Sensitive SERS assay for glyphosate based on the prevention of l-cysteine inhibition of a Au–Pt nanozyme

Abstract

Herein, an indirect SERS sensing assay was developed for the determination of glyphosate (Gly) in tap water. The mechanism of detection was based on relieving the inhibitory effect of L-cysteine (L-cys) on a Au–Pt nanozyme by combining Gly with L-cys through divalent copper ions (Cu²⁺). In this method, a novel nano-chain-like Au–Ag composite with good repeatability was successfully fabricated to detect SERS signals of oxTMB without disturbing TMB Raman signals. Under optimal conditions, the SERS signal intensity of oxTMB (at 1605 cm⁻¹) was proportional to the concentration of Gly. The results showed a good linear response over the concentration ranges of 10 μg L⁻¹ to 1000 mg L⁻¹. The limit of detection and limit of quantitation of Gly were found to be 5 μg L⁻¹ and 10 μg L⁻¹, respectively. In addition, good anti-interference ability against interfering cations and structural analogues deserves to be mentioned. This SERS assay can be used for detection of Gly in tap water that can meet the needs of practical detection.