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Abstract: Chemical surface modification of neuron-surface interfaces is essential for the development of biologically active and functional neural interfaces. Different types of surface modification schemes are required to derivatize either electrode or insulator surfaces, which limits the surface chemistry based neural interface design. Herein, we report a novel and powerful approach for modifying neuron-surface interfaces using mussel-inspired polymer (‘polydopamine film(polyDA)’) for generating effective chemical platforms on both electrode and insulator surfaces simultaneously. We applied polyDAs to common neural interface surfaces (gold, glass, platinum, indium tin oxide, liquid crystal polymer) and subsequently functionalized them by covalently linking biomolecules. The surfaces coated with polyDAs exhibited uniform and reproducible surface properties and they all became neuron-adhesive after linking with poly-d-lysine. In addition, polydopamine-coated microelectrode arrays were readily functional such that spontaneous and evoked neural activities could be recorded from cultured neuronal networks. We have successfully showed that a novel polyDA can be effectively used for the neural interface design. [Copyright &y& Elsevier]

Abstract: In this work, we studied interfacial proton transfer of the self-assembled monolayer (SAM) of 1-(12-mercaptododecyl)imidazole on a gold electrode by faradaic impedance titration method with Fe(CN)6 3− as an anionic redox probe molecule. The surface pK 1/2 was found to be 7.3, which was nearly the same as that of 1-alkylimidazole in solution. We also investigated the electrochemical properties of the SAM-modified electrode by cyclic voltammetry. Cyclic voltammetry was performed (1) in the solution containing Fe(CN)6 3− with repeated alternation of pH values to investigate the electrostatic interaction of the protonated or deprotonated imidazole with Fe(CN)6 3− and (2) in the acidic or basic electrolyte containing Ru(NH3)6 3+ as a cationic redox probe to verify the effect of the polarity of a redox probe. We observed the reversible adsorption/desorption of Fe(CN)6 3− and concluded that the adsorbed Fe(CN)6 3− catalyzed the electron transfer of both Fe(CN)6 3− itself and cationic Ru(NH3)6 3+. [Copyright &y& Elsevier]