A selectivity-enhanced fluorescence imprinted sensor based on yellow-emission peptide nanodots for sensitive and visual smart detection of λ-cyhalothrin.

The development of precise and efficient detection technologies to recognize λ-cyhalothrin (LC) in agricultural products has attracted attention worldwide due to its widespread use and notable toxic effects on humans. Herein, a novel fluorescence biomimetic nanosensor was elaborately designed based on Zn(II)-doped cyclo-ditryptophan (c-WW)-type peptide nanodots and incorporating molecularly imprinted polymer (c-WW/Zn-PNs@MIP) for LC assays. C-WW/Zn-PNs obtained by self-assembly with aromatic cyclic dipeptides as basic building blocks and coordination with Zn(II) have low-toxicity, photostability, and bright yellow fluorescence emission, as a sensitive signal transducer. High-affinity imprinting sites further endow c-WW/Zn-PNs@MIP with superior selectivity and reusability. Based on prominent merits, c-WW/Zn-PNs@MIP demonstrated a good linear range (1-360 μg/L) with a low limit of detection (LOD) (0.93 μg/L), fast kinetics in target capture (10 min), and strong practicability in the capture of LC from real samples (spiked recovery of 81.0-107.7%). Additionally, to attain onsite profiling of LC, a visual platform was developed by integrating c-WW/Zn-PNs@MIP with a smartphone-assisted optical device. This smart evaluation system can capture concentration-dependent fluorescent images and accurately digitize them, enabling quantitative analysis of LC. This study developed a fluorescent c-WW/Zn-PNs@MIP-based smart evaluation system as a novel platform for LC monitoring applications, which not only has enormous economic value but also great environmental health significance.