J o u r n a l P r e -p r o o f 2 Graphical Abstract Highlights  Photoactive TiO2 nanomaterials can solve the actual microbial infectious defies  The microbial cell/TiO2 surface approach is key to get the photo-kill mechanism  Microbial preparation requires a reproducible protocol for proper characterization  Advanced surface characterization techniques can unravel the photo-kill mechanism  Generation of ROS, physical injuries and biocidal features confirm the annihilation J o u r n a l P r e -p r o o f Abstract The approach of this timely review considers the current literature that is focused on the interface nanostructure/cell-wall microorganism to understand the annihilation mechanism. Morphological studies use optical and electronic microscopes to determine the physical damage on the cell-wall and the possible cell lysis that confirms the viability and microorganism death. The key parameters of the tailoring the surface of the photoactive nanostructures such as the metal functionalization with bacteriostatic properties, hydrophilicity, textural porosity, morphology and the formation of heterojunction systems, can achieve the effective eradication of the microorganisms under natural conditions, ranging from practical to applications in environment, agriculture, and so on. However, to our knowledge, a comprehensive review of the microorganism/nanomaterial interface approach has rarely been conducted. The final remarks point the ideal photocatalytic way for the effective prevention/eradication of microorganisms, considering the resistance that the microorganism could develop without the appropriate regulatory aspects for human and ecosystem safety. Introduction and background 1. TiO 2 based materials obtained from TiO 2 and its composites J o u r n a l P r e -p r o o f previous studies have demonstrated that photocatalysis can be considered a promising tool in anticancer therapies, since the photocatalyst can kill cancer cells such as HeLa cells, which cause cervical cancer [7]. The energy absorbed by the photocatalyst comprises the range of ultraviolet and/or visible light, even natural sunlight. When the photocatalyst absorbs light, if the energy of the photons is enough to excite the electrons J o u r n a l P r e -p r o o f 6in the valence band (VB), then they migrate to a higher energy level in the conduction band (CB) of the material, as it is illustrated in Fig. 1. This phenomenon generates the charge carriers known as hole-electron pairs. The photogenerated hole can migrate to the surface of the material and react with water molecules or hydroxyl ions to produce hydroxyl radicals, while the photoexcited electron in the conduction band can react with the adsorbed molecular oxygen to produce superoxide ions [8]. Since the report of Fujishima and Honda about the water splitting process using a TiO2 electrode under UV irradiation, numerous studies have exploited the photoactive properties of this material [9,10]. Several reviews have studied the relationship between the electronic properties of TiO2 with...

Antifungal silver nanocomposites inspired by titanate nanotubes (AgTNTs) were successfully evaluated for the effective inactivation of the phytopathogenic fungus Botrytis cinerea within 20 min. One-dimensional HTiO nanotubes functionalized with silver nanoparticles (AgNPs) exhibit unique surface and antifungal properties for the photoinactivation of B. cinerea. Nanostructured titanates were synthesized by the eco-friendly, practical, microwave-induced, hydrothermal method followed by a highly monodispersive AgNP UV-photodeposition. Protonated nanotubes of ∼11 nm in diameter and four-layers displayed high surface areas, 300 m/g, with a size functionalization of 5 nm for the AgNPs. UV-vis DRS and XPS allowed the characterization and/or quantification of surface reactive species and cytotoxic silver species such as Ag°, Ag. The effective biocidal properties of the nanocomposites were confirmed by using the well-known Gram-negative bacteria Escherichia coli, and then proceeding to the effective inactivation of the phytopathogenic fungus under visible light. The photoassisted inactivation mechanism was examined by HAADF-STEM, HRTEM, and FESEM electronic microscopies. A plasmalemma invagination due to oxidative stress caused by reactive oxygen, silver cytotoxicity species, and AgTNT sharp morphology damage expands the conidia to induce the cell death. The impact of the eco-friendly inactivation is significant because of the ease with which it is carried out and the possibility of being performed in situ with plants like tomato and grapes, which are ranked among the most valuable agricultural products worldwide.

A schematic diagram exhibits the HeLa cell death during PPT treatment using folic acid-conjugated gold nanoparticles (FA–AuNPs) and non-conjugated AuNPs.

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a Palladium-graphene nanostructures (PdGO) with high-quality-graphene layers and well monodispersed palladium nanoparticles (PdNPs) were synthesized by the hydrothermal microwave exfoliation method. The structural and morphological characteristics of PdGO were investigated, and the results indicate that the hydrothermal-microwave method allows both the reduction of the metal precursors and their anchorage on highly exfoliated graphene layers. The synthesized PdGO was then deposited as active layers for sensing hydrogen gas (H2). PdGO-based sensors with gas concentrations from 0.01 to 5 vol. % in air exhibited a very reproducible performance with fast response times (~30 seg) and recovery behavior at room temperature. Impedance response results as a high sensitive feasible sensor technique. Our results show that it is feasible to obtain an efficient H2-sensor with reliable and reproducible sensing properties by means of a simple and cost-effective preparation method under real atmospheric conditions.

Gold catalysts supported on TiO2 doped with Y (1, 3, and 6 wt % of Y) were prepared by the deposition-precipitation with urea method. Two yttrium precursors were used: yttrium acetylacetonate and yttrium nitrate. The Y-TiO2 supports prepared by the sol–gel method allowed the formation of solids with high specific surface area. The incorporation of yttrium restricted the growth of TiO2 anatase crystals and hindered the transformation to the rutile phase. The average gold particle size was very similar in all the prepared catalysts (∼3 nm). Au/Y-TiO2 catalysts showed higher activity and stability at room temperature than Au/TiO2 in the CO oxidation reaction. This behavior is related to the strong anchoring of the gold particles on the structural defects and oxygen vacancies of the support caused by the doping of the anatase with yttrium. The variation of the yttrium precursor (acetylacetonate or nitrate) did not have an important effect on the catalytic activity or the temporal stability of the catalysts. In the samples with a high content of Y, High Resolution Transmission Electron Microscopy (HRTEM) results suggest the segregation of yttrium as Y2O3 on the surface of TiO2. The presence of Y2O3 crystals on the TiO2 surface had a detrimental effect on the catalytic activity.

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