Bandgap and visible-light-induced photocatalytic performance and dye degradation of silver doped HAp/TiO2 nanocomposite by sol-gel method and its antimicrobial activity

Abstract

Silver doped hydroxyapatite and titanium oxide nanocomposites have been obtained by sol-gel techniques with novel antimicrobial activities for biomedical applications. The synthesis of Ca_10-X Ag_X (PO₄)₆(OH)₂ along with titanium oxide nanoparticles with X_Ag = 0 (HAp/TiO₂), 0.1, 0.25 and 0.5 (Ag:HAp/TiO₂-NCS) was performed. The developed crystalline phase was characterized via X-ray diffraction (XRD), and the morphological features were executed via scanning and transmission electron microscopy (SEM/TEM). The HAp/TiO₂ and silver doped HAp/TiO₂ nanocomposites were spherical grains, with needle and flower-like structures. XRD examination revealed the crystalline phases of HAp/TiO₂ and Ag-doped HAp/TiO₂ nanocomposites. The crystallite size of HAp/TiO₂ and Ag-doped HAp/TiO₂ nanocomposites determined from the XRD pattern was ranged between 16 nm and 20 nm. The FTIR analysis confirms the presence of stretching and vibrational peaks for the presence of silver doped HAp/TiO₂. The EDAX analysis showed the existence of major elements of HAp/TiO₂ and Ag-HAp/TiO₂ nanostructured composites. HAp/TiO₂ and silver doped HAp/TiO₂ were active against both Gram-positive and Gram-negative bacteria such as, E. coli (MTCC 443), S. typhi (MTCC 733), and S. aureus (MTCC 3160). The photocatalytic absorption spectrum implied an increased absorption rate of methylene blue by HAp/TiO₂ and silver doped HAp/TiO₂ nanocomposites. The photocatalytic activity revealed that 50% Ag doped HAp/TiO₂ optimally improved photocatalytic activity.

Keywords: Antimicrobial; Dye degradation; Hydroxyapatite; Nanocomposite; Photocatalytic.