Preparation Of MOF-Derived CeO₂-ZnO/rGO And Electrochemical Detection Of Dopamine

Parkinson’s disease is the second most common neurodegenerative disease in the elderly.Dopamine（DA）is an important neurotransmitter that is usually maintained at a certain concentration in the body,and low levels of DA can lead to Parkinson’s dis-ease.Electrochemical methods have good prospects for application in the field of DA detection because of their simplicity,low cost and good selectivity.The most critical factor affecting electrochemical detection is the electrode material,therefore the prep-aration of excellent electrode materials for rapid,simple and highly sensitive DA meas-urement is essential for the early diagnosis of Parkinson’s disease and the adjustment of drug doses.In this paper,Ce-Zn MOF/rGO composites with dandelion-like morphology were prepared and heat-treated to obtain CeO₂-ZnO/rGO composites,providing a new method for obtaining MOF-derived materials with high sensing performance.In the paper,the dandelion-shaped Ce-Zn MOF was prepared by hydrothermal method,gra-phene oxide（GO）was prepared by a modified Hummers method,Ce-Zn MOF/rGO was prepared by in situ growth method,and CeO₂-ZnO/rGO composites were prepared by heat treatment.The morphology and structures of Ce-Zn MOF,Ce-Zn MOF/rGO,and CeO₂-ZnO/rGO were characterized while their formation mechanisms were ana-lyzed,and the electrochemical performance of the CeO₂-ZnO/rGO/ITO electrode for the detection of DA was tested.The effects of the content of polyvinylpyrrolidone（PVP）and rGO,the heat treatment temperature of Ce-Zn MOF and the p H of the buffer solution on the electrochemical performance and detection ability of CeO₂-ZnO/rGO/ITO electrode were investigated,and the selectivity,anti-interference,re-peatability,reproducibility and stability of the CeO₂-ZnO/rGO/ITO electrode for DA detection were tested.And the DA was detected in real human urine.The results showed that the Ce-Zn MOF exhibited a dandelion-shaped morphology of about 4μm in size,consisting of several rods of 50 nm in diameter and2μm in length,and the introduction of different levels of PVP evolved the Ce-Zn MOF from spherical to dandelion-shaped to dumbbell-shaped.The Ce-Zn MOF/rGO and the CeO₂-ZnO/rGO produced by pyrolysis retained their precursor morphology and im-proved the catalytic activity and detection ability for DA.Under the conditions of PVP addition of 200 mg,rGO addition of 25 mg,heat treatment at 400℃and buffer solution p H=7.5,the CeO₂-ZnO/rGO/ITO working electrode exhibited high sensitivity of 17.67μA·μM^-1·cm^-2 and low detection limit of 2.1 n M for DA detection,which was better than most of the same materials.Under the interference of 20μM uric acid（UA）,the CeO₂-ZnO/rGO/ITO electrode can still maintain high sensitivity with good selectivity,and the I-T curve shows good interference resistance in the presence of various other substances.The electrode also exhibited good repeatability,reproducibility and stabil-ity.DA was detected in human urine with recoveries of 96%,109.2%and 107.5%,respectively.The electrode offers potential applications as a material for DA detection.