Sviluppo e caratterizzazione di un nuovo microsensore per il monitoraggio in tempo reale della autossidazione della dopamina

Oxidative stress is responsible of the dopaminergic neuronal death at nigro-striatal level, as in Parkinson's Disease. Reactive oxygen species are responsible of the non enzymatic oxidation of dopamine (DA, so called auto-oxidation). Both, the non-enzymatic dopamine auto-oxidation and the enzymatic one, determine the formation of the corresponding ortho-quinone with the production of anion superoxide (O2-) and hydrogen peroxide (HP). In this study we have developed a novel electrochemical device able to monitor the auto-oxidation of DA, induced by HP, exploiting the different catalytic properties of the materials used as electrochemical transducers. The electrochemical cell consists in a buffer solution at pH 7.4, reproducing the cerebral extracellular environment, an Ag/AgCl pseudoreference electrode, an auxiliary electrode and two working electrodes, one made with epoxycarbon (Ep) and the other one with platinum (Pt). Ep sensors were coated with a poly-dopamine (pDA) permselective polymer, while Pt sensors were coated with poly-orthofenilendiamine (pPD). The developed system is able to record the redox interactions between DA and HP in a homogeneous phase and in the presence of interfering molecule such as ascorbic acid. This relative selectivity of the electrochemical transducers and polymers allowed us to discriminate between HP (at Pt/pPD surface) and DA (at Ep/pDA surface) and record their changes.