Fluorinated Silicon Quantum Dots for Broad-Spectrum Fluorescence Detection of Pyrethroids via Structure-performance Enhancement.

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

Red-emissive fluorescent probes based on PET mechanism for highly sensitive detection and multi-scenario imaging of thiophenol.

Thiophenol (PhSH) is a highly toxic aromatic thiol endangering ecosystems, food safety, and human health. Traditional detection methods are limited by instrument dependence and inability for real-time imaging. This study developed a red-emitting fluorescent probe, TTCP-DN, based on the PET mechanism. The probe employs 5-(4-diphenylamino)benzothiophene as the fluorophore and 2,4-dinitrophenoxy as the PhSH-specific recognition moiety, achieving mitochondrial targeting via a pyridine salt. Without PhSH, fluorescence is quenched; upon PhSH-induced reaction, fluorescence restores at 623 nm. The probe has low detection limit (37.8 nM), large Stokes shift (153 nm), good biocompatibility, and high selectivity. It was applied for mitochondrial imaging in 4 T1 cells, qualitative detection and semi-quantitative concentration trend analysis of PhSH in zebrafish, plant tissues, environmental, food and biological samples (recoveries 95-105%), and fabricated into portable paper-based test strips. This work provides a versatile PhSH detection tool and a paradigm for targeted probes of toxic aromatic pollutants.

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

Tebuconazole (Tbz) is one of the most widely used fungicides in the agricultural field due to its high efficacy, systemic properties, and broad-spectrum activity. However, the presence of excessive Tbz residues can pose a serious threat to both human and animal health. Conventional detection techniques used to monitor Tbz have drawbacks, including the need for costly equipment and laborious processes. Here, we report a simple and efficient fluorescent sensor based on green-synthesized carbon dot (CD)-encapsulated molecularly imprinted polymers (MIPs) for the rapid detection of Tbz. The experimental parameters, including the solvent, sensor amount, pH, and temperature, were systematically optimized. The sensor demonstrated a strong anti-interference capability in the presence of structurally similar pesticides and common metal ions, indicating its reliability in complex environmental systems. Mechanistic investigations revealed that the fluorescence quenching followed a dynamic quenching mechanism driven by charge-transfer interactions, as supported by UV-vis analysis and temperature-dependent studies. Additionally, the sensor demonstrated good stability during prolonged storage and maintained performance after multiple reuse cycles, highlighting its durability and cost-effectiveness. The sensor demonstrated a linear dynamic range of 1-20 nM and a detection limit of 1.09 nM. An imprinting factor of 5.12 was achieved, indicating the high molecular selectivity and strong sensing specificity of CDs@SiO2@MIPs. A smartphone-based fluorescence sensing system enabled the sensitive and reliable detection of Tbz, along with a linear RGB (G/B ratio) response. Tbz was successfully determined using the proposed approach in wheat, corn, and water samples, with recoveries ranging from 96% to 100%. The developed CDs@SiO2@MIP sensor represents a promising platform for advancing on-site, real-time sensing applications.

A pyrene-based fluorescent probe for highly sensitive and selective detection of hydroxylamine in environmental water samples

In this study, a pyrene-based fluorescent probe (PCPA) was designed, synthesized and developed for the detection of HA. In the presence of HA, PCPA was converted to the oxime derivative (PCO) through a nucleophilic addition–elimination reaction, accompanied by significant enhancement in fluorescence at 408/425 nm. Further investigations showed that PCPA displayed high sensitivity (LOD = 0.017 µM, λex = 365 nm) within 20 min and high selectivity over other analytes. Moreover, PCPA was capable of recognizing HA in environmental water samples and showed a recovery rate of 95–104% and relative standard deviations (RSD) of 0.56–2.59%. Portable PCPA-loaded paper-based test strips were facilely prepared, which enabled the on-site detection of HA with the aid of a smartphone. These results are expected to make PCPA a potential alternative for HA detection in the field of environmental monitoring.

G-quadruplex-based fluorescent sensing platform for thiamethoxam detection: integrating multiple signal amplification strategies.

Thiamethoxam, a widely utilized neonicotinoid insecticide, has been extensively applied in agricultural practices, leading to various adverse effects on human health, such as neurotoxicity, developmental issues, and endocrine disruption. Therefore, establishing a comprehensive and standardized surveillance framework for the quantitative determination of thiamethoxam residues in environmental compartments and food matrices is critical for mitigating its chronic toxicological risks to human health. We developed a biosensor for thiamethoxam detection, which leverages the target-induced formation of G-quadruplexes and subsequent Thioflavin T fluorescence enhancement based on Exonuclease III-driven shear amplification and the hybridization chain reaction. Under optimized conditions, this biosensor exhibited a detection range from 10 pg mL-1 to 1 µg mL-1 and a detection limit of 8.7 pg mL-1. Furthermore, the successful detection of thiamethoxam in real samples confirms the biosensor's practical applicability and reliability.

Nitrogen-doped SiQDs and their PVA fluorescent films for rapid fluorescence detection of chlorogenic acid in green coffee beans.

Nitrogen-doped silicon quantum dots (N-SiQDs) were prepared via a one-pot hydrothermal route, and subsequently utilized to establish a fluorescent sensing system for the rapid determination of chlorogenic acid (CGA). Mechanistic studies revealed a mixed quenching mechanism. The inner filter effect arises from the strong spectral overlap between CGA absorption and N-SiQD excitation. Meanwhile, CGA forms a non-fluorescent ground-state complex with N-SiQDs via hydrogen bonding and/or electrostatic interactions, as confirmed by a new absorption peak and a progressive emission red-shift. Such complexation neutralizes surface trap states, resulting in a surprising extension of fluorescence lifetime from 1.84 to 2.71 ns. At elevated CGA concentrations, dynamic collision quenching further contributes, as evidenced by temperature-dependent Stern-Volmer plots. Under optimized conditions, a linear detection window from 0.5 to 12 μg mL-1 and a limit of detection (LOD) of 0.14 μg mL-1 were obtained for the solution-phase sensor, along with a response time of just 30 s. A portable N-SiQDs/PVA fluorescent film was also fabricated, exhibiting optimal excitation/emission at 360/450 nm due to hydrogen bonding-induced surface state lowering. The film sensor exhibited a linear response ranging from 1 to 12 μg mL-1, along with the LOD of 0.28 μg mL-1 and a response time of 2 min. It also demonstrated satisfactory stability and the ability for visual detection. Both approaches were effectively employed to quantify CGA in normal and decaffeinated green coffee beans, and the obtained data were in good agreement with those from HPLC-UV. Compared with other methods, this work offers advantages in fast analysis speed and good device portability, providing a practical tool for CGA detection in the coffee industry.