Cation-surface RADA16-based self-assembling peptide hydrogel with high adhesion and osteogenesis promoting bone regeneration.

Despite the widespread use of various bone repair materials, ideal scaffolds with excellent cell adhesion and satisfactory osteogenesis are still urgently needed for bone defect regeneration. The self-assembling peptide RADA16‑I hydrogel has been widely used for bone defect repair owing to its excellent biocompatibility and favorable cytocompatibility, yet its application is limited by insufficient osteogenesis and weak cell adhesion. In this study, a novel peptide RADA16‑TRSAW was designed by conjugating the positively charged osteogenic short peptide TRSAW to RADA16‑I via solid-phase synthesis. TRSAWmax (mixture of RADA16‑TRSAW and RADA16‑I as 1:1) carried a net positive charge, maintained a stable β‑sheet secondary structure, retained self-assembly capability, and readily formed a hydrogel in PBS. The resulting hydrogel showed a microstructure and rheological properties similar to those of RADA16‑I hydrogel, suitable for cell growth, but with significantly enhanced cell adhesion owing to cationic arginine residues. RNA‑seq confirmed the upregulation of adhesion-related genes and pathways. Moreover, TRSAWmax exhibited excellent biocompatibility, promoted hMSC osteogenic differentiation through the Src‑Erk pathway in vitro, and demonstrated superior osteogenic capability in vivo. This work provides a highly adhesive and osteogenic peptide hydrogel candidate for accelerating bone tissue regeneration.