ABSTRACT
The vast majority of synthetic polymers used in tissue engineering degrade hydrolytically. Hydrolytically degradable polymers can degrade by two different mechanisms, bulk and surface. The trend in biomedical engineering is moving toward materials with bioactivity, biocompatibility, and biodegradability. Degradation prevents stress shielding of new tissue, and, eventually, the polymer disappears and new tissue is left. The mechanical and degradation properties of the polymers can be tailored depending on the copolymer ratios. Several biodegradable polyphosphazenes are under investigation for bone and neural tissue engineering applications. Chitosan is also used to form porous scaffolds for tissue engineering. Chitosan is known to support osteoblast proliferation and phenotype expression. Composites of collagen with hydroxyapatites have been investigated as scaffolds for bone tissue engineering. Decellularized tissues, allografts and xenografts, are excellent scaffolds for tissue engineering. The use of an appropriate material is critical for the fabrication of an implant that performs well both mechanically and biologically.
