Experimental artifacts for morphological tweaking of chemical sensor materials: studies on ZnO.

Sensing mechanisms of gases on solid structures are predominantly surface-dominated. Benign surface features in terms of small grain size, high aspect ratio, large surface area and open and connected porosity, are required to realize a successful sensor material. Such morphological artifacts are a function of the fabrication and processing techniques employed. In this paper, we describe the fabrication of monoshaped and monosized zinc oxide (ZnO) particles by a homogeneous precipitation method, using urea and/or hexmethyltetraamine as the reductant. The effect of operating conditions and experimental variables, such as the relative concentration of the precursors, temperature, and the aging time on the morphology of the resulting particles was studied systematically. These experimental parameters were optimized in order to achieve particles of uniform morphology and of narrow size distribution. Some of these particles were employed for the detection of ammonia gas at room temperature.

Benzyl Alcohol-Mediated Versatile Method to Fabricate Nonstoichiometric Metal Oxide Nanostructures.

Nanostructured metal oxides with cationic or anionic deficiency find applications in a wide range of technological areas including the energy sector and environment. However, a facile route to prepare such materials in bulk with acceptable reproducibility is still lacking; many synthesis techniques are still only bench-top and cannot be easily scaled-up. Here, we report that the benzyl alcohol (BA)-mediated method is capable of producing a host of nanostructured metal oxides (MOx, where M = Ti, Zn, Ce, Sn, In, Ga, or Fe) with inherent nonstoichiometry. It employs multifunctional BA as a solvent, a reducing agent, and a structure-directing agent. Depending on the oxidation states of metal, elemental or nonstoichiometric oxide forms are obtained. Augmented photoelectrochemical oxidation of water under visible light by some of these nonstoichiometric oxides highlights the versatility of the BA-mediated synthesis protocol.

Necrosis of Staphylococcus aureus by the Electrospun Fe- and Ag-Doped TiO2 Nanofibers.

Postsurgery infections cause prolonged hospitalization, incurring increased patient and hospital costs, making it increasingly vital to develop an effective solution for the mitigation and elimination of infection buildup at these sites. Incorporation of a bactericidal device at the infection-prone sites provides the capability of attacking bacterial growth even after the patient has left the hospital. Polycrystalline titanium dioxide (TiO2) is photoactive and possesses antibacterial properties that can mitigate the onset of these infections and aid in wound healing. In this work, TiO2 nanofibers were synthesized by electrospinning. Doping with iron as well as with silver (5 wt% and 1 wt%, resp.) was also carried out to increase their effectiveness towards bactericidal properties. The electrospun fibers were processed and tested in the presence of light in the suspensions of methicillin-susceptible Staphylococcus aureus (MSSA) bacteria, which are the leading infection-inducing bacteria among hospital patients. It was found that upon brief activation (cf. 30 s) by an infrared laser source, greater than 90% of the S. aureus was rendered inactive within cf. 10 min. of exposure, thereby showing the potential of titania nanofibers for effective mitigation of infection.

Mitigation of Staphylococcus aureus-mediated surgical site infections with ir photoactivated TiO2 coatings on Ti implants.

Surgical site infections caused by methicillin-resistant and methicillin-susceptible Staphylococcus aureus (MRSA, MSSA) lead to patient hospitalization for an extended period coupled with concomitant hospitalization resources and cost. The detrimental effect resulting from the onset of these infections poses great health risks, leading to death in some instances. Titanium dioxide (TiO(2) ) is endowed with the unique capability of photoactivity which has been extensively exploited in antibacterial activities. It has been shown to be very effective in its bactericidal efficacy against infection-causing bacterial strains, namely, E. coli and S. aureus. In this study, the use of IR-photoactivated TiO(2) nanocoatings on titanium implants to mitigate the onset of surgical site infections is described. TiO(2) coatings were created on implantable materials by way of an aqueous plasma electrodeposition technique and were used to mitigate the harmful bacterial growth upon brief activation by an infrared (IR) laser source. The necrosis of S. aureus cells was found to exceed 90% within 30 min. following a 30s exposure of the titania-coated model implants (Ti mesh and plate). Promising potential of antibacterial coatings in mitigating surgical site infections has been shown.

Infection mitigation efficacy of photoactive titania on orthopedic implant materials.

In order to impede infection and achieve accelerated wound healing in the postorthopaedic surgery patients, a simple and benign procedure for creating nanotubular or nanofibrillar structure of photoactive TiO(2) on the surface of Ti plates and wires is described. The nanoscale TiO(2) films on titanium were grown by hydrothermal processing in one case and by anodization in the presence of dilute mineral acids under mild and benign conditions in the other. Confocal microscopy results demonstrated at least 50% reduction in the population of E. coli colonies (concentration 2.15 × 10(7) cells/mL) on TiO(2)-coated implants upon an IR exposure of up to 30 s; it required ∼20 min of exposure to UV beam for the same effect. These findings suggest the probability of eliminating wound infection during and after orthopedic surgical procedures by brief illumination of photoactive titania films on the implants with an IR beam.

Facile Synthesis and Characterization of Fe/FeS Nanoparticles for Environmental Applications.

Multicomponent nanoparticles containing two or more different types of functionalities show unique physical and chemical properties, leading to significantly enhanced performance. In this study, we have developed a new one-pot method to prepare Fe/FeS nanoparticles using dithionite at room temperature. The FeS precipitates on the Fe surface are formed by the interaction between dissolved iron species and hydrogen sulfide, one of the decomposition products of dithionite in solution. The resulting Fe/FeS nanoparticles have high surface area, good electrical conductivity, and strong magnetic responsivity. In addition, the Fe/FeS shows a much higher reactivity toward contaminants than the pure Fe nanoparticles. The above synthesized nanoparticles are successfully applied for the rapid removal of trichloroethylene (TCE) from water. The study reveals that Fe/FeS nanoparticles are a promising candidate for the efficient removal of pollutants.