Highly Efficient Mesoporous Core-Shell Structured Ag@SiO2 Nanosphere as an Environmentally Friendly Catalyst for Hydrogenation of Nitrobenzene

SiO2@AuAg/PDA hybrid nanospheres with photo-thermally enhanced synergistic antibacterial and catalytic activity

Wastewater discharged from industrial, agricultural and livestock production contains a large number of harmful bacteria and organic pollutants, which usually cause serious harm to human health. Therefore, it is urgent to find a "one-stone-two-birds" strategy with good antimicrobial and pollutant degradation activity for treating waste water. In this paper, SiO2@AuAg/Polydopamine (SiO2@AuAg/PDA) core/shell nanospheres, which possessed synergistic "Ag+-release-photothermal" antibacterial and catalytic behaviors, have been successfully prepared via a simple in situ redox polymerization method. The SiO2@AuAg/PDA nanospheres showed good catalytic activity in reducing 4-nitrophenol to 4-aminophenol (0.576 min-1 mg-1). Since the AuAg nanoclusters contain both gold and silver elements, they provided a high photothermal conversion efficiency (48.1%). Under NIR irradiation (808 nm, 2.5 W-2), the catalytic kinetics were improved by 2.2 times. Besides the intrinsic Ag+-release, the photothermal behavior originating from the AuAg bimetallic nanoclusters and the PDA component of SiO2@AuAg/PDA also critically improved the antibacterial performance. Both E. coli and S. aureus could be basically killed by SiO2@AuAg/PDA nanospheres at a concentration of 90 μg mL-1 under NIR irradiation. This "Ag+-release-photothermal" coupled sterilization offers a straightforward and effective approach to antimicrobial therapy, and further exhibits high potential in nanomedicine for combating bacterial contamination in environmental treatment and biological fields.

Pd-Coordinated Salinidol-Modified Mixed MOF: An Excellent Active Center for Efficient Nitroarenes Reduction and Selective Oxidation of Alcohols

Selective oxidation of active and inactive alcohol substrates and reduction of nitroarenes is a highly versatile conversion that remains a challenge in controlling functionality and adjustments in metal-organic frameworks (MOFs). On the other hand, it offers an attractive opportunity to expand their applications in designing the next generation of catalysts with improved performance. Herein, a novel mixed MOF consisting of supported 2-hydroxybenzamide (mixed MOF-salinidol) has been fabricated by post-synthetic modifications of mixed MOF. Subsequently, the prepared nanocomposites were modified to impart catalytic sites using palladium chloride ions mixed with MOF-salinidol/Pd (II). After successfully designing and structurally characterizing nanocomposites, we evaluated their activity in oxidizing primary and secondary alcohols using aerobic conditions with molecular oxygen and an air atmosphere. In addition, the stability of (mixed MOF-salinidol/Pd (II)) catalysts under catalytic conditions was also demonstrated by comparing the Fourier-transform infrared spectrum, scanning electron microscopy image, and ICP-OES method before and after catalysis. Based on the results, the active surface area of the synthesized nanocatalyst is large, which highlights its unique synergistic effect between post-synthetic modified MOF and Pd, and furthermore, the availability of catalytic sites from Pd, as demonstrated by outstanding catalytic activity.

Designed Synthesis of Nanostructured Materials as the Heterogeneous Catalysts

The development of nanoscale syntheses and innovative characterization tools resulted in the tailored design of nanostructured materials with versatile abilities in many applications [...].

Characterization and Cytotoxicity Comparison of Silver- and Silica-Based Nanostructures

Core-shell structures are the most common type of composite material nanostructures due to their multifunctional properties. Silver nanoparticles show broad antimicrobial activity, but the safety of their utilization still remains an issue to tackle. In many applications, the silver core is coated with inorganic shell to reduce the metal toxicity. This article presents the synthesis of various materials based on silver and silica nanoparticles, including SiO2@Ag, Ag@SiO2, and sandwich nanostructures-Ag@SiO2@Ag-and the morphology of these nanomaterials based on transmission electron microscopy (TEM), UV-Vis spectroscopy, and FT-IR spectroscopy. Moreover, we conducted the angle measurements due to the strong relationship between the level of surface wettability and cell adhesion efficiency. The main aim of the study was to determine the cytotoxicity of the obtained materials against two types of human skin cells-keratinocytes (HaCaT) and fibroblasts (HDF). We found that among all the obtained structures, SiO2@Ag and Ag@SiO2 showed the lowest cell toxicity and very high half-maximal inhibitory concentration. Moreover, the measurements of the contact angle showed that Ag@SiO2 nanostructures were different from other materials due to their superhydrophilic nature. The novel approach presented here shows the promise of implementing core-shell type nanomaterials in skin-applied cosmetic or medical products.