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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A novel "turn-on" aptasensor for kanamycin (Kana) detection based on a new Förster resonance energy transfer (FRET) pair is reported. A new organic small molecule was employed as a high-efficiency quencher for fluorophore. Based on specific interactions between ssDNA and the quencher, an ingenious and amplified strategy was designed. In the absence of the target, the fluorescence of the fluorophore labeled at the end of the aptamer was quenched. After the binding of the aptamer to the target, the fluorescence was recovered and amplified. The proposed aptasensor showed high specificity, selectivity, and stability in complicated systems. With the P3-based strategy, the limit of detection for Kana is estimated to be 10 nM, which is much lower than the maximum allowable concentration in milk. The recoveries of spiked Kana in milk were in the range 99.8 ~ 105.3% (n = 3). Fortunately, this novel method can be easily extended to other antibiotics such as tobramycin by simply replacing the aptamer, showing great potential as a universal platform for selective, sensitive, and rapid detection of hazardous analytes in food samples. [ABSTRACT FROM AUTHOR]

A Pyrococcus furiosus Argonaute (PfAgo)-based biosensor is presented for alkaline phosphatase (ALP) activity detection in which the ALP-catalyzed hydrolysis of 3′-phosphate-modified functional DNA activates the strand displacement amplification, and the amplicon mediates the fluorescent reporter cleavage as a guide sequence of PfAgo. Under the dual amplification mode of PfAgo-catalyzed multiple-turnover cleavage activity and pre-amplification technology, the developed method was successfully applied to ALP activity determination with a detection limit (LOD) of 0.0013 U L−1 (3σ) and a detection range of 0.0025 to 1 U L−1 within 90 min. The PfAgo-based method exhibits satisfactory analytic performance in the presence of potential interferents and in complex human serum samples. The proposed method shows several advantages, such as rapid analysis, high sensitivity, low-cost, and easy operation, and has great potential in disease evolution fundamental studies and clinical diagnosis applications. [ABSTRACT FROM AUTHOR]

CRISPR/Cas system has been widely applied in the assay of disease-related nucleic acids. However, it is still challenging to use CRISPR/Cas system to detect multiple nucleic acids at the same time. Herein, we combined the preponderance of DNA logic circuit, label-free, and CRISPR/Cas technology to construct a label-free "AND" logical gate for multiple microRNAs detection with high specificity and sensitivity. With the simultaneous input of miRNA-155 and miRNA-141, the logic gate starts, and the activation chain of Cas12a is destroyed; thus, the activity is inhibited and the fluorescence of the signal probe ssDNA-AgNCs is turned on. The detection limit of this method for simultaneous quantitative detection of double target is 84 fmol/L (S/N = 3). In this "AND" logic gate, it is only necessary for the design of a simple DNA hairpin probe, which is inexpensive and easy, and since this method involves only one signal output, the data processing is very simple. What is more important, in this strategy two types of microRNAs can be monitored simultaneously by only using CRISPR/Cas12a and a type of crRNA, which offers a new design concept for the exploitation of single CRISPR/Cas system for multiple nucleic acid assays. [ABSTRACT FROM AUTHOR]

A ratiometric fluorescence sensing strategy has been developed for the determination of Cu2+ and glyphosate with high sensitivity and specificity based on OPD (o-phenylenediamine) and glutathione-stabilized gold nanoclusters (GSH-AuNCs). Water-soluble 1.75-nm size GSH-AuNCs with strong red fluorescence and maximum emission wavelength at 682 nm were synthesized using GSH as the template. OPD was oxidized by Cu2+, which produced the bright yellow fluorescence oxidation product 2,3-diaminophenazine (DAP) with a maximum fluorescence emission peak at 570 nm. When glyphosate existed in the system, the chelation between glyphosate and Cu2+ hindered the formation of DAP and reduced the fluorescence intensity of the system at the wavelength of 570 nm. Meanwhile, the fluorescence intensity at the wavelength of 682 nm remained basically stable. It exhibited a good linear relationship towards Cu2+ and glyphosate in water in the range 1.0–10 µM and 0.050–3.0 µg/mL with a detection limit of 0.547 µM and 0.0028 µg/mL, respectively. The method was also used for the semi-quantitative determination of Cu2+ and glyphosate in water by fluorescence color changes visually detected by the naked eyes in the range 1.0–10 µM and 0.30–3.0 µg/mL, respectively. The sensing strategy showed higher sensitivity, more obvious color changes, and better disturbance performance, satisfying with the detection demands of Cu2+ and glyphosate in environmental water samples. The study provides a reliable detection strategy in the environment safety fields. [ABSTRACT FROM AUTHOR]

The combination of CRISPR/Cas12a and functional DNA provides the possibility of constructing biosensors for detecting non-nucleic-acid targets. In the current study, the duplex protospacer adjacent motif (PAM) in the activator of CRISPR/Cas12a was used as a molecular switch, and a sensitive adenosine triphosphate (ATP) detection biosensor was constructed using an allosteric probe-conjugated PAM site formation in hybridization chain reaction (HCR) integrated with the CRISPR/Cas12a system (APF-CRISPR). In the absence of ATP, an aptamer-containing probe (AP) is in a stem-loop structure, which blocks the initiation of HCR. In the presence of ATP, the structure of AP is changed upon ATP binding, resulting in the release of the HCR trigger strand and the production of long duplex DNA with many PAM sites. Since the presence of a duplex PAM site is crucial for triggering the cleavage activity of CRISPR/Cas12a, the ATP-dependent formation of the PAM site in HCR products can initiate the FQ-reporter cleavage, allowing ATP quantification by measuring the fluorescent signals. By optimizing the sequence elements and detection conditions, the aptasensor demonstrated superior detection performance. The limit of detection (LOD) of the assay was estimated to be 1.16 nM, where the standard deviation of the blank was calculated based on six repeated measurements. The dynamic range of the detection was 25–750 nM, and the whole workflow of the assay was approximately 60 min. In addition, the reliability and practicability of the aptasensor were validated by comparing it with a commercially available chemiluminescence kit for ATP detection in serum. Due to its high sensitivity, specificity, and reliable performance, the APF-CRISPR holds great potential in bioanalytical studies for ATP detection. In addition, we have provided a proof-of-principle for constructing a CRISPR/Cas12a-based aptasensor, in which the PAM is utilized to regulate Cas12a cleavage activity. [ABSTRACT FROM AUTHOR]

A water‐soluble polymeric pyrene‐based polythioacetal (PTA‐Py) with thioacetal units in the main chain is simply synthesized by direct polycondensation of 3, 6‐dioxa‐1, 8‐octanedithiol, 1‐pyrene formaldehyde, and mPEG2k‐SH. The probe PTA‐Py shows a good fluorescence response to Hg2+ ions due to the Hg2+‐promoted deprotection reaction of thioacetal groups to regenerate the original 1‐pyrene formaldehyde compound. After adding Hg2+ to the PTA‐Py solution, the fluorescence intensity (FI) gradually increases with increasing concentrations of Hg2+. Compared with other metal ions, the probe exhibits high sensitivity, good selectivity, and rapid response to Hg2+. The low detection limits are 12.3 nm in ethanol‐PBS buffer and 13.3 nm in water, respectively. The results imply that the simply synthesized water‐soluble polymeric probe had potential applications in the rapid detection of Hg2+ ions in aqueous solutions. Moreover, the polymeric PTA‐Py shows high sensitivity for CH3Hg+ with detection limits of 26.5 nm in ethanol/PBS buffer. In addition, PTA‐Py can efficiently detect Hg2+ ions in HeLa cells. The results demonstrate that a valuable method is developed for biocompatible polymeric sensors for Hg2+ ions in biological and environmental samples. [ABSTRACT FROM AUTHOR]

Exposure to certain metal ions can lead to many diseases including cardiovascular, reproductive, and kidney disorders. Certain inorganic anions and organic species can also adversely affect living organisms as well as pose a severe threat to the environment. Detection and determination of biological analytes or biomarkers can help in the early diagnosis and treatment of several human diseases. Accordingly, great efforts have been devoted to the development of fluorescent and colorimetric sensors. Compared to many other detection techniques, the optical sensor stands unique. Porphyrins are excellent fluorophores with strong absorption and emission in the visible region. This highly conjugated macrocycle can be tuned to desirable properties with proper substituents at the periphery and complex formation with a vast number of metal ions. This detailed review discusses optical sensors that encompass both colorimetric and fluorescence sensors based on porphyrin/metalloporphyrin and their various forms for sensing metal ions, inorganic anions, organic moieties, and biologically significant molecules. In the presence of the concerned analyte, rearrangement of energy level of optical probe occurs and further facilitates interaction with the analyte which is mainly operated through various mechanisms like FRET, PET, ground state complex formation, intramolecular charge transfer, exciplex formation, etc. [ABSTRACT FROM AUTHOR]

Long-term excessive uptake of fluoride through potable water will cause adverse effects on human health. Therefore, it is of great significance to detect and remove excessive fluoride in potable water. Here, we reported a multi-functional Zr-based coordination polymer namely CP-1, which could realize the visual detection and effectively selective adsorption of fluoride. The investigation of fluoride adsorption manifested that the maximum fluoride adsorption capacity of CP-1 could reach 48.78 mg g−1 and selective adsorption capacity kept stable in a wide range of pH. By fluorometric approaches, the detection of limit of F− could achieve 1.55 × 10–6 mol L−1 based on CP-1. Moreover, the fluorescence test paper fabricated by in situ growth of CP-1 onto the surface of filter paper was proved to realize the visual detection of fluoride. [ABSTRACT FROM AUTHOR]

Rapid and sensitive dengue non-structural protein 1 (NS1) detection assay is essential for the treatment of disease and currently releases high medical cost burdens. To address the limitations of conventional LFIA strips, we have developed an improved Sup35NM-Z-based LFIA that immobilizes antibodies on cellulose membranes in an orientated manner to increase the sensitivity of LFIA strips. A dual-functional Sup35NM nanofibril was fabricated by fusion with the antibody binding domain; resultant nanofibril from the amyloid Sup35NM was sprayed on the T-line to orientate the capture antibody and produces fluorescence signals. Antibody binding analysis showed that self-assembly of the Sup35NM monomer does not affect the binding activity of the Z-domain with the antibody. The NS1 for DENV-2 infection was chosen as a model target antigen to assess the feasibility of the Sup35NM-Z-domain-based LFIA platform. Under optimal conditions, the Sup35NM-Z-domain-based LFIA detected NS1 within 15 min with a detection limit of 1.29 ng/ml, while the detection limit of traditional LFIA with the same concentration of anti-NS1-Ab1 on the T-line by conventional physical adsorption was 2.20 ng/ml, 1.7 times higher than that of Sup35NM-Z-domain-based LFIA. As compared to traditional LFIAs, the Sup35NM-Z-based LFIA had a wide detection range of 1.29–625 ng/mL. The LFIA's clinical performance in identifying NS1 was also assessed using 15 clinical samples. The LFIA accurately recognized positive and negative samples, equal to 86.7% accuracy. The developed Sup35NM-Z-domain-based LFIA in this study offers great potential for the identification of target markers because of its greatly improved sensitivity and wider detection range. [ABSTRACT FROM AUTHOR]

A multi-signal aptasensor for thrombin determination is proposed based on catalytically active gold nanoparticles (AuNPs) and fluorescent silicon quantum dots (SiQDs). Yellow 4-Nitrophenol (4-NP) could be converted to colorless 4-Aminophenol (4-AP) by catalytically active aptamer-modified AuNPs (S1-AuNPs). The SiQDs emitted strong blue fluorescence at 455 nm at the excitation wavelength of 367 nm. When thrombin was absent, S1-AuNPs could catalytically reduce yellow 4-NP to colorless 4-AP. When thrombin was added, the aptamer could be transformed into a G-quadruplex structure, which masked the surface-active catalytic sites of AuNPs and restrained the reduction of 4-NP. Thus, the fluorescence of SiQDs was greatly quenched by 4-NP through the inner filter effect (IFE), and the solution color remained yellow. As the concentration of thrombin increased, the catalytic activity of S1-AuNPs decreased. The concentration of 4-NP that was converted to 4-AP declined and the unconverted 4-NP increased. In this process, the absorption peak of 4-NP at 400 nm increased while the fluorescence emission of SiQDs at 455 nm decreased. The linear ranges of the fluorometric and colorimetric aptasensor were 0.5–30 nM and 0.3–30 nM, respectively. The limits of detection (LOD) for the two modes were 0.15 nM and 0.13 nM. Furthermore, a portable sensing platform was constructed by combining the smartphone-based device with the software ImageJ for the determination of thrombin. With the advantages of cost-effectiveness, simplicity of operation and broad applicability, this aptasensor provided a new perspective for on-site determination of thrombin in the clinical field. [ABSTRACT FROM AUTHOR]

Optimization and validation for simultaneous quantitation of four aflatoxins B1, B2, G1, and G2 in peanuts and raisins were performed on ultra‐performance liquid chromatography in a combination of fluorescence detector, without derivatization. The advantages were short analysis time, simple sample handling, and reduced solvent consumption. Instrument detection limits of AFB1, AFB2, AFG1, and AFG2 were 0.07, 0.01, 0.1, and 0.008 μg/kg, respectively, lower than those obtained by LCMSMS and HPLC‐FLD with derivatization. Two solvent mixtures were chosen for two different matrices whose matrix effect was not negligible (2.81%–8.04% for peanuts and 5.63%–11.43% for raisins). The linear ranges were from 0.2 to 20 μg/L for AFB1 and AFG1 and from 0.05 to 5 μg/L for AFB2 and AFG2. The limits of detection and quantification were 0.025–0.1 and 0.075–0.3 μg/kg for peanuts and raisins, respectively. Recoveries at three other concentrations from 0.75 to 125 μg/kg of total aflatoxins were obtained between 76.5% and 99.8% (with RSD < 6%) following the SANTE 11312/2021. Validation parameters complied with the requirements of ISO/IEC 17025:2017. The extracts and the sample could be stabilized at 4°C and 20°C for 24 h and at −20°C for up to 21 days, respectively. Thus, the study can be used as a standard method for the analysis of Aflatoxins (AFs) in peanut and raisin matrices. Investigation of 350 peanut samples collected at Markets in the central districts of HCM city showed that 28.6% were contaminated with AFB1 from 0.31 up to 554 μg/kg; 13.4% contained AFB2, and 5.7% of AFG1 in the range of 0.4–53 μg/kg and 0.4–9.57 μg/kg, respectively; AFG2 (about 0.6%) was detected from 0.45 to 0.75 μg/kg. Meanwhile, 12.8% exceeded the total aflatoxins limit, and 13.4% exceeded the AFB1 limit. AFs were almost not found in the 350 raisin samples. [ABSTRACT FROM AUTHOR]

An ultra fast liquid chromatographic (UFLC) method using fluorimetric detection for the quantitation of Febuxostat (FEB) in human serum was developed by precolumn derivatization with 4- bromomethyl-7-methoxy coumarin (BrMmC). The derivatization was catalyzed with dibenzo-18-crown-6-ether to produce a fluorescent derivative which was determined through fluorescence measurement with excitation at 320 nm and emission at 395 nm wavelengths. A C18 column with 100 cm  4.6 mm, 3 µm particule size was used for the UFLC separation procedure. A mixture of acetonitrile: methanol: 0.05 M aqueous ammonium acetate (pH 5.0) (40:40:20, v/v/v) was used as mobile phase. During the procedure, the flow rate was maintained at 0.5 mL/min. A calibration curve was then plotted as 0.005–3.0 µg/mL with a detection limit of 0.0022 µg/mL and quantification limit of 0.0073 µg/mL. The mean recovery to reveal the accuracy and relative standard deviation (RSD) that indicates the precision of the method were found out to be 85.20 % and less than 3.52 %, respectively. The utility of the new method has been demonstrated by measuring the pharmacokinetics of FEB by administration of 80 mg tablets to a healthy female volunteer, aged 42. [ABSTRACT FROM AUTHOR]

In this work, an automated microfluidic chip that uses negative pressure to sample and analyze solutions with high temporal resolution was developed. The chip has a T-shaped channel for mixing the sample with a fluorescent indicator, a flow-focusing channel for generating droplets in oil, and a long storage channel for incubating and detecting the droplets. By monitoring the fluorescence intensity of the droplets, the device could detect changes in solution accurately over time. The chip can generate droplets at frequencies of up to 42 Hz with a mixing ratio of 1:1 and a temporal resolution of 3–6 s. It had excellent linearity in detecting fluorescein solution in the concentration range 1–5 μM. This droplet microfluidic chip provides several advantages over traditional methods, including high temporal resolution, stable droplet generation, and faster flow rates. This approach could be applied to monitoring calcium ions with a dynamic range from 102 to 107 nM and a detection limit of 10 nM. HIGHLIGHTS: • A microfluidic chip was developed to monitor the dynamic changes in the concentration of a solution. • It has a post-sampling mix and droplet generation structure for backend digital detection. • The response to changes in fluorescein concentration has good linearity. [ABSTRACT FROM AUTHOR]

To develop simultaneous and in-situ detection techniques towards Cr(VI) and Mn(II), Eu/Tb@CDs with white fluorescence were prepared by a one-step hydrothermal method. With the increase of Cr(VI), all fluorescence channels of Eu/Tb@CDs exhibited obvious quenching, and the detection limit (LOD) was 0.10 μM. In the presence of Mn(II), only the fluorescence from Tb and Eu was quenched, while the fluorescence of CDs was not effected. The LOD for Mn(II) was 0.16 μM. More importantly, in the actual water samples where Cr(VI) and Mn(II) coexist, Eu/Tb@CDs can realize their rapid and simultaneous detection by simple spectral calculation. The selective and competitive experiments have also confirmed that the detection of Cr(VI) and Mn(II) was not interfered by common pollutants in groundwater. It is undeniable that the simultaneous detection of multiple targets by one probe not only greatly improves the detection efficiency, but also has important significance for the field monitoring of water quality parameters. [ABSTRACT FROM AUTHOR]

A novel Fe3O4-MWCNTs@Hemin nanocomposite was synthesized using hemin and Fe3O4 with multi-walled carbon nanotubes (MWCNTs) by one-step hydrothermal methods. The as-prepared Fe3O4-MWCNTs@Hemin nanocomposites exhibited excellent peroxidase-like activities in the activation of H2O2. The mechanisms, kinetics, and catalytic performances of Fe3O4-MWCNTs@Hemin were systematically studied. Fe3O4-MWCNTs@Hemin can oxidize dopamine (DA) to dopaquinone in the presence of H2O2, and the intermediate products dopaquinone can further react with β-naphthol to generate a highly fluorescent derivative at 415 nm excitation wavelength. Therefore, an innovative fluorescence platform for the detection of DA was developed. The fluorescence intensity increased linearly with DA concentration in the range 0.33 to 107 μM, with a low detection limit of 0.14 μM. Due to the excellent activity, substrate universality, fast response, high selectivity, and sensitivity of Fe3O4-MWCNTs@Hemin, the proposed fluorescence method was used to analyze complex biological blood samples with a satisfactory result. It demonstrated the significant potential for developing effective and dependable fluorescent analytical platforms for preserving human health. [ABSTRACT FROM AUTHOR]

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This study dealt with determination of ochratoxin A (OTA) in roasted coffee by ultra-performance liquid chromatography and fluorescence detection (UPLC-FLD). Coffee features characteristic sensory properties, contains a wide range of beneficial substances and is among the most sold commodities worldwide. UPLC-FLD method for determination of OTA in ground roasted coffee was optimized and validated. A calibration curve of good linearity (R² > 0.999) was obtained for the range of 0.3-10 ng·ml-1, and the limit of detection and limit of quantification for OTA were 0.1 µg·kg-1 and 0.3 µg·kg-1, respectively. The recovery of certified reference material for OTA ranged between 81.3-112.8 % and the relative standard deviation under repeatibility conditions was 11.7 %. The method was applied to the analysis of OTA in coffee obtained from retail stores in Czech Republic. Sixteen samples (29 %) of roasted coffee were positive, containing OTA in the range from 0.31 µg·kg-1 to 1.06 µg·kg-1. None of the samples analysed exceeded the legislative limit according to EU Commission Regulation No. 1881/2006. [ABSTRACT FROM AUTHOR]

Summary: A fluorescent probe based on carbon dots (CDs) for the detection of sulfoquinoxaline (SQX) in food was studied. White pitaya peel‐derived carbon dots (WCDs) were synthesised by hydrothermal method. The obtained WCDs exhibit excellent fluorescence response towards SQX due to the inner filter effect (IFE) and aggregation‐caused quenching(ACQ), which cause the fluorescence to be quenched. The prepared fluorescent probe has a good linear relationship, and the detection limit of SQX is 24.5 μg L−1. The practicability of the fluorescent probe was further validated in milk, honey, eggs, carp, pork, chicken, beef and pork liver, and the recoveries of SQX range from 93.38% to 103.86%. The fluorescent probe based on WCDs has high selectivity, specificity, sensitivity, reliability and good reproducibility for the detection of SQX. [ABSTRACT FROM AUTHOR]

• A hybrid adsorbent combining COF and BA-CDs was designed. • The boric acid group of COF@VBC@BA-CDs can undergo boron affinity reaction with amatoxins. • Using FD (quantitative) and LC-MS/MS (qualitative) methods for joint detection. • The method has wide linear range, low detection limit and high recovery rate. In recent years, mushroom poisoning has been one of the most important factors of food poisoning in China, timely identification of the toxins contained in mushrooms is crucial for the treatment of patients. In this study, boric acid carbon dots (BA-CDs) can undergo specific boron affinity reactions with amatoxins toxins containing o-dihydroxyl groups by means of boric acid groups. Functional covalent organic framework (COF) and BA-CDs were combined to design a adsorbent with boric acid group (COF@VBC@BA-CDs) was designed to meet the requirements of both fluorescent and pretreated materials for amatoxins. The mushrooms and urine samples were rapid screening using fluorescence detection, and then, for positive samples, the target analytes on the COF@VBC@BA-CDs are collected and eluted for next liquid chromatography tandem mass spectrometry (LC-MS/MS) detection. According to the fluorescence characteristics of COF@VBC@BA-CDs, the fluorescence quenching intensity was linearly correlated with the concentration (2–200 μg/L) and the detection limit was 1.2 μg/L. Meanwhile, the detection limit of LC-MS/MS was 0.5 μg/kg for musroom and 0.2 μg/L for urine, as well as the recovery rate was 72.7–110.1%. This noval method meets the methodological requirements and can be used for actual sample analysis. [ABSTRACT FROM AUTHOR]

• A paper-based material was designed for fluorescence detection and removal of HCHO. • A robust fluorescent probe with 100-fold enhancement was designed as HCHO indicator. • The coated paper was built by degradable resources of cellulose and polyethyleneimine. • The coated paper shown high adsorption and visual detection capacity toward HCHO. • The multifunctional paper was successfully applied for HCHO sensing and adsorption. Indoor air pollution is one of the significant inducing factors of some diseases, such as leukemia, tumors, respiratory disease, and kidney failure. Among these contaminants, formaldehyde has a long release span and is a great threat to our health. However, methods for formaldehyde elimination and detection are limited. Herein, a new paper-based multifunctional fluorescent material was developed for the simultaneous high-efficiency removal and detection of formaldehyde. The paper-based material was fabricated using polyethyleneimine (PEI) and a highly sensitive ratiometric fluorescent probe (FP). The paper-based material can detect formaldehyde with a significant change in fluorescence: the fluorescence at 450 nm decreased by over 75 %, and the fluorescence of FP in the ratiometric channel increased by over 100-fold. Moreover, the formaldehyde elimination rate is up to 99 %. By combining the porous network structures of paper, the abundant amino groups in PEI , and the highly sensitive fluorescent response of FP , the multifunctional fluorescent paper material can be effectively utilized for formaldehyde removal and detection. [Display omitted] [ABSTRACT FROM AUTHOR]

Cr(Ⅵ) residues in livestock and poultry wastewater are a rising concern for human health and biotic environments. For the removal of Cr(Ⅵ), its simultaneous reduction and adsorption represents a sustainable and efficient strategy. Herein, iron nodes on covalently bonded two-dimensional phthalocyanine organic polymer (PcOP-Fe) nanosheets with space-separated dual-active sites are developed for the simultaneous detection and removal of Cr(VI) from wastewater. In the FeN 4 structure of PcOP-Fe nanosheets, Fe acts as an electron capture center, effectively facilitating the accumulation of photogenerated electrons and transferring them to Cr(VI), thereby achieving its photocatalytic reduction. Meanwhile, pyrrolic nitrogen provides excellent adsorption sites, enabling the adsorption of Cr(III) or Cr(0). Fe accumulates the photogenerated electrons from pyrrole N and transfer them to Cr(Ⅵ). The formation of N-Cr(Ⅲ) bonds causes a space-separation between Cr(Ⅵ) and Cr(III). In addition, PcOP-Fe can be used for a Cr(Ⅵ) detection agent. The photoluminescence intensity decreases linearly with increasing Cr(Ⅵ) concentration from 80 μM to 2 mM, with a limit of detection of 0.18 μM. The PcOP-Fe nanosheets exhibit good Cr(Ⅵ) detection and reduction performance in livestock and poultry wastewater, suggesting their suitability for practical sensing applications. Thus, the PcOP-Fe nanosheets with space-separated dual-active sites are promising for the simultaneous detection and removal of Cr(Ⅵ) in water treatment processes. • PcOP-Fe photocatalyst with space-separated active sites were prepared rapidly. • PcOP-Fe enables the detection and removal of Cr(VI) from wastewater. • PcOP-Fe exhibits high sensitivity and selectivity fluorescence detections of Cr(VI). • FeN 4 structure in PcOP-Fe shows adsorption and reduction synergistic activity. • PcOP-Fe modified by Fe showed high reduction activity than PcOP. [ABSTRACT FROM AUTHOR]

A strategy of headspace separation combined fluorescence detection of hydrogen sulfide was proposed with silver-sensitized lanthanide coordination polymer probe via a simple self-made device, possessing the advantages of high sensitivity, selectivity and fast response speed. The hybrid method described here provides an alternative avenue to develop the novel volatile component analysis. [Display omitted] • Fluorescence detection of H 2 S was successfully established using silver-sensitized lanthanide coordination polymer probe. • Headspace separation combined fluorescence detection strategy was verified to solve the problem of poor selectivity. • Hybrid method provides an alternative avenue to develop the novel volatile component analysis. Hydrogen sulfide (H 2 S), playing unique role on signal transmission in various physiological processes, the rapid and accurate monitoring of it is particularly concerned. The drawbacks of fluorescence probe for H 2 S, namely poor selectivity or long response time, have always existed. As a test case, here headspace separation combined fluorescence strategy was attempted, on basis of H 2 S stimuli-responsive AMP/Tb3+/Ag+ or GMP/Tb3+/Ag+ coordination polymer probes. The fluorescence intensity of them is inversely proportional to the concentration of it, due to Ag-S in situ coordination and partial formation of Ag 2 S. Using the hybrid analysis, a quick response of less than 2.0 min and a high selectivity could be obtained. The signal change (Δ I) of AMP/Tb3+/Ag+ or GMP/Tb3+/Ag+ showed good linearity within the range of 0.5–100 μM and 1.0–150 μM, along with a detection limit (3 σ) of 0.2 and 0.4 μM, respectively. When utilized to determine the sulfide level in real samples, it shows recoveries from 96.4 % to 102.3 % with relative standard derivation (RSD) less than 3.0 %. The combination strategy of headspace separation and fluorescence quantitative analysis was verified to effectively eliminate potential interference such as other coexisting non-volatile thiol-containing species, providing a novel avenue to flexibly design the volatile component analysis with high selectivity in complex sample matrixes. [ABSTRACT FROM AUTHOR]

N -linked glycosylation is a ubiquitous protein post-translational modification in which aberrant glycan biosynthesis has been linked to severe conditions like cancer. Accurate qualitative and quantitative analysis of N -glycans are crucial for investigating their physiological functions. Owing to the intrinsic absence of chromophores and high polarity of the glycans, current detection methods are restricted to liquid chromatography and mass spectrometry. Herein, we describe three new imidazolium-based glycan tags: 2'GITag, 3'GITag, and 4'GITag, that significantly improve both the limit of detection and limit of quantification of derivatized oligosaccharides, in terms of fluorescence intensity and ionisation efficiency. Our top-performing derivatisation agent, 4'GITag, shifted the detection sensitivity range from high femtomole to sub-femtomole levels in ESI-MS compared to traditional glycan label, 2AB, enabling the identification of 24 N -glycans in mouse serum, including those bearing sialic acids. Additionally, 4'GITag stabilized Na-salt forms of sialic acids, simplifying the simultaneous analysis of neutral and negative charged N -glycans significantly, avoiding the need for complex derivatisation procedures typically required for the detection of sialylated species. Overall, the favorable performance of imidazolium tags in the derivatisation and sensitive profiling of glycans has the potential for labeling tissue or live cells to explore disease biomarkers and for developing new targeted therapeutic strategies. [Display omitted] [ABSTRACT FROM AUTHOR]

Integrated polyurethane (PU)–based foams modified with PEGylated graphene oxide and folic acid (PU@GO-PEG-FA) were developed with the goal of capturing and detecting tumor cells with precision. The detection of the modified PU@GO-PEG surface through FA against folate receptor-overexpressed tumor cells is the basis for tumor cell capture. Molecular dynamics (MD) simulations were applied to study the strength of FA interactions with the folate receptor. Based on the obtained results, the folate receptor has intense interactions with FA, which leads to the reduction in the FA interactions with PEG, and so decreases the fluorescence intensity of the biosensor. The synergistic interactions offer the FA-modified foams a high efficiency for capturing the tumor cell. Using a turn-off fluorescence technique based on the complicated interaction of FA-folate receptor generated by target recognition, the enhanced capture tumor cells could be directly read out at excitation-emission wavelengths of 380–450 nm. The working range is between 1×10 2 to 2×10 4 cells mL -1 with a detection limit of 25 cells mL -1 and good reproducibility with relative standard deviation of 2.35%. Overall, findings demonstrate that the fluorescence-based biosensor has a significant advantage for early tumor cell diagnosis. [ABSTRACT FROM AUTHOR]

A sensitive and selective method for determining chloramphenicol (CAP) based on RecJf exonuclease-assisted signal amplification and graphdiyne (GDY) is reported. GDY possesses a strong absorptivity for single-stranded DNA and is proposed for the first time as a new specific and eminently sensitive type of fluorescence sensing platform for chloramphenicol. Under the optimized conditions, the assay operates from 10 to 80 µg/L chloramphenicol with a 43.6 ng/L detection limit. The procedure was employed to determine chloramphenicol in food samples, with recoveries from 93.60% to 107.90%. The proposed technique offers a novel development in food safety using sensitive aptasensors for detecting small molecules. [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]

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.)

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. Bbv CI 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. • The Nb.BbvCI-assisted DNA walking machine achieved signal amplification; • The aptasensor exhibited wide linear range and low detection limit; • The aptasensor exhibited excellent selectivity, reproducibility and stability; • The platform realizes the quantification of DON in cornmeal samples; [ABSTRACT FROM AUTHOR]

• A novel Zn-MOF was constructed based on particular binuclear metal clusters. • Zn-MOF shows high selectivity and sensitivity to detect Cr 2 O 7 2- and CrO 4 2− ions with low detection limit. • Zn-MOF can effectively separate MB+ and MG+ from the mixed solution of MB+/MO− and MG+/MO−. A novel Zn-MOF : {[Zn 3 (L) 2 (H 2 O) 4 ]·(H 2 O) 3 ·(CH 3 CN) 3 } n was synthesized from tricarboxylate pyridine ligand 3-(2,4-dicarboxyphenyl) -4-carboxypyridine (H 3 L) under solvothermal conditions. Zn-MOF was a three-dimensional porous framework composed of binuclear metal cluster [Zn 2 (COO) 3 N] and a variety of metal oxygen chains. The fluorescence study of Zn-MOF indicated that the maximum emission peak is 449 nm (λex=335 nm), and it had varying degrees of quenching effect on Cr 2 O 7 2−and CrO 4 2− in water, the limits of detection are 4.29×10−4 M and 9.19×10−5 M, respectively. It also showed good recycling ability, which was a potential multi-functional anion fluorescence probe material. In addition, the dye adsorption and separation experiments of Zn-MOF showed that it can adsorb MB+ and MG+, but almost no adsorption for MO−, and can effectively separate MB+ and MG+ from the mixed solution of MB+/MO− and MG+/MO−. It was a potential multi-functional material for the capacity to selectively separate cationic dyes from anionic and cationic mixed solutions, as well as selective recognition of Cr 2 O 7 2−and CrO 4 2−anions. [Display omitted] [ABSTRACT FROM AUTHOR]

A novel supramolecular polymer gel TBG with white AIE was constructed for fluorescent detection and separation of Fe3+ and H 2 PO 4 −. [Display omitted] • A supramolecular gel TBG with white light emission is synthesized. • TBG can relay the detection of Fe3+ and H 2 PO 4 −. • TBG show highly sensitive response for Fe3+ and H 2 PO 4 −, LODs are 10.08 and 21.87 nM. • Gel TBG could act as a convenient test kit for the detection of Fe3+ and H 2 PO 4 −. White light materials are of great interest due to their wide potential applications in lighting devices, displays and probes. Herein, a novel bis-component white light-emitting supramolecular polymer gel TBG was facilely constructed from tripodal pyridine amides and tripodal imidazole by host–guest self-assembly process. Interestingly, the TBG exhibits strong aggregation-induced emission and can be used for highly efficient and sensitive fluorescence detection of ions (Fe3+ and H 2 PO 4 −) via the fluorescence "On-Off-On" pathway. The limits of lowest detection limits (LODs) for Fe3+ and H 2 PO 4 − were calculated to be 10.08 nM and 21.87 nM, respectively. Meanwhile, the xerogel of TBG could adsorb and separate Fe3+ from aqueous solutions, and the adsorption rate reached 99 %. In addition, a thin film based on the TBG could be used as a convenient test kit for the fluorescence detection of Fe3+ and H 2 PO 4 −. [ABSTRACT FROM AUTHOR]

In numerous malignancies, miRNA-155 is overexpressed and has oncogenic activity because it is one of the most efficient microRNAs for inhibiting apoptosis in human cancer cells. As a result, the highest sensitive detection of the miRNA-155 gene is a technological instrument that can enable early cancer screening. In this study, a miRNA-155 biosensor was created to create a hairpin probe that can bind to the miRNA-155 gene using lambda nucleic acid exonuclease, which can cut the 5′ phosphorylated double strand, and by the DNA probe is recognized by the Cas12a enzyme, which then activates Cas12a to catalyze trans -cutting produces strong fluorescence. Research finding, the target concentration's logarithm and corresponding fluorescence intensity have a strong linear connection, and the limit of detection (LOD) of the sensing system was determined to be 8.3 pM. In addition, the biosensor displayed exceptional specificity, low false-positive signal, and high sensitivity in detecting the miRNA-155 gene in serum samples. This study's creation of a biosensor that has high sensitivity, good selectivity, and is simple to operate provides promising opportunities for research into biosensor design and early cancer detection. [Display omitted] • A highly sensitive biosensor for miRNA-155 detection using λ exonuclease and CRISPR/ cas12a assisted amplification was constructed. • An ultra-sensitive detection sensor platform for miRNA-155 with a detection limit of 8.3 pM. • The biosensor is suitable for the complex human serum environment, and the technology is portable. [ABSTRACT FROM AUTHOR]

A novel fluorescent chemosensor based on the ortho-phenanthroline side-chain polymer-modified attapulgite nanohybrid material (ATP-PR) was prepared. The resulting ATP-PR, extensively characterized, exhibited significant fluorescence quenching at 398 nm upon the introduction of Cu(II) ions in water. With a Cu(II) ion detection range of 0.01–0.12 mg/L, the nanosensor achieved a low limit of detection at 0.17 μmol/L and demonstrated resilience to interference from other ions. The observed fluorescence quenching is likely attributable to a static quenching mechanism, which forms a non-fluorescent coordination complex. The Cu(II) ion adsorption process followed pseudo-second kinetic and Langmuir isotherm models, with a high maximum adsorption capacity of 41.67 mg/g surpassing that of natural ATP. The surface-coating with o-phenanthroline side-chain polymer effectively enhanced ion adsorption. The nanohybrid displayed reproducibility for Cu(II) ion adsorption and elution using hydrochloric acid, showing promise for environmental Cu(II) ion sensing and remediation in water. [Display omitted] • Phenanthroline side-chain polymer was grafted on attapulgite surface. • The theoretical maximum adsorption capacity for Cu(II) was 41.67 mg/g. • The fluorogenic nanosensor had a low detection limit of 0.17 μmol/L for Cu(II). • Co-existing ions had negligible effects on the Cu(II) sensation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two-stage hydrothermal methods were first introduced for sludge to carbon dots. • The carbon dots can detect heavy metals Fe3+ and Hg2+ in power plant wastewater. • The quenching mechanism of Fe3+ is related to the internal filtration effect. • The "turn off-on" mode of Hg2+ is mainly determined by static quenching. • The oxygen-containing functional group is the sensitive factor to Hg2+ detection. With the widespread application of sewage biological treatment technology, a large amount of sewage sludge is generated during the sewage treatment process, which not only poses a threat to the environment but also results in wastage of C and N resources. In this study, the nitrogen self-doped fluorescent carbon dots (N-CDs) with an average particle size of 3.43 nm were synthesized green through a two-stage hydrothermal method. It was found that N-CDs can detect Fe3+ through internal filtration effect (IFE), with a linear detection range of 0–250 μM and a detection limit of 2.207 μM. Furthermore, N-CDs can also serve as a "turn off–on" probe for monitoring Hg2+, with a linear detection range of 2–10 μM and a detection limit of 0.989 μM. Interestingly, oxygen-containing groups were shown to be sensitive to Hg2+, which has been demonstrated for the first time. Moreover, the practical application of N-CDs as a double ion sensor in the detection of Fe3+ and Hg2+ has achieved good results for real power plant wastewater. [ABSTRACT FROM AUTHOR]

Iron ion (Fe3+) is essential for the environment and human health. Detecting Fe3+ in water is crucial, making high-performance detection a key objective. Lanthanide metal-organic frameworks with abundant functional sites have been deemed a promising fluorescence sensor for Fe3+ detection. Currently, most metal-organic framework-based sensors for Fe3+ detection have cumbersome and time-consuming synthesis procedures and long detection times, which greatly limits their practical application. This study aims to construct a hybrid lanthanide metal-organic frameworks-based fluorescence sensor for Fe3+ detection that promises simple and rapid iron ion quantification in water. A novel hybrid lanthanide metal-organic frameworks (ECTMNs) was synthesized in one step using a solvothermal method with only 4 h. The frameworks comprise two metal ions, cerium and europium, serving as metal centers, and 4,4,4,4-(Porphine-5,10,15,20-tetrayl) tetrakis (TCPP) as an organic ligand. With the addition of Fe3+, the host-guest reaction occurred between Fe3+ and ECTMNs probe, leading to the gradual fluorescence burst of ECTMNs probe. A strong linear correlation between ECTMNs fluorescence intensity and Fe3+ concentration (1–90 μM) makes it a reliable sensor for Fe3+ monitoring with a detection limit of 0.3 μM. Moreover, the method was used to analyze real samples (tap water and river water), showing good recoveries (92–98 %) and low relative standard deviations (3.96–6.11 %), making it a promising option for rapidly detecting Fe3+. A rapid synthesis protocol for hybrid lanthanide metal-organic frameworks is proposed in this study. The obtained ECTMNs exhibits good water solubility, high stability, and specificity for Fe3+. Based on ECTMNs, an innovative fluorescence sensor is established for selectively detecting Fe3+ in water, which is a simple operation method with a low detection limit and short sensing time. It provides a novel method for accurately and rapidly detecting Fe3+ in environmental pollution and water safety monitoring. [Display omitted] • A novel one-step synthesis method was proposed for hybrid lanthanide metal-organic frameworks (ECTMNs) with only 4 h. • A facile approach for Fe3+ ions sensing by fluorescence quenching was developed. • A low detection limit of 0.3 μM, and wide linear range of 1–90 μM for Fe3+ ions were achieved. • ECTMNs was successfully applied to the detection of Fe3+ in different water samples. [ABSTRACT FROM AUTHOR]

Sodium benzoate is a commonly used food additive, but its excessive use or residue can pose potential risks to human health. In this study, we developed a novel method using TetraBromo Fluorescein Disodium Carbon Quantum Dots (TBrFD CQDs) for the rapid and accurate detection of sodium benzoate. The feasibility, sensitivity, selectivity, and stability of the method were evaluated. The results demonstrated the feasibility of the proposed method, with a linear correlation between sodium benzoate concentration and fluorescence intensity. The detection limit was calculated to be 0.094 mg L−1. The method exhibited good selectivity and stability, and its applicability was validated in real samples, including two beverages, with recovery rates ranging from 88.78% to 99.02%. This method offers a promising approach for the rapid and on-site detection of sodium benzoate in food, contributing to food safety and consumer health. [Display omitted] • Uniform, dispersed TBrFD CQDs with good morphology. • High selectivity of TBrFD CQDs for sodium benzoate, unaffected by interferences. • Sensitive and stable TBrFD CQDs for sodium benzoate, with low detection limit. [ABSTRACT FROM AUTHOR]

Four fluorimetric probes had been developed to rapidly detect 2,4,6-trinitrophenol (TNP). They were designed and synthesized on the basis of 1,3,4-thiadiazole framework combining calculation with experiment. Among them, SK-1 displayed strong blue emission with fluorescence quantum yield as high as 63.6% in solution. Further evaluation demonstrated that SK-1 displays good selectivity and high sensitivity for rapid and visual detection of TNP. It brought significant changes in both colour and fluorescence emission spectrum. The detection limit was as low as 38 nM. Quenching mechanism was confirmed as photo-induced electron transfer (PET) by nuclear magnetic titration and DFT calculations. What's more, application in real water samples and solid phase paper tests illustrated the practical significance of detection of TNP in both vapor and solution. [ABSTRACT FROM AUTHOR]

In view of the effective detection of highly toxic heavy metal chromium Cr(Ⅵ)ions in printing and dyeing wastewater is rather difficult, the Zr-metal organic framework(Zr-MOF)was synthesized by combining 2,2'-bipyridine-5,5'-dicarboxylic acid(H2L)under solvent thermal reaction. In addition, powder X-ray diffraction characterization demonstrated the high water stability of Zr-MOF, and fluorescence spectroscopy tests confirmed the photoluminescence properties of Zr-MOF. Moreover, the experimental results show that the synthesized Zr-MOF can be used for fluorescence quenching recognition and detection of Cr(Ⅵ)ions, and can resist the interference of a variety of mixed anions. The detection limits(Molar ratio)of Zr-MOF for Cr2O2-7 and CrO2-4 were 2.15×10-9 and 2.33×10-9, respectively. The mechanism by which Cr(Ⅵ)ions cause the fluorescence quenching response of Zr-MOF also was proposed. [ABSTRACT FROM AUTHOR]

Hollow carbon nitride nanosphere (HCNS) was synthesized via the hard template method to improve the fluorescence characteristics, drug delivery ability, and photocatalytic activity. Blue fluorescent HCNS was utilized as a quenching agent and an internal reference to combine with Cy5-labelled aptamer (Cy5-Apt), resulting in an off-on fluorescence aptasensing method for the detection of Salmonella typhimurium (S. typhimurium). Under optimum conditions, this fluorescence assay presented a linear range from 30 to 3 × 104 CFU mL−1 with a detection limit of 13 CFU mL−1. In addition, HCNS was also used as a drug carrier to load chloramphenicol (Cap) molecules. The Cap-loading amount of HCNS could reach 550 μg mg−1 within 24 h, whereas the corresponding Cap-release amount is 302.5 μg mg−1 under acidic and irradiation conditions. The integration of photocatalyst with antibiotic could endow HCNS-Cap with better disinfection performance. The bactericidal efficiency of HCNS-Cap (95.0%) against S. typhimurium within 12 h was better than those of HCNS (85.1%) and Cap (72.9%). In addition, selective disinfection of S. typhimurium was further realized by decorating aptamer. Within 4 h, almost all S. Typhimurium were inactivated by HCNS-Cap-Apt, whereas only 13.3% and 48.2% of Staphylococcus aureus and Escherichia coli cells were killed, respectively. Therefore, HCNS is a promising bio-platform for aptamer-based fluorescence detection and selective disinfection of S. typhimurium. [ABSTRACT FROM AUTHOR]

Copyright of Modern Food Science & Technology is the property of Editorial Office of Modern Food Science & 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.)

Duck tembusu virus (DTMUV), which causes huge economic losses for the poultry industries in Southeast Asia and China, was first identified in 2010. DTMUV disease has become an important disease that endangers the duck industry. A sensitive, accurate, and convenient DTMUV detection method is an important means to reduce the occurrence of the disease. In this study, a CRISPR/Cas13a system was combined with recombinase polymerase amplification to develop a convenient diagnostic method to detect DTMUV. The novel method was based on isothermal detection at 37°C, and the detection was used for visual readout or real-time analysis. The assay was highly sensitive and specific, with a detection limit of 1 copy/μL of the target gene and showed no cross-reactivity with other pathogens. The enhanced Cas13a detection worked well with clinical samples. Overall, a visual, sensitive, and specific nucleic acid detection method based on CRISPR/Cas13a proved to be a powerful tool for detecting DTMUV. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & 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.)

A strategy based on CsPbBr3 quantum dots (QDs) is described for the determination of ziram pesticide. A facile and inert gas-free method was used for the synthesis of CsPbBr3 QDs. The obtained CsPbBr3 QDs displayed turn-off fluorescence behavior for ziram. The fluorescence intensity of the CsPbBr3 QDs (Ex/Em = 365/516 nm) was inversely proportional to the concentration of ziram (0.10 to 50.0 ppm) with a detection limit of 0.086 ppm. Notably, satisfactory recoveries (100 ± 0.25 to 107 ± 5.72%) were obtained in spiked fruit samples, which demonstrated that this method is capable of detecting ziram in real samples. In addition, the mechanism for the detection of ziram was investigated in detail. According to the results, this mechanism can be tentatively explained by fluorescence quenching originating from the increased surface defects and the structural changes of the CsPbBr3 QDs. The detection ability of this strategy shows promising applicability in food safety. [ABSTRACT FROM AUTHOR]

The fabrication of alkaline phosphatase (ALP)-responsive coordination polymer (CP) composite is demonstrated for establishing a fluorescent immunoassay. The CP composite (ThT@GMP/Eu) was synthesized by encapsulating thioflavin T (ThT) into the CP host that was composed of europium ion (Eu3+) and guanine monophosphate (GMP). The ThT@GMP/Eu composite shows a strong fluorescence in aqueous solution due to the confinement effect of GMP/Eu CPs, which restricts the conformational rotation of ThT. However, upon the addition of ALP, the structure of GMP/Eu CPs was disrupted to release ThT into solution. This results in the quenching of the fluorescence of ThT@GMP/Eu. The fluorescence of ThT@GMP/Eu has a linear response that covers 0.8 to 120 mU/mL ALP with a detection limit of 0.26 mU/mL and exhibits excellent specificity towards ALP against other enzymes. On this basis, inspired by the wide application of ALP as an enzyme label in enzyme-linked immunosorbent assay (ELISA), an ALP-based fluorescent immunoassay was further developed for the detection of mouse immunoglobulin G (mIgG). The developed immunoassay displays a linear fluorescent response towards mIgG from 0.8 to 100 ng/mL, and the detection limit is 0.16 ng/mL. The fluorescent immunoassay was successfully applied to the determination of mIgG in serum samples. [ABSTRACT FROM AUTHOR]

Supramolecular gels with metal ion-responsiveness are an important kind of smart materials due to their potential application in environmental monitoring. In this study, a novel l -glutamine-contained 1,8-naphthalimide derivative (NDG) has been designed and synthesized as an organogelator. NDG could self-assemble into stable supramolecular organogels in different kind of solvents, and the gelation process showed bright blue aggregation-induced emission (AIE). The self-assembly behavior, morphology and structure of NDG gels were thoroughly studied by various techniques. Interestingly, the obtained NDG organogel exhibited a fluorescence "turn-off" response for Fe3+ and formed a stable metallogel NDG -Fe3+. The detection limit (LOD) of NDG in diluted solution and gel states for Fe3+ was calculated to be 30.8 nM and 11.5 nM, respectively, indicating high sensitivity. In addition, the blue fluorescence emission of the gel system was restored in the presence of ascorbic acid and then quenched again with oxygen, which showed reversible fluorescence sensing effect and employed as a logic gate at the molecular level. Furthermore, xerogel-based film of NDG emitted strong blue emission and could be utilized as paper-based chemosensor to detect Fe3+. And also, the NDG gel had potential application in fluorescence display material. [Display omitted] • A l -glutamine-contained 1,8-naphthalimide gelator was synthesized with AIE effect. • The organogel exhibited a fluorescence response for Fe3+ by gel-gel transition. • The gel system was potentially constructed as a molecular logic gate. • Paper-based gel film was used in Fe3+ recognition and as display material. [ABSTRACT FROM AUTHOR]

Trypsin-stablized copper nanoclusters were prepared through one-pot strategy and successfully used for tetracycline sensing with excellent sensitivity and selectivity. [Display omitted] • Trypsin-stablized copper nanoclusters was not reported for sensing of tetracycline. • Fluorescence of copper nanoclusters was selectively quenched by tetracycline. • Static quenching and inner filter effect were the main quenching mechanism. • Cu NCs possessed fairly superior linear relationship and low RSD. • Tetracycline detection in real samples displayed satisfactory recoveries. Due to the excellent characteristics, fluorescent copper nanoclusters (Cu NCs) have aroused great interest in recent years. Herein, the simple prepared, environmentally friendly fluorescent Cu NCs were synthesized by using trypsin as the stabilizer and applied for the determination of tetracycline. Uniformly dispersed Try-Cu NCs were obtained with average size of 3.5 ± 0.3 nm and some excellent merits of good water solubility, UV light stability and salt stability. Emission peaks around 460.0 nm were visibly quenched by tetracycline based on static quenching mechanism and inner filter effect (IFE). Two excellent linear relationships were observed between ln(F 0 /F) and tetracycline concentrations in the range of 1–100 μM and 100–300 μM with limit of detection (LOD) of 0.084 μM. Meanwhile, this nanoprobe exhibited an apparent selectivity for tetracycline detection. Moreover, Try-Cu NCs were successfully employed to determine tetracycline in serum and milk samples after facile pretreatment with satisfactory recovery rates and credible standard deviation. The results suggested that this as-prepared Try-Cu NCs had excellent application prospects in the future. [ABSTRACT FROM AUTHOR]

Sensitive detection of copper ion (Cu2+), which is of great importance for environmental pollution and human health, is crucial. In this study, we present a highly sensitive method for measuring Cu2+ in an array of femtoliter wells. In brief, magnetic beads (MBs) modified with alkyne groups were bound to the azide groups of biotin-PEG3-azide (bio-PEG-N 3) via Cu+-catalyzed click chemistry. Cu+ in the click chemistry reaction was generated by reducing Cu2+ with sodium ascorbate. Following the ligation, the surface of the MBs was modified with biotin, which could be labeled with streptavidin-β-galactosidase (SβG). The MBs complex was then suspended in β-galactosidase substrate fluorescein-di-β- d -galactopyranoside (FDG), and loaded into the array of femtoliter wells. The MBs sank into the wells due to gravity, and the resulting fluorescent product, generated from the reaction between SβG on the surface of the MBs and FDG, was confined within the wells. The number of fluorescent wells increased with higher Cu2+ concentrations. The bright-field and fluorescent images of the wells were acquired using an inverted fluorescent microscope. The detection limit of this assay for Cu2+ was 1 nM without signal amplification, which was 103 times lower than that of traditional fluorescence detection assays. [Display omitted] • A digitized assay for Cu2+ detection based on click chemistry was developed. • The digitized assay detection volume is 109 times smaller than the bulk method. • The digitized assay detection limit for Cu2+ is 103 times lower than bulk method. [ABSTRACT FROM AUTHOR]

A highly selective rhodamine hydrazide-based fluorescent chemosensor for Au3+ detection was developed. The aqueous solution of rhodamine N-hydroxysemicarbazide (RHS), in the presence of Au3+, exhibited a significant 55-fold turn-on fluorescence response at 591 nm and a colorimetric change from colorless to pink. Other interested ions including Li+, Na+, K+, Cs+, Mg2+, Ca2+, Ba2+, Pb2+, Mn2+, Co2+, Ni2+, Ag+, Cd2+, Cu2+, Hg2+, Zn2+, Sn2+, Fe2+, Fe3+, Cr3+, Ce3+ did not induce any distinct color/spectral changes. The irreversible detection mechanism occurred via Au3+-promoted 5-exo-trig ring closure to yield 1,3,4-oxadiazole-2-one product. The RHS probe is non-responsive to other biologically relevant metal ions and the limit of detection for Au3+ was calculated to be 0.5 µM with a linear range of 0 to 90 µM. Fluorescence bioimaging of Au3+ in HepG2 cells was also successfully demonstrated. [ABSTRACT FROM AUTHOR]

Highly fluorescent hollow ZrO2@CdTe nanoparticles (NPs) were synthesized efficiently via the hydrothermal method. By changing the hydrothermal time of ZrO2@CdTe NP, the peaks of fluorescence spectra measured at fluorescent excitation of 330 nm were at 540 nm, 590 nm, and 640 nm, respectively. Hollow ZrO2 NPs have a uniform core–shell structure with the size of 178 ± 10 nm and shell of 19 ± 4 nm. The as-prepared yellow-ZrO2@CdTe NPs were used to develop lateral flow assay (LFA) for the sensitive and qualitative detection of C-reactive protein (CRP). The visual limit of detection of the LFA for the CRP antigen was 1 μg/L within 20 min, which is 1000-fold lower than that of colloidal gold-based LFA. In addition, a multiplex lateral flow assay (mLFA) was developed using the as-prepared green and red-ZrO2@CdTe NPs for the simultaneous, specific, sensitive, and qualitative detection of CRP and troponin T (cTnT). The visual limits of detection of CRP and cTnT in mLFA were 10 μg/L and 0.1 mg/L, respectively. The excellent performance of ZrO2@CdTe NPs should facilitate their application in point-of-care technology for the detection of other biomarkers. [ABSTRACT FROM AUTHOR]