Dual-recognition driven sensing platform based on a BSA-Cu NP nanozyme combined with smartphone-assistance for fluorometric/colorimetric monitoring of dopamine.

Developing a highly sensitive approach for neurotransmitter analysis is of vital significance due to their essential role in clinical diagnosis and treatment of disease. Herein, bovine serum albumin templated copper nanoparticles (BSA-Cu NPs) with peroxidase-mimicking activity are designed and synthesized for dopamine detection through the fluorometric/colorimetric dual-mode technique. The experimental results suggest that as-fabricated BSA-Cu NPs can strongly catalyze the decomposition of hydrogen peroxide to produce oxidized substances, accompanied by remarkable color changes of chromogenic agent 3,3',5,5'-tetramethylbenzidine from colorless to blue, revealing peroxidase-like activities of BSA-Cu NPs. However, owing to the strong binding affinity between dopamine (DA) and BSA-Cu NPs, the catalytic activities of synthesized BSA-Cu NPs are inhibited, leading to a significant decrement of absorption peak signal. Meanwhile, the strong fluorescence of BSA-Cu NPs exhibits remarkable quenching due to photo-induced electron transfer. Besides, by integrating paper strips and smartphone software analysis, an intelligent recognition of DA is also fabricated. On the basis of these phenomena, a fluorometric/colorimetric approach based on the BSA-Cu NP nanozyme combined with smartphone-assisted analysis is constructed for detecting dopamine with a detection limit of 5 nM, and 5 nM, respectively. Moreover, the recognition of dopamine in human serum samples is also successfully realized which is verified using high performance liquid chromatography, demonstrating its promising potential in bioanalysis and clinical disease diagnosis.