Preparation and properties of polydimethylsiloxane-regulated oriented microporous poly (L-lactic acid) biomimetic bone repair materials

Despite the exceptional biocompatibility and degradability of Poly ((L)-lactic acid) (PLLA), its brittleness, low melting strength, and poor bone induction makes it challenging to utilize for bone repair. This study used a simple, efficient solid hot drawing (SHD) method to produce high-strength PLLA, using supercritical CO2 (SC-CO2) foaming technology to give PLLA a bionic microporous structure to enhance its toughness, while precisely controlling micropore homogeneity and improving the melt strength by using Polydimethylsiloxane (PDMS). This PDMS-regulated oriented microporous structure resembled that of natural bone, displaying a maximum tensile strength of 165.9 MPa and a maximum elongation at break of 164.2 %. Furthermore, this bionic structure promoted the polarization of mouse bone marrow macrophages (iBMDM), exhibiting a simultaneous pro- and anti-inflammatory effect. This structure also contributed to the adhesion and growth of mouse embryonic fibroblasts (NIH-3 T3), promoting osteogenic differentiation, which paved the way for developing degradable PLLA bone-repair load-bearing materials.