Multifunctional Xanthan Gum–Hydroxyapatite Composite with Enhanced Dye Adsorption, Antibacterial Activity, and Cytocompatibility

Hydroxyapatite (HAp) is a promising biomaterial with potential environmental and biomedical applications; however, its surface properties and functional performance can be improved through polymer modification. In this study, a novel hydroxyapatite xanthan (HAp-XAn) composite was developed and investigated for both environmental and biomedical applications. Comprehensive structural and surface analyses were carried out using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM) measurements. The biocompatibility of HAp and the HAp-XAn composite was assessed with the aid of the MG63 cell line using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay. The findings indicate that both HAp and HAp-XAn exhibit good in vitro cytocompatibility and favorable interactions with osteoblast-like cells, supporting their potential for use in bone-related biomedical applications. The antibacterial properties of HAp and HAp-XAn composites were studied in vitro against Staphylococcus aureus ATCC 25923 (S. aureus) and Escherichia coli ATCC 25922 (E. coli) bacterial strains. The results of the antibacterial assay revealed that HAp-XAn exhibited an improved antibacterial activity compared with HAp. The antibacterial assay highlighted that the inhibitory effect of HAp-XAn increased with the increase in incubation period. The HAp-XAn composite exhibited enhanced methylene blue (MB) adsorption compared with HAp, with the adsorption performance strongly dependent on pH, contact time, and initial dye concentration. Kinetic and equilibrium analyses indicated that the adsorption process was best described by the pseudo-second-order kinetic model and Langmuir isotherm. Overall, the incorporation of xanthan gum improved the adsorption and biological properties of HAp, demonstrating the potential of HAp-XAn as a multifunctional material for dye removal and biomedical applications.