Sol-gel derived calcium phosphate coatings for biomedical applications

Hydroxyapatite (HA) coatings have received considerable attention because they exhibit bone bonding capabilities. Unfortunately the common forms of coating production result in cracking and degradation of HA due to the thickness of the coatings and the elevated temperatures employed. This study demonstrates the production of sub-micron, crack-free calcium phosphate coatings on quartz glass substrates using a sol-gel dip-coating technique and firing temperatures below 1000 degrees C. Coatings fired at 1000 degrees C comprised a mixture of hydroxyapatite (HA) and tricalcium phosphate (TCP). XPS analysis of the coating surface showed that the Ca/P ratio lay in the range 1.5-1.67, and that there was a contribution from carbon in the form of carbonate. It is proposed that the sol-gel coatings comprising a resorbable (TCP) and an insoluble (HA) phase have potential benefits in certain implant applications.