Online Electrochemical Monitoring of Glucose in Rat Brain with Acanthosphere-like CuOOH Nanospheres-based Electrochemical Sensor as Non-enzymatic and O2-independent Detector

This study for the first time establishes a reliable non-enzymatic online electrochemical system (OECS) for selective and continuous measuring glucose in animal cerebral system. We proposed a one-step electrochemical method to synthetize a Cu nanostructure directly onto electrode, and over-oxidize it in NaOH to form acanthosphere-like CuOOH nanospheres (denoted as AN-CuOOH), which can serve as an excellent electrochemical catalyst for glucose oxidation and thus for simple and reproducible non-enzymatic glucose detection in strong alkaline solution. To validate the AN-CuOOH-based sensors for in vivo applications, we connect the sensors to a merged solution of in vivo microdialysis and 0.4M NaOH to set up an OECS for in vivo glucose monitoring in rat brain. The response of this system has strong tolerance to the oxygen and pH fluctuation which may happen in the cerebral brain system during some physiological and pathological processes. The fabricated non-enzymatic OECS has a good linear current response to glucose within a concentration range from 10 to 1000M with sensitivity of 130.22nAM(-1)cm(-2). Additionally, the OECS is stable and does not suffer from the interference coexisting in the cerebral system. With the fabricated non-enzymatic OECS for glucose measurement, the basal level of glucose in the microdialysate from rats striatum was determined to be 248.63M (n=3). Furthermore, the glucose was clearly decreased to 26.37% of the basal level when the rat was undergone by 20min ischemia, and the glucose concentration was gradually restored to 99.15% during 40min of reperfusion. Our work propose a technically simple strategy for the fabrication of a highly reproducible non-enzymatic OECS system free from oxygen and pH interference, which is promising in exploring the molecular mechanism associated with brain functions.