Comparative study of surface modification strategies for interfacial regulation of poly(L-lactic acid)/graphene oxide-hydroxyapatite composite scaffolds

Abstract

Achieving simultaneous mechanical robustness and cytocompatibility in polymer-based scaffolds requires precise interfacial regulation at the nanoscale. Herein, graphene oxide-hydroxyapatite (GO-HA) nanohybrids were engineered via three distinct surface modification strategies—tannic acid (TA) adsorption, polydopamine (PDA) deposition, and poly(D-lactide) (PDLA) grafting—to elucidate how interfacial chemistry governs structural evolution and composite performance in Poly(L-lactic acid) (PLLA) matrices. While all modifications preserved hydroxyapatite crystallinity, they induced differentiated interphase architectures: TA introduced molecular-level surface functionalization with minimal aggregation, PDA formed a conformal interphase layer, and PDLA generated polymer-rich encapsulated structures with enlarged dispersion units. Thermal analysis revealed that PDLA grafting maximized crystallinity and thermal stability due to molecular compatibility with PLLA. However, mechanical evaluation demonstrated that GO-HA-TA achieved superior reinforcement, highlighting the importance of balancing interfacial adhesion with polymer chain mobility. Excessive interphase thickening, despite enhancing crystallization, may constrain deformation adaptability. Furthermore, TA-modified scaffolds exhibited improved wettability and uniform surface morphology. Cytocompatibility assays confirmed high cell viability and negligible cytotoxicity across all groups. This study establishes that optimizing cytocompatible composite scaffolds requires not merely maximizing interfacial compatibility, but strategically balancing adhesion and structural discreteness, identifying surface modification strategies as the most effective route for high-performance PLLA/GO-HA scaffolds.