Visible light activation Ti-based metal organic framework nanoenzyme for colorimetric analysis of dopamine in serum.

Dopamine (DA), a key catecholamine neurotransmitter in the central nervous system, is closely associated with abnormal levels in various diseases such as Parkinson's disease and schizophrenia. Developing a simple and sensitive method for DA detection is of significant clinical importance. This work constructed a visible light-driven colorimetric sensing platform using titanium-based metal-organic frameworks (Ti-MOF) nanozymes for the highly selective detection of DA in serum. Ti-MOF nanozymes were successfully prepared via a solvothermal method, and their peroxidase-like catalytic activity under dark, natural light, and visible light conditions was systematically investigated. The results showed that visible light can act as a precise "switch," significantly enhancing the colorimetric effect of the Ti-MOF-catalyzed TMB-H2O2 reaction. Based on the consumption mechanism of DA molecules on hydroxyl radicals generated during the catalytic process, a "signal-off" colorimetric detection strategy was constructed. This study confirmed that the introduction of visible light enables spatiotemporal controllable regulation of the catalytic reaction, providing a new approach for the design of biosensing platforms based on photo-nanozymes.