Development of a Gelatin-Based Composite Hydrogel Powder with Kaolin and Sr-Doped Hydroxyapatite for Dual Hemostatic and Osteogenic Potential

Effective management of postextraction wounds requires biomaterials that can simultaneously achieve rapid hemostasis and promote bone regeneration. This study aims to develop a multifunctional hydrogel powder incorporating gelatin (Gel), oxidized dextran (ODex), kaolin (KC), and strontium-doped hydroxyapatite (Sr-HA) for synergistic hemostatic and osteoinductive effects. Sr-HA was synthesized and characterized using FTIR, XRD, TEM, and XPS to confirm successful strontium incorporation. Gel/ODex-based composite hydrogels were prepared via Schiff base cross-linking, and their rheological properties, swelling behavior, degradation profiles, and microstructure were systematically evaluated. Hemostatic performance was assessed using rat liver and tail amputation models. Cytocompatibility and osteogenic potential were examined through cell viability assays, ALP and ARS staining, and expression analysis of osteogenesis-related genes and proteins via RT-qPCR and Western blotting. Sr-HA exhibited enhanced crystallinity and chemical integration within the crystalline structure of HA. The Gel/ODex/KC/Sr-HA hydrogel showed improved mechanical strength, controlled degradation, and a porous microstructure. <i>In vivo</i>, it significantly reduced blood loss and shortened hemostasis time. <i>In vitro</i>, the material demonstrated excellent cytocompatibility, promoted early osteogenic differentiation as indicated by elevated ALP activity, and enhanced late-stage mineralization. Gene and protein expression analyses further confirmed upregulation of <i>RUNX2</i>, <i>COL1A1</i>, <i>OPN</i>, and <i>OCN</i> in Sr-containing groups. The Gel/ODex/KC/Sr-HA composite hydrogel powder provides a promising dual-function platform for postextraction wound management, offering rapid bleeding control and promoting osteogenic differentiation <i>in vitro</i>. These findings suggest that the composite possesses integrated hemostatic and osteoinductive potential, supporting its promise for future <i>in vivo</i> bone regeneration studies and clinical translation.