Recent advances on in vivo analysis of ascorbic acid in brain functions

Over the past two decades, there has been increasing focus on ascorbic acid (AA) due to its anti-oxidant and neuroprotective properties as well as its neuromodulating capability. Conventional analytical methods for selective in vivo monitoring of AA mainly involve complex procedures, which lower the temporal resolution and throughput of data gathering. Moreover, analytical methods for selective real-time monitoring of AA exocytosis at a single-cell level is still lacking. The lack of effective methods for AA detection in the central nervous system (CNS) has rendered difficulties in better understanding the roles of AA in brain function. AA is, in itself, electrochemically active, and thereby rationally tailoring the structure of an electrode/solution interface would offer an effective approach to selective electrochemical measurements in the CNS. Guided by this, electrochemical methods have been recently established for AA detection by combining selective electrochemical oxidation of AA at functionalized electrodes with microelectrode techniques and with in vivo microdialysis. This review mainly focuses on recent updates on in vivo detection of AA by modulating the electron transfer of AA to achieve the selectivity for its detection in the CNS, an environment with high chemical complexity. Additionally, the practical implications of the methods in selective and sensitive monitoring the dynamics of AA in different brain functions are also reviewed.