Mass production of morin-stabilized silver nanoparticles: Characterization, antioxidant, and antimicrobial activities.

Phytochemical-conjugated silver nanoparticles (AgNPs) are believed to act as a bridge between nanotechnology and therapy. There is a significant need for green and mass production of such materials due to their extensive applications, especially in the biomedical sector. In this study, morin-stabilized silver nanoparticles (morin/AgNPs) were synthesized on a massive scale using a one-pot solid-state technique. The reaction is achieved by ball milling of morin and silver nitrate powders at ambient temperature without any solvent or toxic reagent. The prepared morin/AgNPs exhibited a semi-hexagonal shape and ranged in size from 21 to 43 nm. The x-ray diffraction results elucidated the formation of highly crystalline AgNPs. Fourier transform infrared and x-ray photoelectron spectroscopic analyses prove that the hydroxyl, carbonyl, and aromatic functionalities in morin are playing major roles in the reduction and stabilization of AgNPs. The antioxidant potential of morin/AgNPs was evaluated utilizing 2,2-Diphenyl-1-picryl-hydrazyl (DPPH) assay. Morin/AgNPs exhibited better free radical scavenging activity (IC50 = 11.7 µg/mL) than morin (IC50 = 14.8 µg/mL). Furthermore, the synthesized AgNPs showed promising antimicrobial activity against Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, Streptococcus mutans, and Candida albicans. The largest inhibition zones were observed against S. aureus (21.2 ± 0.6 mm) and K. pneumonia (20.3 ± 0.5 mm) bacteria. The foregoing results highlighted the prospective application of morin/AgNPs as a promising antioxidant and antimicrobial material for safe medical applications. RESEARCH HIGHLIGHTS: A simple green route for the large-scale production of AgNPs was developed. Morin acts as reducing/stabilizing agent in solid-state synthesis of AgNPs. Morin/AgNPs exhibited promising antimicrobial and antioxidant activity.

Hydrothermal Microwave-Assisted Fabrication of Nanohydroxyapatite Powder and Optimization of Its Nanocomposite Coatings on Magnesium Alloy for Orthopedic Applications.

Developing appropriate protecting coatings for Mg alloy applications is a challenging issue. Herein, nanohydroxyapatite (nanoHAP) powder was first fabricated by the simple hydrothermal microwave-assisted method. A direct current electrophoresis deposition (EPD) of nanoHAP composite coatings on Mg-3Zn-0.8Ca magnesium alloy was successfully executed. Three suspensions with HAP-dispersive resin solution (ETELAC) ratios (in wt %) of 5-5, 5-2.5, and 2.5-2.5 were chosen for optimizing the effect of applied voltage, deposition time, and stirring mode and rates on the EPD process. NanoHAP composite coatings were applied on each sample in single- and double-run depositions. The results revealed that the maximum weight gain on the coated samples was obtained in 5-5 suspension at 50 V under 150 rpm mechanical stirring rate. Surface examination indicated crack-free coating formation with varying grain sizes. Adhesion tests demonstrated high interconnection between the obtained nanocomposite coatings and the alloy substrate. Electrochemical evaluation measurements in SBF at 37 °C indicated that the corrosion resistance of any coated sample is always superior compared to that of the uncoated bare substrate. It was suggested that the EPD of nanoHAP/ETELAC composite coatings on Mg-Zn-Ca alloy can be a good solution for protecting the alloy from the attack of the aggressive ions bound in the SBF environment.

Oxidative coupling of bio-alcohols mixture over hierarchically porous perovskite catalysts for sustainable acrolein production.

The acrolein production from bio-alcohols methanol and ethanol mixtures using AMnO3 (since A = Ba and/or Sr) perovskite catalysts was studied. All the prepared samples were characterized by XRD, XPS, N2 sorption, FTIR, Raman spectroscopy, TEM, SEM, TGA, and NH3-CO2-TPD. The catalytic oxidation reaction to produce acrolein has occurred via two steps, the alcohols are firstly oxidized to corresponding aldehydes, and then the aldol is coupled with the produced aldehydes. The prepared perovskite samples were modified by doping A (Sr) position with (Ba) to improve the aldol condensation. The most catalytic performance was achieved using the BaSrMnO3 sample in which the acrolein selectivity reached 62% (T = 300 °C, MetOH/EtOH = 1, LHSV = 10 h-1). The increase in acrolein production may be related to the high tendency of BaSrMnO3 toward C-C coupling formation. The C-C tendency attributes to that modification have occurred in acid/base sites because of metal substitution.

Antimicrobial activity of new 2,4-disubstituted thiazolidinone derivatives.

A number of new disubstituted 2,5-thiazolidinone derivatives were synthesized and tested for their antimicrobial activity against Bacillus subtilis (Gram-positive), Pseudomonas aeruginosa (Gram-negative), and Streptomyces species (Actinomycetes). They displayed different degrees of antimicrobial activities or inhibitory actions.