Dual Applicability of Polyaniline Coated Gold Nanorods: A Study of Antibacterial and Redox Activity

Abstract

Non-agglomerated, dual-purpose monodispersed gold nanorods (GNRs) were synthesized by using a seed-mediated method, and subsequent in situ chemical polymerization yielded polyaniline-coated gold nanorods (PANI-GNRs). The synthesized GNRs and PANI-GNRs were characterized by electron microscopic analyses, selected-area electron diffraction patterns, and element analyses. The prepared nanomaterials had an average length of 40±0.4 nm and a diameter of 15±0.2 nm. Furthermore, the PANI coating around the GNRs had a thickness of ~21 nm. These nanomaterials were also characterized by ultraviolet- visible and Fourier transform-infrared spectroscopies. While the absorption peaks of GNRs were observed at 520 and 675 nm, those of PANI-GNRs showed absorption maxima at 325 and 665 nm. The combination of 0.91 vol% of aniline with 5 mL of GNRs provided better electrochemical properties at 0.52 V and 1.30 V. The minimum inhibitory concentrations of laser-irradiated PANI-GNRs, PANI-GNRs, and laser-irradiated GNRs against Escherichia coli and Staphylococcus aureus were determined by using the micro-dilution method and compared to those of kanamycin (standard drug), revealing the significant bactericidal activity of laser-irradiated PANI-GNRs. This activity of the PANI-GNRs was also supported by the results of fluorescence and atomic force microscopy imaging. Thus, the synthesized nanomaterials can be potentially utilized for waste water treatment and biomedical/ pharmaceutical applications.