Deposition and characterization of Hydroxyapatite-Chitosan coatings on 304 SS for biomedical devices

During the last years biomaterials have been largely investigated in order to perform and improve biomedical devices. As regards orthopedic field, the most common equipment used (such as implants, bone grafts or screws) are constituted by metallic materials (steel and titanium alloys), characterized by low/medium resistance to corrosion and low osteointegration ability. Furthermore, these factors could produce local inflammations of the tissues surrounding the implants, increasing kinetics of corrosion phenomena. Scientific community has focused the attention on biocoatings interposed between metal and aggressive environment in order to inhibit corrosion. Furthermore, these coatings are able to decrease the ions release and to improve the lifetime of implanted devices. In this work, hydroxyapatite-chitosan composites were studied as coatings of 304 SS steel substrates. Hydroxyapatite was chosen for its bioactivity thanks to its chemical structure similar to bones that makes suitable for osteoconductive action. Chitosan is a polysaccharide derived from chitin, usually extracted from the shells of crustaceans, largely used in medical field as antibacterial agent and/or for drug deliver. Hydroxyapatite-chitosan composites were realized by an innovative method based on galvanic process that consists in a simple galvanic coupled of metals with different redox potentials, which is advantageous firstly because does not require external power supply.