Graphene Oxide/Hydroxyapatite/Silver (rGO/HAP/Ag) nanocomposite: Synthesis, characterization, catalytic and antibacterial activity

Abstract

In this paper, a novel ternary nanocomposite namely reduced graphene oxide/hydroxyapatite/silver (rGO/HAP/Ag) was prepared by a simple hydrothermal method using graphene oxide nanosheets, Ca(NO₃)₂, (NH₄)₂HPO₄, and AgNO₃ as starting materials. The as-prepared nanocomposite was characterized by using various photophysical techniques including Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). Additionally, the antibacterial and catalytic activities of the nanocomposite were evaluated. The results showed that the rGO/HAP/Ag nanocomposite exhibited high performance in the reduction of toxic nitro compounds (4-nitrophenol, 2-nitrophenol, 4-nitroaniline, and 2-nitroaniline) into the less toxic corresponding amines using NaBH₄ within 21-42 min with a rate constant equal to 0.1646, 0.0898, 0.1071 and 0.2 min^-1, respectively. Moreover, the rGO/HAP/Ag nanocomposite could be separated from the reaction mixture due to its heterogeneous nature and reused without any change in structure. In addition, the antibacterial activity of the rGO/HAP/Ag nanocomposite by disk diffusion method was evaluated against Gram-positive bacteria (<em>Bacillus cereus</em> and <em>Staphylococcus aureus</em>) and Gram-negative bacteria (<em>Escherichia coli</em> and <em>Klebsiella pneumonia</em>). The results showed that this novel ternary nanocomposite has good antibacterial activity against Gram-positive bacteria.