title: Characterization of polydopamine thin films deposited at short times by autoxidation of dopamine.
abstract: 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 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. A uniform overlayer analysis of the XPS data indicates that film thickness increased linearly at short deposition times of ≤10 min. At deposition times ≥10 min, the films appeared largely continuous with surface roughness ≈ ≤ 2 nm, as determined by atomic force microscopy (AFM). Pinhole-free films, as determined by anionic redox probe measurements, required deposition times of 60 min or greater.
authors.affiliation: Biomolecular Measurement Division, Material Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA. rebecca.zangmeister@nist.gov
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Zangmeister
authors.forename: Todd A
authors.initials: TA
authors.lastname: Morris
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Tarlov
mesh_terms: D004298:Dopamine / Q000737:chemistry*; D055664:Electrochemical Techniques; D006046:Gold / Q000737:chemistry; D007211:Indoles / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011108:Polymers / Q000737:chemistry*; D013053:Spectrophotometry; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013997:Time Factors; D014965:X-Rays
chemical_list: D007211:Indoles; D011108:Polymers; C568283:polydopamine; D006046:Gold; D004298:Dopamine