Methylmercury-sensitized "turn on" SERS-active peroxidase-like activity of carbon dots/Au NPs nanozyme for selective detection of ochratoxin A in coffee.

Food Chem

Faculty of Life Science and Technology, Kunming University of Science and Technology, Yunnan Province 650500, China; Yunnan Agricultural University, Yunnan Province 650201, China. Electronic address:

Published: February 2024

The improvement and regulation of catalytic performance of nanozyme have long been pursued with sustained efforts. Herein, gold nanoparticles (S-CDs/AuNPs) with weak peroxidase-like (POD) activity were synthesized by Au-S bond using a sulfur doped carbon dots (S-CDs) as reducing agent and stabilizer. However, methylmercury (MeHg) could selectively and sensitively regulate the POD-like activity of S-CDs/AuNPs. The catalytic activity of S-CDs/AuNPs was significantly activated with the addition of MeHg, resulting in a significant enhancement of electromagnetic fields to present an obvious SERS signal. More intriguingly, the introduction of ochratoxin A (OTA) could simultaneously turn off the UV-vis absorbance signals and the surface-enhanced Raman scattering (SERS) signal. Based on these findings, a selective colorimetric-SERS dual-mode OTA detection strategy was established with gold amalgamation (Au@HgNPs) as the probe, and the low limit of detection (LOD) of OTA was 0.29 µgL (Colorimetric) and 0.16 µgL (SERS), respectively, with good recoveries from 95.9 to 104.0% (Colorimetric) and from 96.7 to 108.9% (SERS), respectively. The work paves a new way to design nanozyme-based colorimetric and SERS protocol for traces OTA residues analysis in foodstuff analysis.

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Source
http://dx.doi.org/10.1016/j.foodchem.2023.137440DOI Listing

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