Hassan A. Shehata

Thermo-and pH-sensitive hydrogel membranes composed of poly(N-isopropylacrylamide)-hyaluronan for biomedical applications: Influence of hyaluronan incorporation on the membrane properties

Interpenetrating hydrogel membranes consisting of pH-sensitive hyaluronan (HA) and thermo-sensitive poly(N-isopropylacrylamide) (PNIPAAM) were synthesized using redox polymerization, followed by N,N-methylenebisacrylamide (BIS) and epichlorohydrin (EPI) were added as chemical crosslinkers. The interaction between membrane compositions has been characterized by FTIR spectroscopy and discussed intensively. The result indicates that HA incorporation in membranes increase the gel fraction, swelling uptake, and the flexibility/elasticity of crosslinked membranes, however it reduced oppositely the mechanical elongation of membranes. PNIPAAm-HA hydrogels responded to both temperature and pH changes and the stimuli-responsiveness was reversible. However, in vitro bioevaluation results revealed that the released ampicillin during the burst release time was sharply influenced and increased with increasing HA contents in membranes; afterwards it became sustainable. Whereas, high HA contents in hydrogels unexpectedly impacted negatively on the cells viability, owing to the viscosity of cell culture media changed. A big resistance was observed against microbial growth of Staphylococcus aureus, Salmonella typhi, and Candida albicans in case of pure PNIPAAm hydrogel membranes without HA or ampicillin. However, HA incorporation or the loaded ampicillin in membranes showed unexpected easily microbial growth. The fast release performance with dual pH-thermo-sensitive hydrogels were suggested as promising materials for quick drug carrier in the biomedical field.

One-step synthesis of silver nanoparticles embedded with polyethylene glycol as thin films

Abstract Silver nanoparticles (Ag NPs) embedded and stabilized with polyethylene glycol (PEG) were synthesized as colloids by heating and exposure to sunlight (direct and indirect) irradiation as green method. The deposition of Ag NP-PEGs onto Si-wafers was also made using the electrospray ionization deposition technique. The generating of Ag NP-PEGs as colloids was examined by UV–visible spectroscopy (UV–Vis) and transmission electron microscopy (TEM). The chemical composition of the resulted nanocomposites was evaluated by Fourier transform infrared (FTIR) and that of thin-film surfaces by X-ray photoelectron spectroscopy. Structure–property relationships of Ag-PEG nanocomposites prepared by heating were discussed in dependence on the time of heating. The UV–visible results confirmed the successful synthesis of spherical Ag NPs with absorption peaks at a wavelength of λ = 413 nm for the heating method and at λ = 418 as well as 449 nm for direct and indirect exposure to the sunlight. Ag-PEG nanocomposite thin films showed excellent antimicrobial activity. These results revealed that the Ag-PEG nanocomposites thin films can be used as potential materials in biomedical applications.

Modeling and optimizing Acid Orange 142 degradation in aqueous solution by non-thermal plasma.

The effects of the high voltage electrode material, initial pH of the solution, initial concentration of Fe2+, and time of plasma treatment on the efficiency of Acid Orange 142 (AO142) degradation were studied and evaluated. Furthermore, based on the Box-Behnken response surface methodology (BBD-RSM), a model between response (decolorization efficiency %) and influencing factors was proposed to estimate the interactive effects and optimize the process conditions. The proposed model was adequate with an R2 of 0.8005 which is in reasonable agreement with the R2adj of 0.9307. According to the model, the optimum conditions were steel as a high voltage electrode, an initial pH 3.0, an initial Fe2+ concentration 0.9 mM, and 20 min time of treatment to obtain a decolorization efficiency of 95.05%. In addition, the analytical results of UV-Vis, FT-IR, TOC and GC-MS indicated the degradation of the dye molecule.