Controlled release and long-term antibacterial activity of reduced graphene oxide/quaternary ammonium salt nanocomposites prepared by non-covalent modification

In order to control the long-term antibacterial property of quaternary ammonium salts, dodecyl dimethyl benzyl ammonium chloride (rGO-1227) and rGO-bromohexadecyl pyridine (rGO-CPB) were self-assembled on surfaces of reduced graphene oxide (rGO) via pi-pi interactions. The obtained rGO-1227 and rGO-CPB nanocompounds were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The antibacterial activities were evaluated on Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Both rGO-CPB and rGO-1227 reduced the cytotoxicity of the pure antimicrobial agents and presented strong antimicrobial properties. Especially, CPB could be loaded efficiently on the surface of rGO via pi-pi conjugate effect, which resulted in a nanocomposite presenting a long-term antibacterial capability due to the more important quantity of free pi electrons compared to that of 1227. When comparing the advantages of both prepared nanocomposites, rGO-CPB displayed a better specific-targeting capability and a longer-term antibacterial property. (C) 2016 Elsevier B.V. All rights reserved.