In vitro and in vivo toxicological evaluation of transition metal-doped titanium dioxide nanoparticles: Nickel and platinum.

Transition metal-doped titanium dioxide nanoparticles (M-TiO2 NPs) have been studied to enhance the activity of TiO2 NPs in biomedical applications. In this study, in vitro and in vivo toxicological aspects of M-TiO2 NPs were reported to assess the safety of these materials. M-TiO2 NPs were synthesized via a photo-deposition technique. Nickel (Ni) and platinum (Pt) were used as dopants. Physicochemical properties, cytotoxicity, phototoxicity, gene ontology (GO) and dermal toxicity of M-TiO2 NPs were investigated. Ni-TiO2 (Ni, 1.02%) and Pt-TiO2 (Pt, 0.26%) NPs were sphere shape crystals with nanoscale size. ARPE-19 cells were more susceptible to Pt-TiO2 NPs (EC50, 0.796 mg/mL) than Ni-TiO2 NPs (EC50, 2.945 mg/mL). M-TiO2 NPs were rated as probably phototoxic to phototoxic. GO suggested binding function and metabolic processes as a risk mechanism of M-TiO2 NPs. In vivo toxicological effects of Ni-TiO2 NPs were not observed on body weight, serum aspartate transaminase/alanine transaminase levels, and skin histology at 61.5-6150 mg/kg. Specifically, skin thickness was not significantly modified (max. 33.2 ± 8.7 µm) and inflammation grade was less than level 2 (max. 1.2 ± 0.4). From these results, Ni-TiO2 and Pt-TiO2 NPs show promise as enhanced photocatalysts for safe and sustainable usage.

Photocatalytic antibacterial application of zinc oxide nanoparticles and self-assembled networks under dual UV irradiation for enhanced disinfection.

BACKGROUND: Zinc oxide (ZnO) nanoparticles and their networks have been developed for use in various applications such as gas sensors and semiconductors. AIM: In this study, their antibacterial activity against Escherichia coli under dual ultraviolet (UV) irradiation for disinfection was investigated. MATERIALS AND METHODS: ZnO nanoparticles were synthesized and immobilized onto silicon (Si) wafers by self-assembly. The physicochemical properties and antibacterial activity of ZnO nanoparticles and their networks were evaluated. Gene ontology was analyzed and toxicity levels were also monitored. RESULTS: Synthesized ZnO nanoparticles were spherical nanocrystals (<100 nm; Zn, 47%; O, 53%) that formed macro-mesoporous three-dimensional nanostructures on Si wafers in a concentration-dependent manner. ZnO nanoparticles and their networks on Si wafers had an excellent antibacterial activity against E. coli under dual UV irradiation (>3log CFU/mL). Specifically, arrayed ZnO nanoparticle networks showed superior activity compared with free synthesized ZnO nanoparticles. Oxidative stress-responsive proteins in E. coli were identified and categorized, which indicated antibacterial activity. Synthesized ZnO nanoparticles were less cytotoxic in HaCaT with an IC50 of 6.632 mg/mL, but phototoxic in Balb/c 3T3. CONCLUSION: The results suggested that ZnO nanoparticles and their networks can be promising photocatalytic antibiotics for use in next-generation disinfection systems. Their application could also be extended to industrial and clinical use as effective and safe photocatalytic antibiotics.

Dual UV irradiation-based metal oxide nanoparticles for enhanced antimicrobial activity in Escherichia coli and M13 bacteriophage.

Metal oxide (MO) nanoparticles have been studied as nano-antibiotics due to their antimicrobial activities even in antibiotic-resistant microorganisms. We hypothesized that a hybrid system of dual UV irradiation and MO nanoparticles would have enhanced antimicrobial activities compared with UV or MO nanoparticles alone. In this study, nanoparticles of ZnO, ZnTiO3, MgO, and CuO were selected as model nanoparticles. A dual UV collimated beam device of UV-A and UV-C was developed depending upon the lamp divided by coating. Physicochemical properties of MO nanoparticles were determined using powder X-ray diffractometry (PXRD), Brunauer-Emmett-Teller analysis, and field emission-scanning electron microscopy with energy-dispersive X-ray spectroscopy. Atomic force microscopy with an electrostatic force microscopy mode was used to confirm the surface topology and electrostatic characteristics after dual UV irradiation. For antimicrobial activity test, MO nanoparticles under dual UV irradiation were applied to Escherichia coli and M13 bacteriophage (phage). The UV-A and UV-C showed differential intensities in the coated and uncoated areas (UV-A, coated = uncoated; UV-C, coated ≪ uncoated). MO nanoparticles showed sharp peaks in PXRD patterns, matched to pure materials. Their primary particle sizes were less than 100 nm with irregular shapes, which had an 8.6~25.6 m2/g of specific surface area with mesopores of 22~262 nm. The electrostatic properties of MO nanoparticles were modulated after UV irradiation. ZnO, MgO, and CuO nanoparticles, except ZnTiO3 nanoparticles, showed antibacterial effects on E. coli. Antimicrobial effects on E. coli and phages were also enhanced after cyclic exposure of dual UV and MO nanoparticle treatment using the uncoated area, except ZnO nanoparticles. Our results demonstrate that dual UV-MO nanoparticle hybrid system has a potential for disinfection. We anticipate that it can be developed as a next-generation disinfection system in pharmaceutical industries and water purification systems.