Chitosan microporous foam filled 3D printed polylactic acid-pearl macroporous scaffold: Dual-scale porous structure, biological and mechanical properties.

A bone scaffold with well-designed porous structure and material composition is essential for bone regeneration as it supports various biological functions. In this study, a dual-scale porous polylactic acid-pearl/chitosan (PLA-P/CS) scaffold was developed by integrating 3D printing and conventional techniques. An interconnected macroporous PLA-P scaffold with pore sizes ranging from 680-800 μm was fabricated using FDM 3D printing. Additionally, a microporous CS foam with pore sizes of 10-200 μm was prepared via freeze-drying within the macropores of the 3D-printed scaffold. The microporous CS foam enhanced the scaffold's hydrophilicity while preserving its favorable mechanical properties. Moreover, the dual-scale porous structure demonstrated improved biomineralization, due to its larger specific surface area and increased nucleation sites, along with the electrostatic adsorption provided by the amino and hydroxyl functional groups of chitosan. Furthermore, cell culture experiments revealed the dual-scale porous structure, and the effects of CS enhanced the cellular response of BMSCs. More importantly, a 12-week in vivo study on rat skull defect repair demonstrated that the dual-scale porous PLA-P/CS scaffold exhibited enhanced bone formation. These findings suggest that designing a graded porous structure and optimizing material composition can effectively enhance biological responses, thereby facilitating bone regeneration.