UiO-66@TiO2/Au heterojunction-like SERS substrate based on adsorption-induced aggregation for detection of thiamethoxam and triazophos in apple juice

Abstract

Heterojunction-like substrates have drawn significant attention in surface enhanced Raman spectroscopy (SERS) owing to their multi-enhancement characteristics. In this study, the core-shell architectures of UiO-66@ TiO₂ were fabricated for capture and enrichment of organophosphorus pesticides (OPs) in solution. After absorption of OPs, the SERS-active nanoparticles of Au were assembled on the core-shell architectures to form UiO-66@TiO₂/Au substrate via Au-S bonding between OPs molecule and AuNPs and electrostatic interactions between UiO-66@TiO₂ and Au, resulting in adsorption-induced aggregation of Raman signal for OPs. The proposed method of adsorption-induced aggregation could be used for detecting thiamethoxam and triazophos in apple juice with detection limit of 3.51 μg/L and 0.66 μg/L, respectively. Furthermore, the satisfactory recovery rates, ranging from 91.98% to 104.31% for thiamethoxam and from 91.47% to 116.47% for triazophos, indicated that the prepared heterojunction-like substrate could be potentially used for trace detecting OPs in foods.