Modification of SWCNTs with hybrid materials ZnO–Ag and ZnO–Au for enhancing bactericidal activity of phagocytic cells against Escherichia coli through NOX2 pathway

Zinc oxide-silver (ZnO–Ag), and zinc oxide-gold (ZnO–Au) nano-composites were prepared through wet chemical process and laced into single-walled carbon nanotubes (SWCNTs) to yield ZnO–Ag-SWCNTs, and ZnO–Au-SWCNTs hybrids. These nano-composite-laced SWCNTs hybrids were characterized using Raman spectroscopic, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses. The hybrids were evaluated for their effects on phagocytic cells and bactericidal activity against the gram-negative bacteria E. coli. Their phagocytic cell activities and intracellular killing actions were found to be significantly increased, as the ZnO–Ag-SWCNTs and ZnO–Au-SWCNTs nano-hybrids induced widespread clearance of Escherichia coli. An increase in the production of reactive oxygen species (ROS) also led to upregulated phagocytosis, which was determined mechanistically to involve the phagocyte NADPH oxidase (NOX2) pathway. The findings emphasized the roles of ZnO–Ag- and ZnO–Au-decorated SWCNTs in the prevention of bacterial infection by inhibiting biofilm formation, showing the potential to be utilized as catheter coatings in the clinic.