Composite scaffolds of carboxymethyl cellulose enriched with porous graphitic carbon nitride nanosheets: A novel approach to bone defect repair

This study investigated the regenerative capacity of composite scaffolds based on carboxymethyl cellulose and hydroxyapatite containing g-C₃N₄ for promoting bone defect regeneration. The investigation included both in vitro and in vivo assessments. To select the optimal composite scaffold, the Box-Behnken design method was employed, considering four factors ([nHAp], [g-C₃N₄], stirring speed, and stirring time) at three levels. By determining the appropriate responses (percentage of porosity and density), 27 modes were proposed for the construction of composite scaffolds. The predicted values of the independent factors for the optimal formulation were [nHAp] = 0.6 g/mL, [g-C₃N₄] = 0.15 mg/mL, stirring speed = 600 rpm, and stirring time = 35 min. The results of XRD, FTIR, FE-SEM, TGA, swelling, biodegradability, and mechanical studies confirmed that the fabricated scaffold sample exhibited ideal behavior for use in bone tissue engineering. Scaffolds were tested in a rabbit model, and radiographs were prepared. The clinical results showed that rabbits treated with scaffolds containing a high amount of g-C₃N₄ exhibited higher bone regeneration compared to those treated with lower amounts of g-C₃N₄. According to the study, CCH/g-C₃N₄ scaffolds with enhanced porosity, mechanical strength, bioactivity, and biocompatibility were achieved through optimization utilizing the Box-Behnken Design (BBD). These improved characteristics make the scaffolds attractive candidates for tissue engineering applications.