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The nitrogen-doped carbon dots (N-CDs) were prepared by using coke powder as carbon source and one-step hydrothermal method. The N-CDs were studied as a fluorescent chemosensor for determining Cr(VI) in water. The selective, sensitive, reproducibility and stability of as-prepared N-CDs were investigated. The morphology, composition and properties of N-CDs were characterized by a series of methods. The fluorescence quenching of N-CDs by Cr(VI) was explored. The experimental results reveal that the obtained N-CDs have great hydrophilicity and strong luminescence properties, which demonstrates the successful doping of nitrogen into the CDs. The surface-active groups and emission wavelength range of CDs increase due to the electronegativity and electron donor effect of doping N atom. Furthermore, the N-CDs exhibit good photochemical properties for the detection of Cr(VI), including a wide linear range from 0.3 to 200 µM (R2=0.9935) and a low detection limit of 0.10 µM at the signal-to-noise ratio of 3 (S/N=3). Moreover, the N-CDs as a sensor was used successfully for Cr (VI) detection in real water samples with recovery rates of 99.9%–110.6%. This sensor also shows highly reproducibility and stability. The N-CDs fluorescent chemical sensor may be a potential candidate for applying in the field of other fluorescent chemical sensing, catalysis, photoelectric devices and other fields. [ABSTRACT FROM AUTHOR]

Inborn errors of monoamine neurotransmitter metabolism are rare genetic diseases classified as catecholamine and serotonin metabolism disorders or neurotransmitter transportopathies. To diagnose these orphan diseases, monoamine metabolites have been identified and validated as cerebrospinal fluid (CSF) biomarkers: 5‐hydroxy‐tryptophane, 5‐hydroxy‐indol‐acetic acid, 3‐ortho‐methyl‐DOPA, homovanillic acid, and 3‐methoxy‐4‐hydroxyphenylglycol. The present work presents a UHPLC–MS/MS method developed for the quantification of these metabolites in CSF and compares it with a previously described UHPLC with fluorescence detection (UHPLC‐FD) method. MS/MS detection was performed in positive electrospray ionization and multiple reaction monitoring mode. The UHPLC–MS/MS and UHPLC–FD methods were validated in terms of accuracy, linearity, precision and matrix effect. The lower limits of quantification (LLOQ) ranged between 0.5 and 10 nm and between 1 and 5 nm for the UHPLC–MS/MS method and the UHPLC–FD one, respectively. We verified the applicability of both methods by analyzing 30 CSF samples. The measured concentrations were comparable with the reference values described in the literature. The two methods allowed pathological samples to be distinguished from healthy ones for clinical diagnosis. UHPLC–MS/MS and UHPLC–FD methods exhibited very close LLOQs. As the UHPLC–MS/MS method is more selective, it allows faster analysis with a run time of 6 min per run vs. 10 min for the UHPLC–FD method. [ABSTRACT FROM AUTHOR]

In this study, a naked-eye visible and fluorescence-on Ag+ probe based on two-dimensional material MXene was successfully constructed. This study investigated the π–π and dispersive interactions between MXene and rhodamine-6G, and the reduction and growth of silver ions on the MXene surface. The characterization by transmission electron microscopy and X-ray photoelectron spectroscopy confirmed our conjecture about this process. This probe shows competent highly selective real-time detection of Ag+ in aqueous solution with a 0.035 μM detection limit, which is also capable of Ag+ sensing in living cells. Comparing the fluorescence response of the probe to silver ions in the presence of other metal ions, it is confirmed that the probe has good selectivity to silver ions. In particular, this probe can also be carried out to detect and track Ag+ levels in living cells. The discoveries provide fresh insights into the detection and analysis of silver ions in environmental and biological samples. Meanwhile, this method also provides ideas for constructing MXene-based sensing platforms. [ABSTRACT FROM AUTHOR]

The polymerase chain reaction is an important technique in biological research. However, it is time consuming and has a number of disadvantages. Therefore, real-time PCR technology that can be used in real-time monitoring has emerged, and many studies are being conducted regarding its use. Real-time PCR requires many optical components and imaging devices such as expensive, high-performance cameras. Therefore, its cost and assembly process are limitations to its use. Currently, due to the development of smart camera devices, small, inexpensive cameras and various lenses are being developed. In this paper, we present a Compact Camera Fluorescence Detector for use in parallel-light lens-based real-time PCR devices. The proposed system has a simple optical structure, the system cost can be reduced, and the size can be miniaturized. This system only incorporates Fresnel lenses without additional optics in order for the same field of view to be achieved for 25 tubes. In the center of the Fresnel lens, one LED and a complementary metal-oxide semiconductor camera were placed in directions that were as similar as possible. In addition, to achieve the accurate analysis of the results, image processing was used to correct them. As a result of an experiment using a reference fluorescent substance and double-distilled water, it was confirmed that stable fluorescence detection was possible. [ABSTRACT FROM AUTHOR]

A multi pathogenic microorganisms determination method is reported using DNA composites encapsulated DNA silver nanocluster (AgNCs)/graphene oxide (GO)-based system through rolling cycle (RCA) amplification. Firstly, two different RCA-based DNA composites are assembled, coupled with thousands of DNA-stabilized AgNCs probe and ssDNA aptamer specific for two pathogen bacteria targets. GO was then introduced into the system to capture ssDNA aptamer of DNA composites and as a selective fluorescence quencher of DNA/AgNCs. Upon recognizing the target bacteria, ssDNA aptamer part would combine with bacteria and release from the surface of GO. Thus, DNA/AgNCs of RCA-based DNA composites can generate strong fluorescence signal. With the fluorescent report of RCADNA-AgNCs/530 and RCADNA-AgNCs/625, the assay successfully detect Escherichia coli and Staphylococcus aureus at concentrations as low as 38 CFU/mL, and a highly selective and efficient sensing platform was achieved. Therefore, this RCA/DNA-AgNCs/GO-based platform shows excellent application in multi pathogenic microorganisms determination and potential clinic therapy. [ABSTRACT FROM AUTHOR]

DNA micelles formed by hydrophobic, self-assembly of amphiphilic DNA monomers have enormous potential in biological imaging owing to its unique and programmable, three-dimensional nanostructure. Herein, we rationally design double-stranded DNA oligonucleotides with two cholesterols that can spontaneously form the lipid-mediated DNA micelles and generate the high fluorescence signal after the formation of DNA-templated copper nanoclusters (CuNCs). Furthermore, the DNA aptamer specific to MUC1 protein, aberrantly overexpressed on the surface of cancer cells, is attached to lipid-mediated DNA micelles to confer the selectivity towards the target cancer cells. With the well-defined DNA nanostructures, the cell membrane of MUC1-positive cancer cells are stained by CuNCs exhibiting an intense, red fluorescence signal, which are clearly distinguished from MUC1-negative cancer cells. This approach may not only expand the application scope of both DNA micells and CuNCs, especially in the area of cellular imaging, but also provides a basis for developing other types of DNA nanostructures to detect target biomarkers. [ABSTRACT FROM AUTHOR]

Acetaldehyde is regarded as an important flavor compound in alcoholic beverages. With the advantages of rapidity, low cost and high sensitivity, fluorescent probe could be used as a new tool for the detection of acetaldehyde. Here, an effective fluorescence sensing method based on fluorescent probe N1 (FPN1) was established in this study. The function of FPN1 relies on the nucleophile substitution reaction and photoinduced electron transfer (PET), resulting in a fluorescence increase. Remarkably, the pretreatment background removal method (BRM) was successfully applied for removal of the interference of pyruvate and acetal. The linearity range (LR), limit of detection (LOD) and recovery of the fluorescence sensing method with BRM were 0.0053–200 mg/L, 0.0016 mg/L and 94.02–108.12%, respectively, which showed a broader detection range and better performance on sensitivity compared with the traditional quantitation using gas chromatography (GC). Furthermore, successful application of the method in real samples indicated the advantages of low-cost and rapidity for small-scale detection while assuring the accuracy, which provides a new strategy for the detection of acetaldehyde concentration in alcoholic beverages. [ABSTRACT FROM AUTHOR]

In this work, we present a multifunctional Lab-on-Chip (LoC) platform based on hydrogenated amorphous silicon sensors suitable for a wide range of application in the fields of biochemical and food quality control analysis. The proposed system includes a LoC fabricated on a 5 cm × 5 cm glass substrate and a set of electronic boards for controlling the LoC functionalities. The presented Lab-on-Chip comprises light and temperature sensors, a thin film resistor acting as a heating source, and an optional thin film interferential filter suitable for fluorescence analysis. The developed electronics allows to control the thin film heater, a light source for fluorescence and absorption measurements, and the photosensors to acquire luminescent signals. All these modules are enclosed in a black metal box ensuring the portability of the whole platform. System performances have been evaluated in terms of sensor optical performances and thermal control achievements. For optical sensors, we have found a minimum number of detectable photons of 8 × 104 s−1·cm−2 at room temperature, 1.6 × 106 s−1·cm−2 in presence of fluorescence excitation source, and 2.4 × 106 s−1·cm−2 at 90 °C. From a thermal management point of view, we have obtained heating and cooling rates both equal to 2.2 °C/s, and a temperature sensor sensitivity of about 3 mV/°C even in presence of light. The achieved performances demonstrate the possibility to simultaneously use all integrated sensors and actuators, making promising the presented platform for a wide range of application fields. [ABSTRACT FROM AUTHOR]

In this work, we examine how strain exerted on individual ZnO nanorods (NRs) can influence the fluorescence signals that are emitted from fluorophore molecules and subsequently coupled into and guided along the NR. We elucidate the relationships between the incremental levels of compressive and tensile strain on the NRs and measured fluorescence intensity of a model fluorophore, rhodamine 6G (R6G), as a function of the position on the NRs. We reveal that compressive strain on the NRs leads to a decrease in the guided fluorescence signal, while tensile strain leads to an increase in the fluorescence intensity. Compared to an unstrained state, approximately 35% decrease (increase) in R6G fluorescence intensity was observed from ZnO NRs when they were under compressive strain of −14% (tensile strain of +10%). Further, our systematic acquisition of the incremental addition of uniaxial strain result in a linear relationship of the coupled fluorescence signal and the amount of applied strain. The degree of fluorescence intensification on nanorod ends (DoF), which is a quantitative indicator for the amount of R6G signals coupled into and waveguided to the NR ends compared to those on the main body, also exhibits a linear relationship with strain. These outcomes, in turn, demonstrate that strain alters the waveguiding capabilities of ZnO NRs in a predictable manner, which can be exploited to modulate and optimize fluorescence and other light signals emitted by a nearby source. Considering the wide utility of ZnO NRs in photonics, optoelectronics, and sensors, insights from our study may be highly valuable to effectively controlling and enhancing optical signals from chemical and biological analytes through strain. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) have recently emerged as a new major and ubiquitous environmental pollutant with still undefined, yet potentially high risks for human health and ecosystems. This has prompted growing public concern along with an increasing number of scientific studies. In particular, recent research has highlighted the need for a standardized methodology to monitor microplastics in different media, particularly in water. This study reports on the use of a new particle counter for the quantitative detection of MPs in water samples based on real-time analysis of fluorescence emissions. The instrument was calibrated using two types of plastic particles, i.e., polyvinyl chloride and high-density polyethylene, selected as examples of high- and low-density plastics, respectively. Specific solvents were used to match the different plastic densities. Measurements were also carried out on particles obtained from wastewater samples collected at the inlet and outlet of specific units of a municipal wastewater treatment plant after sieving, filtering, digestion with hydrogen peroxide to remove degradable organic matter and resuspension in the solvents employed during the calibration step. A Fourier transform infrared spectroscopy analysis performed on the same wastewater samples confirmed the presence of MPs, and, in particular, of polyethylene, in some of the samples in which the highest concentrations were measured applying the proposed method. Therefore, the novel particle counter described in this paper could represent a promising method to quantitatively measure MP concentrations in water samples. [ABSTRACT FROM AUTHOR]

An enzyme-linked fluorescent immunoassay (ELFIA) method has been developed for the quantitative analytical determination of the herbicide active ingredient glyphosate in environmental matrices (surface water, soil, and plant tissues). Glyphosate, as a ubiquitous agricultural pollutant, is a xenobiotic substance with exposure in aquatic and terrestrial ecosystems due its extremely high worldwide application rate. The immunoassay developed in Project Aquafluosense is part of a fluorescence-based instrumentation setup for the in situ determination of several characteristic water quality parameters. The 96-well microplate-based competitive immunoassay method applies fluorescence signal detection in the concentration range of 0–100 ng/mL glyphosate. Application of the fluorescent signal provides a limit of detection of 0.09 ng/mL, which is 2.5-fold lower than that obtained with a visual absorbance signal. Beside the improved limit of detection, determination by fluorescence provided a wider and steeper dynamic range for glyphosate detection. No matrix effect appeared for the undiluted surface water samples, while plant tissues and soil samples required dilution rates of 1:10 and 1:100, respectively. No cross-reaction was determined with the main metabolite of glyphosate, N-aminomethylphosphonic acid, and related compounds. [ABSTRACT FROM AUTHOR]

A rapid fluorometric method was established to detect glyphosate by using cerium ion and pyrophosphate ion (Ce-PPi) coordination polymer networks (CPNs). Based on coordination of cerium ion (Ce3+) and pyrophosphate ion (PPi), fluorescent Ce-PPi CPNs were synthesized by simple selfassemble process, and the structure and properties were characterized. Upon introducing glyphosate, the ligand field effect of PPi with Ce3+ was weakened resulting in a decrease in fluorescence of Ce-PPi CPNs. Based on this principle, the quantitative detection of glyphosate was achieved by optimizing the conditions, with R² of 0.997 2 and the detection limit of 0.014 μmol/L. The established method based on Ce-PPi CPNs possessed outstanding sensitivity and exclusive selectivity for rapid detction of glyphosate, and could be used for the detection of glyphosate in tap water and apple samples. The limit of quantitation (LOQ) was 0.05 mg/kg and the recoveries were between 77% and 87%. The method provided a potential choice for the rapid, on-site and real-time, detection of glyphosate. [ABSTRACT FROM AUTHOR]

Herein, we present a comprehensive investigation of rationally designed zinc selenide (ZnSe) nanostructures to achieve highly negatively charged ZnSe nanostructures. A Microwave-assisted hydrothermal synthesis method was used to synthesize three types of ZnSe nanostructures, i.e., nanorods, µ-spheres and nanoclusters, as characterized by a zeta potential analyzer, X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy and BET, which were labeled as type A, B and C. Three different solvents were used for the synthesis of type A, B and C ZnSe nanostructures, keeping other synthesis conditions such as temperature, pressure and precursors ratio constant. Based on two heating time intervals, 6 and 9 h, types A, B and C were further divided into types A6, A9, B6, B9, C6 and C9. ZnSe nanostructures were further evaluated based on their fluorescent quenching efficiency. The maximum fluorescence quenching effect was exhibited by the ZnSe-B6 type, which can be attributed to its highly negative surface charge that favored its strong interaction with cationic dye Rhodamine B (Rh-B). Further, the optimized ZnSe-B6 was used to fabricate an aptasensor for the detection of a food-based toxin, ochratoxin-A (OTA). The developed aptasensor exhibited a limit of detection of 0.07 ng/L with a wide linear range of 0.1 to 200 ng/L. [ABSTRACT FROM AUTHOR]

Phytate in plants (inositol phosphates, InsPs) affects mineral bioavailability. However, methods for their quantification may lead to variable results, and some are nonspecific (spectrophotometric techniques). In this study, ion-pair high-performance liquid chromatography (HPLC) was coupled with post-column derivatization to allow fluorescence detection (FLD, λ excitation 324/λ emission 364 nm) of InsPs. The fluorescence derivatization reaction, the main input of this study, was based on a ternary complex among phytate, iron(III), and 1,10-phenanthroline. Phytic acid (InsP 6 ) and three other InsPs (InsP 3-5 ) were analyzed in peanuts and soybean products after extraction in HCl 0.66 M, followed by purification on strong anion exchange cartridges. The novel method, named IP-HPLC-FLD, selectively separated InsP 3-6 with linear ranges between 600 and 2000 mg 100 g -1 ( R 2 > 0.99). The limits of detection and quantification were between 120-180 and 340-540 mg 100 g -1 , respectively. As the relative standard deviations were under 10%, the IP-HPLC-FLD method is suitable for phytate analysis.

Creating an analytical probe to track extremely mutagenic picric acid (PA) is essential for human health and the environment. Here, we developed a straightforward and quick fluorescence analytical method utilizing 3-aminopropyltrimethoxysilane (3-APTMS)-functionalized curcumin carbon quantum dots (CQDs) for the fast and selective detection of PA. Solvothermal carbonization and functionalization of curcumin with 3-APTMS were used to create multifunctional CQDs, which were then characterized using UV-vis spectroscopy, Fourier transform infrared (FTIR), X-ray diffraction (XRD), ζ-potential, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Our CQDs, as synthesized with an average diameter of 3.4 nm, exhibited excitation-dependent emission behavior, demonstrating 63.85% yield, 1.59% quantum yield, and fluorescence lifetime decay broader than a single exponential. The addition of picric acid significantly reduced the fluorescence (FL) emission intensity of CQDs and caused a noticeable color shift in visible as well as UV light. Throughout the 0.1-2.5 μM range, the calibration curve of the suggested assay demonstrated favorable linearity between quenched FL emission intensity and PA concentration, with the lowest detection limit of 88.96 nM. The CQD shows antioxidant activity at low concentrations (<0.07 mg/mL), measured by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay (colorimetry and electrochemically). Further, we encapsulated our CQDs in the liposome to make it biocompatible for cell imaging for future study. The results indicate the efficacy of CQDs as a nanoprobe for the selective detection of PA, retaining a few of the primary properties of natural curcumin-like antioxidant activity while having significantly higher bioavailability and water solubility; they can be used as a modifier in semiconductors for photocatalytic application and can also be a promising fluorescence probe in cell imaging.

Multi-wavelength emission fluorescent manganese-nitrogen co-doped carbon dots (Mn, N co-doped CDs) were synthesized by solvothermal method using β-cyclodextrin, O-phenylenediamine, and manganese chloride as raw materials. The prepared Mn, N co-doped CDs were used as fluorescent nanosensing platforms for the detection of metal ions and biomolecules and were found to be capable of fluorescence detection of tannic acid (TA) and hafnium (Hf) ion at 320, 380, and 480 nm excitation wavelengths with multi-response linear ranges of 0.7 ~ 1.2 µM and 6.35 ~ 13 µM and detection limits of 0.45 µM and 6.3 µM, respectively. The wide linear ranges and low detection limits may be due to the fluorescence resonance energy transfer effect between the platform and TA and Hf ions. In addition, it was found that Mn, N co-doped CDs had good photostability, biocompatibility, and low cytotoxicity, which could be used for in vitro fluorescence imaging of exogenous TA and Hf ion imaging in U2OS osteosarcoma cells. Thus, the probe has a promising application in biomedical fields as a new multi-responsive fluorescence nanosensing platform member., Competing Interests: Declarations. 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. Ethical approval: This research did not involve human or animal samples. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Deoxynivalenol (DON) contamination in cereals is a widespread issue with global implications, necessitating the development of efficient detection methods. Here, a fluorescent aptasensor integrating target-responsive DNA three-way junction (TWJ) and DNA walking machine was developed to detect DON. The DON-specific aptamer (Apt) and the walker (Walker DNA) are integrated into TWJs. TWJs initiate the DNA walking machine with the assistance of Nb.BbvCI to provide signal amplification for sensing events. The constructed fluorescent aptasensor selectively recognizes and detects DON. Additionally, the sensing platform explored the quantitative relationship between fluorescence signal changes and DON concentration, achieving a limit of detection (LOD) of 0.009 ng/mL. Ultimately, the method performed well in the detection of cornmeal samples with recoveries ranging from 95.49 % to 100.82 %. The method demonstrates good stability and is expected to be a potential candidate for the accurate detection of DON in grains., Competing Interests: Declaration of competing interest 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., (Copyright © 2024. Published by Elsevier Ltd.)

A dual-mode immunoassay method was developed for colorimetric and fluorescence detection of aflatoxin B1 (AFB1) based on streptavidin-induced gold nanoparticle aggregation (AuNP@SA). AuNP-modified streptavidin-biotin labeling AFB1 complete antigen aggregations (AuNP@SA@Bio-BSA-AFB1) were synthesized as the competitive binding and dual-mode probe. AuNP@SA@Bio-BSA-AFB1 aggregations possessed high colorimetric and fluorescence quenching intensities. AFB1 antibodies modified immunomagnetic microspheres were used as the capture probe. The competitive binding between AFB1 and AuNP@SA@Bio-BSA-AFB1 leads to changes in color and fluorescence intensity. The detection limit of the colorimetric method is 6.95 ng·mL -1 , while that of the fluorescence method is 0.07 ng·mL -1 . The practicality of the proposed strategy was demonstrated by determining AFB1 in spiked peanut samples., Competing Interests: Declarations. Ethics approval: The study was performed in accordance with the ethical standards. Competing interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Industrialization has led to environmental pollution with various hazardous chemicals including pollution with metals. In this regard, the development of highly efficient analytical methods for their determination has received considerable attention to ensure public safety. Currently, scientists are paying more and more attention to the automation of analytical methods, since it permits fast, accurate, and sensitive analysis with minimal exposure of analysts to hazardous substances. This review discusses the automated methods with fluorescent detection developed for metal determination since 2000. It is evident that flow-injection analysis (FIA) with no preconcentration or with solid-phase preconcentration are predominant compared to liquid-phase preconcentration systems. FIA systems are also more widespread than sequential injection analysis (SIA) systems. Moreover, a significant number of works have been devoted to chromatography-based methods. Atomic fluorescence detectors significantly prevail over molecular fluorescence detectors. It must be highlighted that most of the methods result in good figures of merit and performance characteristics, demonstrating their superiority in comparison with manual systems.

A new analytical method for the rapid detection of histamine (HA) in beverages using fluorescence detection has been devised. It is primarily based on the use of o-phthalaldehyde (OPA) as a derivatizing agent. This unstable complex has been efficiently stabilized by addition of surfactants. The physicochemical variables that influence the sensitivity of the method and the fluorescence properties of the complex species in surfactant solutions have been optimized. Different surfactants were checked: the anionic sodium dodecyl sulfate, the cationic hexadecyltrimethylammonium chloride and the nonionic tricosa(ethylene glycol)dodecyl ether C 12 E 23 . All surfactants stabilize the HA:OPA complex for long times. C 12 E 23 provides excellent stability to the complex and higher fluorescence emission, allowing robust analysis conditions. Linear calibration curves allowing effective histamine determination and low limits of detection and quantification were established and the characteristics of the analysis method was validated. The correlation coefficient for histamine detection by fluorescence was 0.9978. The detection and quantification limits for histamine were 0.576 and 1.92 mg∙L -1 , respectively., Competing Interests: Declaration of competing interest 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., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this study, we showcase the fabrication of two nanorings resembling beehives using intricately designed donor-acceptor (D-A) fluorophores. The D-A fluorophores, featuring three twisted fluorene groups on each side of the acceptor group, adopt a bent conformation that promotes the creation of a nanoring morphology upon aggregation. With porosity for maximum binding sites, high emission efficiency, and well-organized arrangements, the nanoring-based hives offer exceptional sensitivity and selectivity in the detection of organic sulfides. Particularly, nanorings formed from benzselenodiazole-containing molecules exhibit heightened sensitivity, achieving a limit of detection (LOD) of 0.2 ppb for dimethyl sulfide and 17 ppb for dimethyl disulfide. Due to its unparalleled sensitivity and selectivity, which was not achievable with previous optical sensors, this technology enables the continuous monitoring of meat spoilage in its early stages on an hourly basis. This provides crucial insights into the exact moments when freshness begins to deteriorate and how long the meat can be stored for.

A multifunctional COF@HOF (ETTA-DFP@TCBP-HOF) composite is prepared by adding red-fluorescent ETTA-DFP COF to the blue-fluorescent TCBP-HOF preparation system through molecular hydrogen bonding or π - π stacking interactions in situ one-pot synthesis. ETTA-DFP@TCBP-HOF is a multifunctional material for the quantitative detection and simultaneous adsorption of 4-nitrophenol (4-NP) and metamitron (MET) in aqueous solution. As a dual-emission fluorescent sensor, the ETTA-DFP@TCBP-HOF has both fluorescence of TCBP-HOF at 474 nm and ETTA-DFP COF at 592 nm, which shows a ratiometric response to 4-NP and MET with high selectivity, good sensitivity, good anti-interference performance and fast response. As a adsorbent, ETTA-DFP@TCBP-HOF displays rapid adsorption kinetics, and acceptable adsorption capacity for 4-NP and MET. In conclusion, this work constructs a novel multifunctional hybrid material with dual-emission center of HOF and COF, which can not only be used as a ratiometric fluorescent probe for detection, but also for removal of hazardous pollutants, suggesting a new strategy for environmental remediation and human health., Competing Interests: Declaration of competing interest 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., (Copyright © 2024 Elsevier Inc. All rights reserved.)

A method using pH gradient to modify the phospholipid dissociation has been developed using hybrid magnetoliposomes with encapsulated enzyme laccase, which has been immobilized on hydrophilic magnetic nanocrystals (PAA-MNCs) retained in the reaction/detection zone of a microfluidic system. The hybrid magnetoliposomes act as micro containers, providing the safe transfer of the enzyme to the reaction/detection site, where it is retained, and preconcentration of the enzyme in this place occurs, which improves the system's sensitivity. The use of pH change involves the lack of external molecules to release the encapsulated materials. The laccase-mediated redox oxidation of the fluorescent substrate 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS) to form its non-fluorescent oxide form has been used as the indicator reaction. The method was applied to determine potential laccase inhibitors in beverages and fruits. The study of the inhibitory effect has focused on compounds that follow different mechanisms: cysteine, malic acid, and fumaric acid. The dynamic ranges of the calibration graphs of these compounds were between 0.05-100, 0.02-100, and 0.1-100 μmol L -1 , respectively. The detection limits have been established between 6 and 30 nmol L -1 , and the precision expressed as the percent of relative standard deviation (RSD%) was between 2.5 and 5.1%. The overall microfluidic system showed a sampling frequency of 8 h -1 . The method has been applied to determine fumaric acid as a laccase inhibitor in several juice samples (apple, pear, and grape), with recovery values between 85 and 101%. The results were comparable to those obtained using a LC reference method., Competing Interests: Declarations Competing interests The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Lithium thionyl chloride (Li-SOCl 2 ) batteries are widely used due to their high energy density and long shelf life. However, the corrosive nature of SOCl 2 poses a safety hazard, necessitating effective leak detection methods. We report an approach for real-time fluorescent detection of SOCl 2 leakage in Li-SOCl 2 batteries using a tetraphenylethene-based nanofilm. The nanofilms were prepared through the interfacial confined self-assembly method and exhibit excellent flexibility, homogeneity, tunable size and thickness, and adaptability to various substrates, enabling easy integration into sensor devices. They possess high photochemical stability and a photoluminescence quantum yield exceeding 25%, demonstrating their potential as high-performance fluorescent sensing material. The nanofilms also exhibit high sensitivity, good reproducibility, and selectivity toward SOCl 2 detection. Upon exposure to SOCl 2 vapor, the nanofilm shows a red-shifted and fluorescence quenching response, attributed to the protonation of the acylhydrazone bond in the nanofilm by the hydrolysis product of SOCl 2 , which disrupts the electronic structure of the nanofilm and leads to a decrease in the fluorescence intensity and a shift in the emission wavelength. A detection limit of ∼1.31 ppt and excellent repeatability over 300 cycles are demonstrated, highlighting their high sensitivity and reliability. This work paves the way for a highly sensitive and reliable leak detection system for Li-SOCl 2 batteries, enhancing their safety and reliability in various applications.

An inverted DNA tetrahedron-mediated modular DNA walker was developed for the determination of sulfadimethoxine. The inverted DNA tetrahedron scaffold raises several advantages of recognition module including appropriate lateral space, multiple recognition domains, and cost-effectiveness. The proposed inverted DNA tetrahedron-based recognition module exhibited better binding affinity and kinetics toward target antibiotic than that of other DNA tetrahedron counterparts. Upon specific binding with target, the released bipedal DNA walking strand hops to the signal amplification module and moves stochastically with assistant of nicking enzyme. By coupling these two modules, a good linear relationship between the fluorescence intensity of supernatant and the concentration of sulfadimethoxine was achieved in the range 0.1-100 nM, and the limit of detection was 64.7 pM. Furthermore, this modular DNA walker had also successfully applied to spiked honey and milk samples with satisfactory recoveries from 91.5 to 108.8%, demonstrating its practical sensing capability., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

A novel assay was developed based on a turn-off fluorescent probe using the in situ generation of carbon dots (CDs) by means of UV/H 2 O 2 advanced oxidation of carbohydrates for the detection of bisphenol A (BPA) in food. Different parameters involved in the synthesis of CDs for the direct recognition of BPA have been optimised and a sensing mechanism is outlined. The presence of H 2 O 2 during CD synthesis causes a fluorescence enhancement due to the action of highly oxidant HO · radicals formed throughout the photochemical reaction. Phenolic compounds such as BPA can be easily degraded by the UV/H 2 O 2 oxidation process, acting as a HO · free radical scavengers. This results in a decrease in the fluorescence that can be related to the BPA concentration. Under optimal conditions, a detection limit of 15 µg/kg of BPA and a quantification limit of 46 µg/kg of BPA in food samples were obtained. The repeatability and reproducibility, expressed as relative standard deviation and obtained for two concentration levels (30 µg/kg and 200 µg/kg, n = 5), were less than 2.0% and 6.4%, respectively. The proposed procedure was applied to the analysis of five samples of canned foods (sweet corn, peas, mushrooms, cockles and natural tuna), obtaining concentrations in the range 29.8-49.9 µg/kg of sample. Recovery studies were conducted at two concentration levels (100 and 400 µg BPA/kg of sample), resulting in recoveries in the range 99-101%. Method validation against two certified reference materials was also successfully performed. The experimental results demonstrate that the novel approach is suitable for the detection and quantification of BPA in canned foods., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Setophoma terrestris is an important phytopathogenic fungus listed by China as a harmful fungus subject to phytosanitary import control. This pathogen is a threat to a wide range of plants, particularly as the causal agent of onion pink root rot, one of the most severe diseases of onions. In order to provide rapid identification and early warning of S. terrestris and prevent its spread, we have developed a rapid, accurate, and visually intuitive diagnostic assay for this pathogen, by utilizing recombinase polymerase amplification (RPA), coupled with CRISPR/Cas12a cleavage and fluorescence-based detection systems or paper-based lateral flow strips. The developed RPA-CRISPR/Cas12a assay exhibited remarkable specificity for the detection of S. terrestris. Moreover, this protocol can detect the pathogen at a sensitivity level of 0.01 pg/μL, which significantly outperforms the 1 pg/μL sensitivity achieved by the existing qPCR-based detection method. The entire diagnostic procedure, including DNA extraction, the RPA reaction, the Cas12a cleavage, and the result interpretation, can be accomplished in 40 min. Furthermore, the successful application of the assay in infected plant samples highlighted its potential for rapid and accurate pathogen detection in agricultural settings. In summary, this RPA-CRISPR/Cas12a diagnostic method offers a potentially valuable technological solution for quarantine and disease management.

Antioxidants are substances that have the ability to resist or delay oxidative damage. Antioxidants can be used not only for the diagnosis and prevention of vascular diseases, but also for food preservation and industrial production. However, due to the excessive use of antioxidants, it can cause environmental pollution and endanger human health. It can be seen that the development of antioxidant detection technology is important for environment/health maintenance. It is found that traditional detection methods, including high performance liquid chromatography, gas chromatography, etc., have shortcomings such as cumbersome operation and high cost. In contrast, the nanozyme-based detection method features advantages of low cost, simple operation, and rapidity, which has been widely used in the detection of various substances such as glucose and antioxidants. This article focuses on the latest research progress of nanozymes for antioxidant detection. Nanozymes for antioxidant detection are classified according to enzyme-like types. Different types of nanozyme-based sensing strategies and detection devices are summarized. Based on the summary and analysis, one can find that the development of commercial nanozyme-based devices for the practical detection of antioxidants is still challenging. Some emerging technologies (such as artificial intelligence) should be fully utilized to improve the detection sensitivity and accuracy. This article aims to emphasize the application prospects of nanozymes in antioxidant detection and to provide new ideas and inspiration for the development of detection methods.

Avian Leukosis Virus (ALV) is a retrovirus that induces immunosuppression and tumor formation in poultry, posing a significant threat to the poultry industry. Currently, there are no effective vaccines or treatments for ALV. Therefore, the early diagnosis of infected flocks and farm sanitation are crucial for controlling outbreaks of this disease. To address the limitations of traditional diagnostic methods, which require sophisticated equipment and skilled personnel, a dual-tube detection method for ALV-J based on reverse transcription isothermal amplification (RAA) and the CRISPR-Cas13a system has been developed. This method offers the advantages of high sensitivity, specificity, and rapidity; it is capable of detecting virus concentrations as low as 5.4 × 10 0 copies/μL without cross-reactivity with other avian viruses, with a total testing time not exceeding 85 min. The system was applied to 429 clinical samples, resulting in a positivity rate of 15.2% for CRISPR-Cas13a, which was higher than the 14.7% detected by PCR and 14.2% by ELISA, indicating superior detection capability and consistency. Furthermore, the dual-tube RAA-CRISPR detection system provides visually interpretable results, making it suitable for on-site diagnosis in remote farms lacking laboratory facilities. In conclusion, the proposed ALV-J detection method, characterized by its high sensitivity, specificity, and convenience, is expected to be a vital technology for purification efforts against ALV-J., Competing Interests: The authors declare no conflict of interest.

A reusable fluorescent nanoprobe was developed using DNA-functionalized metal-organic framework (MOF) for ratiometric detection of Hg 2+ . We utilized a zirconium-based MOF (UiO-66) to encapsulate tris(bipyridine) ruthenium(II) chloride (Ru(bpy) 3 2+ ), resulting in Ru(bpy) 3 2+ @UiO-66 (RU) with red fluorescence. The unsaturated metal sites in UiO-66 facilitate the attachment of thymine-rich single-strand DNA (T-ssDNA) through Zr-O-P bond, producing T-ssDNA-functionalized RU complex (RUT). The T-ssDNA selectively binds to Hg 2+ , forming stable T-Hg 2+ -T base pairs and folding into double-stranded DNA, which permits the intercalation of SYBR Green I (SGI) and activates its green fluorescence. In the presence of Hg 2+ , SGI fluorescence increases in a dose-dependent manner, while Ru(bpy) 3 2+ fluorescence remains constant. This fluorescence contrast enables RUT to serve as an effective ratiometric nanoprobe for Hg 2+ detection, with a detection limit of 3.37 nM. Additionally, RUT demonstrates exceptional reusability due to the ability of cysteine to remove Hg 2+ , given its stronger affinity for thiol groups. The RUT was successfully applied to detect Hg 2+ in real water samples. This work advances the development of ratiometric fluorescence nanoprobe based on DNA-functionalized MOFs., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

The paramount importance of anticounterfeiting measures in safeguarding consumers from counterfeit products lies in their ability to ensure product safety and reliability. Advanced luminescent anticounterfeiting materials, particularly those responsive to multiple stimuli, afford a dynamic and multilayered security assurance. This study presents the synthesis of a novel material, Eu/Tb@GC-3, via postsynthetic modification, which exhibits notable photoluminescent properties with emission at 544 and 614 nm. The material demonstrates high selectivity and sensitivity in detecting Nitrofural and Enrofloxacin, with limits of detection at 0.0122 and 0.0280 μM, respectively. Furthermore, multistimulus responsive luminescent fibers and inks were developed, facilitating intelligent anticounterfeiting labels. The integration of these labels with back-propagation neural networks (BPNNs) significantly enhances pattern recognition and authentication capabilities, providing an efficacious strategy to combat counterfeit products and ensure consumer safety.

The rapid and accurate detection of programmed death-ligand 1 (PD-L1) expression is of great value in the diagnosis and treatment of tumors. ELISA-based traditional method is the gold standard for protein detection, but there are still some shortcomings, especially the antigen-antibody dependence, greatly increased the detection time and cost. This work constructed a label-free fluorescent probe for rapid and sensitive detection of PD-L1 using a truncated aptamer as recognition molecules and double-stranded DNA specific dyes (SYBR Green I) as signal units. After a series of optimization conditions, this probe has good detection capability for PD-L1 in buffer solution with the detection limit as low as 0.68 ng/mL. Due to the specific recognition ability of aptamer and target, this method also has good selectivity for PD-L1 detection. The recovery of PD-L1 in human serum samples ranges from 86.20 to 96.36%. Compared with other methods, this strategy does not need to be marked, and does not need other complex design and purification process, but simple operation process and strong anti-interference ability. The whole detection process can be completed within 20 min and has good application prospect. This work will provide reference for drug dosage and prognosis evaluation of specific tumor therapy., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Octreotide is a synthetic cyclic octapeptide analogue of somatostatin-14. It is mainly administered for the treatment of acromegaly, severe diarrhea, and neuroendocrine neoplasias. In this work, a hydrophilic interaction liquid chromatography (HILIC) method with fluorescence (FL) detection was developed and validated for the quantitation of octreotide in solutions for injection. Chromatographic separation was performed on an XBridge®-HILIC analytical column under isocratic elution with a short chromatographic run time of less than 10 min. The mobile phase consisted of ammonium bicarbonate 8.6 mM (pH 8.1)/acetonitrile 35/65 (v/v). The high sensitivity and selectivity of the fluorescence detection, with the excitation wavelength (λexcitation) set at 280 nm and the emission wavelength set at (λemission) 330 nm, enabled a simple sample preparation procedure that included only dilution steps. The calibration curve showed good linearity with a correlation coefficient greater than 0.998. The method was successfully applied to the analysis of commercially available octreotide injection forms.

Due to its wide use in agriculture, a convenient and sensitive detection method for triazophos is urgent need. In this study, a terbium-based metal-organic framework (Tb-MOF) is mildly prepared as a fluorescent probe for triazophos detection. The fluorescence of Tb-MOF can be quenched by triazophos through the inner filter effect (IFE) and static quenching effect (SQE). The fluorescence analysis exhibits high sensitivity and limit of detection of 0.12 ng·mL−1 with a linear range of 3–800 ng·mL−1 to triazophos. The fluorescence analysis displays good selectivity towards triazophos. In addition, this method has been successfully applied to the detection of triazophos in tap water and strawberry with good recovery rates. More importantly, a fluorescent paper-based sensor and a logic gate operation for the detection of triazophos based on the Tb-MOF are designed. This strategy was simple, free of modification and complicated operation, and easy to operate, which has good prospects for future applications of triazophos detection.

In this study, we have successfully prepared surface modified zinc oxide quantum dots (M-ZnO QDs) with ultra-stable fluorescence and excellent hydrophilicity through introducing (3-aminopropyl)triethoxysilane (APTES). The as-prepared M-ZnO QDs under the optimum condition presented strong yellow fluorescence emission under 355 nm excitation and showed satisfied reproducibility. Physical and chemical properties of the synthesized ZnO QDs were further studied by various characterization techniques. Transmission electron microscopy showed homogeneous distribution of spherical M-ZnO QDs with the average particle size of 4.03 nm. According to the characteristic that metal ions can quench fluorescence, M-ZnO QDs-based fluorescence sensor for the detection of Cu2+ in aqueous solution is developed in this work, which has the advantages of excellent selectivity, good sensitivity and a wide linear range. The limit of detection was 0.51 μM and the linear detection range was 1–200 μM for Cu2+ determination. The practicability of the fluorescent probe is further validated in the lake water and the satisfactory spiked recoveries of Cu2+ ranges from 99.1 % to 108.8 %. Besides, M-ZnO QDs displayed concentration inhibition effect and strain effect on the growth of fungi. Thus, the as-prepared M-ZnO QDs are demonstrated to be promising for Cu2+ determination and anti-fungal applications.

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.

Apomixis is a unique reproductive process that produces fertile offspring without the combination of sperm and egg cells. This process perfectly reproduces maternal DNA, making it possible to fix heterosis during reproduction. Malus shizongensis is a newly discovered species that is closely related to Malus hupehensis Rehd. After de-male bagging, it was found that the fruit set rate reached 78.7%. Preliminary analysis indicated that M. shizongensis have apomictic reproductive characteristics. In this work, we employed paraffin sectioning and electron scanning microscopy to explore apomixis in M. shizongensis during the development of male–female gametes and embryo sacs. Stigma fluorescence assays showed that pollen germination was normal, but less pollen entered the ovaries. Additionally, analysis of anthers indicated the presence of dysplasia and paraffin sectioning revealed that the pollen mother cells were aborted due to abnormal disintegration of the tapetum layer. Taken together, our results indicate that the primary causes of apomixis in M. shizongensis are anther dysplasia and male gamete development failure, resulting in reduced pollen tube entry into ovaries and reduced reproduction of female gametes. In conclusion, this study provide a theoretical basis and technical supports for apple stock breeding and apple industry development.

pH and GSH dual-responsive nanoparticles with fluorescence detection were successfully prepared from the polydopamine coating on the surface of mesoporous silica via disulfide bonds (MSN-SS-PDA). The average diameter of nanoparticles was about 80–100 nm with a well-ordered mesoporous structure. The outer layer of PDA was about 10.0 nm acting as a pH and GSH sensitive gatekeeper to control drug release. Doxorubicin (DOX) was loaded into mesoporous channels to evaluate the drug loading capacity and controlled release performance. TPE-4OH, an aggregation-induced emission (AIE) luminescence, was adhered to the surface of PDA for detection of drug release in real-time. The drug release from MSN-SS-PDA nanoparticles was enhanced under acidic solutions or high GSH concentrations. The fluorescence intensity decreased gradually with the drug release, which can be used for monitoring of release process. Besides, the nanoparticles exhibited good photothermal conversion capability due to the PDA layer under near-infrared light irradiation at 808 nm. These nanoparticles present a promising future for combination therapy and real-time tracking of the release process. [ABSTRACT FROM AUTHOR]

Two water-soluble single-benzene-based chromophores, 2,5-di(azetidine-1-yl)-tereph- thalic acid (DAPA) and its disodium carboxylate (DAP-Na), were conveniently obtained. Both chromophores preserved moderate quantum yields in a wide range of polar and protonic solvents. Spectroscopic studies demonstrated that DAPA exhibited red luminescence as well as large Stokes shift (>200 nm) in aqueous solutions. Femtosecond transient absorption spectra illustrated quadrupolar DAPA usually involved the formation of an intramolecular charge transfer state. Its Frank–Condon state could be rapidly relaxed to a slight symmetry-breaking state upon light excitation following the solvent relaxation, then the slight charge separation may occur and the charge localization became partially asymmetrical in polar environments. Density functional theory (DFT) calculation results were supported well with the experimental measurements. Unique pH-dependent fluorescent properties endows the two chromophores with rapid, highly selective, and sensitive responses to the amino acids in aqueous media. In detail, DAPA served as a fluorescence turn-on probe with a detection limit (DL) of 0.50 μM for Arg and with that of 0.41 μM for Lys. In contrast, DAP-Na featured bright green luminescence and showed fluorescence turn-off responses to Asp and Glu with the DLs of 0.12 μM and 0.16 μM, respectively. Meanwhile, these two simple-structure probes exhibited strong anti-interference ability towards other natural amino acids and realized visual identification of specific analytes. The present work helps to understand the photophysic–structure relationship of these kinds of compounds and render their fluorescent detection applications. [ABSTRACT FROM AUTHOR]

In the present study, real-time fluorescence loop–mediated isothermal amplification (flo-LAMP) and visual colorimetric (vis-LAMP) assays were established for Diodon identification. LAMP primers were designed for the Diodon cytochrome oxidase I gene, and their high specificity was validated against 21 other fish species. LAMP has a minimum detection limit of 0.5 pg/μL for genomic DNA. Furthermore, LAMP identified Diodon in both cooked and digested samples, with the results showing high application potential. The set of LAMP assays was carried out within 1 h under constant temperature conditions. For the flo-LAMP, a positive result was judged by an S-shaped amplification curve. For the vis-LAMP, the results were observed with the naked eye during daylight. Therefore, these rapid, reliable, sensitive, and inexpensive Diodon identification methods could be used to monitor the presence of fish from the Diodon genus in the food industry and detect cases of Diodon poisoning. [ABSTRACT FROM AUTHOR]

As an important detection tool in biochemistry, fluorescence detection has wide applications. Quantitative detection can be achieved by detecting fluorescence signals excited by excitation light at a specific wavelength range. Therefore, the key to fluorescence detection is the stable control of the excitation light and the accurate acquisition of weak photoelectric signals. Moreover, to improve portability and instantaneity, devices are developing in miniaturization and integration. As the core of such devices, fluorescence detectors should also have these features. Under this circumstance, we designed a highly integrated and diminutive fluorescence detector and focused on its excitation light driving and photoelectric signal processing. A current–light dual negative feedback light-emitting diode (LED) driving circuit was proposed to obtain constant current and luminance. In addition, a silicon photodiode (PD) was used to receive and convert the fluorescence signal to an electric signal. Then, amplifying, filtering, and analog-to-digital (A/D) converting were applied to make the detection of weak fluorescence signals possible. The test results showed that the designed circuit has wonderful performance, and the detector shows good linearity (R2 = 0.9967) and sensitivity (LOD = 0.077 nM) in the detection of fluorescein sodium solution. Finally, a real-time fluorescence polymerase chain reaction (real-time PCR) of Legionella pneumophila was carried out on a homemade platform equipped with this detector, indicating that the detector met the requirements of real-time PCR detection. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic poses a threat to global health. Due to its high sensitivity, specificity, and stability, real-time fluorescence quantitative (real-time PCR) detection has become the most extensively used approach for diagnosing SARS-CoV-2 pneumonia. According to a report from the World Health Organization, emerging and underdeveloped nations lack nucleic acid detection kits and polymerase chain reaction (PCR) instruments for molecular biological detection. In addition, sending samples to a laboratory for testing may result in considerable delays between sampling and diagnosis, which is not favorable to the timely prevention and control of new crown outbreaks. Concurrently, there is an urgent demand for accurate PCR devices that do not require a laboratory setting, are more portable, and are capable of completing testing on-site. Hence, we report on HDLRT-qPCR, a new, low-cost, multiplexed real-time fluorescence detection apparatus that we have developed for on-site testing investigations of diverse diseases in developing nations. This apparatus can complete on-site testing rapidly and sensitively. The entire cost of this instrument does not exceed USD 760. In order to demonstrate the applicability of our PCR instrument, we conducted testing that revealed that we achieved gradient amplification and melting curves comparable to those of commercially available equipment. Good consistency characterized the testing outcomes. The successful detection of target genes demonstrates the reliability of our inexpensive PCR diagnostic technique. With this apparatus, there is no need to transport samples to a central laboratory; instead, we conduct testing at the sampling site. This saves time on transportation, substantially accelerates overall testing speed, and provides results within 40 min. [ABSTRACT FROM AUTHOR]

Constructing a luminescent covalent organic framework (LCOF) via an ultrasound-assisted one-step reaction used for "one to many" recognition of targets is a challenge. In this work, we report a fluorescent sp2c-covalent organic framework (COF) (TzDA–BTAN–COF) containing a regular nanoporous structure, uninterrupted π-electron delocalization, and an electron-deficient unit. We explore the use of the TzDA–BTAN–COF for the visual inspection and fluorescent quantitative analyses of hazardous substances. The TzDA–BTAN–COF, as a Janus sensor, exhibited double nature with different fluorescence properties: "turn-on" and "turn-off." Fluorescence enhancement was exhibited in the presence of electron-rich ofloxacin (OFLX) and fluorescence quenching in the presence of electron-deficient picric acid (PA) and aristolochic acid (AAS). The fluorescence-on and -off sensing mechanism might be attributed to the photoinduced electron transfer by the electron transfer from the donor to the acceptor based on theoretical calculations. In addition, the TzDA–BTAN–COF has been used for the highly sensitive fluorescence detection of PA, AAS, and OFLX. It exhibited good linearity toward PA, AAS, and OFLX over the range from 0.1 to 80, 0.01 to 100, and 0.01 to 1 μg mL–1 with a limited detection of 32.1, 3.3, and 3.0 ng mL–1, respectively. Meanwhile, the real samples were measured, with satisfactory recoveries (95.0–105.5%) and reliable analytical results. The TzDA–BTAN–COF is the first nanoporous COF Janus fluorescence sensor for the "one to many" recognition and fluorescence detection of different hazardous substances by dual functional fluorescence-on and -off sensing. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science 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 Food Research & Development is the property of Food Research & Development 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.)

The excessive use of antibiotics in agriculture leads to their contamination in food and water; it is highly demanded to develop new functional materials for their fast and on-site detection. In this paper, we synthesized a zinc(II)-trimesic acid metal–organic framework (Zn-BTC) by microwave and explored its practical application for the detection of chlortetracycline (CTC) based on conformational variation mechanism. A limit of detection (LOD) of 24 nM was estimated for CTC according to the 3σ principle. Due to their similar unique structural properties, other tetracyclines also produce fluorescence enhancement upon adsorption with Zn-BTC, which can be used to distinguish tetracyclines from other antibiotics. Based on the properties, a test paper was fabricated by loading Zn-BTC on glass fiber filter paper. The paper could be used for non-contact visual detection of CTC, suggesting great application potential in water quality monitoring. [ABSTRACT FROM AUTHOR]

Bee pollen is one of the hive products that is of most interest today due to its multiple beneficial health properties, making it an increasingly popular food supplement. Bee pollen contains many bioactive compounds, such as fatty acids, vitamins, minerals, proteins, and amino acids, among others. In the present study, the free amino acid content was determined in bee pollen by using liquid chromatography coupled to a fluorescence detector. Sample treatment consisted of a solvent extraction of the free amino acids with ultrapure water and a further centrifugation of the extract, which was repeated twice. After that, it was necessary to perform a pre-column derivatization of the amino acids using a combination of two reagents (o-phthalaldehyde and 9-fluorenylmethyl chloroformate) prior to their separation in a Gemini® C18 reverse phase column in gradient elution mode. The analytical performance was evaluated, and several commercial bee pollen samples were analyzed. Significant differences in the free amino acid profile and concentration, which ranged between 19 and 192 mg/g, were observed depending on the botanical origin of the samples. [ABSTRACT FROM AUTHOR]

The rational design and exploitation of fluorescent nanomaterials with excellent properties is of great significance for the detection of lamotrigine (LTG). Herein, a novel lanthanide metal–organic framework was prepared via the self-assembly of a Tb3+ ion and an H2DimTA ligand. The as-prepared material exhibits a lamellar nanostructure with plenty of pyrazole nitrogen sites (specific recognition sites for LTG), which can directly act as fluorescence detectors toward LTG detection. Their outstanding performance with a low limit of detection (1.89 μM), superior anti-interference capability, rapid response, and excellent durability shows their great potential in the field of fluorescence detection. [ABSTRACT FROM AUTHOR]

The fabrication of efficient fluorescent probes that possess an excellent sensitivity and selectivity for uric acid is highly desirable and challenging. In this study, composites of silver nanoparticles (AgNPs) wrapped with nitrogen-doped carbon quantum dots (N-CQDs) were synthesised utilising N-CQDs as the reducing and stabilising agents in a single reaction with AgNO3. The morphology and structure, absorption properties, functional groups, and fluorescence properties were characterised by transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, ultraviolet spectroscopy, fluorescence spectroscopy, and X-ray diffraction spectroscopy. In addition, we developed a novel method based on AgNPs/N-CQDs for the detection of uric acid using the enzymatic reaction of uric acid oxidase. The fluorescence enhancement of the AgNPs/N-CQDs composite was linear (R2 = 0.9971) in the range of 2.0–60 μmol/L, and gave a detection limit of 0.53 μmol/L. Trace uric acid was successfully determined in real serum samples from the serum of 10 healthy candidates and 10 gout patients, and the results were consistent with those recorded by Qianxinan Prefecture People's Hospital. These results indicate that the developed AgNP/N-CQD system can provide a universal platform for detecting the multispecies ratio fluorescence of H2O2 generation in other biological systems. [ABSTRACT FROM AUTHOR]