Tailoring of hot spots in plasmonic microgels for dynamic SERS detection of multi-pesticides by suction-release strategy

Tailoring smart surface-enhanced Raman scattering (SERS) substrates with tunable "hot spots" has invoked widely attention due to its unique structures and plasmonic features. Herein, we develop a "suction-release" SERS strategy (SRSS) for dynamic detection of targeted analytes by utilizing a stimulus-responsive three-dimensional (3D) AgNPs-decorated Basil-seeds microgels (ABM). Crucially, this smart ABM enable precisely tailoring 3D hot spots region by regulating the ambient temperature and moisture. The dynamically tunable ABM serves as a stabilized domain for high-density loading of AgNPs, as well as an adsorption matrix for concentration of the analytes in hot spots region, thereby allowing simultaneously regulating 3D structures and capturing target molecules in plasmonic sites. Most importantly, due to the reversible structures and plasmonic properties, the ABM can clean themselves when immersed in iodide solution, thus achieving recyclable and credible SERS analysis of solid samples. The ABM-based SRSS displays superior sensitivity and uniformity for in-field analysis of multiple pesticides over a large range of 2 × 10-6-104 μM. The proposed sensing strategy offers great potential for reliable quantitative SERS detection of complexed media and in-situ process analysis.