A hydroxyapatite coating covalently linked onto a silicone implant material

A novel composite consisting of hydroxyapatite (HAp) microparticles covalen tly coupled onto a silicone sheet was developed. Initially, an acrylic acid (AAc) -grafted silicone sheet with a 16.7 mug/cm(2) surface graft density was prepared by corona-discharge treatment. The surface of sintered, spheri cal, carbonated HAp particles with an average diameter of 2.0 mum was subse quently modified with amino groups. The amino group surface density of the HAp particles was calculated to be approximately one amino molecule per 1.0 nm(2) of particle surface area, These samples were characterized with Four ier transform infrared spectrometry and X-ray photoelectron spectroscopy. A fter the formation of ammonium ionic bonds between both samples under aqueo us conditions, they were reacted at 180 degreesC for 6 h in vacuo to form c ovalent bonds through a solid-phase condensation. The HAp particles were co upled to the AAc-grafted silicone surface by a covalent linkage. Further im provements in the adhesive and bioactive properties of the HAp-coated silic one material are expected. (C) 2001 John Wiley & Sons, Inc.