Green Synthesis of Highly Dispersed Zinc Oxide Nanoparticles Supported on Silica Gel Matrix by Daphne oleoides Extract and their Antibacterial Activity.

BACKGROUND: ZnO nanoparticles (ZnO-NPs) are one of the most popular metal oxide nanoparticles, which exhibit significant antibacterial properties against various pathogens. Among nanoparticle synthesis methods, the green synthesis using plant extract is considered as an eco-friendly and cost-effective method for ZnO-NPs production, compared to the chemical procedures. BACKGROUND: This study aimed to evaluate the green synthesis of ZnO-NPs loaded on silica gel matrix (ZnO/SG nanocomposite) by using methanol leaf extract of Daphne oleoides as a new extract and a cost-effective method. Furthermore, the antibacterial activity of the synthesized structure is evaluated against some pathogenic bacteria and the results are compared with unsupported ZnO-NPs. MATERIALS AND METHODS: For ZnO/SG nanocomposite synthesis, a solution of Zn (NO3)2 was stirred with silica gel. Then the Daphne oleoides extract was added and stirred continuously until white precipitate was formed. The precipitate was heated at 200 ˚C for calcination, and ZnO/SG nanocomposite was obtained. The phytochemical constituents of leaf extract were then analyzed by gas chromatography-mass spectrometry (GC-MS). Afterwards, the structure of ZnO-NPs on SiO2 matrix (ZnO/SG nanocomposite) was characterized by field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction analysis (XRD), and Fourier transform infrared spectroscopy (FTIR). Surface area measurement was also determined by Brunauer-Emmett-Teller (BET) techniques. Furthermore, the antibacterial activity of ZnO/SG nanocomposites against pathogenic bacteria was evaluated using agar-based disk diffusion method standardized by clinical and laboratory guidelines. RESULTS: The leaf extract of Daphne oleoides encompassed five major polyphenolic components. The results of the nanocomposite structure showed that ZnO-NPs with an average particle size of 38 nm were obtained and stabilized on the silica gel matrix. The BET surface area measurement of ZnO/SG nanocomposite was compared with unsupported ZnO-NPs, and the results indicated that the surface area of ZnO/SG nanocomposite was increased. Furthermore, the structure showed more powerful antibacterial activity against pathogens than unsupported ZnO-NPs. CONCLUSIONS: Green synthesis of ZnO-NPs supported on the silica gel matrix with the leaf extract of Daphne oleoides is a benign and effective procedure for ZnO/SG nanocomposite synthesis. Embedding ZnO-NPs in silica gel matrix prevents the agglomeration of nanoparticles and prepare homodispersed nanoparticles. This structure revealed great antibacterial activity against many pathogens.

Biosynthesis and Antibacterial Activity of ZnO Nanoparticles by Artemisia aucheri Extract.

BACKGROUND: Green approach to nanoparticles, including metal oxides Because of an inevitable disadvantage of physical or chemical synthesis routes is attractive nowadays. ZnO nanoparticles play a key role in the medicals and drugs area. OBJECTIVES: In this study, biosynthesis of ZnO nanoparticles with new approach to enhanced the Antimicrobial properties against gram-negative and gram-positive was performed by use of a new type of plant extract, Artemisia aucheri, in an environmentally friendly, cost-effective, simple procedure way. MATERIALS AND METHODS: By adding Zn(NO3)2 to A. aucheri methanol extract followed by stirring The resulted solution and final heat treatment in 200 °C the ZnO nanoparticles were synthesized. Disc diffusion method was applied to evaluation the Antimicrobial properties of the extract and nanoparticles towards resistance into Escherichia coli (gram-negative) and Staphylococcus aureus (gram-positive). RESULTS: X-ray diffraction pattern (XRD) result showed all of the peaks proportion to ZnO and no other peaks were detected, also demonstrated nanostructure nature with crystallite size about 9 nm. In the Fourier transform infrared spectroscopy (FTIR), there is a band in the 550 cm-1 which is corresponded to ZnO. Also 76 nm average particle size obtained by DLS experiments. Energy-dispersive X-ray spectroscopy (EDS) analysis showed strong peaks for Zn and O, support supposition of ZnO nanoparticles. Field emission scanning electron microscopy (FESEM) images indicated spherical rounded particles with the size of average 30 nm. Antibacterial tests showed effective diameter about 11 and 10 mm for plant extract and also 7 and 5 mm for ZnO nanoparticles against E. coli (gram-negative) and S. aureus (gram-positive) in agar disc diffusion method, respectively. CONCLUSIONS: Biosynthesized ZnO nanoparticles could be a good candidate for antibacterial activity, both against E. coli (gram-negative) and S. aureus (gram-positive) especially for versus E. coli.

Preparation of polyacrylamide/polylactic acid co-assembled core/shell nanofibers as designed beads for dapsone in vitro efficient delivery.

The main aim of this study is to synthesize and prepare polyacrylamide (PAM)/polylactic acid (PLA) co-assembled core/shell nanofibers in order to investigate an effective dapsone-loaded capability and dapsone-release in the aqueous medium. Dapsone (4,4-diamino-diphenyl sulfone) has high permeability and low solubility in water. In vitro release testing indicates that maximum incorporation of the dapsone nanoemulsions into core/shell nanofibrous structures were 77.71 after 400 min. Products were characterized with X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR), Thermo-Gravimetric Analysis (TGA), Dynamic light scattering (DLS) analysis, Contact Angle Measurement (CAM) and nitrogen adsorption [i.e. Brunauer-Emmett-Teller (BET) Surface Area Analysis] techniques. The porosimetric measurements of the nanofibers structures showed that high porosity diameter, adsorption cross-section area, pore volumes and dead volume were obtained as 0.162 nm2, 0.1005 cm3g-1 and 15.693 cm3, respectively. TGA curve of the core/shell nanofibrous structures shows thermal stability between 240 °C and 260 °C.