Authors: JeongCheol Lee Sung Baek Cho Seung Jin Lee SangHoon Rhee
Publish Date: 2009/09/01
Volume: 44, Issue: 17, Pages: 4531-4538
Abstract
Nucleation and growth mechanism of apatite on a bioactive and degradable PLLA/SiO2–CaO composite with a thick PLLA surface layer were investigated compared to that on a bioactive but nondegradable polyurethane PU/SiO2–CaO composite with a thick PU surface layer The bioactive SiO2–CaO particles were made by a sol–gel method from tetraethyl orthosilicate and calcium nitrate tetrahydrate under acidic condition followed by heat treatment at 600 °C for 2 h The PLLA/SiO2–CaO and PU/SiO2–CaO composites were then prepared by a solvent casting method which resulted in thick PLLA and PU surface layers respectively due to precipitation of SiO2–CaO particles during the casting process Two composites were exposed to SBF for 1 week and this exposure led to form uniform and complete apatite coating layer on the PLLA/SiO2–CaO composite but not on the PU/SiO2CaO composite These results were interpreted in terms of the degradability of the polymers A practical implication of the results is that a postsurface grinding or cutting processes to expose bioactive ceramics to the surface of a composite with a thick biodegradable polymer layer is not required for providing apatite forming ability which has been considered as one of the pragmatic obstacles for the application as a bone grafting material
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