Accelerated degradation of poly(l-lactide) bone scaffold: Crystallinity and hydrophilicity

The too low degradation rate of poly (l-lactic acid) (PLLA) hinders its wide application as scaffold for bone tissue engineering to some extent due to high amount of crystal region, although PLLA possesses good biocompatibility, biodegradability and processibility. In this study, l-lactic (L-LA) was incorporated into PLLA bone scaffold fabricated by selective laser sintering (SLS) to promote the degradation. The mechanism was that L-LA was disperced among PLLA molecular chain and weakened the intermolecular forces, which interfered the rearrangement of PLLA molecular chain and resulted in a reduced crystalline region during the recrystallization process under the action of laser sintering. Besides, the addition of L-LA introduced large amounts of hydrophilic functional groups (such as –COOH and –OH) into the scaffold, which was beneficial for water molecules to contact with PLLA molecular chain. The results indicated that the melting point of PLLA scaffold moved toward lower temperature and the crystallinity decreased from 17.71% to 13.76% when the content of L-LA increased from 0 to 20%. And correspondingly, the weight loss increased from 1.06% to 8.20% after immersed in phosphate buffer solution (PBS) for 4 weeks, demonstrating the accelerated degradation rate of scaffold. Additionally, the scaffold possessed good cytocompatibility for cell adhesion and growth as the number and adhesion area of cells increased with culturing time.