Potent antibacterial activity of a novel silver nanoparticle-halloysite nanotube nanocomposite powder.

Halloysite nanotubes (HNTs), natural nanotube, have been developed as a support for loading of antibacterial agents. Firstly, HNTs were modified by silane coupling agent (KH-792). And then, modified HNTs were immersed in silver nitrate solution and a complex reaction between the two amino groups of KH-792 and silver ions formed, leading to large clusters on the surface of HNTs. Finally, these silver containing clusters were converted into silver nanoparticles (Ag NPs) with about 5nm diameter by reduction process. A new antibacterial agent, Ag NPs/HNTs, was characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and scanning transmission electron microscopy-energy dispersive X-ray analysis (STEM-EDX). The antibacterial test indicated that Ag NPs/HNTs showed good antibacterial performance against Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus).