جستجوی مقالات مرتبط با کلیدواژه « antibacterial properties » در نشریات گروه « شیمی »

Moringa plant with the scientific name Moringa oleifera L. has important medicinal chemical compounds including flavonoids, which have antioxidant and anticancer properties. In this research, the properties of metal nanoparticles such as Iron, Copper, Zinc and Silver biosynthesized from the aqueous extract of M. oleifera plant have been studied, and then the antioxidant and antibacterial properties of the aqueous extract obtained from the aerial parts of this plant and the nanoparticles have been studied. The resulting metal was treated. The size and structure of metal nanoparticles obtained from Moringa plant aqueous extract were confirmed by scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. The amount of antioxidant activity was measured using the DPPH method and the antibacterial properties of Moringa plant aqueous extract and metal nanoparticles obtained from it were measured with the help of disk diffusion and MIC method on two types of bacteria E. coli and S. aureus. The highest amount of antioxidant activity (89.23%) was related to copper nanoparticles at a concentration of 500 μg/ml. As well as E. coli bacteria were more sensitive than S. aureus to the same concentrations of the used treatments and had bigger inhibition zone. Additionally, the diameter of the inhibition zone (in millimeters) was also dependent on the concentration and grew with increasing concentration. The use of copper nanoparticles (especially in higher concentrations) has more antibacterial properties. In terms of survival rate and growth of cultured bacteria using the MIC method, the IC50 of E. coli bacteria compared to S. aureus bacteria in equal concentrations to the applied treatments was low, and the results demonstrated the high sensitivity of E. coli bacteria strain to S. aureus bacteria. According to the obtained results, a significant difference was observed between the aqueous extract obtained from the M. oleifera plant and the metal nanoparticles biosynthesized from it in terms of antioxidant and anticancer activity.

In this study, zinc oxide (ZnO) nanoparticles were synthesized using Wild Mentha pulegium extract without the use of chemicals and then embedded in chitosan biopolymer. The optical, structural and morphological properties of the prepared ZnO were investigated by various characterization methods including UV-vis, XRD, EDAX, FTIR and FESEM measurements. The average size of ZnO nanoparticles was estimated to be 45.4 nm using the Debye Scherrer equation. Also, X-ray diffraction result showed that the synthesized sample has a wurtzite crystal structure without any additional or oxide peaks and it is consistent with previous reports. According to the results obtained from the EDX-Map measurement, the presence of Zn in the structure that was synthesized using the extract was confirmed. Also, the prepared transparent and biocompatible polymer coating showed good antibacterial and UV filtering properties for packaging applications.

Two new branched hexadentate amines, 4,7- bis (2-pyridylmethyl)-4,7-diazaundecane-1,10-diamine (L5) and 5,8-bis(2-pyridylmethyl)-5,8-diazadodecane-1,12-diamine (L6), have been synthesized. Condensation with 2-hydroxy-5-methylisophthalaldehyde in the presence of manganese(II), zinc(II) and cadmium(II) ions in methanol leads to produce six new Schiff base macrocyclic complexes [MSb1]2+ and [MSb2]2+ with two 2-pyridylmethyl pendant arms. The resulting compounds were characterized by IR, elemental analysis, Mass and by 1H and 13C NMR in the case of Cd(II) and Zn(II). These compounds are quite stable in air and can be stored in a desiccator for long periods without decomposition. The synthesized complexes were screened for their antibacterial activities against four bacterial; (Escherichia coli) PTcc 10009,) Bacillus cereus (ATCC 7064,) taphylococcus subrogation (Lio) و Staphylococeus aureus (ATCC 6633, strains and the complexes showed antibacterial effects.

In this work, CuO nanoparticles were synthesized using leaf extract of walnut and persimmon plants as chelating and capping agents. The prepared CuO NPs were investigated by FT-IR, XRD, FESEM, EDS, TEM and TGA. Reaction of the phenolic compounds in the aqueous leaf extracts with CuCl2 solution form insoluble Cu2 nanocomplexes which then transform into CuO NPs by heat treatment at 300 °C. It will be expected, the metal ions are connected to constituents of extract from nearby carbonyl and hydroxyl groups on phenyl ring or alone OH groups. Decreasing of mass in thermal analysis of Cu2 nanocomplexes show that these materials are decomposed and transformed into CuO NPs. According to the TEM images, the mean particles size of spherical CuO NPs prepared from the leaf extract of walnut was in the range of 20 nm. The Cu2 nanocomplexes or CuO NPs exhibit antibacterial activity against some pathogenic bacterial strains such as Escherichia coli and Staphylococcus aureus.

In this study, we investigated the antibacterial properties of silver nanocomposites in standard and flame-retardant expandable polystyrenes (EPS). To prepare the silver-polystyrene nanocomposite, we solved polymers separately in a solvent before adding nanoparticles into the solution. For both of EPS samples, three different gelatin yellowish solutions of silver nanoparticles in polystyrene were synthesized at 12.5, 25 and 37.5 µg/cm3. TEM and XRD imaging showed that the silver nanoparticles were about 20 nm in diameter. Additionally, SEM imaging was used for the investigation of silver nanoparticles distribution and also morphology of the nanocomposite cross sections. Samples were laid on polymeric nanocomposite disks to study the antimicrobial properties of them in the presence of gram-negative E. coli ATCC 25922 bacteria and gram-positive Staphylococcus aureus ATCC 6538 bacteria through the standardized single disk. Our comparative study showed that flame-retardant expandable polystyrene-silver nanocomposite does not have any antimicrobial property against these bacteria, while standard expandable polystyrene-silver nanoparticle has some antibacterial potential on Staphylococcus aureus ATCC 6538 which was dependent on concentration levels of the silver nanoparticles. Results of this work could be justified based on the roles of silver nanoparticle concentrations, impurities in polystyrenes and structure of the microorganisms. This research may be considered as a base for investigations on antimicrobial properties of polystyrene nanocomposites as well as vast industrial and healthcare applications of them in the future.

In this research, coaxial electrospinning method was used for preparing the core-shell fibers of polycaprolactone PCL and polyvinyl alcohol PVA, and silver nanoparticles were added through the reduction of silver nitrate in core solution before processing. The presence of silver nanoparticles was proved by observing the absorption peak in UV-visible spectroscopy test in the range of 420-430 nm. Antibacterial properties were investigated according to ATCC100 standard by usage of E.coli and S.aureus bacteria on single layer fibers mat of PCL, PVA, PCL containing silver and PVA containing silver, as well as core-shell fibers mat of PVA-Ag/PCL and PCL-Ag/PVA. The results showed that core-shell fibers have strong antibacterial properties like single layer fibers containing silver. Also, adding silver nanoparticles caused a slight enhancement in contact angle or hydrophobicity of the fibers. The water vapor transmission rate test exhibited that WVTR value decreased with the addition of silver and fabricating core-shell fibers while in comparison with commercial wound dressing, this value is more close to human WVTR value.