Dual nanozymes based fiber microelectrode towards dopamine detection in urinalysis and living cell secretion

Dopamine (DA) is a crucial neurotransmitter involved in regulating multiple human body functions. Accurate detection of dopamine levels is essential for disease diagnosis, monitoring, and treatment. Herein, a dual nanozymes modified flexible fiber microelectrode was successfully fabricated with graphene fiber (GF) as the substrate, followed by hydrothermal growth of ZnO nanorods, in-situ growth of metal-organic framework (MOF) and gold nanoparticles step by step. The hierarchical structure, special microenvironment combining with the catalytic activity of nanozymes (MOF and Au nanoparticles) make GF/ZnO/MOF@Au fiber microelectrode show excellent performance in dopamine detection, with a linear range of 2 μM-100 μM, a detection limit as low as 0.189 μM, and a sensitivity of 4.43 μA μM^-1 cm^-2. This microelectrode could be used for the detection of DA in urine, also for real-time monitoring of DA released by living cells, which offers a new pathway for the diagnosis and monitoring of dopamine-related diseases.