DFT theoretical and experimental investigation of gelatin-loaded niobium-doped calcium apatite ceramics to elucidate its structural and electronic characteristics

Owing to its ability to imitate the characteristics of natural bones, the biomedical community has extensively investigated the use of biphasic ceramic material comprising of hydroxyapatite (HAP) and tricalcium phosphate (β-TCP), for hard-tissue engineering purposes, particularly bone restoration. It is believed to enhance the material's breakdown process and promote the formation of new bone when combined with gelatin to produce a composite. However, this is contingent upon the material's electrical and structural characteristics. Gelatin/NbHAP (GNbHAP), and gelatin/HAP (GHAP) prepared by solvent casting differ in structural, and electronic properties. This difference is determined experimentally using characterization methods (such as X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and Raman spectroscopy) and theoretically, using density functional theory (DFT) in the Gaussian 09 program utilizing the B3LYP functional method. XRD tests on the gelatin based HAP composites with and without niobium doping show that the composites are less crystalline, with weak crystalline peaks for gelatin, HAP, and niobium at their own 2θ values when they are pure. The FTIR measurements reveal the functional groups for the title structures under study. Several electronic parameters evaluated by theoretical study (DFT) show that GNbHAP induces significant changes in reactivity indices when compared to GHAP. Moreover, the GNbHAP composite is a better bioceramic material for hard-tissue engineering usage than the GHAP composite, as evidenced by alterations in the theoretical parameters including polarizability, dipole moment, and electric susceptibility. • Gelatin-HAP (GHAP) and its niobium doped system showed poor crystallinity. • Changes in global reactivity and electronic parameters are observed for gelatin-HAP. • GNbHAP shows a better material breakdown process and encourages new bone formation. • Theoretical bandgap energies of the composites agree with the experimental values.