All-biobased polylactic acid/cellulose nanofiber tissue engineering scaffolds molded by microcellular foaming

Tissue engineering scaffolds (TESs) play a crucial role in regenerative medicine by providing structural support for cell adhesion, proliferation, differentiation, and tissue formation. However, developing TESs that simultaneously meet the requirements of biocompatibility, mechanical robustness, structural controllability, and cost-effective manufacturing remains a significant challenge. In this study, fully bio-based TESs were fabricated using polylactic acid (PLA) reinforced with cellulose nanofibers (CNFs) via a green and scalable microcellular injection molding process. The incorporation of CNFs derived from renewable biomass, significantly enhanced the rheological property, crystallinity, and foaming behavior of PLA. Compared with the PLA foams fabricated by regular foam injection molding (RFIM), the pore size of the PLA/CNF foam fabricated by mold-opening foam injection molding (MOFIM) was decreased by 96.5%, with the pore density increased by 7 orders of magnitude. The tensile toughness and impact strength were improved by up to 276.5% and 40.0%, reaching 6.4 MJ/m³ and 2.1 kJ/m², respectively. Thanks to the improved scaffold architecture and introduced hydroxyl groups, the PLA/CNF foam enabled outstanding cell viability and proliferation, as evidenced by abundant live cells, uniform distribution, and minimal cell death. This work provides a sustainable and scalable strategy for developing high-performance TESs with tunable pore structures for biomedical applications.