Antibacterial wallpaper through nanotechnology. ‘Zinc oxide (ZnO) is considered a workhorse of technological development exhibiting excellent electrical, optical, and chemical properties with a broad range of applications as semiconductors, in optical devices, piezoelectric devices, surface acoustic wave devices, sensors, transparent electrodes, solar cells, antibacterial activity etc. Thin films or nanoscale coating of ZnO nanoparticles on suitable substrates are viewed with great interest for their potential applications as substrates for functional coating, printing, UV inks, e-print, optical communication (security-papers), protection, barriers, portable energy, sensors, photocatalytic wallpaper with antibacterial activity etc. Various methods like chemical, thermal, spin coating, spray pyrolysis, pulsed laser deposition have been used for thin film formation but they are limited to solid supports such as metal, metal oxides, glass or other thermally stable substrates. Coating of ZnO nanoparticles on thermolabile surfaces is scarce and coating on paper was yet to be reported. Paper as a substrate is an economic alternative for technological applications having desired portability and flexibility. Researchers from the National Tsing Hua University in Taiwan found a way of coating paper with ZnO nanoparticles using ultrasound.’
Green Chemistry Article: Preparation and characterization of ZnO nanoparticles coated paper and its antibacterial activity study, Kalyani Ghule, Green Chem., 2006, DOI: 10.1039/b605623g. Abstract: Coating of ZnO nanoparticles on paper surface has potential technological applications. With this motivation, a simple approach of ultrasound assisted coating of paper with ZnO nanoparticles (20 nm) without the aid of binder is reported for the first time in this work. The ultrasound assisted coating approach concurs with green chemistry as it is simple and environmentally friendly. Scanning electron microscope is used to characterize the surface morphology showing ZnO nanoparticles bound to cellulose fibers. Further characterization of coated surface is performed by attenuated total reflectance-Fourier transform infrared, X-ray diffraction, and time-of-flight secondary ion mass spectrometry in positive ion detection mode along with its imaging capability. The effect of ultrasound irradiation time on ZnO nanoparticles loading is estimated by thermogravimetric analysis. A plausible coating mechanism is proposed. The ZnO nanoparticles coated paper is found to possess antibacterial activity against Escherichia coli 11634.