FTIR and NMR study of poly(lactide-co-glycolide) and hydroxyapatite implant degradation under in vivo conditions

Degradation of PGLA and PGLA + HAP composite in biological environment proceeds faster than under in vitro condition. Concentration of glycolidyl units in the copolymer chain decreases and that of lactidyl units increases during in vivo degradation both, in PGLA and in PGLA + HAP composite. However, in the case of the composite the decrease of glycolidyl units concentration is slower and after 6 weeks of degradation the contents of lactidyl and glycolidyl units remain stable. On the other hand, PGLA + HAP composite degrades faster than pure PGLA. The addition of HAP nanoparticles distinctly accelerates degradation of PGLA copolymer which is probably connected with the increase of hydrophilicity of the composite and inhibition of semi-crystalline lactidyl domains formation during the degradation process. Observation of the bone tissue after implantation of PGLA + HAP allows to conclude that the degradation of the composite occurs simultaneously with the implant replacement by the bone cells.