Oxidase-like VC MXene nanozyme with inherent antibacterial properties for colorimetric sensing.

The microbial environment greatly affects the performance of colourimetric sensors, especially the interference of bacteria in the sample detected. This paper reports the fabrication of an antibacterial colorimetric sensor based on VC MXene synthesized via simple intercalation and stripping. The prepared VC nanosheets can mimic oxidase activity towards 3,3',5,5'-tetramethylbenzidine (TMB) oxidation without exogenously adding HO. Further mechanistic studies showed that VC nanosheets could effectively activate the oxygen adsorbed on their surface, which in turn causes an increase in the bond length and a decrease in the magnetic moment of oxygen through electron transfer from the nanosheet surface to O. The VC nanosheets also exhibited excellent broad-spectrum antibacterial activity through the outbreak of reactive oxygen species. Owing to its unique catalytic activity and the inherent antibacterial ability for mimicking oxidase, a colorimetric sensing platform was developed to effectively determine L-cysteine levels at a detection limit of 30.0 nM (S/N = 3). It is impressive that the detection results of L-cysteine in various complex microbial environments are also very satisfactory. This study broadens the biological use of MXene-based nanomaterials through their satisfactory enzymatic activity and provides a simple and efficient colorimetric strategy for detection techniques used in complex microbial environments.