Zein coatings were obtained by electrophoretic deposition (EPD) on commercially pure titanium substrates in an as-received state and after various chemical treatments. The properties of the zein solution, zeta potential and conductivity, at varying pH values were investigated. It was found that the zein content and the ratio of water to ethanol of the solution used for EPD, as well as the process voltage value and time, significantly influence the morphology of coatings. The deposits obtained from the solution containing 150 g/L and 200 g/L of zein and 10 vol % of water and 90 vol % of ethanol, about 4–5 μm thick, were dense and homogeneous. The effect of chemical treatment of the Ti substrate surface prior to EPD on coating adhesion to the substrate was determined. The coatings showed the highest adhesion to the as-received and anodized substrates due to the presence of a thick TiO2 layer on their surfaces and the presence of specific surface features. Coated titanium substrates showed slightly lower electrochemical corrosion resistance than the uncoated one in Ringer’s solution. The coatings showed a well-developed surface topography compared to the as-received substrate, and they demonstrated hydrophilic nature. The present results provide new insights for the further development of zein-based composite coatings for biomedical engineering applications.
1 August 2023 in Journal of the Electrochemical Society
Cu- and Mg-doped mesoporous sol-gel bioactive glasses (MSGG) were developed and their microstructure was investigated. Selected biological tests were also performed to assess their suitability for the functionalization of polymer zein coatings. The electrophoretic deposition (EPD) conditions to obtain composite coatings on Ti-13Nb-13Zr substrates were determined. The coatings with excellent adhesion to the substrates were macroscopically uniform, exhibiting open porosity and high roughness. The surfaces of the samples coated with MSGG/zein coatings became more hydrophilic than the titanium alloy substrates. However, with increase of the volume fraction of glass particles in the coatings, the contact angle increased. The coated alloy showed enhanced resistance to electrochemical corrosion in Ringer’s solution. The chemical composition of the glass used in the coating affected the parameters of wettability and resistance to electrochemical corrosion. Both coating types showed an increase in the antibacterial properties against Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria compared to pure zein. However, no significant differences were observed after a 24 h-long test.