Self-assembly synthesis of Ag@PANI nanocomposites as a tandem enzyme utilizing a highly efficient label-free SERS method to detect saccharides

Abstract

Surface Enhanced Raman Scattering (SERS), with good reproducibility and stability, is an analytical testing technique that uses metals or metal nanoparticles as detection substrates, and it can also be used to characterize the information from molecular vibration. In this paper, we first report a facile one-step approach that allows the fabrication of assembled Ag NPs induced by polyaniline (PANI). Ag@PANI nanocomposites have the dual functions of saccharide-oxidase-like and peroxidase-like activities. Therefore, they can be used as a tandem enzyme to produce hydrogen peroxide from saccharides and catalyze the oxidation of TMB. At the same time, they can be considered as a SERS substrate to obtain the characteristic peaks of TMB_ox. In addition, on the basis of SERS, the effects of the Ag⁺ concentration, temperature and pH on the activity of Ag@PANI nanocomposites as the tandem enzyme are further explored. Under the optimal conditions, the common saccharides (sucrose, fructose, glucose and lactose) were detected with linear correlation (R²) in different concentration ranges, and ultra-sensitive detection of various saccharides under label-free conditions was achieved.