Nanostructured Microelectrode Based Enzymatic Biosensors for Monitoring Neurometabolic Markers in the Brain

MATIAS REGIART; MAURO BERTOTTI; ELIANA FERNANDES; ANA LEDO; CHRISTOPHER BRETT; RUI M. BARBOSA.

Congreso; 72nd Annual Meeting of the International Society of Electrochemistry; 2021

International Society of Electrochemistry

Traumatic brain injury (TBI) is a leading cause of mortality, morbidity, and long-term disability, with long-lasting social and economic consequences. A metabolic dysfunction characterized by a reduction in oxidative metabolism is observed after TBI events. The magnitude and profile of this metabolic disorder impact neuronal viability and clinical outcome, which can be confirmed by the observation that persistent low glucose levels and an increase in the lactate/glucose ratio are associated with poor outcome in patients with TBI. Therefore, understanding the dynamic fluctuation of these metabolic substrates is of utmost importance for prognosis and the definition of therapeutic strategies in the clinical setting [1].In the present work, we explore the numerous advantages of carbon fiber microelectrodes (CFM), such as versatility, low price, and small size [2] for the development of enzyme-based microbiosensors for glucose and lactate measurements in brain tissue and plasma. Bare CFM modified with gold nanopores (NPG) using the Dynamic Hydrogen Bubble Template (DHBT) method exhibited remarkable electrochemical properties, like high specific surface area, uniform large pore volume, and excellent electrocatalytic activity [3]. The effect of time and potential on the nanoporous gold films electrodeposition was optimized. In order to enhance the sensitivity and the electrocatalytic properties towards H2O2 detection, platinum nanoparticles (PtNPs) were electrodeposited onto the NPG film [4]. The nanostructured microelectrode platform was modified through glucose-oxidase (GOx)/lactate oxidase (LOx) immobilization by cross-linking with glutaraldehyde. High selective measurements were attained by electropolymerization with a perm selective layer of meta-phenylenediamine and by using a null sensor [5]. The morphological characteristics and electroanalytical performance of the microbiosensors were assessed, respectively, by scanning electron microscopy and electrochemical techniques.The PtNPs/NPG/CFM shows a high sensitivity to H2O2 (3452.11 nA µM-1 cm-2) at +0.4 V vs. Ag/AgCl, with negligible interference effects. These results support the potential of the microbiosensor to be used as a valuable tool to investigate the complex nature of neurometabolic biomarkers in brain tissue linked to neuronal activation in both physiology and pathological conditions.