Synergistic effects of functional additives on the physico-mechanical and biological properties of poly(L-lactic acid) composites for cardiovascular implant applications

Statement of Purpose: Biodegradable poly(L-lactic acid) (PLLA) has been widely used as a promising material for vascular stents. Thermal processing is necessary to manufacture PLLA for cardiovascular stents. However, PLLA is vulnerable to thermal degradation when processed at high temperature. Undesired decrease of molecular weight caused by depolymerization reactions not only reduces the mechanical properties after implantation, but also accelerates the degradation rate in body. ¹ In addition, the acidic environment induced by byproducts of the degraded PLLA matrix leads an inflammatory response to the implanted site. Magnesium hydroxide (MH) nanoparticles have been used as a mechanical reinforcing agent and pH neutralizing agent for biomaterials, such as PLLA. ² In this study, bulk modification of PLLA was performed with addition of thermal stabilizers, plasticizer, and MH nanoparticles to improve their thermal and mechanical properties and suppress acidic byproduct-induced inflammatory response. We believe that the bulk modification of biodegradable PLLA using functional additives will have great potential in various biomedical applications.