Effect of Light on the Antifungal Activity of Submicron Particles Based on Tungsten Oxide

The behavior of semiconducting electrodes for photoelectrolysis of water is examined in terms of the physical properties of the semiconductor. The semiconductor‐electrolyte junction is treated as a simple Schottky barrier, and the photocurrent is described using this model. The approach is appropriate since large‐band‐gap semiconductors have an intrinsic oxygen overpotential which removes the electrode reaction kinetics as the rate‐limiting step. The model is successful in describing the wavelength and potential dependence of the photocurrent in WO3 and allows a determination of the band gap, optical absorption depth, minority‐carrier diffusion length, flat‐band potential, and the nature of the fundamental optical transition (direct or indirect). It is shown for WO3 that minority‐carrier diffusion plays a limited role in determining the photoresponse of the semiconductor‐electrolyte junction. There are indications that the diffusion length in this low carrier mobility material is determined by diffusion‐controlled bulk recombination processes rather than the more common trap‐limited recombination. It is also shown that the fundamental optical transition is indirect and that the band‐gap energy depends relatively strongly on applied potential and electrolyte. This effect seems to be the result of field‐induced crystallographic distortions in antiferroelectric WO3.

Photoelectrolysis and physical properties of the semiconducting electrode WO2

Antifungal activity of zinc oxide nanoparticles against Botrytis cinerea and Penicillium expansum

Metal oxide nanoparticles have marked antibacterial activity. The toxic effect of these nanoparticles, such as those comprised of ZnO, has been found to occur due to an interaction of the nanoparticle surface with water, and to increase with a decrease in particle size. In the present study, we tested the ability of ZnO nanoparticles to affect the viability of the pathogenic yeast, Candida albicans (C. albicans). A concentration-dependent effect of ZnO on the viability of C. albicans was observed. The minimal fungicidal concentration of ZnO was found to be 0.1 mg ml(-1) ZnO; this concentration caused an inhibition of over 95% in the growth of C. albicans. ZnO nanoparticles also inhibited the growth of C. albicans when it was added at the logarithmic phase of growth. Addition of histidine (a quencher of hydroxyl radicals and singlet oxygen) caused reduction in the effect of ZnO on C. albicans depending on its concentration. An almost complete elimination of the antimycotic effect was achieved following addition of 5 mM of histidine. Exciting the ZnO by visible light increased the yeast cell death. The effects of histidine suggest the involvement of reactive oxygen species, including hydroxyl radicals and singlet oxygen, in cell death. In light of the above results it appears that metal oxide nanoparticles may provide a novel family of fungicidal compounds.

https://iopscience.iop.org/article/10.1088/0957-4484/22/10/105101/pdf

Antifungal activity of ZnO nanoparticles--the role of ROS mediated cell injury.

FUNDAMENTALS: ACTIVE SPECIES, MECHANISMS, REACTION PATHWAYS Identification and Roles of the Active Species Generated on Various Photocatalysts Photocatalytic Reaction Pathways - Effects of Molecular Structure, Catalyst, and Wavelength Catalytic Mechanisms and Reaction Pathways Drawn from Kinetic and Probe Molecules IMPROVING THE PHOTOCATALYTIC EFFICACY Design and Development of Active Titania and Related Photocatalysts Modified Photocatalysts Immobilisation of a Semiconductor Photocatalyst on Solid Supports: Methods, Materials and Applications Wastewater Treatment Using Highly Functional Immobilized TiO2 Thin Film Photocatalysts Sensitization of Titania Semiconductors: A Promising Strategy to Utilize Visible Light Photoelectrocatalysis for Water Purification EFFECTS OF PHOTOCATALYSIS ON NATURAL ORGANIC MATTER AND BACTERIA Photocatalysis of Natural organic Matter in Water: Characterization and Treatment Integration Waterborne E. coli Inactivation by TiO2 Photo-Assisted Processes: A Brief Overview MODELING. REACTORS. PILOT PLANTS Photocatalytic Treatment of Water: Irradiance Influences A Methodology for Modeling Slurry Photocatalytic Reactors for Degradation of an Organic Pollutant in Water Design and Optimization of Photocatalytic Water Purification Reactors Photocatalysis Soliar Pilot Plants. Commercially Available Reactors

Photocatalysis and water purification : from fundamentals to recent applications

Background/Purpose Silver nanoparticles are receiving increasing attention in biomedical applications. This study aims at evaluating the antifungal properties of silver nanoparticles against the pathogenic fungus Trichosporon asahii . Methods The growth of T. asahii on potato dextrose agar medium containing different concentrations of silver nanoparticles was examined and the antifungal effect was evaluated using minimum inhibitory concentration. Scanning and transmission electron microscopy were also used to investigate the antifungal effect of silver nanoparticles on T. asahii . Results Silver nanoparticles had a significant inhibitory effect on the growth of T. asahii . The minimum inhibitory concentration of silver nanoparticles against T. asahii was 0.5 μg/mL, which was lower than amphotericin B, 5-flucytosine, caspofungin, terbinafine, fluconazole, and itraconazole and higher than voriconazole. Silver nanoparticles obviously damaged the cell wall, cell membrane, mitochondria, chromatin, and ribosome. Conclusion Our results demonstrate that silver nanoparticles have good antifungal activity against T. asahii . Based on our electron microscopy observations, silver nanoparticles may inhibit the growth of T. asahii by permeating the fungal cell and damaging the cell wall and cellular components.

Effect of Light on the Antifungal Activity of Submicron Particles Based on Tungsten Oxide

References

Photoelectrolysis and physical properties of the semiconducting electrode WO2

Antifungal activity of zinc oxide nanoparticles against Botrytis cinerea and Penicillium expansum

Antifungal activity of ZnO nanoparticles--the role of ROS mediated cell injury.

Photocatalysis and water purification : from fundamentals to recent applications

The antifungal effect of silver nanoparticles on Trichosporon asahii