HA-analogs of aptamers. The analogue of HA was environmental-friendly obtained on the polymer chains of carbonized polymer dots (CPDs) without complex functionalization, in which the histidine was used as the polymer precursors for the first time (His-CPDs). After modification with aptamer, the analogue of HA on the His-CPDs would combine with the aptamer, leading to the agglomeration of His-CPDs and the fluorescence quenching. In the presence of HA, the HA would compete with the analogue of HA to react with the aptamer, leading to the dissociation of the agglomerates and the recovery of fluorescence. Under optimized conditions, the proposed fluorescent aptasensor can sensitively detect HA in 7 min ranging from 50 ng/mL to 40 µg/mL with the limit of detection (LOD) of 30 ng/mL. More importantly, this proposed fluorescent aptasensor can sensitively detect histamine in human serum and real sardine samples without complex pre-processing, showing great potential in the medical diagnosis of histamine intoxication and anaphylactic shock. [ABSTRACT FROM AUTHOR]

Super‐resolution techniques like single‐molecule localisation microscopy (SMLM) and stimulated emission depletion (STED) microscopy have been extended by the use of non‐covalent, weak affinity‐based transient labelling systems. DNA‐based hybrid systems are a prominent example among these transient labelling systems, offering excellent opportunities for multi‐target fluorescence imaging. However, these techniques suffer from higher background relative to covalently bound fluorophores, originating from unbound fluorophore‐labelled single‐stranded oligonucleotides. Here, we introduce short‐distance self‐quenching in fluorophore dimers as an efficient mechanism to reduce background fluorescence signal, while at the same time increasing the photon budget in the bound state by almost 2‐fold. We characterise the optical and thermodynamic properties of fluorophore‐dimer single‐stranded DNA, and show super‐resolution imaging applications with STED and SMLM with increased spatial resolution and reduced background. [ABSTRACT FROM AUTHOR]

It is highly desirable to develop facile methods to improve the processability of porous materials for industrial applications. Herein, the preparation of a novel near‐infrared emitting hybrid aerogel (PCS‐CA) is reported by physically blending a porous material with chitosan. The applied porous material (PCS‐CZ‐O‐DCM) is obtained from a near‐infrared emission semiconductor compound (CZ‐O‐DCM) and octavinylsilsesquioxane (OVS). PCS‐CZ‐O‐DCM can detect tetracycline hydrochloride selectively and rapidly in various solution with an extremely low detection limit of 0.29 µm for fluorescence quenching. It also exhibits an outstanding sunlight‐driven photodegradation activity for antibiotics even in the absence of additional oxidation agents or pH control. PCS‐CA also performs better than PCS‐CZ‐O‐DCM powder. A PCS‐CA‐based glass device is further fabricated, which enables a larger amount of water purification of antibiotics by a continuous flow‐through system by light‐driven degradation. By blending with a soft polymer matrix, improved processability can be applied to insoluble porous materials. As a result, a novel functional devices can be realized which provides a new way to apply insoluble porous materials. [ABSTRACT FROM AUTHOR]

This study synthesized the NaGdF4@NaGdF4: Yb, Tm@NaGdF4: Yb, Nd upconversion nanoparticles (UCNPs), combined with another three-layer structure NaYF4@NaYF4: Yb, Er@NaYF4 UCNPs, with a core-shell-shell structure, effectively suppressing fluorescence quenching and significantly improving upconversion luminescence efficiency. Two types of modified UCNPs were coupled with antibodies against fenpropathrin and procymidone to form signal probes, and magnetic nanoparticles were coupled with antigens of fenpropathrin and procymidone to form capture probes. A rapid and sensitive fluorescence immunoassay for the simultaneous detection of fenpropathrin and procymidone was established based on the principle of specific binding of antigen and antibody and magnetic separation technology. Under the optimal competitive reaction conditions, different concentrations of fenpropathrin and procymidone standards were added to collect the capture probe-signal probe complex. The fluorescence values at 542 nm and 802 nm were measured using 980 nm excitation luminescence. The results showed that the detection limits of fenpropathrin and procymidone were 0.114 µg/kg and 0.082 µg/kg, respectively, with sensitivities of 8.15 µg/kg and 7.98 µg/kg, and they were applied to the detection of fenpropathrin and procymidone in tomatoes, cucumbers, and cabbage. The average recovery rates were 86.5~100.2% and 85.61~102.43%, respectively, with coefficients of variation less than 10%. The results showed good consistency with the detection results of high-performance liquid chromatography, proving that this method has good accuracy and is suitable for the rapid detection of fenpropathrin and procymidone in food. [ABSTRACT FROM AUTHOR]

Five covalently bonded polyoxometalate (POM)-porphyrin hybrids were synthesized by reacting the Wells–Dawson type polyoxometalate [N(C4H9)4]5H4P2W15V3O62 with five tris-functionalized porphyrins containing different numbers of tris groups at different peripheral positions. These hybrids were thoroughly characterized using elemental analysis, NMR (1H, 31P, and 51V), mass spectrometry (ESI-MS, MALID-TOF-MS), FT-IR, UV-Vis, and fluorescence spectroscopies. The results proved that different quantities (one, two, and three) of the vanadium-capped Wells–Dawson type metal–oxide cluster P2W15V3O629− can be grafted onto a porphyrin moiety via covalent bonding with different orientations, depending on the number and position of peripheral functional groups on the porphyrin. Interestingly, remarkable fluorescence quenching (60% in 3Py-P@1POM, 75% in trans-2PyP@2POM, 80% in cis-2PyP@2POM, 85% in cis-2PhP@2POM, and 55% in 1Py-P@3POM, as compared to the fluorescence intensity of their corresponding porphyrin precursor) was observed under excitation (λexc = 328 nm), indicating electron transfer from the porphyrin moiety to the POM moiety through covalent linkage. [ABSTRACT FROM AUTHOR]

WLEDs have been widely used in lighting and display equipment due to their energy-saving and environment-friendly advantages, but it is still a great challenge to construct high-quality single-phase white light materials for the preparation of WLEDs. In this work, three Ln–MOFs (HNU-82–84) with the same structure were synthesized by assembling rare earth ions (Tb3+, Eu3+, La3+) and 4,4′,4′′-nitrilotribenzoic acid (H3TCA) ligands. The structure and optical properties of the three compounds were investigated. Under the ultraviolet lamp, HNU-82–84 displays green light, red light, and blue light emission, respectively. Based on the RGB principle, aiming at the single-phase white material, the proportion of adding rare earth ions is reasonably adjusted to design and synthesize the Ln–MOF (Eu0.015Tb0.037La0.148-TCA) with CIE chromaticity coordinates of (0.319, 0.344). In addition, the WLED was prepared by Eu0.015Tb0.037La0.148-TCA and commercial LED lamps. Furthermore, HNU-82 has strong fluorescence emission and good water stability and can be used to detect nitrofurazone (NZF) and nitrofurantoin (NFT). The concentrations of the aqueous solutions of NZF and NFT had a well correlated linear relationship with the fluorescence quenching effect of HNU-82, and the detection limits were 6.60 × 10−7 mol L−1 and 4.62 × 10−7 mol L−1, respectively. Hence, HNU-82 also has potential as a fluorescent sensor for the detection of NZF and NFT in the aquatic environment. [ABSTRACT FROM AUTHOR]

A fluorescence assay for the detection of 4-nitrophenol (4-NP), α-glucosidase (α-Glu) activity and α-Glu inhibitors (AGIs) is developed based on the inner filter effect (IFE), a flexible and simple signal transfer strategy. In this assay, silicon nanoparticles (Si NPs) synthesized under mild and easily accessible conditions are employed as fluorescent indicators. 4-NP efficaciously quenches the fluorescence of Si NPs through the IFE at a very rapid rate, thus achieving 4-NP detection in a mix-to-read manner, which is suitable for on-site detection. The quenching mechanism has been comprehensively studied and confirmed. More significantly, based on the fact that 4-NP can be generated through α-Glu-catalyzed hydrolysis of 4-nitrophenyl-α- D -glucopyranoside (NPG), the fluorescence detection of α-Glu activity is legitimately achieved by employing NPG as the substrate. The linear ranges for 4-NP and α-Glu activity detection are 0.5–60 μM and 0.5–60 mU mL−1 with low detection limits of 0.074 μM and 0.094 mU mL−1, respectively. This method not only can preciously assay targets in real samples, but is also capable of screening AGIs as drugs as well as assessing their inhibition efficiency. [ABSTRACT FROM AUTHOR]

In this study, we successfully constructed a high‐performance fluorescent material for the detection of toxic pollutants in water, [Cd(2‐bpmh)(BDC)H2O]n (1) (2‐bpmh=1,4‐bis(2‐pyridyl)‐2,3‐diaza‐1,3‐butadiene, H2BDC=terephthalic acid), which achieved high yield under the condition of solvothermal reaction. Single crystal X‐ray analysis revealed that complex 1 forms a one‐dimensional chain structure, which is further assembled into a three‐dimensional structure through hydrogen bonding interactions. The luminescence sensing research showed that 1 not only displayed excellent luminescence quenching efficiency, but also could specifically recognize Cr2O72−, CrO42− and Fe3+ ions in water. [ABSTRACT FROM AUTHOR]

The induced quenching in fluorescence upon addition of copper (Cu2+) ions and subsequent regain with aqueous hydrogen sulphide (HS−) was studied with a series of coumarin di(picolyl)amine-based compounds, with varying electron withdrawing/donating abilities. The coumarin analogue with an amino group at the 7-position was the most emissive, followed by the methoxy-variant with both the t-butyl- and difluoro-variants being weakly emissive. The amino-variant was also most responsive to quenching upon the addition of Cu2+ ions and was the most responsive to the subsequent addition of HS− ions. All compounds were shown to form predominately a 1:1 copper(II) complex, supported by mass spectral studies and X-ray crystallography. This investigation sheds light on the structural aspects of the copper-sensor interactions and subsequent copper sequestration, contributing to the understanding of their fluorescence properties and potential applications in sensing and imaging. [ABSTRACT FROM AUTHOR]

A greener approach was applied for gold nanoparticles (AuNPs) synthesis via simple, non-hazardous and environment-friendly route utilizing the fruit peel extract of Manilkara zapota (sapodilla). The phytochemical screening of peel extract revealed that this extract act as a reductant and stabilizer concurrently for surface-functionalized AuNPs synthesis. The UV-Vis spectroscopy, FTIR, XRD, SEM-EDX and HR-TEM were employed to confirm the fabricated AuNPs. Moreover, a proficient fluorescence approach for the determination of thiourea (TU) based on fluorescence resonance energy transfer between rhodamine B (RB) and synthesized AuNPs, promotes fluorescence quenching. On addition of TU, the fluorescence of RB was recovered due to competitive adsorption between thiourea and RB on the surface of AuNPs, Which induces further aggregation of AuNPs. In optimal state, the linear relationship between the fluorescence recovery efficiency and TU concentration with the linear range from 0.02 − 1.0 ppm and the calculated detection limit was 0.017 ppm. The proposed fluorometric method was effectively utilized for TU detection in the actual sample with a good recovery percentage. [ABSTRACT FROM AUTHOR]

In this work, we have synthesized a vinyl functional group containing 4, 4′-bis (1, 3-diphenoxypropane) diacrylic acid organic linker, which was used in construction of novel Cu-MOF (1) and Ni-MOF (2) through a solvothermal method. The synthesized MOFs were characterized by FT-IR, PXRD, TGA, FE-SEM, and EDAX. In particular, Cu-MOF can be used as a bifunctional sensor for detection of arginine and H2S by a fluorescence "turn-off" mechanism with low limit of detection of 0.5 µM and 3.1 µM with quick response time (< 1 min) respectively. On the other hand, Ni-MOF demonstrated to have capability for selective detection of H2S only by quenching mechanism in the presence of various other biologically important analytes. The limit of detection was found to be 3.0 µM and showed rapid quenching in fluorescence intensity (< 1 min). Organic linker 4,4′-bis(1,3-diphenoxypropane) diacrylic acid was used to construct Cu-MOF and Ni-MOF, which are showing good selectivity and sensitivity towards arginine and H2S using turn- off quenching mechanism. [ABSTRACT FROM AUTHOR]

In this work, an easy facile and cost-effective hydrothermal method was used to synthesize the carbon quantum dots (CQD) doped graphitic carbon nitride (g-C3N4) as well as their potential application in sensing Fe3+ ions selectively. The photoluminescence properties of CQD, g-C3N4, and CQD/g-C3N4 have been studied, and a strong blue luminescence with excitation wavelength-independent, pH-sensitive, and ionic strength-dependent luminescence was observed, as confirmed by UV–vis absorption, X-ray powder diffraction, Fourier transform infrared spectroscopy, transmission electron microscope, and Field emission scanning electron microscope. The prepared CQD doped g-C3N4 illustrated a highly sensitive and selective response towards Fe3+ ions in comparison with the prepared CQDs. Less than 335 nm ultraviolet light, the CQD emits blue photoluminescence and also has better water solubility, biocompatibility, and excellent stability, with a significant quantum yield of 36.1%. The improved electronic properties and surface chemical reactivity caused by N atoms in CQD of CQD-g-C3N4 promote coordination between functional groups on the CQD surface and Fe3+ ions, resulting in a significant fluorescence quenching effect of the CQDs in the presence of Fe3+ ions. This "on–off" luminescence CQDs nanoprobe for Fe3+ ions had a linear relationship between ln(F0/F) and the concentration of Fe3+ ions, and a limit of detection (LOD) was measured to be 2.8 nM with a linear range of 20–100 µM under ideal conditions. Furthermore, ascorbic acid (AA) was used to reduce Fe3+ to Fe2+ ions, resulting in the recovery of CQD fluorescence. Additionally, the analysis of Fe3+ ions in the drinking water, tap water, and lake water samples showed that the proposed method has the potential to be used in the metal analysis of environmental samples. [ABSTRACT FROM AUTHOR]

The pursuit of a cost-effective and green synthetic approach to chemical sensors and their application in the sensing of toxic and harmful substances is a never-ending exercise for scientists and researchers. Preparation of fluorescent carbon dots (C-dots) from biomass using water as a solvent and a hydrothermal autoclave to provide the required synthesis temperature offers a cheap and environmentally friendly synthetic approach. Herein, we report a faster, less costly and ecofriendly hydrothermal synthetic approach of carbon dots from Citrullus vulgaris peels as a precursor. The as-prepared carbon dots exhibited hydroxyl, carbonyl and amide functional groups on the surface and an amorphous structure with a particle size distribution of 1.7-3.0 nm. Moreover, the carbon dots displayed intense blue emission fluorescence at 470 nm after excitation at 400 nm. The as-prepared carbon dots demonstrated effective application without further modification towards the selective and sensitive optical recognition of 2-nitrophenol used in the manufacture of explosives. A limit of detection of 2.28x10-7 M was achieved, and no fluorescence quenching was observed in the presence of other nitroaromatic and benzene derivatives indicating excellent selectivity towards 2-nitrophenol. Finally, further studies are required to investigate the potential for the as-prepared carbon dots to monitor nitroaromatic pollutants in real environmental systems. [ABSTRACT FROM AUTHOR]

A versatile mono-Schiff compound consisting of o-aminobenzene-hydroxyjulolidine (ABJ-MS) has been easily synthesized using a one-step reaction. ABJ-MS displays four diverse fluorescence responses to the addition of Zn2+/Al3+/Fe3+/Ag+, with the maximum fluorescence emission at 530 nm undergoing a hypsochromic shift to 502/490/440/430 nm, synchronously with the discriminating fluorescence enhancement being 10.6/22.8/2.6/7.1-fold, respectively. However, the addition of Cu2+ into ABJ-MS leads to an opposite behavior, namely, fluorescence quenching. Meanwhile, ABJ-MS also displays distinct absorption changes after adding these five metal ions due to different binding affinities between them and ABJ-MS, which gives ABJ-MS quite a versatile detecting nature for Cu2+/Zn2+/Al3+/Fe3+/Ag+. Moreover, ABJ-MS can mimic a series of versatile AND/OR/INH-consisting logic circuits on the basis of the Cu2+/Zn2+/Al3+/Fe3+/Ag+-mediated diverse optical responses. These will endow the smart ABJ-MS molecule and potential applications in the multi-analysis chemosensory and molecular logic material fields. [ABSTRACT FROM AUTHOR]

Sensing of lectins are utmost necessary for its inflammatory, digestive disorder, gut pains and toxicity to human beings and for this purpose we have chosen polythiophene (PT) for its exciting optoelectronic properties. Because of precise carbohydrate specificities of lectin and to make PT water soluble for sensing of lectin, we have synthesized polythiophene-g-poly(N,N-dimethylaminoethyl methacrylate) -co-poly(glucose-hydroxyethyl methacrylate) (PT-g-pDMAEMA-co-pGLU-HEM), [PTDG]) from polythiophene macroinitiator (PTI) by copolymerizing DMAEMA and GLU-HEM monomers mixture with CuCl/HMTETA catalyst/ligand followed by hydrolysis using alcoholic NaOMe solution. The Mn of PTI was 38000, polydispersity 2.5, head-tail (H-T) regioregularity 70 mol % and Mn of unhydrolyzed PTDG is 98,900. The UV-Vis spectra of PTDG solution shows two absorption peaks at 430 and 462 nm but it shows a sharp emission peak at 544 nm which quenches with increasing pH. Concanavalin A (ConA) shows an absorbance peak at 278 nm and with addition of PTDG solution absorbance intensity increases showing hypochromic effect. Benesi–Hildebrand plot of reciprocal molar extinction coefficients with concentration suggests 1:1 complex formation between PTDG and ConA. With addition of ConA fluorescence quenching of PTDG solution occurred and using the fluorescence intensity ratio vs concentration plot the limit of detection (LOD) of Con A lectin is found to be 57 µg/L and storing the polymer solution for two months exhibits good durability. The morphology of PTDG changes from vesicle to compound micellar aggregate on addition of Con A lectin. We have synthesized a polythiophene glcopolymer (PT-g-pDMAEMA-co-pGLU-HEM), PTDG) using ATRP technique and its UV-Vis and fluorescence spectra indicates pH responsivity and lectin sensing property with LOD of 57 µg/L. [ABSTRACT FROM AUTHOR]

We report a fluorescent assay for the determination of vitamin B12 (VB12) based on the inner filter effect (IFE) of 1,3-propanedithiol-functionalized silver nanoparticles (PDT-AgNPs). PDT was simply functionalized on the surface of AgNPs through Ag–thiol interaction, which leads to significantly enhanced fluorescence, with excitation and emission at 360 and 410 nm, respectively, via their thiol-mediated aggregation. Since target VB12 has strong absorption centered at 360 nm, which is almost completely overlapping with the excitation spectra of PDT-AgNPs, the VB12 induced strong quenching of the fluorescence of PDT-AgNPs via IFE. The IFE-based mechanism for the fluorescence quenching of PDT-AgNPs in the presence of VB12 was confirmed by the analyses of Stern–Volmer plots at different temperatures and fluorescence decay curves. The fluorescence-quenching efficiency of PDT-AgNPs was linearly proportional to the concentration of VB12 in a wide range of 1 to 50 μM, with a lower detection limit of 0.5 μM, while preserving excellent selectivity toward target VB12 among possible interfering molecules. Furthermore, the PDT-AgNPs-mediated assay succeeded in quantitatively detecting VB12 in drug tablets, indicating that PDT-AgNPs can serve as an IFE-based fluorescent probe in pharmaceutical preparations by taking advantages of its ease of use, rapidity, and affordability. [ABSTRACT FROM AUTHOR]

Curcumin (Cur) possesses diverse biological and pharmacologic effects. It is widely used as a food additive and therapeutic medicine. A study to determine a sensitive detection method for Cur is necessary and meaningful. In this work, double rare earth ions co-doped fluorescent coordination polymer nanoparticles (CPNPs) were developed for the Cur detection. The CPNPs were synthesized by using adenosine monophosphate (AMP) as bridge ligands via coordination self-assembly with Ce3+ and Tb3+. The AMP-Ce/Tb CPNPs exhibited the characteristic green fluorescence of Tb3+ and had high luminescence efficiency. Under the optimal conditions, the fluorescence intensity of AMP-Ce/Tb CPNPs could be significantly quenched by Cur. The fluorescence quenching extent at λex/λem of 300 nm/544 nm showed a good linear relationship with the Cur concentration in the range of 10 to 1000 nM. The detection limit was as low as 8.0 nM (S/N = 3). This method was successfully applied to the determination of Cur in real samples with satisfactory results. The luminescence mechanism of AMP-Ce/Tb CPNPs and the fluorescence quenching mechanism of the CPNPs by Cur were both examined. [ABSTRACT FROM AUTHOR]

The interaction of orphenadrine hydrochloride (ORD) with the model protein, bovine serum albumin (BSA), was investigated using a variety of spectroscopic techniques such as steady-state fluorescence, ultraviolet–visible, Fourier transform infrared, 3-D spectroscopy, and electrochemical methods under physiological conditions. Stern–Volmer plots were used to calculate fluorescence quenching at various temperatures. The findings point to a static quenching mechanism between ORD and BSA. At various reaction times, the binding sites (n) and binding constants (K) of ORD to BSA were recorded. Thermodynamic parameters ∆H0, ∆S0 and ∆G0 between ORD and BSA were calculated and reported. The average binding distance (r) between the donor (BSA) and acceptor (ORD) molecules was predicted using Förster's theory. Three-dimensional fluorescence spectra, Fourier transform infrared spectra, and synchronous fluorescence studies all supported the alternations in protein structure following the interaction with ORD. A displacement study using site probes such as warfarin, ibuprofen, and digitoxin confirmed ORD binding at Sudlow's site I of BSA. The effect of common metal ions such as Cu2+, Ni2+, Ca2+, Co2+, and Zn2+ on binding constant values was investigated and reported. [ABSTRACT FROM AUTHOR]

A naphthalene diimide dye with two side amine arm was prepared. Uv–Vis and fluorescence spectroscopic techniques are used for their photophysical and solvatochromic characteristics in different solvents. The Lippert-Mataga plot for naphthalene diimide demonstrated a negative linear dependence by increasing polarity. Results showed naphthalene diimide is more polar in the ground than in the excited state. A quenching study was conducted for interacting the naphthalene diimide as a fluorophore and graphene oxide as a quencher. Fluorescence quenching-based platforms in nanoscale have been used in sensing systems. Raman, FTIR, Uv–Vis and fluorescence spectroscopic techniques were used to study the quenching mechanism. The results indicated that graphene plays an effective quencher against the naphthalene diimide, with a quenching efficiency 91%. The Stern–Volmer analysis results show a mix of static and dynamic quenching mechanisms. The binding constant of the quencher-fluorophore and the number of binding sites have been reported. Thermodynamic parameters of their interaction were evaluated. The negative values of the Gibbs free energy confirm that the complexation process is spontaneous. Meanwhile, the positive entropy value confirms that the favorable pathway process. [ABSTRACT FROM AUTHOR]

Doxorubicin is a common chemotherapeutic drug used to treat a variety of cancers. Monitoring the concentration of doxorubicin in human biological fluids is vital for treatment. In this work, we report an aptamer-functionalized, 808 nm-excited core–shell upconversion fluorescence sensor for specific detection of doxorubicin (DOX). Upconversion nanoparticles and DOX are used as energy donors and energy acceptors respectively. Aptamers immobilized on the surface of upconversion nanoparticles act as the molecular recognition element for DOX. The binding of DOX to the immobilized aptamers results in the fluorescence quenching of the upconversion nanoparticles via a fluorescence resonance energy transfer process. The relative fluorescence intensity exhibits a good linear response to DOX concentration in the range of 0.5 μM to 55 μM with a detection limit of 0.5 μM. The aptasensor displays high specificity and anti-interference against other antibiotics, common ions, and biomolecules owing to strong and specific interactions of aptamers towards DOX. The sensor is further applied for the detection of DOX in urine with spike recoveries of nearly 100%. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) were found to significantly quench the fluorescence of bambuterol hydrochloride (BAM) and its active metabolite terbutaline sulfate (TER). The intrinsic fluorescence intensity of each of BAM (at 264/292 nm) and TER (at 276/306 nm) decreased by the gradual addition of AgNPs. Quenching of the steady state fluorescence of BAM and TER probably resulted from the energy transfer to the photo-excited state of AgNPs. The estimated Stern–Volmer quenching constant at several temperature settings proved that the quenching mechanism of the two drugs was dynamic quenching in case of BAM while it was static quenching in case of TER. The number of binding sites, binding constants, and corresponding thermodynamic parameters depending on the interaction system were estimated at 293, 313, and 333 °K and the results obtained were interpreted. [ABSTRACT FROM AUTHOR]

[Display omitted] Aggregation-induced emission (AIE) and antenna effect (AE) are two significant behaviors that have attracted increasing attention. However, it is challenging to achieve the synergistic effect of AIE and AE in luminescent materials for more extensive applications. Here, four gelatinous Ln3+ coordination polymers (Ln-CPs) are synthesized by self-assembly of ciprofloxacin (CIP), adenosine monophosphate (AMP), and Ln3+ ions in aqueous medium. Encouragingly, a remarkable increase in the characteristic fluorescence of Ln3+ and a significant decrease in CIP are observed along with increasing concentration of Ln-CPs, which is attributed to the large aggregates formed by self-assembly that strictly constrain the intramolecular motions of antenna ligands, thereby achieving the aggregation-enhanced AE. More meaningfully, Eu-CP not only shows a rice-like morphology at high aggregation state, but also provides an opportunity for the selective detection of alkaline phosphatase (ALP). A new flower-like polymer is formed upon incubating Eu-CP with ALP, accompanied by the fluorescence quenching of Eu3+ and recovery of CIP, a ratiometric determination of ALP in the range of 0.1–6.0 U·L−1 is thus achieved. Additionally, ALP assay in human serum and bioimaging in living cells have been successfully performed. This research opens a new horizon for the fabrication of Ln3+-based luminescent materials with promising applications. [ABSTRACT FROM AUTHOR]

Polydiacetylenes (PDAs) are conjugated polymers that have been widely exploited for their chromogenic and fluorogenic transitions upon exposure to external stimuli and biomolecules of interest. Herein, we propose a comparative study of the polymerization dynamics of two diacetylene derivatives, TzDA1 and TzDA2, in the form of aggregates in suspension prepared by reprecipitation method from organic solvents in water, varying the diacetylene concentration and solvent proportions, and sonication in water, varying the time and temperature. Both derivatives bear a tetrazine fluorophore, which serves both to increase the fluorescence quantum yield of the system and to track the polymerization by fluorescence quenching exclusively by the blue-PDA, and differ by the chain termination. It was shown that adding a butyl ester function in TzDA2 to a simple urethane (TzDA1) influences the polymerizability and kinetics of polymerization of the aggregates in suspension. In addition, we showed that also the preparation method and preparation conditions do have an influence on the polymerization dynamics, suggesting that a careful study of these properties should be carried out before investigating the applications of such objects. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Dalian University of Technology / Dalian Ligong Daxue Xuebao is the property of Journal of Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Image guided photodynamic therapy (PDT) combines fluorescence tracing and phototherapy, which can achieve a more accurate and effective treatment effect. However, traditional photosensitizers are limited by the aggregation-caused fluorescence quenching (ACQ) effect and low reactive oxygen species (ROS) generation in a hypoxic environment, resulting in poor imaging and treatment effect. Herein, we report a tricyano-methylenepyridine (TCM)-based Type I aggregation-induced emission (AIE) photosensitizer (TCM-MBP), the strong electron acceptance (D-A) effect extends the wavelength to near-infrared (NIR) region to reduce the autofluorescence interference, and oxygen atoms provide lone pair electrons to enhance the inter system crossing (ISC) rate, thereby promoting the generation of more triplet states to produce ROS. The AIE photosensitizer TCM-MBP exhibited low oxygen dependence, NIR emission, and higher ROS production compared to commercially available Ce 6 and RB. After encapsulation with DSPE-PEG2000, TCM-MBP nanoparticles (TCM-MBP NPs) could penetrate to visualize cells and efficiently kill cancer cells upon light irradiation. This study provides an oxygenindependent AIE photosensitizer, which has great potential to replace the commercial ACQ photosensitizers. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan University of Technology Natural Science Edition is the property of Henan University of Technology Journal Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Scientiarum Naturalium Universitatis Sunyatseni / Zhongshan Daxue Xuebao is the property of Sun-Yat-Sen University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study presents the development of a portable fluorometer with a smartphone application designed to facilitate the early screening of chronic kidney and renal diseases by enabling the sensitive detection of urinary albumin. Utilizing a fluorescence-based aptasensor, the device achieved a linear calibration curve (0.001–1.5 mg/mL) with a linearity of up to 0.98022 and a detection limit of 0.203 µg/mL for human serum albumin (HSA). The analysis of 130 urine samples demonstrated comparable performance between this study's fluorometer, a commercial fluorometer, and the standard automated method. These findings validate the feasibility of the portable fluorometer and aptasensor combination as a reliable instrument for the sensitive and specific measurement of HSA in urine samples. Moreover, the fluorometer's portability offers potential applications in portable point-of-care testing, enhancing its utility in clinical settings for early disease screening. [ABSTRACT FROM AUTHOR]