Long-term antibacterial protected cotton fabric coating by controlled release of chlorhexidine gluconate from halloysite nanotubes

In this work, an environmentally friendly antibacterial composite was prepared by loading natural halloysite nanotubes (HNTs) with chlorhexidine gluconate (CG). Fourier transform-infrared spectroscopy and X-ray diffraction demonstrated that CG could be successfully loaded on HNTs without changing the crystalline structure of HNTs. In vitro drug release assay showed that CG could be released from HNTs in a sustainable manner and could last as long as about ten days. Inhibition zone test suggested that the new composite displayed significant bacterial killing activity. In addition, the composite was deposited on the surface of cotton fabric by dip-coat technique. Our results showed that the HNTs/CG composite could be distributed on the cotton fabric and possessed better thermal stability and hydrophilicity properties than raw cotton fabric. HNTs/CG-coated cotton fabric exhibited over 98% bacterial reduction of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, and still showed over 90% antibacterial activity even after being washed 20 times. MTT test and animal skin irritation tests indicate that HNTs/CG-coated cotton was nontoxic to mouse fibroblast cells (L929) and gave no irritation to the rabbit's skin. Thus, HNTs/CG composite is a safe and promising antibacterial agent and has great potential application in the textile field.