Ti3C2Tx MXene-derived TiO2/C-QDs as oxidase mimics for the efficient diagnosis of glutathione in human serum

Abstract

Nanozyme-based colorimetry was suggested to be a rapid method for biomarker (e.g. glutathione) detection, but this method suffers from lack of efficiency and low-toxicity nanozymes till now. Herein, quantum dots of TiO₂ loaded on carbon (TiO₂/C-QDs) oxidase-like nanozymes were prepared via a hydrothermal treatment of tiny and few-layered Ti₃C₂T_x MXene nanosheets, which possess abundant thermodynamic metastable Ti atoms on MXene margins as raw materials for the preparation of TiO₂/C-QDs. The oxygen vacancy in TiO₂ on the surface of the carbon matrix can facilitate O₂ adsorption in the solution and generate reactive oxygen species (ROS), thereby quickly oxidizing 3,3′,5,5′-tetramethylbenzidine (TMB) to its oxidized form (TMB_ox) in the absence of H₂O₂. After adding glutathione (GSH), TMB_ox was able to be restored to TMB, which resulted in a corresponding decrease in the UV-vis absorbance value at 652 nm. Furthermore, this assay possesses good selectivity, excellent specificity and high sensitivity (limit of detection: 0.2 μM), which made it possible to efficiently detect GSH in complex biological samples such as human serum.