Bio-inspired recognition of dopamine versus ascorbic acid

The concept of a bio-inspired oxidation reaction is used along with self-assembled monolayers for the selective recognition of dopamine over ascorbic acid (AA) in this work. Self-assembled monolayers with negatively charged terminal groups are manipulated for selective sensing of dopamine (DA). It is observed that the recognition sensitivity is increased in the mixed monolayer configuration, and this is increased further when copper ions are included in the SAM matrix by chelation. Monolayers of mercaptoundecanoic acid (MUA) and mercaptobenzothiazole (MBT) and mixed monolayers with decanethiol (DT) (viz., DT+MUA and DT+MBT) are used in the present investigations. Good selectivity is observed in the case of the Au/MUA, Au/MUA/Cu2+ and Au/(DT+MUA)/Cu2+ films. The oxidation of AA and DA occurs as two separate peaks in these configurations and hence better recognition is achieved.