Carbon-dot-encapsulated molecularly imprinted polymer as a selective optical sensor for the monitoring of tebuconazole in food samples.

A robust cd-based coordination polymer with high sensitivity for fluorescent detection of cefixime in environmental water and milk samples.

Antibiotic misuse and residues can disrupt ecological balance and compromise food safety, making the development of highly selective and sensitive antibiotic detection methods crucial. In this study, a two-dimensional cadmium-based coordination polymer {[Cd₃(ndda)₃(bpy)₁.₅(H₂O)₃]·H₂O} (CP 1) was successfully synthesized via a solvothermal method and applied for the detection of the widely used antibiotic cefixime (CEX). The structure of CP 1 was systematically characterized using multiple analytical techniques, and its fluorescence properties were investigated. The results demonstrate that CP 1 can rapidly (within 1 min) and selectively identify CEX in aqueous solution even in the presence of interfering substances. The material not only exhibits an excellent detection limit (8.49 nM) but also can be reused for up to five cycles. Based on the structural features of CP 1 and experimental evidence, the fluorescence quenching mechanism is proposed to involve a synergistic effect of competitive absorption (CA) and photoinduced electron transfer (PET). Furthermore, when applied to the detection of CEX in environmental water and milk samples, CP 1 achieved satisfactory recovery rates and low relative standard deviations. This study confirms that CP 1, as a fluorescent probe material, holds significant potential for CEX detection in food safety monitoring and environmental analysis.

AI-Integrated Molecularly Imprinted Gate-Controlled Nanozyme-Based Field-Deployable Multimodal Assay of Per- and Polyfluoroalkyl Substances in Environmental Waters.

The significant risks posed by per- and polyfluoroalkyl substances (PFAS) to water quality and public health have attracted increasing attention as a class of emerging contaminants. Efficient onsite assay of PFAS in environmental waters is critical for risk traceability, early warning, and safeguarding water security, yet it is hindered by challenges in accuracy, practicality, and intelligence. Here, we proposed a universal artificial intelligence (AI)-assisted molecularly imprinted polymer (MIP) gate-controlled the enzyme-like activity of nanozyme strategy-driven multimodal onsite assay for PFAS in environmental waters, with perfluorooctanoic acid (PFOA) selected as the model target. Briefly, MIP-encapsulated Fe-doped coordination polymer (MIP@Fe-BDC) nanozyme was prepared, and MIP@Fe-BDC possessed peroxidase-like (POD-like) activity. Owing to the selective binding capability conferred by MIP, only PFOA could inhibit POD-like activity of MIP@Fe-BDC. This inhibition prevented the oxidation of colorless 3,3',5,5'-tetramethyl-benzidine (TMB) to its blue oxidized form (oxTMB), thereby interrupting the colorimetric and photothermal signal enhancement as well as the fluorescence signal quenching triggered by oxTMB, resulting in a linear response between PFOA and colorimetric/fluorescence/photothermal signals. To achieve onsite detection, a low-cost MIP@Fe-BDC-based test paper was developed. Multimode images were collected via a smartphone and a thermal imager, and then analyzed using a residual neural network with 18-layer (ResNet18) model for real-time quantitative feedback, in which the whole detection process was completed in just 8.0 min. Moreover, these results were consistent with those obtained using the liquid chromatography-mass spectrometry (LC-MS) method, implying the superior accuracy. This work provides an innovative and universal solution for the portable, low-cost, rapid, efficient, and intelligent onsite surveillance, traceability, and early warning of PFAS in environmental waters, which is of great significance for preventing and controlling environmental water pollution and protecting public health.

Field-deployable supramolecular fluorescent sensing platform for selective dual-mode detection of thiamethoxam in complex environmental matrices

A carbazole-benzothiazole-based fluorescent probe embedded in paper, cellulose, and chitosan sensors for visual and rapid detection of bisulfite in food samples.

Bisulfite (HSO3-) is widely used as a food additive, yet its excessive residue poses potential health risks. Herein, a novel fluorescent probe TC-FV-BT was developed for the detection of HSO3-. Upon addition of HSO3-, the nucleophilic addition disrupted the π-conjugation of the probe, giving rise to a distinct fluorescence enhancement with bright orange emission. TC-FV-BT exhibited a rapid response, a low detection limit of 0.077 μM, and excellent selectivity. The sensing mechanism was confirmed by 1H NMR titration, HRMS, and DFT calculations. Furthermore, TC-FV-BT was successfully immobilized onto paper, cellulose acetate (CA), and chitosan (CS) film substrates to construct a portable visual detection platform, which was applied to the analysis of HSO3- in ten complex food matrices. Notably, the CS film-based sensor displayed superior anti-interference performance in high-oil and high-pigment samples. This work provides a versatile and practical platform for on-site rapid monitoring of HSO3- in food safety applications.

MOF-based fluorescent molecularly imprinted polymer nanosensor for the determination of aflatoxin M1 in water and cow milk with exceptional sensitivity

Contamination of food and feed with fungal aflatoxins is a major problem. Even extremely minute amounts of aflatoxins can be fatal to humans and animals if ingested with food or feed. Therefore, presenting analytical methods for the detection/determination of aflatoxins (e.g., aflatoxin M1, AFM1) is highly required for food contamination control. Here, we report a novel, highly sensitive fluorometric nanosensor for the rapid determination of AFM1 in water and cow milk. The proposed nanosensor is based on a fluorescent molecularly imprinted polymer (FMIP) comprising a molecularly imprinted polymer coating onto a chitosan-coated fluorescent metal organic framework (MOF). The FMIP was fabricated from a newly synthesized functional monomer, which was then conjugated with chitosan and used to coat the fluorescent MOF prior to its polymerization. The synthesized materials, including functional monomer, MOF, and FMIP were characterized using FTIR, 1H-NMR, DSC, XRD, dynamic light scattering, zeta potential measurement, and transmission electron microscopy (TEM) imaging. The analytical performance of the nanosensor was investigated and the incubation time was found to be 20 min, indicating the rapid analytical procedure. The nanosensor exhibited a limit of detection of 2.89 pg L−1 and a limit of quantification of 9.63 pg L−1, supporting the ultra-high sensitivity of the nanosensor. In addition, the fluorescence vs. concentration relationship is linear (r2 = 0.9945) over a wide concentration range of 3.3–63.3 pg L−1. Furthermore, the obtained recovery values are in the range 95.76–105.41% with a standard deviation of 1.72–2.65, indicating the high accuracy and precision of the nanosensor. Therefore, the FMIP-based nanosensor can be successfully applied to the determination of AFM1 in profoundly dilute water and cow milk samples.

Signal-enhanced photoelectrochemical aptasensor for the detection of sulfadiazine based on Fe3O4/3D g-C3N4 heterojunction.

The contamination of the environment with the sulfadiazine (SDZ) antibiotic poses a significant risk to human and animal health and contributes to the emergence of drug-resistant bacteria. Conventional detection methods are often time-consuming and require sophisticated instrumentation. Herein, we developed a sensitive SDZ detection method based on a high-performance photoelectrochemical (PEC) aptasensor. Using an iron oxide (Fe3O4) functionalized three-dimensional graphitic carbon nitride (3DCN) nanocomposite. The 3DCN substrate was initially prepared through supramolecular self-assembly employing an ionic liquid as a template, followed by thermal polycondensation. Then, Fe3O4 nanoparticles bearing abundant hydroxyl groups were covalently anchored onto the 3DCN matrix via a solvothermal method. The incorporation of Fe3O4 broadened the visible-light absorption, facilitating charge separation and transport, and acting as an effective electron donor. Operating in a "signal-on" mode, the proposed aptasensor exhibited excellent analytical performance with a broad linear range (0.1 nM-1000 nM), a low detection limit (215 pM), and outstanding selectivity, stability, and reproducibility. The practical applicability was successfully validated by detecting SDZ in river water and milk with recoveries of 98.1-99.8%. Overall, the Fe3O4/3DCN-based PEC aptasensor is a robust, sensitive, cost-effective with good potential for food safety, environmental monitoring, and public health protection.