A fluorescent microsensor for the selective detection of bifenthrin

Ruthenium complex based nanocomposite film with enhanced and selective electrochemical sensing of bifenthrin pesticide

Bifenthrin (BF), a widely used pyrethroid pesticide in farming, lacks highly sensitive and selective sensors despite its extensive application. Ruthenium complexes are very effective for selective sensing applications but suffer from structural instability at elevated conditions, electrochemical activity, and the use of costly electrolytes. This work improves their electrochemical activity and mechanical strength by incorporating silver nanowires and replacing the costly electrolyte with abundant KCl + PBS, resulting in enhanced signal performance. Herein, a ruthenium complex containing composite film was immobilized on a platinum (Pt) electrode using Langmuir Blodgett technique. The fabricated sensor has been characterized by differential pulse voltammetry (DPV) based electrochemical technique. The BF pesticide sensing parameters, including the limit of detection (LOD), linear range (LR), and sensitivity, were evaluated using SWV, DPV, and CV techniques. Among these, the DPV technique demonstrated the best performance, achieving a sensitivity of 0.648 μA cm-2 μM-1, a LR of 1-10 μM, and a LOD of 1 μM. The relative standard deviation (RSD) values using DPV are found to be 6.3% (repeatability study), 3% (reproducibility study), 8% (metal ion interference), 5% (organic species interference), and 2% (real sample study), which are much lesser than the World Health Organization (WHO) recommendation of RSD value on the pesticide (i.e. 20%). The BF sensor demonstrated a selectivity of 2× difference of peak height response compared to similar pesticides. The reported pesticide sensor will open new options for sensor research using metal complex-based LB film nanocomposite.

Innovative detection mechanism for deltamethrin based on a dual-emitting Fluoroprobe and its application in a smartphone-based photoelectric conversion device

Pyrethroids are widely used insecticides worldwide, while their on-site and rapid detection still faces technological challenges. Herein, an innovative detection mechanism was designed for deltamethrin, a typical kind of type II pyrethroids, based on a dual-emitting fluoroprobe consisting of NH2-SiQDs and Eu3+. Deltamethrin can rapidly hydrolyze into 3-phenoxybenzaldehyde (3-PBD) and react specifically with fluoroprobe, causing fluorescence quenching of SiQDs while maintaining the fluorescent stability of Eu3+. Building upon the above fluorescence-responsive principle, SiQDs@Eu3+ provided satisfactorily dual-emitting signals, realizing the highly-selective and sensitive detection of deltamethrin. Correlation between the surface structure of SiQDs and their absorption spectra was in-depth unraveled by TD-DFT calculation and FT-IR analysis. As for the analytical performance, the recovery and LOD of deltamethrin in lettuce, provided by SiQDs@Eu3+, were comparable or even superior over conventional chromatographic analysis. Meanwhile, an innovative smartphone-based optical device was developed, which greatly decreased errors caused by the previously reported smartphone-based fluorescence detection.

Capillary-based fluorescence microsensor with polyoxometalates as nanozyme for rapid and ultrasensitive detection of artemisinin

A novel capillary-based fluorescence microsensor for artemisinin was developed with functional polyoxometalates (POMs) as nanozyme by a layer-by-layer self-assembly strategy. Vanadomolybdophosphoric heteropoly acid (H₅PMo₁₀V₂O₄₀, PMoV₂) and tungstophosphoric heteropoly acid (Na₅PW₁₁O₃₉Cu, PW₁₁Cu) with high peroxidase-like activity were synthesized and immobilized on capillary to catalyze artemisinin/thiamine reaction and generate the amplified fluorescence signal. The wide linear range up to 13.0 μM with the low limit of detection of 0.03 μM (S/N = 3) was achieved for the determination of artemisinin by using the proposed POMs-microsensor. The method has been successfully used to detect artemisinin in human plasma and antimalarial drugs with satisfactory accuracy. This work developed a novel capillary fluorescence microsensor with functional POMs as nanozyme, which can serve as a promising candidate in fluorescence microanalysis.