pH-regulated release of dopamine from well-ordered self-assembled monolayers: Electrochemical studies

• A facile and reliable route to attach the amine drugs to the electrode surface is introduced.
• Aldehyde terminated SAMs can release the dopamine in a controlled manner by pH triggering.
• Reversible loading and releasing of dopamine from the SAMs surfaces was observed.
• Rate of release of the amine drug from the present SAMs surface was evaluated.

In the present work, gold electrode modified with novel aldehyde-terminated self-assembled monolayers (SAMs) was used for controllable load and release of dopamine molecules by pH triggering. Electrochemical techniques including cyclic voltammetry (CV) and electrochemcial impedance spectroscopy (EIS) were employed to investigate the SAMs characteristic on the gold electrode surface. The electrochemical experiments indicated Faradaic behavior for the electrode surface after its modification with dopamine. Notably, it was observed that decreasing the conditioning pH, results in a decrease of peak currents, presumably due to the hydrolysis of the terminal imine bonds and releasing the dopamine moiety into the solution. Moreover, the preliminary kinetics studies were done for dopamine release from the SAMs surface as a model to design future drug delivery systems. Finally, the rate constant of dopamine release from the SAMs modified surface estimated to be 0.167 day− 1 at pH = 3.

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