Ultrasensitive Bisphenol A sensing based on responsive plasmonic nanoparticles

We report a simple, highly sensitive Bisphenol A (BPA) sensor using BPA-responsive gold nanoparticles (AuNPs) as optical probes. A diazonium carrying ligand was synthesized to self-assemble a monolayer film on AuNPs with the diazonium ions exposed on their surface. One BPA can generate two azobenzene moieties with two diazonium ions via an azo coupling reaction. Thus it can crosslink AuNPs, and induce their aggregation and color change. The BPA concentration-dependent color and UV absorption spectra changes of AuNPs provide the visualization or UV absorption detection of BPA with a fast response (4 min), a broad linear range (0.1-4 nM) and a low limit of detection (0.02 nM).