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Tryptophan is one of important amino acids in the human body, therefore its detection is particularly important. The 3,5‐bis(4‐pyridyl)‐4‐amino‐1,2,4‐triazole (BPAT) organic molecule was designed to be used as fluorescence detectors to detect tryptophan molecules for the interaction between the host and the guest. BPAT shows good sensitivity and selectivity towards tryptophan compared with other amino acid molecules. The limit of detection obtained from formula 3δ/KSV is considered to be 5.43 × 10−7 mol/L. We speculated that this change is mainly caused by the hydrogen bond between tryptophan and the host molecule BPAT. This conjecture was verified by the controlled experiments with other host molecules. [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]

The development of molecularly imprinted monolith (MIM) for pipette-tip solid-phase extraction (PT-SPE) for sample pretreatment is challenging. In this work, a wax-based molecularly imprinted monolith (WMIM) was successfully prepared with a hybrid method by integration of the traditional packing SPE column and MIM, including preparation of the salt column inside the pipette, polymerization of wax-based imprinted column (WIC) outside the pipette, and immobilization of WIC inside the pipette tip. To ensure the penetration of samples and solvents during the PT-SPE, micrometer-range interconnected macropores were tailor-made via the salt-template sacrifice method. For the production of high affinity imprinted sites within the WIC, octadecanoic acid was used as functional monomer in the paraffin matrix. In terms of the adsorption property, the synthesized WIC exhibited a specific affinity to cardiovascular drugs, with an imprinting factor (IF) of 4.8 for the target analyte. Moreover, the WMIM-based PT-SPE was coupled with fluorescence spectrophotometry for the target propranolol determination (the excitation and emission wavelengths were 294 nm and 343 nm, respectively). This analytical method showed high recovery of target detection in different real samples (R > 90%), good sensitivity, and accuracy (R2 = 0.99, LOD = 0.03 ng mL−1). We believe this work could provide a significant contribution for the fabrication of MIM and promote an emerging trend of developing elution-free materials for sample pretreatment. [ABSTRACT FROM AUTHOR]

A synchronous fluorescence spectroscopy (SFS) sensor for pethidine detection is described based on UiO-66 metal–organic frameworks (MOFs) modified with N-doped carbon quantum dots (N-CQDs) embedded in hydrogel nanocomposites. Benefitting from the inovative design of the doping method in the carbonaceous structure, N-CQDs were successfully deposited in the pores of the UiO-66 network. Then, N-CQDs were employed as a sensitive segment toward the target molecules. UiO-66 was used for sensitive and selective sensing of the bonding interactions between N-CQDs and pethidine so that the electron transfer process from UiO-66 to the pethidine-N-CQD complex results in quenching the SFS intensity of UiO-66. To embed the stable and suitable sensing interface for pethidine assessment, the designed nanomaterial was inserted into the hydrogel network. This nanocomposite hydrogel showed two well-resolved emission peaks at 300 nm and 350 nm under ∆λ = 70, which corresponded to N-CQDs and UiO-66, respectively. The SFS sensing platform was employed for ratiometric detection of pethidine with a low limit of detection of 0.002 μg mL−1 over a wide concentration range from 0.005 to 1.0 μg mL−1. The accurate monitoring of pethidine with a good recovery of 90.8–101.5% indicated their independency from matrix effects for pethidine detection in human plasma being a complicated biological matrix. Scheme 1. General procedure for synthesizing N-CQDs@UiO-66/PVA hydrogel-based nanoprobe and its application for pethidine determination [ABSTRACT FROM AUTHOR]

Continuous-flow PCR (CF-PCR) can realize rapid DNA amplification because of the high temperature variation rate. However, off-line detection methods for PCR may induce cross contamination. To overcome this problem, we herein fabricated an integrated CF-PCR and electrophoresis microfluidic chip. The optimal voltage applied in the electrophoresis part of the microfluidic chip was achieved by simulation in COMSOL. Coating the inside wall of the microchannel can inhibit electroosmotic flow and improve the resolution for DNA fragments. The temperature distribution of the serpentine part can meet the PCR and has no obvious suppressive effect on sample separation. Finally, we have performed the amplification of target genes for Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola and detected the corresponding PCR products in the microfluidic chip within 11 min. Such work provides a new method for the rapid detection of bacteria. [ABSTRACT FROM AUTHOR]

We developed an extensible LED-induced fluorescence detection module with a highly integrated and ultra-compact structure. A target-oriented design methodology was used to demonstrate the module's optimal design. Lucigenin solution was used as a test sample in evaluation trials to demonstrate the module's quantitative fluorescence detection capability. Results showed that the integrated module has an outstanding linear response in the range of 0–1 μmol·L−1, with sensitivity and limit of detection (LOD) of 0.1692 V/μmol·L−1 and 0.03 μmol·L−1, respectively. Statistical analyses showed that our integrated module has extremely high repeatability and accuracy, i.e., the values of Pearson's correlation coefficient and root-mean-square error exceeded 0.9995 and 1.8‰, respectively. More importantly, the integrated module possesses favorable extensibility and can realize on-demand rapid fluorescence-signal detection of other targets using appropriate parameter combinations. This module offers new opportunities for reliable, cost-effective and easy-to-use fluorescence-signal detection, especially in resource-constrained fluorescence detection applications. [ABSTRACT FROM AUTHOR]

A fast and efficient fluorescent probe based on carbon quantum dots (CQDs) was studied to detect ferric ions (Fe3+) in tap water. Cow milk-derived carbon quantum dots (CMCQDs) were synthesized via hydrothermal method using milk as the carbon source. The size, morphology, surface composition, optical properties and stability of the CMCQDs were fully characterized. The obtained CMCQDs show blue fluorescence, uniform distribution, small particle size and excellent fluorescence stability. There is a specifically quenching effect on CMCQDs by Fe3+, so the CMCQDs can be employed as a fluorescence probe for determination of Fe3+ with high selectivity and sensitivity. The limit of detection (LOD) is 0.6 μmol/L in the range of 0.1–20 μmol/L (R2 = 0.9911). Herein, the fluorescent quenching of CMCQDs is thought to result from the by the unique chelation or coordination between Fe3+ and surface functional groups of CMCQDs. The sensitive and selective fluorescent probe was confirmed to demonstrate high potential in Fe3+ detection in tap water. Highlights: Cow milk-derived carbon quantum dots (CMCQDs) were synthesized for sensitive and selective detecting Fe3+ in tap water. The sensing mechanism of the detection is result from the unique chelation or coordination between Fe3+ and surface functional groups of CMCQDs. The limit of detection (LOD) is 0.6 μmol/L in the range of 0.1-20 μmol/L. [ABSTRACT FROM AUTHOR]

[Display omitted] • Innovative designing of in-situ grown fluorescent spherical ball-shaped nanocomposite. • Formative insights divulging the porosity and structural integrity of the nanocomposite. • Hollow architecture of MCHS augmenting charge transfer to boost sensing process. • Dual sensing capability for Cu(II) and TNP based on a single sensor platform. • Achieved 99 % removal efficiency of Cu(II) ions with q max value of 523.56 mg/g. Environmental remediation in the jurisdiction of wastewater treatment is considered a critical global priority. Evidence suggests that mesoporous carbon hollow sphere (MCHS) has been extensively employed for electrochemical applications owing to its distinctive structure and efficient mass or charge transfer abilities. The distinctive amalgamation comprising a high surface area and intrinsic porosity from the metal–organic framework (MOF) and mesoporous spherical carbon shells offer enrichment in active analytical sites. To the extent of our understanding, no sensors have yet been created using a hybrid of MOFs and MCHSs. The current study utilizes in-situ fabricated MCHS and MOF-based novel fluorescent nanocomposite (Zn-MOF@MCHS) for the proficient sensing and adsorptive removal of environmental contaminants. Field emission scanning electron microscopy, High-resolution transmission electron microscopy and several other characterizations were employed to validate the physical attributes of the synthesized nanocomposite. These attributes could be advantageous in enhancing the adsorption and sensing functionalities of a material. The proposed system adaptably detects TNP (2,4,6-trinitrophenol) and Cu(II) ions (Stern-Volmer constants, K sv = 0.36 × 106 M−1 and 0.83 × 104 M−1 respectively) along with efficient adsorption (99 % removal) of Cu(II) ions featuring a maximum adsorption capacity (q max) of 523.56 mg/g. The low detection limits i.e., 0.368 µM for Cu(II) ion and 0.301 µM for TNP, demonstrated outstanding selectivity and sensitivity of Zn-MOF@MCHS. The nanocomposite pertains to a surface area of 18.600 m2/g, adheres to second-order kinetics and exhibits optimal fitting to the Langmuir isotherm model to adsorb Cu(II) ions. X-ray Photoelectron Spectroscopy and zeta-potential analysis diligently scrutinize mechanistic evidence for the sensing and adsorption studies. Through experimental outcomes, the newly proposed nanoscale fluorescent composite showed the potential to serve as a universal platform for detecting and removing metal ions and detecting nitro compounds sensitively. [ABSTRACT FROM AUTHOR]

The aim of this work was to develop a fluorescence method based on the polydopamine-polyethyleneimine (PDA-PEI) copolymerization, which was subsequently applied for the determination of 3-monochloropropane-1,2-diol (3-MCPD) in food contact papers (FCMs). PEI could provide an alkaline environment and then react with dopamine (DA) to produce copolymers by Michael addition and Schiff-base reactions. This copolymer has a strong fluorescence emission at 527 nm. We found that amino groups of DA and PEI could also react with 3-MCPD in an alkaline medium, which improved the morphology and fluorescence intensity of PDA-PEI copolymers. The fluorescence intensity of the polymers was linear but inversely proportional to the concentration of 3-MCPD in the range of 10.0–500.0 μg kg−1 and the detection limit was 2 μg kg−1. The standard addition method was used in FCMs to demonstrate the practical applicability and the spiked recoveries ranged from 99.8 to 110.3 %. Finally, the levels of 3-MCPD in different FCMs (n = 70) were determined by the proposed method. The detection frequencies ranged from 25 % to 100 % and both the highest detection frequency and levels were observed in kitchen papers. More than half of the samples did not comply with the limits recommended by the German Federal Institute for Risk Assessment, suggesting that 3-MCPD released from FCMs is a major route of human exposure. [Display omitted] • The copolymerization between DA/PEI and 3-MCPD was used for fluorescence analysis. • It could be used for the determination of 3-MCPD in food contact papers (FCMs). • It does not require home-made functional material, and toxic or harmful reagents. • The detection frequencies of 3-MCPD in FCMs ranged from 25 % to 100 %. [ABSTRACT FROM AUTHOR]

• Three CDs (CDs1, CDs2, CDs3) with strong antibacterial activity were designed. • The CD1 have antibacterial and sensing dual function applications. • The CDs1 can accurately detect tetracycline antibiotics in real milk. Bacterial infections pose a significant threat to global health, necessitating the development of novel antibacterial materials. Tetracycline antibiotics (CTC, OTC, TC) are low-cost and widely abused in recent years. However, they were easily absorbed by the human body and long-term exposure to tetracycline could contribute to some adverse reactions and diseases. So there is a need for novel antimicrobial agents and a rapid, sensitive detection method of tetracycline antibiotics. In this study, we synthesized three carbon dots (CDs1, CDs2, CDs3) from quaternary ammonium salts via a hydrothermal method. Antibacterial assays against Staphylococcus aureus and Escherichia coli demonstrated their potent antibacterial activity with minimum inhibitory concentrations(MIC) determined as 39 μg/mL, 78 μg/mL, and 9.8 μg/mL, respectively. Notably, CDs3 exhibited the highest antibacterial effectiveness, attributed to its smaller size and higher chlorine content compared to CDs1 and CDs2. Additionally, CDs1, characterized by its high fluorescence quantum yield and stability, demonstrated remarkable specificity and robust anti-interference capabilities in detecting tetracycline antibiotics, including chlortetracycline (CTC), oxytetracycline (OTC), and tetracycline (TC). Leveraging the internal filtration effect mechanism, CDs1 exhibited detection limits of 0.18 μmol/L for CTC, 0.15 μmol/L for OTC, and 0.13 μmol/L for TC, respectively. The effectiveness of this detection method was further confirmed through validation in real milk samples, confirming the practical utility of CDs1 in food safety testing. The low toxicity of carbon dots were synthesized using a simple one-step hydrothermal method, which was fast, cost-effective, and easy to achieve large-scale production. Our findings underscore the potential of CDs derived from quaternary ammonium salts, demonstrating promising performance in antibacterial applications and providing insights into food safety testing methodologies. [Display omitted] [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]

• One novel fluorescent Cu-CP has been hydrothermally prepared. • Cu-CP exhibits great water stability. • Cu-CP is further employed as a versatile fluorescence sensor for Cr(VI) / Mn(VII), NFT / NFZ and ACAC. • The possible sensing mechanism has also been elaborately researched. Advanced methods for both biological and environmental hazardous pollutants are of sustained interest. Herein, a new coordination polymer, namely, [Cu 2 (OH)(1,2,4-bca)(bmoe)]·H 2 O (Cu-CP) has been hydrothermally constructed with a mix-ligand strategy, employing 1,2,4-benzenetricarboxylic acid (1,2,4-bca) and 1,1′-bis(1H-benzimidazolyl) oxydiethane (bmoe) as organic ligands. The intrinsic strong blue-light emission and the great stability in water solutions with the broad range of pH values (pH = 4 − 12) of Cu-CP provide a platform for practical fluorescence sensing application in water samples. Fluorescence measurements reveal that Cu-CP displays interesting multi-responsive dection activities toward toxic heavy-metal ions Cr 2 O 7 2- / CrO 4 2− / MnO 4 −, nitrofuran antibiotics nitrofurantoin (NFT) / nitrofurazone (NFZ) and acetylacetone (ACAC) in aqueous solutions achieving both high sensitivity and low detection limits (micromolar for Cr(VI) / Mn(VII) / ACAC and nanomolar for NFT / NFZ). Furthermore, the interference experiments have verified its excellent selectivity. A synergetic contribution of internal filtration effect (IFE) and Förster resonance energy transfer (FRET) between Cr 2 O 7 2- / CrO 4 2− / MnO 4 − and the framework of Cu-CP realize the fluorescence quenching behavior for Cr(VI) / Mn(VII) detection, while FRET, IFE and photoinduced electron transfer (PET) mechanisms are synergistically responsible in the case of NFT / NFZ, ACAC sensing supported by the molecular simulations and UV−vis spectral overlap experiments. This present work affords precious guidance for the effective and facile design and preparation of multifunctional luminescent coordination polymers with promising performance. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of Tb-MOF based on boric acid functionalization. • Tb-MOF was used for the detection and adsorption of gallic acid. • Capable of rapid and selective detection of GA in green tea. • Tb-MOF has good adsorption effect on GA. Gallic acid (GA) is widely applied as an antioxidant in foods and pharmaceuticals. In this study, a boronic acid functionalized metal–organic framework (Tb-MOF) is developed for fluorescence detection and adsorption of GA. Tb-MOF is constructed by coordination polymerization of terbium ions (Tb3+) with 3,5-dicarboxyphenylboronic acid (BBDC). The resulted Tb-MOF exhibits green fluorescence emission at 546 nm under an excitation of 280 nm. However, the green emission of Tb-MOF decreases in the presence of GA due to the formation of borate esters between phenolic hydroxyl groups of GA and hydroxyl groups of Tb-MOF. Under optimized conditions (40 mmol·L−1 Tris-HCl buffer solution of pH = 6.2 and reaction time of 25 min), the sensor shows a wide detection range of 5 ∼ 200 μmol·L−1 with a correlation coefficient (R2) of 0.9950. Meanwhile, Tb-MOF shows good selectivity and sensitivity to GA (the limit of detection (LOD) is 0.44 μmol·L−1). Additionally, Tb-MOF is used to investigate GA adsorption. The corresponding adsorption data can be suitably described by Langmuir isotherm and pseudo-second-order models with a maximum adsorption capacity of 6.03 mg·g−1. The above results demonstrate the potential of prepared Tb-MOF in integrating GA detection and adsorption in water samples. [ABSTRACT FROM AUTHOR]

• Compared with powder, Tb-Co-MOF film is stable, easy to control and no waste as a fluorescent sensor. • The flexibility of the film was increased by adding BMA to the preparation of the film. • The fluorescent film can be reused more than 20 times after being washed with distilled water after sensing. Therefore, it has excellent reversibility. • Compared with powder, Tb-Co-MOF film has the advantages of high sensitivity, good selectivity, it has great potential for practical application. A novel bimetallic organic framework material based on 3,5-di (2′, 4′ - dicarboxylphenyl) benozoic acid (H 5 L) ligand, named {[Tb 9 CoL 6 (H 2 O) 6 (H 3 O)]·4DMF·2H 2 O} n [L = C 23 H 9 O 10 , DMF = N, N- Dimethylformamide) (Tb-Co-MOF), had been successfully synthesized by solvothermal method. The structure and properties of Tb-Co-MOF were characterized by single-crystal X-ray diffraction, elemental analysis, thermogravimetric analysis, powder X-ray diffraction, ultraviolet spectrum, infrared spectrum and fluorescence spectrum. This results indicated that Tb-Co-MOF was crystallized in the trigonal system with the R 3 space group and it was a novel three-dimensional structure, good thermal stability and luminous performance. Fluorescent film was prepared with Tb-Co-MOF powders by polymer embedding method. This film had high fluorescence recognition ability for histamine (HIS), Fe3+ ion and Cr 2 O 7 2− anion, so it could be used as a selective fluorescence sensor for them. Their detection limits were 1.43 μmol·L−1, 0.94 μmol·L−1 and 0.96 μmol·L−1, respectively. Compared with the powder MOFs, the fluorescence film had the advantages of high sensitivity, good selectivity, fast response speed, high stability and strong reversibility, which provided a certain reference for the application of metal-organic framework materials in environmental detection. [Display omitted] In order solve the problems of instability caused by poor solubility and high cost caused by difficult recovery of powdered MOFs fluorescence materials. In this study, a novel lanthanide bimetallic-organic frameworks fluorescence material Tb-Co-MOF was innovatively prepared into fluorescent film. The fluorescence film was used to detect HIS, Fe3+ and Cr 2 O 7 2−. It provides some reference for the sensor detection technology of metal-organic framework in water, atmosphere and other environment. [ABSTRACT FROM AUTHOR]

The effective differentiation and detection of multiple tea polyphenols are often challenging due to their subtle structural similarities. Although post-column derivatization HPLC strategies are commonly employed to distinguish multiple targets, the short physical distance between chromatographic column and detector limits reaction time, thereby reducing the derivatization efficiency. Dopamine (DA) reacts rapidly with resorcinol to form fluorescent azamonardine products, making fast fluorometric derivatization of tea polyphenols containing resorcinol motifs possible. In this study, a DA-driven rapid and post-column fluorescence derivatization method has been applied to sensitively detect eight tea polyphenols. This method is based on fluorescence derivatization and possesses low background interference, high sensitivity, and excellent reproducibility. Moreover, the practical application of this proposed fluorometric derivatization platform was further validated by simultaneous identification of multiple tea polyphenols in different tea samples. This work has great potential to become an alternative to the National Standard method for tea polyphenols determination. [Display omitted] • Dopamine can act as novel fluorescence derivatization agent for tea polyphenols. • The retention time of tea polyphenols is extended after derivatization. • Eight tea polyphenols are distinguished using post-column derivatization HPLC. • The analysis of tea polyphenols contents in different tea samples is realized. [ABSTRACT FROM AUTHOR]

Metal-organic framework (MOF) materials are three-dimensional structures formed by the combination of metal ions and organic ligands. So far, various typical metal organic framework materials have emerged, such as ZIF-8, MOF-5, UIO-66, etc. These traditional MOF materials have the advantages of simple synthesis, high porosity, and high stability, and have great research potential in the field of fluorescence sensing. However, MOF materials with excellent luminescent properties often involve fine regulation of organic ligands to ensure that fluorescence emission can be achieved between metal ions and organic ligands through energy transfer and photo induced electron transfer. The long synthesis cycle and cumbersome preparation process pose challenges for the research of fluorescent MOF materials. Combining MOF materials with luminescent guests is an effective way to prepare simple fluorescent chemical sensors. These luminescent guests include quantum dots, organic dyes, fluorescent nanoparticles, etc. They have the characteristic of high luminescence quantum yield, but high concentrations often lead to aggregation and collision, which in turn cause emission quenching. MOF materials with excellent porosity and specific surface area can serve as an ideal platform for encapsulating luminescent guests and preventing their aggregation. The preparation of MOF@luminescent guest composite material (MOF@LG) is easy to synthesize, which not only effectively improves the poor fluorescence performance of MOFs themselves, but also preserves the excellent fluorescence performance of luminescent guests. Composite materials often have excellent solid-state luminescence performance, making them a good choice for constructing a simple fluorescence sensing platform. [Display omitted] • The feasibility of MOF encapsulation of luminescent guest was analyzed. • The luminescent guest types of MOF package were investigated. • Systematically browsed the research on the application of MOF@LG in different environmental health fields case. • The existing challenges and countermeasures of MOF@LG are analyzed. [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]

Novel Keggin-type POM with a three-dimensional supermolecule structure demonstrates its exceptional selectivity and high sensitivity towards Fe3+, HPO 4 2− and CrO 4 2− as a fluorescence probe along with excellent electrochemical activity towards NaNO 2. [Display omitted] The escalating development of the national industry has led to a growing apprehension regarding water pollution. Therefore, there is an urgent need to develop a rapid, convenient, and highly sensitive method for detecting water pollutants. In this study, we successfully prepared a novel Keggin-type polyacid hybrid material with zero-dimensional structure [Zn 2 (C 10 H 6 NO 2) 2 (C 10 H 7 NO 2) 4 ][ZnCl(C 10 H 7 NO 2) 3 ] 2 [HPMo 12 O 40 ] 2 (1) through steam heating using 2,3-quinoline dicarboxylic acid, phosphomolybdic acid and Zn(NO 3) 2 along as precursors. However, it was observed that 2,3-quinoline dicarboxylic acid (H 2 L = C 11 H 7 NO 4) loses a carboxyl group from a new quinoline-3-carboxylic acid ligand (HL1 = C 10 H 7 NO 2) during the synthesis process of 1. Our investigations have revealed two distinct forms for Zn2+, form A involves coordination with one Zn ion, three ligands and one chloride ion while form B forms a binuclear cluster [Zn 2 (C 10 H 6 NO 2) 2 (C 10 H 7 NO 2) 4 ]2+ by coordinating with two L1−1 and four HL1 ligands. These structures are further extended into 3D supramolecular architectures via π-π packing between one-dimensional chains formed by connecting the Keggin-type polyoxometalates through multiple hydrogen bonds. Additionally, we explore the fluorescence and electrochemical properties of compound 1. These results demonstrate its exceptional selectivity and high sensitivity towards Fe3+, HPO 4 2− and CrO 4 2− as a fluorescence probe and excellent electrochemical activity towards NaNO 2. Furthermore, the reaction mechanism was thoroughly examined. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cu-Cy exhibited reversible FL quenching/recovery via redox-modulated IFE. • Cu-Cy showed good stability against pH, temperature, UV irradiation, and storage. • The method could monitor ALP in biological samples and screen ALP inhibitors. • The method could identify the saliva of healthy persons and patients with periodontitis. The cost-effective and eco-friendly monitoring of alkaline phosphatase (ALP) activity is crucial for the diagnosis and treatment of various diseases. In this study, we investigated the utilization of a two-dimensional (2D) sheet-like copper-cysteamine (Cu-Cy) as a fluorescence probe for the detection of ALP activity. It was found that the fluorescence emission of Cu-Cy could be reversibly switched off and on by the alternate addition of manganese dioxide nanosheets (MnO 2 NSs) and ascorbic acid (AA) based on a redox-modulated inner filter effect. Additionally, owing to its 2D structure and exceptional stability, Cu-Cy exhibited effective reusability for at least four cycles without any noticeable loss in sensing performance. Based on these findings, an efficient fluorescent approach was designed for ALP detection by monitoring the generation of AA through the hydrolysis of L -ascorbic acid 2-phosphate catalyzed by ALP. The assay achieved a detection limit of 0.1 U/L with a linear detection range from 1 to 100 U/L. Furthermore, this sensing method enabled the detection of ALP in human serum and saliva samples, as well as distinguishing between the saliva of healthy individuals and patients with periodontitis. Moreover, this approach demonstrated significant potential for ALP inhibitor screening, thus offering promising prospects for clinical diagnosis and treatment of ALP-related diseases. [ABSTRACT FROM AUTHOR]

In this study, nitrogen-phosphorus co-doped quantum dots (NP@CQDs) were synthesized by a one-step hydrothermal method using citric acid and ammonium dihydrogen phosphate as raw materials. They were used for the detection of three quinolone antibiotics (ciprofloxacin, norfloxacin and ofloxacin) in food waste digestate filtrate with good accuracy and applicability. The NP@CQDs have good stability of fluorescence properties with a quantum yield of up to 43 %. Taking ofloxacin as an example, the linearity was good in the concentration range of 5μmol/L to 300μmol/L (R 2 =0.991), and the limit of detection was 0.035μmol/L. Experimentally, it was demonstrated that the electron-donating groups on the NP@CQDs could interact with the aromatic ring groups in the antibiotics in a substituent manner, the degree of conjugation was enhanced, the excited state electron transfer was restricted, the photoinduced electron transfer (PET) reaction was suppressed, and the fluorescence was enhanced. This study provides an opportunity to develop a fluorescent ratio type probe for the detection of trace quinolone antibiotics in complex water samples rich in interferants. [Display omitted] • The quantum yield of NP@CQDs is 43 %, while the CQDs is 11.92 %. • Based on fluorescence sensitization effect, NP@CQDs detected antibiotics in digestate filtrate. • Electron-donating groups produce substituent effects to inhibit PET and enhance fluorescence. • Electrostatic repulsive forces energizing electron leaps and enhancing fluorescence. [ABSTRACT FROM AUTHOR]

This study highlights the aqueous synthesis of CdTe/ZnS core/shell quantum dots (QDs) and their application as fluorescence sensors for detecting critical metabolites, including folic acid, glucose, and vitamin C, in real biological samples. The synthesized QDs exhibit excellent quantum efficiency, stability, and biocompatibility, enhanced by mercaptopropionic acid (MPA) ligands, enabling eco-friendly and accurate sensing. Detection limits of 0.84 µg/mL for folic acid, 0.33 mM for glucose, and 1.15 µg/mL for vitamin C were achieved with high linearity (R2 > 0.97). These results underscore the potential of CdTe/ZnS QDs in advanced biosensing technologies, offering sensitive and selective metabolite detection through a robust FRET-based mechanism. The versatility and aqueous solubility of these QDs pave the way for their integration into multiplex diagnostic systems for enhanced biomedical applications. [ABSTRACT FROM AUTHOR]

An intelligent fluorescence sensing platform based on entropy-driven toehold-mediated strand displacement cycle reaction for point-of-care testing of miRNA. [Display omitted] • A self-designed AuNPs@A@B1/B2 sensor for specific recognition of miRNA (e.g. miRNA-125a-5p). • Fluorescence amplification of dual reporter molecules using entropy-driven toehold-mediated chain displacement reaction. • An miniaturized intelligent fluorescence sensing platform has been built for fluorescence sensitive detection. • This miRNA sensor has broad application prospects in the clinical diagnosis of various diseases. MicroRNA (miRNA) has gradually become an emerging biomarker for early diagnosis and prognosis of various diseases due to its specific gene expression and high stability. With the development of molecular diagnosis and point-of-care testing (POCT) technology, developing simple, fast, sensitive, efficient, and low-cost miRNA sensors is of great significance for clinical applications and emergency rapid diagnosis. At present, entropy-driven toehold mediated chain displacement reaction, as a promising enzyme free isothermal amplification technique, is an important tool for ultra-sensitive biosensing applications. In this study, we used gold nanoparticles (AuNPs) as carriers and quenchers, modified them using self-assembled triple chain composite substrates AuNPs@A@B1/B2, and used dual reporter molecules for cascade cyclic amplification to amplify fluorescence signals, which proposed a fluorescent biosensor based on this reaction and build an intelligent fluorescence sensing platform for rapid detection of miRNA. We designed a highly specific self-programmable sensor using the acute ischemic stroke (AIS) biomarker miRNA-125a-5p as a sample, and achieved sensitive detection of miRNA in the range of 0.01 μM∼10 μ M under optimal conditions. It broke through the traditional detection limitations of weak signals and liberated the fluorescence detection environment. In summary, this creative miRNA biosensor combined with POCT has demonstrated extraordinary detection potential, broad application prospects in the early diagnosis and prognosis monitoring of AIS, provides a novel miRNA universal detection strategy for the fields of biological and life sciences. [ABSTRACT FROM AUTHOR]

A multifunctional platform was contrived through assimilation of highly fluorescent Boerhavia diffusa weed derived carbon dots, CoFe 2 O 4 and boehmite nanoparticles (CoFe 2 O 4 -CD@Boehmite) for the trace level fluorescence detection of lethal pesticide Methyl parathion (MP) and uranyl ions (UO 2 2+) ions in aqueous sample. Besides the formed nanocomposite was methodically studied for photocatalytic degradation of toxic Tetracycline (TC) antibiotic. [Display omitted] • Utilization of Boerhavia diffusa leaves as a biomass source for Carbon dots. • CoFe 2 O 4 -Carbon dots@Boehmite (CDBHCF) was constructed via hydrothermal method. • CDBHCF was applied for fluorescence sensing of methyl parathion and UO 2 2+ ions. • Nanocomposite exhibited admirable photodegradation ability towards Tetracycline. • Magnetic nanocomposites presented excellent performance even after recycling. In view of exploiting natural resources for designing of effectual materials in favor of detection and obliteration of water pollutants, a fluorescent nanomaterial (CDBHCF) based on biomass derived carbon dots (CDs) was constructed. The CDs and cobalt ferrite (CF) particles were anchored on boehmite (BH) which served as a support material for CDs. The CDBHCF nanocomposite was prepared via facile hydrothermal treatment for selective recognition of Methyl parathion (MP) pesticide and uranyl ions (UO 2 2+). The corresponding structural, morphological and opto-electronic properties of the nanomaterials have been investigated by different physicochemical techniques. The fluorescent CDBHCF probe was employed to detect extremely low concentration of MP and UO 2 2+ with detection limit of 22.4 nM and 4.4 nM, respectively. Ultimately, the proposed sensing platform was validated through real sample analysis. Besides, CDBHCF nanocomposite was utilized for photocatalytic abolition of Tetracycline (TC) in water samples. Initially, the impact of various operational parameters on the degradation efficiency, including catalyst dosage and initial pH were thoroughly examined. Under optimized conditions, the fabricated CDBHCF nanocomposite demonstrated excellent results for photocatalytic degradation of TC (92 % degradation in 120 min) under visible light illumination. Thus, the proposed strategy delivered an innovative insight for dual purpose of CDBHCF nanocomposite: as a fluorescent probe for real time monitoring and as a photocatalyst for removal of pollutants via simple photocatalytic degradation. [ABSTRACT FROM AUTHOR]

• A portable platform for the quantitative detection of colorimetric and fluorescent solutions. • The system is equipped with dual light sources that facilitate both bright-field and fluorescence detection. • The platform maintains detection stability, demonstrating a deviation of 1.93% to 3.41%. The color of liquids is crucial in food safety, pharmaceuticals, cosmetics, and environmental monitoring. Traditional color measurement methods typically require expensive spectrophotometers, limiting their utility in rapid testing and cost-effective applications. This study developed a cost-effective, portable dual-mode colorimetric and fluorescence sensing platform with using the TCS230 sensor and STM32F103ZET6 microcontroller for real-time RGB color detection. Equipped with built-in white and ultraviolet light sources, the platform operates reliably across different environmental conditions, aided by its darkroom design and white balance calibration strategy to minimize ambient light interference. Tests with fluorescent and dye solutions show stability and reliability of the platform. The relationship between color saturation and concentration under different concentrations showed the excellent correlation coefficients above 0.99 for CuSO 4 and KMnO 4 solutions. The measurement deviations of 1.93% to 3.41%, render it an efficient tool for on-site and multiple-mode color testing. [ABSTRACT FROM AUTHOR]

The fluorescence detection of amino compounds and the evaluation of their content in environmental samples are vital, not only for assessing food quality but also for studying soil organic matter. Here, we present the synthesis and application of a novel fluorescent probe, 4-(9-acridone)benzylmethyl carbonochloride (APE-Cl), for detecting amino compounds via a chloroformate reaction with fluorescence detection. The complete derivatization reaction of APE-Cl with amino compounds can be accomplished in aqueous acetonitrile within 5 min at room temperature, using 0.2 M borate buffer (pH = 9.0). APE-amine derivatives exhibited intense fluorescence with an excitation maximum at λex 254 nm and an emission maximum at λem 418 nm. All derivatives demonstrated high stability, strong fluorescence, and elevated ionization potential under atmospheric pressure chemical ionization (APCI-MS) in positive ion detection mode. The method, combined with gradient elution, provides baseline resolution of common amine derivatives on a reversed-phase C18 column. The LC separation for the derivatized amines shows good reproducibility with aqueous acetonitrile as the mobile phase. The relative standard deviations (n = 6) for each amine derivative are < 3.99%. The detection limits (at a signal-to-noise ratio of 3) per injection ranged from 1.68 to 11.2 femtomole. The established pre-column derivatization method for determining amino compounds in practical samples proved to be satisfactory. [ABSTRACT FROM AUTHOR]

Monoclonal antibody drugs (mAb) are widely used to treat various diseases. Keeping quality of mAbs is crucial to maximize efficacy and minimize adverse effects. To this end, mAb content in the drug product must be precisely quantified. As methods for the determination of mAbs, absorbance measurement at 280 nm, the ligand binding assay based on ELISA, or the LC-MS/MS method based on the surrogate peptide approach is usually used. However, these methods have drawbacks in terms of selectivity, reliability, and cost, respectively. The present method is based on the surrogate peptide approach where a peptide specific to the mAb is determined by a post-column derivatization LC system with fluorescence detection and the König reaction, which is usually used for the detection of cyanide and its derivatives. The detection mechanism was the production of cyanide from the surrogate peptide by chloramine T and the generated cyanide was detected by the König reaction. In this study, adalimumab was used as a model target protein. The calculated LOD and LOQ of the present method were 0.31 μg/mL and 0.94 μg/mL, respectively. The intra-day accuracies and precisions were 127.1 % and 2.94 % for 5 μg of adalimumab and 101.6 % and 10.2 % for 50 μg of adalimumab, respectively. The inter-day accuracies and precisions were 121.8 % and 5.71 % for 5 μg of adalimumab and 101.8 % and 6.98 % for 50 μg of adalimumab, respectively. Our quantitatively determined amount of adalimumab in Humira® was in good agreement with the specified value. This method only requires a conventional LC system, not an LC-MS/MS system. By extending the application of the König reaction, we open the door to a new surrogate peptide approach for the determination of proteins including monoclonal antibody drugs. [Display omitted] • We demonstrated a new application of the König reaction for the determination of monoclonal antibody drug. • Adalimumab was quantified by the determination of a surrogate peptide specific to it. • The sensitivity of the technique was superior to that of the LC-MS/MS method. [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]

Two series of hyperbranched conjugated polymers were synthesized via straightforward oxidative coupling polymerization, starting from star-shaped triphenylamine compounds with different internal π-spacers, each varying through the electron-withdrawing properties and rigidity. Excellent total reaction yields were achieved, exceeding 80 % under emulsion reaction conditions, particularly when employing compounds with high electron-withdrawing character (-CN). The polymers containing p -phenylene-vinylene and mixed p -phenylene (vinylene)-ethynylene structures were obtained predominantly as insoluble powders, mainly due to their fully aromatic backbone structure or highly cross-linked formed networks, and their chemical structures were validated by FT-IR analysis. Optical studies revealed that polymers synthesized under classical reaction conditions exhibited enhanced π-conjugation compared to those obtained via emulsion oxidative conditions, which was clearly reflected in a red-shift of the absorption and emission maxima. Conversely, the use of surfactants along with planar and rigid triple bonds facilitated the formation of more porous polymer networks, with the highest specific surface areas of 492 m2g-1, compared to analogous networks based on vinylene hyperbranched polymers (99 m2g-1) and (cyano)vinylene hyperbranched polymers (44 m2g-1). The fluorescence emission of these polymers as solid dispersions in chloroform, although of low intensity for the CN-containing polymers, enables them to detect the nitro-aromatic derivatives via fluorescence quenching. The dependence of both detection limit and emission quenching efficiency on the polymers backbone structure and employed synthesis method was obvious. Notably, the Stern-Volmer quenching constant (K SV) was highest for TNP, reaching 17.9 × 103 M-1 in the case of p -phenylene-vinylene polymer synthesized under emulsion reaction conditions, indicating promising avenues for the development of solid-state fluorescence sensors. [Display omitted] • Porous hyperbranched conjugated polymers containing triphenylamine are synthesized. • Both classical and emulsion chemical oxidative polymerizations are involved. • The polymer's properties depend on both chemical structure and synthesis protocols. • The polymers exhibit high thermostability and fluorescence as solid-state dispersions. • Their ability to detect nitroaromatics is demonstrated by fluorescence quenching. [ABSTRACT FROM AUTHOR]

Alkaline phosphatase (ALP) is abnormally expressed in some cancers and promotes the growth, metastasis, and invasion of cancer cells. The detection of ALP is of great significance for both pathological study and clinical detection. In this work, a europium (Eu)-based fluorescence detection sensor was prepared in a mild reaction condition. LaF 3 :Eu nanoparticles was mixed with ethylene imine polymer (PEI) and Ag+ ions. PEI was used as stabilizer and reducing agent, and Ag+ ions were reduced as molecular-like silver clusters (ML-Ag NCs). The fluorescence of LaF 3 :Eu nanoparticles was enhanced by ML-Ag NCs through energy transfer. When ascorbic acid 2-phosphate (AAP) was hydrolyzed to ascorbic acid (AA) in the presence of ALP, AA reduced Ag+ ions to silver nanoparticles (Ag NPs) and quenched the fluorescence of LaF 3 :Eu/PEI/Ag. The activity of ALP was detected by measuring the fluorescence intensity of Eu3+ at 618 nm. In the concentration range from 2.0 to 16.0 U/L, the fluorescence intensity ratio ((F 0 –F)/F 0) had a linear relationship with the logarithm of ALP concentration. The limit of detection (LOD) was 1.3 U/L. Moreover, the ALP activity was detected successfully in cancer cells by this method. The sensing platform has application potential in the detection of ALP activity in biological systems. [Display omitted] • Fluorescence of LaF 3 :Eu is enhanced by molecule-like silver clusters. • ALP is detected by quenching the fluorescence of LaF 3 :Eu/PEI/Ag with AAP hydrolysate. • The high and low contents of ALP in various cancer cells are distinguished. [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]

The antibiotic tetracycline (TC) significantly pollutes water bodies, adversely impacting ecosystems and human health. In this work, a bifunctional platform for simultaneous detection and removal of TC was successfully constructed by in-situ growth of Zr-MOF in BC microspheres. The in-situ growth ensured the stability, while the design of the aerogel microspheres improved the processability, convenience, and recyclability. The macropores and mesopores in the aerogel microspheres significantly improved the molecular mass transfer efficiency, and the sensitivity and selectivity of TC detection and adsorption were improved due to the size-sieving effect of the abundant micropores of Zr-MOF and the supramolecular interaction of the ligand. Owing to the hierarchical pore structure, the adsorption capacity reaches as high as 317.6 mg/g. The enrichment during the adsorption process enhances the interaction between TC and Zr-MOF, thereby significantly improving the detection sensitivity of TC. As expected, BMAT 3 H 5 has a LOD as low as 28 ± 0.012 nM and a K SV as high as 1.89 ± 0.001 × 106 M−1, providing excellent detection performance compared to other work in recent years. The good selectivity to TC was theoretically validated through simulations with Materials Studio software (MS). It provides a novel and practical bifunctional platform for efficient fluorescence detection and adsorption of TC, which has a broad application prospect in the fields of environmental monitoring, water treatment, and food safety testing. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A miniaturized normal-stacking micellar electrokinetic chromatography (NS-MEKC-FL). • Integration of in-capillary derivatization with the NS-MEKC was employed. • Harmonization of in-capillary chemical modification and CE separation performance. • The method is rapid and reliable for monitoring opioids in clinical serum samples. A rapid, sensitive, and solvent-free normal-stacking micellar electrokinetic chromatography method for measuring morphine sulfate and morphine-6-glucuronide in human serum using codeine phosphate as an internal standard has been developed. The integration of in-capillary derivatization and fluorescence detection for minimizing operator and environmental concerns was employed. For peak intensification and sharpness, the normal-stacking mode was utilized, wherein the capillary was pre-filled with a water plug for four seconds prior to sample loading. Upon injection of serum samples into capillary via hydrodynamic mode for 20 s and application of a separation voltage of 10 kV (21 ± 1°C), the low ionic strength within the water plug area facilitates the movement of analyte ions being tested, allowing them to reach the background electrolyte containing 75 mM disodium tetraborate decahydrate (pH 10.5), 0.35 mM potassium ferricyanide, and 80 mM sodium dodecyl sulfate. At the boundary between the water plug zone and background electrolyte, sharply intensified zones were achieved. Morphine sulfate, morphine-6-glucuronide and codeine phosphate were then oxidized into highly fluorescent pseudo-derivatives while traveling through the capillary. The mean recoveries of morphine sulfate and morphine-6-glucuronide ranged from 88.21 to 97.54 and 87.62 to 97.12 %, respectively. After a single oral dose of a controlled-released morphine sulfate tablet, the proposed method effectively measured the tested analyte and its metabolite, morphine-6-glucuronide in clinical human specimens. The environmental sustainability of the method is evaluated through the Green Analytical Procedure Index and the analytical greenness metric for sample preparation, while the Blue Applicability Grade Index is utilized to assess its practicality. [ABSTRACT FROM AUTHOR]

Functionalized carbon quantum dots (CQDs) show great potential for application in the field of food safety. CQDs have attracted widespread attention in this regard due to the wide range of sources of raw materials for their synthesis, and their good biocompatibility and stable fluorescence. This paper analyses the properties of CQDs and compares with those of conventional semiconductor quantum dots (SCQDs). It analyses the similarities and differences between hydrothermal carbonization, pyrolysis and microwave-assisted synthesis of CQDs, and reviews the principles and methods of functionalization of CQDs through surface modification and doping. Finally, it discusses the applications of functionalized CQDs in food safety, such as detection and sensing, bio-inhibition and photocatalytic degradation, and the mechanisms of detection.

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.

Infectious disease outbreaks have seriously endangered global health owing to the scarcity of testing materials and techniques. Diversified materials and methods should be urgently developed for rapid detection and discrimination of pathogenic microorganisms. Conjugated polymer (CP) materials are macromolecular compounds comprising numerous covalently bonded luminescent units. They have excellent light-harvesting and optical signal amplification capabilities owing to the transmission of excitation energy along their backbone. In recent years, CP materials have aroused research enthusiasm in the biosensors field because of their outstanding optoelectronic properties. This brief manuscript provides an overall review of recent progress achieved in CP-based systems for pathogen sensing.

A remarkable growth was noticed in the development of molecularly imprinted polymers (MIPs), which have used as efficient synthetic antibodies that contain selective cavities to the target molecule. Hereunder, a novel strategy using MIP as a sorbent in solid-phase extraction was coupled to a fluorescence method for ellagic acid (EA) purification and immediate detection. The synthesis of magnetic-MIP (MMIP) using a rapid and green ultrasound technology was assessed by central composite design to determine the optimal polymerization conditions for a high-imprinting polymer. The MMIP was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning/transmission electron microscopy, which accurately confirmed the functional, magnetic, and morphological features of MMIP. The prepared MMIP was demonstrated to be selective for EA compared to many similar phenols. The spectrofluorometric method showed a linear range from 0.05 to 2 μg·mL−1 of EA, and the limits of detection (LOD) and quantification (LOQ) were 0.005 and 0.02 μg·mL−1, respectively. Besides, the novel proposed smartphone method using the ultraviolet lamp as the excitation source presented a linear range from 0.2 to 4 μg·mL−1, a LOQ of 0.2 μg·mL−1, and a LOD of 0.07 μg.mL−1. The proposed strategy revealed high efficiency in the extraction and detection of EA in grape, redberry, and green tea. Effectively, the calculated recoveries were ranging from 80 to 102% with low values of relative standard deviation (

In this study, three compounds A1, A2, and A3 and fluorescent probes T1, T2, T3, and T4 were designed and synthesized. 1H NMR, 13C NMR, and MS characterization and elemental analysis were used to confirm A1–A3 and T1–T4. A1–A3 and T1–T4 formed diagnostic molecules by "click" reactions. A1–A3 and T1–T4 did not significantly increase cell death at concentrations of 80 μmol/L. Preliminary screening of the compounds for antibacterial activity revealed that A2 has better antibacterial activity against Agrobacterium tumefaciens. The synthesized compounds and fluorescent probes can be targeted and combined in the physiological condition to form diagnostic molecules for fluorescence detection of Agrobacterium tumefaciens. The binding sites of A1–A3 were deduced theoretically using the AutoDock Vina software docking tool. Further study of the mechanism of the antibacterial action of these compounds is likely to identify new agents against resistant bacterial strains. [ABSTRACT FROM AUTHOR]

The applicability of capillary electrophoresis (CE) with light-emitting diode-induced fluorescence detection (LEDIF) for the separation of sugars in honey samples was studied. An amount of 25 mM ammonium acetate (pH 4.5) with 0.3% polyethylene oxide (PEO) was found to be optimal for the efficient separation of carbohydrates. 8-aminopyrene-1,3,6-trisulfonic acid (APTS) was used for the labeling of the carbohydrate standards and honey sugars for fluorescence detection. The optimized method was applied in the quantitative analysis of fructose and glucose by direct injection of honey samples. Apart from the labeling reaction, no other sample preparation was performed. The mean values of the fructose/glucose ratio for phacelia honey, acacia honey and honeydew honey were 0.86, 1.61 and 1.42, respectively. The proposed method provides high separation efficiency and sensitive detection within a short analysis time. Apart from the labeling reaction, it enables the injection of honeys without sample pretreatment. This is the first time that fluorescence detection has been applied for the CE analysis of sugars in honeys. [ABSTRACT FROM AUTHOR]

One of the most significant characteristics, which biosensors are supposed to satisfy, is robustness against abundant molecules coexisting with target biomolecules. In clinical diagnoses and biosensing, blood, plasma, and serum are used daily as samples. In this study, we conducted a series of experiments to examine the robustness of all-dielectric metasurface biosensors, which comprise pairs of a highly fluorescence-enhancing silicon nanopellet array and a transparent microfluidic chip. The metasurface biosensors were shown to have high performance in detecting various targets from nucleic acids to proteins, such as antigens and antibodies. The present results show almost four-order wide dynamic ranges from 0.16 ng/mL to 1 μ g/mL for prostate-specific antigen (PSA) and from 2 pg/mL to 25 ng/mL for carcinoembryonic antigen (CEA). The ranges include clinical criteria for PSA, 4 ng/mL and CEA, 5 ng/mL. To date, a systematic demonstration of robustness has not been reported regarding the metasurface biosensors. In detecting cancer markers of PSA and CEA in human serums, we demonstrate that the metasurface biosensors are robust enough in a wide target concentrations, including the clinical diagnosis criteria. [ABSTRACT FROM AUTHOR]

With the development of nanotechnology, fluorescent silicon nanomaterials have been synthesized and applied in various areas. Among them, silicon quantum dots (SiQDs) are a new class of zero-dimensional nanomaterials with outstanding optical properties, benign biocompatibility, and ultra-small size. In recent years, SiQDs have been gradually utilized for constructing high-performance fluorescent sensors for chemical or biological analytes. Herein, we focus on reviewing recent advances in SiQD-based fluorescent biosensors from a broad perspective and discussing possible future trends. First, the representative progress for synthesizing water-soluble SiQDs in the past decade is systematically summarized. Then, the latest achievement of the design and fabrication of SiQD-based fluorescent biosensors is introduced, with a particular focus on analyte-induced photoluminescence (fluorescence) changes, hybrids of SiQDs with other materials or molecules, and biological ligand-modification methods. Finally, the current challenges and prospects of this field are highlighted. [ABSTRACT FROM AUTHOR]

Traditional stereomicroscopy (SM) is limited for the identification of microplastics of less than 500 µm in wastewater treatment plants (WWTPs). Accordingly, novel methods for the accurate quantification of these microplastics are needed. In this study, we investigated the polymer type, morphology, size distribution, and abundance of microplastics in each unit of three selected WWTPs by SM and a fluorescence-based protocol (FR) combined with FTIR. Using the FR method, most microplastics detected in the three WWTPs were 50–200 µm in size. Polyethylene, polypropylene, and polyamide were the main polymer types, and the distributions of fibers, films, and debris were determined. Despite highly similar microplastic removal rates (78.6‒95.2% (SM) and 77.4‒94.2% (FR)) in the WWTPs by the two methods, the microplastic abundances obtained by FR (405‒6987 items/L) were approximately 2 orders of magnitude higher than the corresponding results by SM (1‒21 items/L). In addition, a considerable number of small-sized microplastics (< 500 µm) were detected in the effluents (405‒947 items/L) using FR. These results clearly reveal that microplastics in WWTPs have been seriously underestimated in most previous studies based on SM. Further research should focus on the environmental risks of small-sized microplastics from WWTPs. [ABSTRACT FROM AUTHOR]

Perfluorooctanoic acid (PFOA) is a new type of organic pollutant in wastewater that is persistent, toxic, and accumulates in living organisms. The development of rapid and sensitive analytical methods to detect PFOA in environmental media is of great importance. Fluorescence detection has the advantages of high efficiency and low cost, in which fluorescent probes have excellent fluorescence properties, excellent bio-solubility, and remarkable photostability. It is necessary to review the fluorescence detection routes for PFOA. In addition, the up-conversion of fluorescent materials (UCNPs), as fluorescent materials to prepare fluorescent probes with, has significant advantages and also attracts the attention of researchers, however, reviews related to their application in detecting PFOA and comparing them with other routes are rare. Furthermore, there are many strategies to improve the performance of up-conversion fluorescent probes including SiO2 modification and amino modification. These strategies can enhance the detection effect of PFOA. Thus, this work reviews the types of fluorescence detection, the design, and synthesis of UCNPs, their recognition mechanism, properties, and their application progress. Moreover, the development trend and prospects of these detection probes are given. [ABSTRACT FROM AUTHOR]

Rose Bengal (RB) is a fluorescent dye with several potential biomedical applications, particularly in dermatology. Due to RB's poor physicochemical properties, several advanced delivery systems have been developed as a potential tool to promote its permeation across the skin. Nevertheless, no validated quantitative method to analyse RB within the skin is described in the literature. Considering RB exhibits a conjugated ring system, the current investigation proposes fluorescence-based techniques beneficial for qualitatively and quantitatively determining RB delivered to the skin. Notably, the development and validation of a fluorescence-coupled HPLC method to quantify RB within the skin matrix are herein described for the first time. The method was validated based on the ICH, FDA and EMA guidelines, and the validated parameters included specificity, linearity, LOD, LLOQ, accuracy and precision, and carry-over and dilution integrity. Finally, the method was applied to evaluate RB's ex vivo permeation and deposition profiles when loaded into dermatological formulations. Concerning qualitative determination, multiphoton microscopy was used to track the RB distribution within the skin strata, and fluorescence emission spectra were investigated to evaluate RB's behaviour when interacting with different environments. The analytical method proved specific, precise, accurate and sensitive to analyse RB in the skin. In addition, qualitative side-analytical techniques were revealed to play an essential role in evaluating the performance of RB's dermatological formulation. [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 simple, selective, rapid, sensitive and less costly green automated solid phase extraction bio-analytical high-performance liquid chromatographic-based technique with fluorescence detection (Aut-SPE-BA-HPLC-FL) for the quantification of levofloxacin in human serum samples has been developed and validated. The serum samples were loaded into the chromatographic system without prior treatment and then injected into short (20 mm × 4.6 mm, 20 µm) protein-coated (PC) µBondapak CN (µBCN) silica pre-column (PC-µBCN-pre-column). Levofloxacin was retained and pre-concentrated on the head of the PC-µBCN-pre-column, while proteins and other polar components were eliminated using phosphate buffer saline (PBS), pH 7.4, as the first mobile phase in the extraction step. Levofloxacin is then transferred to the analytical column; ZORBAX Eclipse XDB-C18 (150 mm × 46 mm, 5 µm), through the aid of a column-switching valve technique, on-throughs the elution mode using the second mobile phase containing a methanol and phosphate buffer (0.05 M, pH 5) in a ratio of 70:30 (v/v). Levofloxacin signals were detected using a fluorescence detector operated at excitation/emission wavelengths of 295/500 nm. The proposed Aut-SPE-BA-HPLC-FL methodology showed linearity over a levofloxacin concentration range of 10–10,000 ng/mL (r2 = 0.9992), with good recoveries ranging from 87.12 to 97.55%. Because of the validation qualities in terms of linearity, recovery, precision, accuracy, selectivity and robustness, the Aut-SPE-BA-HPLC-FL method has been used in some clinical trials for therapeutic drug monitoring and the pharmacokinetic study of levofloxacin in human serum. [ABSTRACT FROM AUTHOR]

Machine learning and image processing have been combined to identify and detect defects in mature citrus fruit at night, which has great research and development significance. First, a multi-light vision system was used to collect citrus UV images, and from these, 1500 samples were obtained, 80% of which were training and 20% were experimental sets. For a support vector machine (SVM) model with "2*Cb-Cr", "4*a-b-l", and "H" as the training features, the accuracy of the final training model in the experimental set is 99.67%. Then, the SVM model was used to identify mature citrus regions, detect defects, and output the defective citrus regions label. The average running time of the detection algorithm was 0.84097 s, the accuracy of citrus region detection was 95.32%, the accuracy of citrus defect detection was 96.32%, the precision was 95.24%, and the recall rate was 87.91%. The results show that the algorithm had suitable accuracy and real-time performance in recognition and defect detection in citrus in a natural environment at night. [ABSTRACT FROM AUTHOR]

A magnetic molecularly imprinted probe (MMIP@QD) was synthesized by reverse microemulsion method using CdTe QDs, Fe3O4, and molecularly imprinted polymer as the fluorophore, magnetic carrier, and recognition sites, respectively. The nanoparticle was characterized by transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, and vibrating sample magnetometry (VSM). In the optimal experimental condition, fluorescent emission intensity (measured at excitation wavelengths of 350 nm) was quenched linearly with increasing malachite green (MG) concentration from 0.8 to 28.0 μM with LOD of 0.67 μM. Simultaneously, it was observed that the maximum absorption wavelength was blue shifted gradually with the increase of MG concentration. The inner filter effect, static quenching, and band gap transition were interpreted as the mechanisms of fluorescence quenching and wavelength shift. Thermodynamic studies indicated that the quenching reaction proceeded spontaneously. The developed sensor was applied to detect MG in seawater samples. Satisfactory recoveries of MG in spiked seawater ranged from 83.6 to 122.1% with RSD < 1.8%. [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]