Biomaterials Used for Tissue Engineering

Biomaterials Used for Tissue Engineering:

2. 1 Polymers:
From the origin point of view, there are two categories: natural and synthetic polymers. From the lifetime point of view, there are two categories as well: biodegradable and non-biodegradable polymers. The mostly used natural poly¬mers are collagens and the most widely employed synthetic polymers are poly (?-hydroxy acids).
If the sample size is very large, e.g. the smallest dimension is larger than five centimeters, and then the aliphatic polyester may undergo a surface erosion process. Although the major degradation mech¬anism of aliphatic polyesters is hydrolysis, the degradation rate of different ali¬phatic polyesters is different. Because the major degradation products of aliphatic polyesters are acids, the massive release of acid may surpass the capacity of the surrounding tissue to eliminate it, and this may cause an elevated inflammatory reaction. In particu¬lar, if there is poor vascularization at the implantation site, the local environ¬ment may be seriously disturbed. Chang and other researchers have studied mixing basic bioceramics, such as tricalcium phosphate (TCP) and hydroxya¬patite (HA), into polyesters to buffer the acidic by-products. The bioceramic¬polyester composite can not only avoid the formation of an unfavorable pH en¬vironment for the cells, but can also improve the capacity of the environment to promote bone tissue regeneration. The other problem with pure synthetic polymers is the lack of cellular recognition and therefore difficult to make dynamic communication between synthetic materials and cells. One way to overcome this problem is grafting the short functional peptides on the surface of synthetic polymers.