Antibacterial effectiveness of metallic nanoparticles deposited on water filter paper by magnetron sputtering

There is a high interest in nanomaterials that effectively deactivate different types of bacteria and provide alternatives to chemical substances and antibiotics. This research is reporting the antibacterial performance in contaminated water of flexible structures consisting of thin metallic films deposited on water filter paper. Coatings were performed at low temperatures using high vacuum direct current (DC) magnetron sputtering deposition. The effectiveness of different metallic nanoparticles in functionalizing the fibrous surfaces and deactivating bacteria from water was tested during the experiment. The surface morphology of coated filter paper was characterized using digital optical microscopy and scanning electron microscopy (SEM). The fibrous substrates provided large area of exposure for metals to bacteria. X-ray diffraction and Energy Dispersive X-ray Spectrometer (EDS) were used to identify the chemical composition of the structures. The antibacterial performance was evaluated against Escherichia coli (E-coli) and total coliforms using the standardized membrane filtering technique for water and wastewater examination. Silver and copper effectively deactivate coliforms from water with copper providing higher performance. The antibacterial effect of copper and silver coatings with different thicknesses as well as the nanolayered combination of the two metals was also investigated. It was observed that coatings remained adherent to substrates and the antibacterial performance was maintained over consecutive exposures.