Preparation and characterization of apatite deposited on silk fabric usingan alternate soaking process

Apatite-deposited silk fabric composite materials were developed using a ne w alternate soaking process. The characteristics of deposited apatite were studied using scanning electron microscopy (SEM), X-ray diffaction (XRD), F ourier transform infrared spectrophotometry (FTIR), and X-ray photoelectron spectroscopy (XPS). Apatite weight increased with alternating soaking in a calcium solution [200 mM aqueous calcium chloride solution buffered with t ris-(hydroxymethyl) aminomethane and HCl (pH 7.4)] and a phosphate solution (120 mM aqueous disodium hydrogenphosphate) changed every hour. SEM showed that apatite deposited after 21 or more repeated soakings was over 20 mu m thick. XRD showed that with alternate soakings, the apatite crystals depos ited on silk fabric elongated along the axis. FTIR and XPS indicated the ex istence of carbonate, HPO42-, and Na+ ions in addition to constituent ions of hydroxyapatite. A loss of HPO42- and Na+ ions in the deposit upon furthe r soaking might be associated with an increasing apatite crystallinity. Apa tite deposited on silk by the alternate soaking process was a deficient apa tite containing carbonate, HPO42- and Na+ ions as in a natural bone tissue. Thus, this apatite-silk composite material might be potentially bioactive. (C) 2000 John Wiley & Sons, Inc.