Anti-microbial Activity of Acrylic Resins with In-Situ Generated Nanosilver on Cariogenic Planktonic and Biofilm Bacteria

Abstract Polymethylmethacrylate (PMMA

Antibacterial ethylene propylene rubber impregnated with silver nanopowder: AgNP@EPR

Following our interest in reaching for a molded rubber article with possible detergent contact applications, durable silver nanopowder (AgNP) is synthesized by arc discharge, then mixed with varying ratios of ethylene propylene rubber (EPR), affording novel AgNP@EPR nanocomposites. X-ray diffraction (XRD) patterns of AgNP as well as AgNP@EPR show no trace of impurity, while scanning electron microscopy (SEM) indicates an average diameter of 50 nm for the former. Transmission electron microscopy (TEM) images while confirm the SEM results, show quite a few 5 nm AgNP particles lying beside some micro crumbs. Our DC arc discharge technique involves explosion of movable silver anode and static cathode by a current pulse between 5 to 10 A cm-2. A solution blending method is employed for preparation of AgNP@EPR nanocomposites. The AgNP is first dispersed in toluene using an ultrasonic homogenizer, and then thoroughly mixed with EPR in the same solvent whose removal gives nanocomposites of 2, 4, 6 and 8 vol% AgNP in EPR,  showing strong antibacterial activity against both Escherichia coli and Staphylococcus aureus

Nano Fe(OH)₃/zeolite as a novel, green and recyclable adsorbent for efficient removal of toxic phosphate from water

284-293Magnetic Fe(OH)3 is dispersed and stabilized over zeolite, giving rise to nano Fe(OH)3/zeolite, which is used as an efficient, recyclable absorbent for phosphate removal from water. Phosphate removal is insensitive to the ionic concentration, yet is directly proportional with the concentration of the adsorbent, and is inversely proportional with the initial phosphate concentration and pH. The coexisting nitrate and bicarbonate anions have no significant influence on phosphate adsorption, while the presence of citrate or silicate decreases such adsorption. In contrast, the presence of acetate increases the phosphate removal. Kinetic data are well fitted in the pseudo-second-order model. High phosphate uptake capability and good reusability make Fe(OH)3/Zeolite a potentially attractive adsorbent for the removal of toxic phosphate from water. Evidently this type of work is a step forward for large scale elimination of undesired contaminants from water which may benefit the world community

Synergistic performance of a new bimetallic complex supported on magnetic nanoparticles for Sonogashira and C–N coupling reactions

Abstract This paper describes the synthesis of a novel Cu–Ni bimetallic system comprising of magnetic nanoparticles, as the core, and 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole (4-ABPT), as a conjugated bridge, between nickel and copper species. With low Cu and Ni loading (0.06 mol% Ni, 0.08 mol% Cu), the resulting Fe3O4@SiO2@4-ABPT/Cu–Ni showed to be a highly efficient catalyst for the Sonogashira and C–N cross-coupling reactions. The developed catalyst was well characterized by FT-IR, XRD, EDX-mapping, FE-SEM, TEM, ICP, VSM, TGA/DTG/DTA, LSV, and XPS techniques. Fe3O4@SiO2@4-ABPT/Cu–Ni nanocatalyst was compatible with a wide range of amines and aryl halides in the Sonogashira and C–N cross-coupling reactions and offered desired coupling products in high to excellent yields under palladium- and solvent-free conditions. Based on the XPS results, the 4-ABPT ligand can adjust electron transfer between Ni and Cu in Fe3O4@SiO2@4-ABPT/Cu–Ni, promoting the formation and stabilization of Cu+ and Ni3+ species. Electronic interactions and the synergistic effect between these metals increased the selectivity and activity of Fe3O4@SiO2@4-ABPT/Cu–Ni catalyst in the Sonogashira and C–N cross-coupling reactions compared with its monometallic counterparts. Additionally, the magnetic properties of Fe3O4@SiO2@4-ABPT/Cu–Ni facilitated its separation from the reaction mixture, promoting its reuse for several times with no significant loss in its catalytic activity or performance

Antimicrobial properties of poly (methyl methacrylate) acrylic resins incorporated with silicon dioxide and titanium dioxide nanoparticles on cariogenic bacteria

Aim: To assess the effects of adding nano-titanium dioxide (nano-TiO 2 ) and nano-silicon dioxide (nano-SiO 2 ) and their mixture to poly (methyl methacrylate) (PMMA) to induce antimicrobial activity in acrylic resins. Materials and Methods: Acrylic specimens in size of 20 mm × 20 mm × 1 mm of 0.5% and 1% of nano-TiO 2 (21 nm) and nano-SiO 2 (20 nm) and their mixture (TiO 2 /SiO 2 nanoparticles) (1:1 w/w) were prepared from the mixture of acrylic liquid containing nanoparticles and acrylic powder. To obtain 0.5% and 1% concentration, 0.02 g and 0.04 g of the nanoparticles was added to each milliliter of the acrylic monomer, respectively. Antimicrobial properties of six specimens of these preparations, as prepared, were assessed against planktonic Lactobacillus acidophilus and Streptococcus mutans at 0, 15, 30, 45, 60, 75, and 90 min follow-up by broth dilution assay. The specimens of each group were divided into three subgroups: Dark, daylight, or ultraviolet A (UVA). The percent of bacterial reduction is found out from the counts taken at each time point. Statistical Analysis: Data were analyzed using one-way analysis of variance and Tukey′s post hoc analysis. Results: Exposure to PMMA containing the nanoparticles reduced the bacterial count by 3.2-99%, depending on the nanoparticles, bacterial types, and light conditions. Planktonic cultures of S. mutans and L. acidophilus exposed to PMMA containing 1% of TiO 2 /SiO 2 nanoparticles showed a significant decrease (P 0.05) was observed in the counts of S. mutans and L. acidophilus in PMMA without the nanoparticles exposed to UVA. Conclusions: PMMA resins incorporated with TiO 2 /SiO 2 nanoparticles showed strong antimicrobial activity against the cariogenic bacteria