Evaluation of Boron/Strontium Co‐Substituted‐Hydroxyapatite Incorporated Collagen Composite Scaffolds: Physicochemical, Thermal, Mechanical, Biological, and Sustained‐Release Investigations

Abstract

Large bone defects caused by trauma, disease, or aging often exceed the natural regenerative capacity of bone, requiring clinical interventions such as grafts or prosthetic replacements. In native bone, hydroxyapatite nanocrystals are hierarchically embedded within type‐I collagen fibers, providing both mechanical strength and biological functionality. In this study, a collagen‐based composite scaffold containing boron/strontium co‐substituted hydroxyapatite (Col‐BSH) was developed to enhance the bioactivity of collagen through the incorporation of bioactive ions. Composite scaffolds with varying ceramic phase contents (low, medium, high) were characterized in terms of their physicochemical, thermal, and mechanical properties, along with 28‐day boron and strontium release behavior. Thermal analyses revealed improved stability in both Col‐H and Col‐BSH composite series. Mechanical tests demonstrated the Col‐BSH‐M composite with ∼25 wt.% ceramic phase exhibited optimal performance, with a maximum strength of 113.74 ± 5.73 kPa and toughness of 1149.97 ± 38.24 kJ/m3. In vitro release studies indicated boron and strontium release were between 14–18 mg/L and 6–21 mg/L, respectively, for Col‐BSH‐M over 28 days. The composites exhibited good hemocompatibility and cytocompatibility. Furthermore, a preliminary in vivo study conducted at an ectopic site demonstrated the angiogenic and osteogenic properties of Col‐BSH‐M. Consequently, the Col‐BSH‐M scaffold has shown promising potential for bone tissue engineering applications.