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This study investigated the electrophoretic deposition (EPD) of the natural polymer zein combined with bioactive glass (BG) particles. Through the deposition of various BG compositions, namely 45S5 BG and Cu-doped BG, this work sought to demonstrate the ability of the films to potentiate the formation of hydroxyapatite (HA) in contact with simulated body fluid (SBF). Following incubation in SBF, the physical and chemical surface properties of the EPD films were evaluated using different characterization techniques. The formation of HA at the surface of the coatings following immersion in SBF was confirmed using Fourier transform infrared spectroscopy (FTIR). The results demonstrated HA formation in all coatings after seven days of immersion in SBF. Coating morphology and degradation of the zein films were characterized using environmental scanning electron microscopy (ESEM). The results confirmed EPD as a very convenient room temperature technique for production of ion releasing, bioactive, and antibacterial coatings for potential application in orthopedics.

Coatings of zein and zein/bioactive glass composites were produced on 316L stainless steel using anodic electrophoretic deposition (EPD). Zein and 45S5 bioactive glass were dispersed in a binary water/ethanol solution. The effects of the zein and bioactive glass concentrations as well as different water/ethanol ratios on the coating characteristics were investigated. Also, the influence of applied voltage and deposition time were analyzed. Prior to EPD, the zeta potential of zein, bioactive glass and zein/bioactive glass suspensions were measured as a function of the pH. The coatings were investigated by optical microscopy, scanning electron microscopy and atomic force microscopy. Coatings with pure zein are homogeneous when using an electrical field strength below or equal to 0.05 V/m. Higher voltages led to a discoloration of the solution which could result from a conformational change of zein. The co-deposition of zein/bioactive glass is very sensitive to the applied voltage and the concentration of zein. High concentrations of zein (10 g/L) increase the viscosity of the solution and reduce the electrophoretic mobility of the bioactive glass. Equal concentration of zein and bioactive glass at a pH of 7.5 with a low electric field strength were found to be the optimum conditions.

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Polyaniline (PANI) composite coatings were prepared by polymerising aniline (ANI) monomers, which were previously embedded in an insulator polymer matrix (PMMA, PVK or PS), in an atmosphere saturated with aqueous HCl–(NH4)2S2O8 solution. The optical spectra and electrical measurements of these coatings clearly show the formation of the emeraldine salt of PANI in the composite materials. Sheet resistance data as well as an SEM morphology study suggest a surface polymerisation of aniline in the PANI–PMMA and PANI–PS composite coatings, whereas a volumetric polymerisation of aniline is evident in the PANI–PVK samples. The low percolation threshold (pc) values of these coatings suggest a fibre structure of the PANI phase inside the composite materials. The curves of current versus temperature show a higher electrical property stability of the PANI–PVK composite coatings than of a PANI single film. Copyright © 1999 John Wiley & Sons, Ltd.