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The rise in prevalence and drug resistance in Staphylococcus aureus of dairy animals require an alternative to antibiotics. Nanoparticles particularly metallic nanoparticles are a wise approach to modulating drug resistance. The current study thus focuses on the replacement of antibiotics with ZnO, MgO, and Fe2O3 nanoparticles. To achieve this goal, 200 cattle milk samples were collected aseptically and screened for subclinical mastitis using the purposive sampling technique. Following Bergey's manual of determinative bacteriology, S.aureus was identified and antibiotic susceptibility was tested using clinical laboratory and standard institute guidelines. On the other hand, resistant strains were put to antibacterial testing assay against metallic nanoparticles both by well diffusion and broth microdilution method. To analyze the data, both probability and non-probability statistical tools were applied using SPSS version 22 of statistical software at 5% probability. The current study showed 24.56% of S. aureus positive from commercial dairy while the resistance of these isolates against gentamicin, enrofloxacin, levofloxacin, and vancomycin was found to be 50, 40, 30, 30%, respectively. On the other hand, a disc diffusion assay was concluded with 24.525±0.806 mm (ZnO) followed by 16.475±0.950mm (MgO) and 13.150±1.392mm (Fe2O3). MgO stood first to contribute lowest Minimum inhibitory concentration (MIC) (1.302±0.564 mg/mL) followed by Fe2O3 (2.930±1.691 mg/mL) and ZnO (3.906±0.000 mg/mL). MIC of ZnO was recorded to be 18.23±11.93 mg/mL, 15.63±0.0 mg/mL, 13.02±4.5 mg/mL, 7.81±6.77 mg/mL, 5.21±2.26 mg/mL, and (3.906±0.000 mg/mL) at 04, 08, 12, 16, 20 and 24th h of incubation. A similar trend was followed by other nanoparticles at different hours of incubation. The study thus concludes a rise in resistant strains of S. aureus in bovine milk while metallic nanoparticles as effective alternatives. [ABSTRACT FROM AUTHOR]

Alternative and modified therapeutic approaches are key elements in culminating antibiotic resistance. To this end, an experimental trial was conducted to determine the cytotoxicity and antibacterial potential of composites of magnesium oxide (MgO) nanoparticles and antibiotics stabilized in sodium alginate gel against multi-drug-resistant Staphylococcus aureus isolated from a houbara bustard. The characterization of preparations was carried out using X-ray diffraction (XRD), scanning transmissible electron microscopy (STEM), and Fourier-transform infrared spectroscopy (FTIR). The preparations used in this trial consisted of gel-stabilized MgO nanoparticles (MG), gel-stabilized tylosin (GT), gel-stabilized ampicillin (GA), gel-stabilized cefoxitin (GC), gel-stabilized MgO and tylosin (GMT), gel-stabilized MgO and cefoxitin (GMC), and gel-stabilized MgO and ampicillin (GMA). The study presents composites that cause a lesser extent of damage to DNA while significantly enhancing mitotic indices/phases compared to the other single component preparations with respect to the positive control (methyl methanesulphonate). It was also noted that there was a non-significant difference (p > 0.05) between the concentrations of composites and the negative control in the toxicity trial. Studying in parallel trials showed an increased prevalence, potential risk factors, and antibiotic resistance in S. aureus. The composites in a well diffusion trial showed the highest percentage increase in the zone of inhibition in the case of GT (58.42%), followed by GMT (46.15%), GC (40.65%), GMC (40%), GMA (28.72%), and GA (21.75%) compared to the antibiotics alone. A broth microdilution assay showed the lowest minimum inhibitory concentration (MIC) in the case of GMA (9.766 ± 00 µg/mL), followed by that of GT (13.02 ± 5.64 µg/mL), GMC (19.53 ± 0.00 µg/mL), GA (26.04 ± 11.28 µg/mL), GMT (26.04 ± 11.28 µg/mL), MG (39.06 ± 0.00 µg/mL), and GC (39.06 ± 0.00 µg/mL). The study thus concludes the effective tackling of multiple-drug-resistant S. aureus with sodium-alginate-stabilized MgO nanoparticles and antibiotics, whereas toxicity proved to be negligible for these composites. [ABSTRACT FROM AUTHOR]

Poly(N-isopropylacrylamide-co-acrylic acid) microgels [P(NIPAM-co-AAc)] with 2, 4, 6 and 8 mole percentage of N,N-methylene-bis-acrylamide were used as micro-reactors for the fabrication of Ag nanoparticles using the in situ reduction method. The pure and hybrid microgels were characterized by Fourier transform infrared and Ultraviolet-Visible spectroscopies. Silver-poly(N-isopropylacrylamide-coacrylic acid) hybrid microgels [Ag-P(NIPAM-co-AAc)] with different crosslinker contents were used as catalysts for reduction of nitrobenzene (NB) in aqueous medium in order to investigate the effect of crosslinker content on the value of apparent rate constant (kapp). 0.041, 0.146, 0.2388 and 0.255 min-1 were found as values of kapp for catalytic reduction of NB using hybrid microgels with 2, 4, 6 and 8 mole percentage of crosslinker, respectively. The effect of crosslinker feed content of hybrid microgels on catalytic activity for reduction of NB was compared to that of reduction of p-nitrophenol in aqueous medium. [ABSTRACT FROM AUTHOR]

Poly(N-isopropylacrylamide-co-allyl acetic acid) [p(NIPAM-co-AAAc)] microgels were synthesized in aqueous medium by free radical emulsion polymerization using N-isopropylacrylamide as monomer, allylacetic acid as comonomer, and N,N-methylene-bis-acrylamide as cross-linker. Silver nanoparticles were fabricated inside the microgels by in situ reduction of silver ions. Microgels were analyzed by UV-visible spectroscopy, FTIR, XRD, TEM, and DLS. The formation of silver nanoparticles was confirmed by UV-visible spectroscopy. UV-visible spectra of the Ag-poly(N-isopropylacrylamide-co-allyl acetic acid) hybrid microgels showed a prominent absorption peak at about 411 nm. This peak was due to the surface plasmon resonance effect of silver nanoparticles. The hybrid microgels were used as catalyst for the reduction of nitroarenes. The reduction reactions were found to be first order with respect to nitroarenes with the values of apparent rate constant (kapp) equal to 0.248, 0.215, and 0.089 min-1 for 4-nitrophenol, 4-nitroaniline, and nitrobenzene respectively at 27 °C in aqueous medium. Silver nanoparticles were found to be a more effective and efficient catalyst for reduction of 4-nitrophenol and 4-nitroaniline as compared to nitrobenzene. [ABSTRACT FROM AUTHOR]

We synthesized poly(N-isopropylacrylamide-co-acrylic acid) microgels with 1, 3, 5, and 7 mol percentage of acrylic acid. Silver nanoparticles were fabricated inside these microgels at room temperature. Pure microgels were characterized by Fourier transform infrared (FTIR) spectroscopy and dynamic light scattering (DLS). Hybrid microgels were characterized by UV-Visible spectroscopy. The size of the silver nanoparticles increased with an increase in the content of acrylic acid. Catalytic activity of these hybrid microgels was investigated using UV-Visible spectrophotometry. Induction time decreased from 8.8 to 2.6 min and the value of apparent rate constant decreased from 0.226 to 0.109 min-1, when the content of acrylic acid was increased from 1 to 7 mol %. This decrease in induction time was due to decrease in the surface area of nanoparticles present within the microgels with an increase in the feed contents of acrylic acid. The decrease in the value of apparent rate constant was due to an increase in the size of nanoparticles fabricated within the microgels with an increase in mol percentage of acrylic acid. The linear relation between apparent rate constant and feed contents of acrylic acid can be used for quantitative analysis of contents of acrylic acid present in polymer microgels. [ABSTRACT FROM AUTHOR]