Physiologically Relevant Online Electrochemical Method for Continuous and Simultaneous Monitoring of Striatum Glucose and Lactate Following Global Cerebral Ischemia/Reperfusion

TLDR

The study introduces a physiologically relevant electroanalytical method for simultaneous online monitoring of striatal glucose and lactate after global cerebral ischemia/reperfusion. The method integrates in vivo microdialysis with dual split‑disk plastic carbon film electrodes functionalized with glucose and lactate dehydrogenase biosensors, methylene green–SWNT electrocatalyst, and external perfusion of NAD⁺ aCSF to maintain pH and provide cofactors. The platform shows high selectivity, pH and O₂ tolerance, good linearity, stability, minimal cross‑talk, enabling continuous simultaneous monitoring and providing a new tool for studying energy metabolism in physiological and pathological states.

Abstract

This study demonstrates a new electroanalytical method with a high physiological relevance for simultaneous online monitoring of glucose and lactate in the striatum of the rat brain following global cerebral ischemia/reperfusion. The online analytical method is based on the efficient integration of in vivo microdialysis sampling with an online selective electrochemical detection with the electrochemical biosensors with dehydrogenases, i.e., glucose and lactate dehydrogenases, as recognition elements. The dehydrogenase-based electrochemical biosensors are developed onto the dual split-disk plastic carbon film (SPCF) electrodes with methylene green (MG) adsorbed onto single-walled carbon nanotubes (SWNTs) as the electrocatalyst for the oxidation of dihydronicotiamide adenine dinucleotide (NADH) at a low potential of 0.0 V (vs Ag/AgCl). Artificial cerebrospinal fluid (aCSF) containing NAD+ is externally perfused from a second pump and online mixed with the brain microdialysates to minimize the variation of pH that occurred following the cerebral ischemia/reperfusion and to supply NAD+ cofactor and O2 for the enzymatic reactions of dehydrogenases and ascorbate oxidase, respectively. As a result, the developed online electroanalytical method exhibits a high selectivity against the electrochemically active species endogenously existing in the cerebral systems and a high tolerance against the variation of pH and O2 following cerebral ischemia/reperfusion. This property, along with the good linearity and a high stability toward glucose and lactate as well as little cross-talk between two biosensors, substantially makes this method possible for the continuous, simultaneous, and online monitoring of glucose and lactate in the rat brain following global cerebral ischemia/reperfusion. This study establishes a new and effective platform for the investigation of the energy metabolism in physiological and pathological processes.