Evaluation of hydrogenated physically small carbon electrodes in resisting fouling during voltammetric detection of dopamine

In this work, a hydrogenated film deposited on physically small carbon cylinder electrodes was used to minimise electrode fouling that is commonly encountered during electrochemical detection of the neurotransmitter dopamine in vivo. Electrode fouling generally arises from the inhibition of electron transfer reactions on an electrode surface covered by hydrophilic surface active agents including proteins, peptides and lipids present in a biological matrix. The hydrophobic hydrogenated film discourages adsorption of these agents and hence acts as a protective membrane against fouling. Characterisation of the hydrogenated carbon electrodes in three redox systems including Fe (CN)₆ ^{3 -}, ferrocene and anthraquinone-2,6-disulfonate supported a reduction of carbonyl functionalities and surface oxides on the hydrogenated carbon electrodes. These electrodes were found to remain stable for at least 3 months and they exhibited more resistance towards fouling compared to bare carbon electrodes. Cyclic voltammetry of dopamine at hydrogenated carbon cylinder electrodes in the presence of bovine serum albumin (as a model protein) and N-formyl methionyl leucionyl phenylalanine (a model peptide) showed a 5.5% (0.6% standard deviation; N = 5 electrodes) decrease in the limiting current. A detection limit (based on three times the standard deviation of the blank signal) of 750 nM was also estimated when dopamine was detected at hydrogenated carbon cylinder electrodes in the presence of bovine serum albumin and N-formyl methionyl leucionyl phenylalanine in vitro.