2D oxygen-terminated TiB2 nanosheets acted as an oxidase-like nanozyme via an unusual catalytic mechanism for colorimetric detection of dopamine

Dopamine (DA) is a critical catecholamine neurotransmitter in the human body, making its assay highly significant for clinical diagnosis. In this study, two-dimensional (2D) oxygen-terminated TiB 2 nanosheets (NSs) were synthesized and characterized, exhibiting remarkable oxidase-like activity. These oxygen-terminated TiB 2 NSs can directly catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to oxTMB without requiring external oxidants such as H 2 O 2 or partially reduced oxygen (PROS). Interestingly, DA was found to effectively reduce the amount of oxTMB in the catalytic system. Based on this unique catalytic mechanism, a colorimetric sensor for DA detection was developed. The presence of antioxidants such as glutathione (GSH) and L-cysteine (L-Cys) in the samples failed to interfere the DA detection. It is contributed to the PROS-free catalytic mechanism of oxygen-terminated TiB 2 NSs and strong reduction ability of DA toward oxTMB. The sensing platform has a linear detection range of 0.1–8 μM with the detection limit (LOD) of 0.025 μM (3 σ / S ) and the quantification (LOQ) limit of 0.083 μM (10 σ / S ). Notably, oxygen-terminated TiB 2 NSs retained their high oxidase-like catalytic activity in the diluted real samples, highlighting their potential for biosensing applications.