title: Electrochemical self-assembly of melanin films on gold.
abstract: An electrochemical method for self-assembling melanin films on the Au(111) surface from melanin aggregates in alkaline media is reported. Electrochemical data combined with scanning tunneling microscopy (STM), atomic force microscopy, and Auger electron spectoscopy show that the amount and structure of the deposited melanin film depend on the potential (E) applied to the electrochemical interface and deposition time. Film formation takes place at a noticeable rate at E = -1.0 V (vs SCE). High-resolution STM images at the early stages of growth show small particles, 5-8 nm in size and 0.3-0.4 nm in height, forming ordered arrays that follow closely the Au(111) topography. The size of the melanin particles increases as the film thickness increases, reaching 150 nm for deposits grown for 16 h. The deposited films are electrochemically active, showing well-defined redox couples preceding the hydrogen evolution reaction.
authors.affiliation: Departamento de Química Física, Universidad de La Laguna, Avda. Astrofísico Francisco Sánchez, 38071 La Laguna, Tenerife, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Díaz
authors.forename: Yurima
authors.initials: Y
authors.lastname: Gimeno
authors.forename: Pilar
authors.initials: P
authors.lastname: Carro
authors.forename: Sergio
authors.initials: S
authors.lastname: González
authors.forename: Patricia L
authors.initials: PL
authors.lastname: Schilardi
authors.forename: Guillermo
authors.initials: G
authors.lastname: Benítez
authors.forename: Roberto C
authors.initials: RC
authors.lastname: Salvarezza
authors.forename: Alberto Hernández
authors.initials: AH
authors.lastname: Creus
mesh_terms: D018441:Biofilms; D004563:Electrochemistry / Q000379:methods; D006046:Gold; D007700:Kinetics; D008543:Melanins / Q000737:chemistry*; D016252:Microscopy, Scanning Tunneling / Q000379:methods; D008968:Molecular Conformation; D013053:Spectrophotometry
chemical_list: D008543:Melanins; C041877:eumelanin; D006046:Gold