| 1. |
- Mohl, Melinda, et al.
(author)
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Titania nanofibers in gypsum composites : an antibacterial and cytotoxicology study
- 2014
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In: Journal of Material Chemistry B. - : Royal Society of Chemistry. - 2050-750X .- 2050-7518. ; 2:10, s. 1307-1316
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Journal article (peer-reviewed)abstract
- Further developments of antibacterial coatings based on photocatalytic nanomaterials could be a promising route towards potential environmentally friendly applications in households, public buildings and health care facilities. Hereby we describe a simple chemical approach to synthesize photocatalytic nanomaterial-embedded coatings using gypsum as a binder. Various types of TiO2 nanofiber-based photocatalytic materials (nitrogen-doped and/or palladium nanoparticle decorated) and their composites with gypsum were characterized by means of scanning (SEM) and transmission (TEM) electron microscopy as well as electron and X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX) techniques. These gypsum-based composites can be directly applied as commercially available paints on indoor walls. Herein we report that surfaces coated with photocatalytic composites exhibit excellent antimicrobial properties by killing both methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA) under blue light. In the case of MSSA cells, the palladium nanoparticle-decorated and nitrogen-doped TiO2 composites demonstrated the highest antimicrobial activity. For the MRSA strain even pure gypsum samples were proven to be efficient in eradicating Gram-positive human pathogens. The cytotoxicity of freestanding TiO2 nanofibers was revealed by analyzing the viability of HeLa cells using MTT and fluorescent cell assays.
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| 2. |
- Sarkar, Anjana, 1978-, et al.
(author)
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Photocatalytic activity of TiO2 nanoparticles : effect of thermal annealing under various gaseous atmospheres
- 2012
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In: Nanotechnology. - : Institute of Physics Publishing (IOPP). - 0957-4484 .- 1361-6528. ; 23:47, s. 475711-475719
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Journal article (peer-reviewed)abstract
- The structure, composition and photocatalytic activity of TiO2 nanoparticles annealed in various gas atmospheres (N2, NH3 and H2) were studied in this work. The effect of treatment on crystal structure, particle size, chemical composition and optical absorbance were assessed by means of x-ray diffraction, transmission electron microscopy, x-ray photoelectron spectroscopy and diffuse optical reflectance/transmittance measurements, respectively. Photocatalytic properties of the materials were evaluated by three different methods: degradation of methyl orange in water, killing of Staphylococcus aureus bacteria and photogeneration of radicals in the presence of 3-carboxy-2,2,5,5-tetramethyl pyrrolidine-1-oxyl (PCA) marker molecules. The results indicate that the correlation between pretreatment and the photocatalytic performance depends on the photocatalytic processes and cannot be generalized.
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| 3. |
- Trunina, Natalia A., et al.
(author)
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Monitoring of TiO2 and ZnO Nanoparticle Penetration Into Fnamel and Dentine of Human Tooth IN VITRO and Assessment of Their Photocatalytic Ability
- 2014
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In: IEEE Journal of Selected Topics in Quantum Electronics. - 1077-260X .- 1558-4542. ; 20:3, s. Article Number: UNSP 7300108-
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Journal article (peer-reviewed)abstract
- Penetration of nanoparticles into tooth enamel and dentine is of significant interest upon solving problems related to reduction of tooth sensitivity, enamel strengthening, disinfection, restoration as well as cosmetic bleaching. This paper aims at studying the process of nanoparticle penetration into tooth enamel and dentine samples using nonlinear optical microscopy and at investigating the influence of the same nanoparticles on the generation of free radicals using the electronic paramagnetic resonance technique. We presented in vitro measurements demonstrating that nonlinear optical microscopy, namely, two-photon-excited autfluorescence, second harmonic generation, and hyper-Rayleigh scattering-based microscopy can be used for monitoring and imaging TiO2 and ZnO nanoparticle penetration into tooth tissues. The results indicate that ZnO nanoparticles penetrated into the human tooth enamel and dentine up to a depth of 12 and 45 mu m, respectively, and TiO2 nanoparticles penetrated into dentine to a depth of 5 mu m. The penetration mainly- occurs along either enamel rods or dentinal tubules. Permeability of the dentine was found to be higher than that of enamel (for ZnO particles) by one order of magnitude and the diffusion rate was affected by the particle size being higher for smaller, submicron particles (ZnO) than for micronsized aggregates (TiO2 I. Nitrogen-doped TiO2 nanoparticles generate more radicals in the UV-VIS spectral range in comparison to pristine TiO2 (anatase) and ZnO nanoparticles, therefore, they can potentially be used for disinfection purposes of superficial tooth areas (up to 5-mu m deep).
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