Determination of lead in food by surface-enhanced Raman spectroscopy with aptamer regulating gold nanoparticles reduction

Abstract

Lead ion (Pb2+) is a main heavy metal in food that causes heavy teratogenicity and carcinogenicity. In this study, a rapid and sensitive SERS method for detecting Pb2+ in food was established by aptamer regulating gold nanoparticles reduction. The reduction of HAuCl4 catalyzed by H2O2 is a slow process, and graphene oxide (GO) has excellent catalytic performance for the reaction, which enabled the system to generate gold nanoparticles (AuNPs) with high Raman activity. When the aptamer was introduced into the system, its binding with GO reduced the reaction speed. Upon adding Pb2+ to the system, the aptamer preferentially combined with Pb2+ and GO was released to accelerate the AuNPs production. The concentration of the AuNPs was proportional to the intensity of the added Raman signal molecule 4-MBA and the main Raman peak of Pb2+ appeared at 1595.80 cm−1. The ability of a novel aptamer (M4-16) and traditional aptamers (T30695, TBA) for Pb2+ determination was compared, and the concentration of the aptamer, HAuCl4 and heating time were optimized to build optimal detection system. After several pretreatment of the original SERS spectroscopy, combined with the comparison of various models, the first-order derivative preprocessing combined with competitive adaptive reweighted sampling model achieved the best performance (Rc = 0.9966, Rp = 0.9972), the detection limit for Pb2+ was 0.1 μg L−1. The combination of SERS technology and chemometrics is a promising method that could be used to achieve rapid and highly sensitive detection of Pb2+ in food.