Current interest in melanin films derived from the autoxidation of dopamine stems from their use as a universal adhesion layer. Here we report chemical and physical characterization of polydopamine films deposited on gold surfaces from stirred basic solutions at times ranging from 2 min to 60 min, with a focus on times 10 min. Data from Fourier transform infrared (FTIR), x-ray photoelectron spectroscopy (XPS), and electrochemical methods suggest the presence of starting (dopamine) and intermediate (C=N containing tautomers of quinone and indole) species in the polydopamine films at all deposition times. Using the uniform over layer analysis of the XPS data, it was observed that film thickness increases linearly at these short deposition times. The films appear largely continuous with surface roughness ca. 2 nm, as determined by AFM. Pin-hole free films, as determined by redox probe measurements, required deposition times of 60 minutes or greater.
Pub Type: Journals
Dopamine, polydopamine, melanin, FTIR, AFM, XPS, electrochemical analysis, morphology.