Effect of chitosan on the formation of hydroxyapatite (HAp) coatings on titanium by electrodeposition technique

In this study, hydroxyapatite (HAp) coatings were electrodeposited onto titanium (Ti) substrates using an aqueous solution containing 0.167 M CaCl₂ + 0.1 M NH₄H₂PO₄. The effect of chitosan on the formation of HAp coatings were investigated by adding various amount of chitosan ranging from 5 to 20 vol. %. The electrodeposition was carried out at 80 °C for 30 min under constant applied potential at - 1.5 V vs Ag/AgCl. Prior to electrodeposition, the Ti substrates were pre-treated by acid etching to remove oxide and obtain desired roughness surface. The incorporation and intermingling of chitosan in the HAp coatings reduce the amount of space found between the needlelike structures in the pure HAp coatings by `filling in´ the space. However, excessive amount of chitosan added in the deposition solution (i.e.: 20 vol. %) caused it to compete with calcium ions to incorporate with phosphate ions and dominating the coatings. XRD patterns, FTIR spectra and EDAX analyses confirmed that the presence of chitosan in the HAp coatings. So, considering its economic and simple production, a hybrid HAp/chitosan coating is thought to be an attractive candidate for future applications as biomedical implants material.