Hydrogels allow the precise growth tracking of plasmonic gold nanoparticles for mercury analysis

Abstract

Gold nanostructures have been significantly employed as attractive sensing probes for environmental and biological analysis. Nevertheless, due to the environment-sensitive local surface plasmon resonance of gold nanostructures and their actively interacting surfaces, the weak anti-interferences and low sensitivity of the sensing routes restrict their practical performances. To achieve amplified signals and eliminate the interference caused by non-specific aggregation and dispersion, gold nanoplasmonics are in situ synthesized and subsequently stabilized by the network skeleton in the agarose hydrogels. Herein, the gold nanoparticle-staining agarose hydrogel sensing strategy has two intriguing characteristics. First, the aqueous solutions of hydrogels allow the chemical reaction, resulting in the growth of plasmonic gold nanostructures. Second, the agarose skeleton in situ stabilizes the nanoparticles and prevents the non-specific responses of aggregated plasmonic probes in complex environmental and biological samples. The signals are synchronously recorded, which accordingly correspond to the slight morphological changes in the plasmonic nanostructures. Based on the Hg-involved growth process of gold nanoparticles, toxic mercury ions are optically measured at concentrations ranging from 10.0 nM to 2.0 μM with the detection limit of 1.25 nM. The real-time monitoring of plasmonic nanomaterials in hydrogels promotes precise growth tracking for the development of nanotechnology and environmental analysis.