Electrodeposition of hydroxyapatite–silver–chitosan nanocomposite coatings

Hydroxyapatite (HA)–Ag–chitosan nanocomposite coatings were electrochemically deposited on various conductive substrates and studied using X-ray diffraction analysis, thermogravimetric and differential thermal analysis, energy dispersive X-ray spectroscopy, scanning and transmission electron microscopy. It was shown that the coating composition can be varied by the variation of AgNO3 or HA concentration in the solutions used for electrodeposition. Nanocomposite coatings were deposited as HA–Ag–chitosan monolayers or multilayers containing individual HA–chitosan and Ag–chitosan layers. The coating thickness was varied in the range of 0−20 µm by the variation of deposition time for individual layers and by the variation of the number of different layers. Inductively coupled plasma optical emission spectroscopy studies showed that the Ag+ release rate from the Ag–chitosan layer can be reduced in the layered structure using a HA–chitosan layer. The obtained results can be used for the development of biocompatible antimicrobial coatings with controlled Ag+ release rate. Electrochemical impedance spectroscopy and potentiodynamic polarization studies showed that the multilayer coatings provide corrosion protection of the stainless steel substrates in Ringer's physiological solutions.