Biocompatible BSA-AuNP@ZnCo2O4 nanosheets with oxidase-like activity: Colorimetric biosensing and antitumor activity

Abstract

In this paper, we developed a novel nanocomposite sensor toward detection of glutathione (GSH) and glutathione S-transferase (GST) via convenient colorimetric analysis. The ZnCo2O4 sheets were synthesized by a deep eutectic solvent, and decorated with Au nanoparticles (AuNPs) as well as bovine serum albumin (BSA) by a simple chemical reduction technique. The prepared BSA-AuNP@ZnCo2O4 composites was attested to have remarkable oxidase like activity, which capable of oxidizing colorless TMB to blue oxidized TMB (oxTMB). Then, the reaction mechanism was investigated in detail by electron paramagnetic resonance (EPR) analysis. It was proved that the oxidation of TMB stemmed from the production of abundant active oxygen species (•OH, O2•− and 1O2) by the interaction between BSA-AuNP@ZnCo2O4 and dissolved oxygen. The catalytic activity of BSA-AuNP@ZnCo2O4 was inhibited by GSH, which lead to the fading of blue oxTMB. Thus, a sensitive and specific analysis method was established for GSH detection with a detection limit of 0.0885 μM and a linear detection range between 0.50 and 15.00 μM. Furthermore, GST reduced the GSH reducibility by promoting the reaction of GSH and 1-chloro-2,4-dinitrobenzene (CDNB). The GSH detection method could be extended to the colorimetric determination of GST with a 0.137 U·L−1 detection limit and a working range from 0.25 to 17.50 U·L−1. And it was further successfully extended toward GSH and GST detection in human serum samples with satisfactory results. At last, the cytotoxicity of BSA-AuNP@ZnCo2O4 was researched against U87, HEB and HCT-116 cells, which stated its non-cytotoxic effect for normal cells and antitumor activity for cancer cells. In conclusion, the proposed method based on BSA-AuNP@ZnCo2O4 nanomaterials is sensitive, economical and highly efficient that might result in a great influence on the following enzyme research.