Biological Evaluation of Polydimethylsiloxane Modified by Calcium Phosphate Nanoparticles for Potential Application in Spine Surgery

The biological properties of a composite made of polydimethylsiloxane matrix and two kinds of calcium phosphate nanoparticles (hydroxyapatite, beta tricalcium phosphate) were tested by means of in vitro and in vivo investigations. Chemical and phase analyses of the nanoparticles were performed. The effects of different volume fractions of nanoparticles were investigated. Human osteoblast-like cell cultures (MG 63) demonstrated that the addition of 5–15 vol.% of nanoparticles had a significantly positive effect on osteoblast viability, and that high concentration did not support cell proliferation. The highest rates of osteointegration in pig bone were attained for implants modified by 15 vol.% hydroxyapatite and more intensive formation of new bone tissue was observed. Our study indicates that hydroxyapatite probably better imitates the composition and structure of the mineral phase of real bone.