SYNTHESIS, CHARACTERIZATION AND CYCLAZATION OF PYRAN USING Ag2O NANOPARTICLE FROM NATURAL SOURCE “GINGER”

This study was aimed to synthesis Ag2O nanoparticles (N.P.s) utilizing the Ginger plant (Zingiber officinale) extract. As catalysts for pyran derivatives formation employing a three-component coupling reaction among aromatic and aliphatic aldehydes, malononitrile, and dimedone. The nanoparticles exhibit robust catalytic activity with high productivity. Results revealed that Ag2O NPs improved various vital features, like higher yields, reaction time, simple chemical separation, catalytic economic efficiency, and quick process. This study aimed to cyclize heterocyclic compounds to provide new hetero compounds applying nano-oxides obtained from natural (unmanufactured) sources and used in several medical, pharmaceutical, and industrial implementations. The outcomes nanoparticles were examined by Fourier Transform Infrared spectroscopy (FTIR) and transmission electron microscopy (T.E.M.); the chemical characteristics of the outcome compounds were tested by spectroscopy techniques (FTIR spectroscopy and 1H-NMR).

Green synthesis of silver nanoparticles using psychrotolerant strains of Tulasnella albida from South Orkney Islands (Antarctica)

Nanoparticles are widely studied due to their possible uses in biological and technological systems. Four psychrotolerant strains of Tulasnella albida isolated from Antarctica were tested and compared in their ability to synthesize silver nanoparticles. The four strains were capable of synthesizing silver nanoparticles with the addition of AgNO3 (final concentration of 0.5 mM), showing similar results under the same conditions: 28°C, 200 rpm, pH 9. Additionally, we registered the synthesis of nanoparticles at 6°C using biomass generated at the same temperature. For the characterization of synthesized nanoparticles, TEM and SEM microscopy analyses were performed. The images obtained showed the existence of spherically shaped silver nanoparticles with a log-normal size distribution centered at 2 nm diameter for 28°C. The largest ones showed a capping shell around them, appearing associated with the formation of small silver nanoparticles. Theoretical calculations of optical absorption based on core-shell Ag-Ag2O nanoparticles were used to characterize the experimental absorption spectra of silver nanoparticles colloids. This work contributes to expanding the studies and possible technological applications of psychrotolerant organisms in the industry, particularly in the green synthesis of nanoparticles at suboptimal conditions.

The interaction of Ag2O nanoparticles with Escherichia coli: inhibition–sterilization process

Silver-based antibacterial agents have obtained wide attention due to the fact that bacteria in the environment is ubiquitous, which has become one of the most difficult problems for human health. However, the antibacterial mechanism and process are still inconclusive. Here, Ag2O nanoparticles (NPs) with uniform spherical morphology and small size (around 30 nm) were prepared. The as-prepared Ag2O NPs induced high antibacterial activity (100% inhibition ratio) against E. coli. A two-step antibacterial process was proposed and confirmed, which divided into inhibition and sterilization steps. The optical density measurement, malondialdehyde concentration detection, morphologic imaging with electronic microscopy and Fourier transform infrared spectroscopic analysis unveiled the interaction of Ag2O NPs with E. coli, which verified the inhibition–sterilization process we proposed.

Design of Mn and Zr incorporated Ag2O nanoparticles and their enhanced photocatalytic activity driven by visible light irradiation for degradation of rose bengal dye

Mn, Zr co-doped Ag2O nanoparticles were blended through a wet chemical strategy, and the physicochemical properties of doped and co-doped silver oxide nanoparticles were characterized.

Green-synthesis of Ag2O nanoparticles for antimicrobial assays**

Silver oxide nanoparticles (Ag2O NPs) in the aqueous colloidal state were synthesized using the green method. Aqueous silver nitrate was prepared and mixed jointly with an aqueous extract of Lawsonia inermis (henna) leaf and heated with stirring at 75 °C for 1h. Then, an aqueous colloidal solution of Ag2O NPs with a dark brown colour is forming. The physicochemical characterization of Ag2O NPs was studied using different techniques. A polycrystalline structure of (Ag2O/Ag) in face-centred cubic and cubic phases was revealing via grazing incident X-ray diffraction (GIXRD) patterns. Energy-dispersive X-ray analysis (EDX) spectra confirmed GIXRD results through peaks corresponding to the silver and oxygen elements making up the accurate composition of the silver oxide. UV-Vis absorbance peak of the localized surface plasmon resonance (SPR) appeared at the visible region and exhibited a blueshift at ∼425 nm with an energy bandgap ∼2.8 eV. The surface morphology and the size of the silver nanoparticles were analyzed using high resolution (FE-SEM) microscopy. FTIR spectra of Ag2O NPs has showed a shift in the bands compared to those produced by aqueous extract of the henna leaf (only). (0.4 molars) Ag2O NPs has showed excellent antimicrobial activity assays against all the pathogens microbe's strains. Henna plant extract (only) has showed poor activity compared to Ag2O NPs. In comparison, the inhibition zone diameter of the gram-negative Bacteria is more considerable than the gram-positive bacteria. Moreover, Ag2O NPs activity against Bacteria is more prominent than fungi.