Green Synthesis of Oat-Derived Carbon Quantum Dot/Gelatin Hydrogel Scaffolds: Enhanced Structural Stability and Bioactivity for Potential Bone Repair

The development of sustainable, biocompatible scaffolds with enhanced structural stability remains a primary challenge in bone tissue engineering. In this study, structurally reinforced nanocomposite scaffolds were successfully fabricated by integrating green-synthesized carbon quantum dots (CQDs) into a gelatin (G) matrix, offering an innovative platform that mimics the organic–inorganic interfaces of natural bone tissue. The CQDs were derived from oatmeal via a sustainable, green hydrothermal route, serving simultaneously as zero-dimensional reinforcing fillers and bioactive agents within the biopolymer network. To ensure an additive-free fabrication process that avoids toxic chemical cross-linkers, dehydrothermal (DHT) treatment was employed, successfully modulating the interfacial and chemical cross-linking interactions between the gelatin chains and the oxygen-rich surface groups of the CQDs. Structural characterization confirmed the uniform dispersion of CQDs (average diameter 7–8 nm) within the porous gelatin framework. The incorporation of CQDs significantly improved the physicochemical properties of the scaffolds; the G/CQD 5% formulation emerged as the optimal composition, exhibiting a 118% increase in compression modulus compared to pristine gelatin. The composite demonstrated tuned swelling kinetics and a significantly reduced degradation rate, restricting mass loss after 14 days of incubation to approximately 24% compared to 40% for pristine gelatin, which is essential for maintaining a structural template during the initial stages of tissue formation. Bioactivity assays in simulated body fluid (SBF) confirmed the rapid, biomimetic induction of a crystalline hydroxyapatite layer with a natural Ca/P ratio of 1.61 within 14 days. Furthermore, preliminary in vitro assessments using Human Skin Fibroblasts (HSFs) confirmed excellent general cytocompatibility, with cell viability exceeding 90%. This study highlights the unique potential of utilizing biomass-derived carbon nanostructures and clean manufacturing processing to engineer multifunctional scaffolds with enhanced structural stability and intrinsic bioactivity for potential bone defect repairs.