IMPROVED ELECTROCHEMICAL PROPERTIES OF STEARATE-GRAPHITE PASTE ELECTRODES AFTER ALBUMIN AND PHOSPHOLIPID TREATMENTS

Stearate-graphite paste electrodes (SGEs) exhibit enhanced dopamine se nsitivity and insensitivity to ascorbic acid electrocatalytic effects in vitro following exposure to unidentified constituents of rat brain tissue homogenates. The present study utilized voltammetry and chronoa mperometry to compare the electrochemical characteristics of brain-tre ated SGEs to those treated with potential brain constituent candidates (albumin proteins and phospholipids). Albumin treatments markedly att enuated interference from ascorbate catalytic effects whereas lipids e nhanced both electrode capacitance and sensitivity to dopamine. Combin ed treatments resulted in electrochemical properties that were similar to brain-treated SGEs. Potential mechanisms by which albumin may atte nuate ascorbate electrocatalysis of dopamine were investigated using h igh performance liquid chromatography, with electrochemical detection. The reduction in ascorbate electrocatalytic effects at albumin-treate d SGEs may be due to nucleophilic binding of dopamine oxidation produc ts to albumin attached to the electrode surface. Therefore, the unambi guous detection of dopamine by SGEs in vivo may be related to interact ions with factors in brain having similar surface-modifying properties .