Description
Two common neurotransmitters, dopamine and serotonin, are electrochemically active that can be detected through amperometry with conventional neural probes. However, lactic acid is a non electrochemically active molecule that cannot be detected by these conventional probes. Lactic acid can be found in the brain as a metabolite of energy production and when a buildup of lactic acid occurs, it can lead to lactic acidosis and potentially harm the brain. Lactic acidosis can hamper normal mitochondrial functions and has been linked to seizures and can be caused by ischemia or hypoxia. In order to detect lactic acid our group at SDSU manufactured glassy carbon electrodes which are more versatile than conventional carbon fiber electrodes and are functionalizing these glassy carbon electrodes by immobilizing an enzyme to catalyze lactic acid into a molecule that is electrochemically active. By immobilizing lactate oxidase into a chitosan matrix we were able to cause a reaction that resulted in hydrogen peroxide, which has a redox potential of 1.2 V. We were able to use various methods such as fast scan cyclic voltammetry (FSCV), FTIR, and potentiostat readings to characterize, understand the chemical reactions occurring, and qualify these functionalized glassy carbon electrodes. The neural probes that were fabricated were able to detect lactic acid with an electrode surface area of 1413 um2.The overall length of the neural probe was roughly 16.75 mm long including it 8.375 mm long shank. The probe was able to detect various concentrations, but provided a variety of responses. The limit of detection was calculated based on the calibration curve obtained after testing the neural probe with a lactic acid concentration range of 10 nM to 2000 nM to give us a value of 1.25 nM.
