Silk Fibroin-Modified Titanium Implants for Bone Tissue Engineering: Structural Basis, Functionalization and Composite Strategies.

Bone scaffolds represent a common surgical approach for repairing bone defects, and the clinical demand for effective graft substitutes remains high due to the limited availability of autologous bone. Titanium (Ti) and its alloys are widely used as load-bearing implants; however, their inherent biological inertness hinders early osteogenesis and delays osseointegration. With advances in bone tissue engineering, biofunctionalized 3D-printed porous Ti scaffolds have emerged as a promising strategy to overcome these limitations. Among the various biomaterials investigated, silk fibroin (SF) has attracted considerable interest owing to its excellent biocompatibility, controllable biodegradability, tunable mechanical properties, and intrinsic capacity for drug loading. The integration of SF onto Ti scaffolds through coatings, hydrogels, or composite structures mitigates the biological inertness of Ti and confers additional functionalities, such as controlled drug release, osteogenic stimulation, and immunomodulation. This review summarizes the structural characteristics, drug-delivery behavior, and degradation mechanisms of SF, and highlights current evidence on its osteogenic and anti-inflammatory effects both in vitro and in vivo when combined with porous Ti scaffolds. Furthermore, we discuss emerging multifunctional strategies, including composite coatings incorporating hydroxyapatite, metal-ion doping, and SF-based hydrogel systems. Overall, this review provides comprehensive insights into SF-enhanced Ti scaffolds for next-generation bone repair.