O3-Annealing Effect on the Etching Resilience of a TiO2/Al2O3 filter Prepared by Atomic Layer Deposition.

This research investigates the improvements of ozone (O3) annealing on the optical and etching characteristics of TiO2/Al2O3 multilayer band-pass filters designed for potential optoelectronic applications. The band-pass filters were fabricated using atomic layer deposition (ALD), and their performance was systematically analyzed after the addition of O3 annealing at moderate temperatures (up to 300 °C). Results reveal that O3 annealing improves the optical transmittance of the multilayers by approximately 40% without significant spectral changes (∼6 nm). The observed enhancement in the transmittance is attributed to the improved stoichiometry of TiO2. By filling in the oxygen vacancies created during the fabrication process, it reduces its extinction coefficient. Furthermore, the O3 annealing enhances the stability of TiO2 against wet etching, improving the uniformity of etched surfaces. Etching on the ozone-annealed multilayer was up to 8 times more homogeneous, as observed in the roughness. The relatively short duration of the O3 annealing process, approximately 1.6 h, makes it a cost-effective alternative compared to using ozone in the ALD process, which can last several hours for thick optical coatings.

UV Sensitivity of MOS Structures with Silicon Nanoclusters.

Selective UV sensitivity was observed in Metal-Oxide-Semiconductor structures with Si nanoclusters. Si nanocrystals and amorphous Si nanoparticles (a-Si NPs) were obtained by furnace annealing of SiOx films with x = 1.15 for 60 min in N2 at 1000 and 700 °C, respectively. XPS and TEM analysis prove phase separation and formation of Si nanocrystals in SiO2, while the a-Si NPs are formed in SiO1.7 matrix. Both types of structures show selective sensitivity to UV light; the effect is more pronounced in the structure with nanocrystals. The responsivity of the nanocrystal structure to 365 nm UV light is ~ 4 times higher than that to green light at 4 V applied to the top contact. The observed effect is explained by assuming that only short wavelength radiation generates photocarriers in the amorphous and crystalline nanoclusters.

Controlled antifungal behavior on Ti6Al4V nanostructured by chemical nanopatterning.

Infections associated with bone implant prostheses are mainly related to bacterial contaminations. Recent investigations have suggested an important role of opportunistic fungal cells associated with non-responding antibacterial treatments. Thus, in order to evaluate the early Candida albicans (C. albicans) behavior; we built on Ti6Al4V surfaces nanopores (NPs) with controlled diameters applying oxidative nanopatterning for 30 (NP30) and 60 min (NP60). As a result of nanopatterning NPs with diameters of 12 and 24 nm were synthesized. Physicochemical differences were observed between both types of NPs, the most highlighting of which are anatase phase formation and improved hydrophilicity of NP60. C. albicans adhesion and colonization was assessed using scanning electron microscopy and by yeast counting for viability evaluation. The fungal behavior on the substrates was significantly different, showing an initial exopolysaccharide secretion stimulated by the nanopatterned surfaces. Larger NPs led to an important reduction in viability with decreased cell-surface contact bonds. The obtained results demonstrate that special control in the fabrication of nanostructured TiO2 materials can improve the early fungal resistance, especially for dental implants.

Enhanced antifungal activity by disinfected titanium dioxide nanotubes via reduced nano-adhesion bonds.

We have provided evidence that the beneficial effect of super-oxidized water (SOW) disinfected Ti6Al4V-TiO2 nanotubes (NTs) can reduce bacterial adhesion and biofilm formation. However, the need of antifungal nanostructured surfaces with osteoactive capabilities is an important goal that has been arising for dental implants (DI) applications. Thus, in the present study we isolated and tested the effects of Candida albicans (C. albicans) on disinfected, wetter and nanoroughness NTs compared to a non-modified control. Moreover, we elucidated part of the fungal adhesion mechanism by studying and relating the mycotic adhesion kinetics and the formation of fungal nanoadhesion bonds among the experimental materials, to gain new insight of the fungal-material-interface. Similarly, the initial behavior of human alveolar bone osteoblasts (HAOb) was microscopically evaluated. NTs significantly reduced the yeasts adhesion and viability with non-outcomes of biofilm than the non-modified surface. Cross-sectioning of the fungal cells revealed promoted nano-contact bonds with superior fungal spread on the control alloy interface; meanwhile NTs evidenced decreased tendency along time; suggesting, down-regulation by the nanostructured morphology and the SOW treatment. Importantly, the initial performance of HAOb demonstrated strikingly promoted anchorage with effects of filopodia formation and increased vital cell on NTs with SOW. The present study proposes SOW treatment as an active protocol for synthesis and disinfection of NTs with potent antifungal capability, acting in part by the reduction of nano-adhesion bonds at the surface-fungal interface; opening up a novel route for the investigation of mycotic-adhesion processes at the nanoscale for bone implants applications.

Disinfection of titanium dioxide nanotubes using super-oxidized water decrease bacterial viability without disrupting osteoblast behavior.

Amorphous titanium dioxide (TiO2) nanotubes (NTs) on Ti6Al4V alloy were synthesized by anodization using a commercially available super-oxidized water (SOW). The NT surfaces were sterilized by ultraviolet (UV) irradiation and disinfected using SOW. The adhesion and cellular morphology of pig periosteal osteoblast (PPO) cells and the behavior of Staphylococcus aureus (S. aureus) cultured on the sterilized and disinfected surfaces were investigated. A non-anodized Ti6Al4V disc sterilized by UV irradiation (without SOW) was used as control. The results of this study reveal that the adhesion, morphology and filopodia development of PPO cells in NTs are dramatically improved, suggesting that SOW cleaning may not disrupt the benefits obtained by NTs. Significantly decreased bacterial viability in NTs after cleaning with SOW and comparing with non-cleaned NTs was seen. The results suggest that UV and SOW could be a recommendable method for implant sterilization and disinfection without altering osteoblast behavior while decreasing bacterial viability.