Effect of Silver Decoration and Light Irradiation on the Antibacterial Activity of TiO₂ and ZnO Nanoparticles

Abstract

This work emphasizes to use silver decorative method to enhance the antibacterial activity of TiO2 and ZnO nanoparticles. These silver decorated nanoparticles (hybrid nanoparticles) were synthesized by using sodium borohydride as a reducing agent, with the weight ratio of Ag precursors: oxide nanoparticles = 1: 30. The morphology and optical property of these hybrid nanoparticles were investigated using transmission electron microscopy (TEM) and UV–vis spectroscopy. The agar-well diffusion method was used to evaluate their antibacterial activity against both Staphylococcus aureus and Escherichia coli bacteria, with or without light irradiation. The TEM images indicated clearly that silver nanoparticles (AgNPs, 5-10 nm) were well deposited on the surface of nano-TiO2 particles (30-60 nm). Besides, smaller AgNPs (< 2 nm) were dispersed on the surface of nano-ZnO particles (20-50 nm). UV-vis spectra confirmed that the hybridization of Ag and oxide nanoparticles led to shift the absorption edge of oxide nanoparticles to the lower energy region (visible region). The antibacterial tests indicated that both oxide pure nanoparticles did not exhibit inhibitory against bacteria, with or without light irradiation. However, the presence of AgNPs in their hybrids, even at low content (< 40 mg/mL) leads to a good antibacterial activity and the higher inhibition zones under light irradiation as compared to that in dark was observed.

Discovery and mechanistic characterization of a structurally-unique membrane active peptide

“…A unifying feature for MAPs is their amphipathicity with different degrees of cationicity and hydrophobicity, possibly contributing to their membrane activity 38,39,40 . Some of the most intensely studied MAPs are ones that exhibit a primarily a-helical structure, either in solution or upon interacting with a membranous environment, as this might provide them with a continuous hydrophobic surface 1,41 .…”

Đặc điểm dịch tễ học và một số yếu tố liên quan tới viêm tiểu phế quản mức độ nặng ở trẻ em nhiễm virus hợp bào hô hấp

“…Pediatr Infect Dis J. 2003; 22(6): 483-490. doi:10.1097/01.inf.0000069765.43405.3b. This is a cross-sectional descriptive study aimed to assess the epidemiological characteristics of severe bronchiolitis in children with respiratory syncytial virus (RSV) and explore factors associated with severe infection.…”