Characterization of silver nanoparticles prepared by wet chemical method and their antibacterial and cytotoxicity activities

Purpose: To investigate the efficiency of silver nanoparticles synthesized by wet chemical method, and evaluate their antibacterial and anti-cancer activities.Methods: Wet chemical method was used to synthesize silver nanoparticles (AgNPs) from silver nitrate, trisodium citrate dehydrate (C6H5O7Na3.2H2O) and sodium borohydride (NaBH4) as reducing agent. The AgNPs and the reaction process were characterized by UV–visible spectrometry, zetasizer, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). The antibacterial and cytotoxic effects of the synthesized nanoparticles were investigated by agar diffusion method and MTT assay respectively.Results: The silver nanoparticles formed were spherical in shape with mean size of 10.3 nm. The results showed good antibacterial properties, killing both Gram-positive and Gram-negative bacteria, and its aqueous suspension displayed cytotoxic activity against colon adenocarcinoma (HCT-116) cell line.Conclusion: The findings indicate that silver nanoparticles synthesized by wet chemical method demonstrate good cytotoxic activity in colon adenocarcinoma (HCT-116) cell lines and strong antibacterial activity against various strains of bacteria.Keywords: Wet chemical, Silver nanoparticles, Characterization, Diffusion method, Antibacterial, Cytotoxic activit

Novel Green Synthesis and Characterization of Nanopolymer Porous Gold Oxide Nanoparticles

Purpose: To develop a novel approach to green synthesis of nano-polymer porous gold oxide nanoparticles, and examine the effects of the temperatures on their surface.Methods: Green synthesis of nano-polymer porous gold oxide nanoparticles (GONPs) using cetyle trimethylammonium bromide (CTAB) surfactant with a mixture of Olea europaea fruit and Acacia Nilotica extracts, was performed using sol-gel method. The nanoporous particles were characterized by UV (ultraviolet (UV) visible spectroscopy and dynamic light scattering (DLS) while a zetasizer was applied to determine their average particle size. Their surface morphology and shape were assessed by transmission electron microscopy (TEM) and scanning election microscopy (SEM) while surface area was measured using nitrogen gas adsorption method.Results: TEM and SEM images showed a smooth, cylindrical or spherical, and cluster shapes, and porous surface morphology. Increase in calcination temperature resulted in increase in surface area and pore volume of nanoparticles. This feature yielded GONPs that were unique with a high surface area of 146.706 m2/g.Conclusion: The approach used in this study constitutes a new and rapid green synthesis of porous nanoparticles of gold oxide under simple conditions. Furthermore, increase in GONPs surface area is enhanced by increase in calcination temperature.Keywords: Gold oxide, Nanoporous, Green synthesis, Olea europaea, Acacia Nilotica, Surface area, Nanopolymer, Surface morpholog

Preparation, characterization and antibacterial effects of eco-friendly gold nanorods

Purpose: To synthesize and characterize eco-friendly gold nanorods (Au-NRs) and to assess their effects against two bacterial strains.Methods: Synthesis of eco-friendly gold nanorods was done from an aqueous solution of chloroauric acid and cetyltrimethylammonium bromide by mixing Olea europaea fruit and Acacia nilotica husk extracts with the latter as a reducing agent. The synthesis was monitored by ultraviolet–visible (UV) spectrophotmetry and a zetasizer, while the morphology of the resulting nanorods was assessed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) coupled with an energy-dispersive spectrophotometer (EDS). The effect of the prepared eco-nanorods on growth of Escherichia coli and Staphylococcus aureus bacteria were investigated by agar diffusion method.Results: The synthesized Au-NRs were mostly rod-shaped, with mean size of 96 nm. They exhibited a potent antibacterial activity against Gram-positive and  Gram-negative microorganisms (Escherichia coli and Staphylococcus aureus).Conclusion: The findings suggest that the nanoformulation of the biomaterial mix of Olea europaea fruit and Acacia nilotica husk extracts is a cost-effective, eco-friendly, and non-toxic synthesis of Au- NRs which has therpeautic potential.Keywords: Olea europaea, Acacia nilotica, Gold nanorods, Eco-friendly synthesis, Gram-positive and Gram-negative microorganism

Green Synthesis, Characterization, and Antibacterial Activity of Silver/Polystyrene Nanocomposite

A novel, nontoxic, simple, cost-effective and ecofriendly technique was used to synthesize green silver nanoparticles (AgNPs). The AgNPs were synthesized using orange peel extract as a reducing agent for silver nitrate salt (AgNO3). The particle size distribution of AgNPs was determined by Dynamic Light Scattering (DLS). The average size of silver nanoparticles was 98.43 nm. The stable dispersion of silver nanoparticles was added slowly to polystyrene solution in toluene maintaining the temperature at 70°C. The AgNPs/polystyrene (PS) nanocomposite solution was cast in a petri dish. The silver nanoparticles encapsulated within polymer chains were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) equipped with Energy Dispersive Spectroscopy (EDS) in addition to Transmission Electron Microscopy (TEM). The green AgNPs/PS nanocomposite film exhibited antimicrobial activity against Gram-negative bacteria Escherichia coli, Klebsiella pneumoniae and Salmonella, and Gram-positive bacteria Staphylococcus aureus. Thus, the key findings of the work include the use of a safe and simple AgNPs/PS nanocomposite which had a marked antibacterial activity which has a potential application in food packaging

Epidemiology of Chlamydia trachomatis in the Middle East and north Africa: a systematic review, meta-analysis, and meta-regression.

BACKGROUND: The epidemiology of Chlamydia trachomatis in the Middle East and north Africa is poorly understood. We aimed to provide a comprehensive epidemiological assessment of C trachomatis infection in the Middle East and north Africa. METHODS: We did a systematic review of C trachomatis infection as well as a meta-analysis and meta-regression of C trachomatis prevalence. We searched PubMed and Embase, as well as regional and national databases up to March 13, 2019, using broad search terms with no language or year restrictions. Any document or report including biological measures for C trachomatis prevalence or incidence was eligible for inclusion. We extracted all measures of current (genital or rectal), recent, and ever infection with C trachomatis. We estimated pooled average prevalence in different populations using random-effects meta-analysis. Factors associated with prevalence and sources of between-study heterogeneity were determined using meta-regression. FINDINGS: We identified a total of 1531 citations, of which 255 reports contributed to 552 C trachomatis prevalence measures from 20 countries. No incidence measures were identified. Pooled prevalence of current genital infection was 3·0% (95% CI 2·3-3·8) in general populations, 2·8% (1·0-5·2) in intermediate-risk populations, 13·2% (7·2-20·7) in female sex workers, 11·3% (9·0-13·7) in infertility clinic attendees, 12·4% (7·9-17·7) in women with miscarriage, 12·4% (9·4-15·7) in symptomatic women, and 17·4% (12·5-22·8) in symptomatic men. Pooled prevalence of current rectal infection was 7·7% (4·2-12·0) in men who have sex with men. Substantial between-study heterogeneity was found. Multivariable meta-regression explained 29·0% of variation. Population type was most strongly associated with prevalence. Additional associations were found with assay type, sample size, country, and sex, but not with sampling methodology or response rate (about 90% of studies used convenience sampling and >75% had unclear response rate). There was no evidence for temporal variation in prevalence between 1982 and 2018. INTERPRETATION: C trachomatis prevalence in the Middle East and north Africa is similar to other regions, but higher than expected given its sexually conservative norms. High prevalence in infertility clinic attendees and in women with miscarriage suggests a potential role for C trachomatis in poor reproductive health outcomes in this region. FUNDING: National Priorities Research Program from the Qatar National Research Fund (a member of Qatar Foundation)