Three-dimensional Ag–tannic acid–graphene as an antibacterial material

Abstract

In this paper, a facile, economical and environmentally friendly synthetic method was developed to fabricate a Ag nanoparticle (NP) decorated graphene (GR/TA/Ag) composite with tannic acid (TA) as a reducing agent and stabilizing agent. The GR/TA/Ag composite was fully characterized using Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible absorption spectroscopy (UV-vis), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that Ag NPs with diameters of up to 6 nm were homogeneously and uniformly deposited on graphene sheets. With an increasing concentration of AgNO₃ used for immersion, the amount of Ag NPs loaded kept increasing without aggregation or deformation. The antibacterial properties of the GR/TA/Ag composite were studied using Gram-negative E. coli ATCC 25922 and Gram-positive S. aureus ATCC 6538 via both the disk diffusion method and the shaking flask method. The disk diffusion method results showed that the synthesized GR/TA/Ag composite had great release antibacterial properties owing to the loading of Ag NPs. In addition, the presence of TA gave the composite good non-release antibacterial properties, based on the results of the shaking flask method. The ingenious combination of the release-killing capabilities of Ag NPs and the contact-killing capabilities of TA bestow two-level antibacterial activity on the GR/TA/Ag composite, promoting the GR/TA/Ag composite as part of a new generation of powerful antibacterial agents with promising applications.