Graphene oxide/silver nanohybrid: Optimization,antibacterial activity and its impregnation on bacterial cellulose as a potential wound dressing based on GO‐Ag nanocomposite‐coated BC

Recently, bacterial cellulose (BC) based wound dressing have raised significant interests in medical fields. However, to our best knowledge, it is apparent that the BC itself has no antibacterial activity. In this study, we optimized graphene oxide‐silver (GO‐Ag) nanohybrid synthesis using Response Surface Methodology and impregnate it to BC and carefully investigate their antibacterial activities against both the Gram‐negative bacteria Escherichia coli and the Gram‐positive bacteria Staphylococcus aureus. We discover that, compared to silver nanoparticles, GO‐Ag nanohybrid with an optimal GO suspension's pH and ratio is much more effective and shows synergistically enhanced, strong antibacterial activities at rather low dose. The GO‐Ag nanohybrid is more toxic to E. coli than that to S. aureus. The antibacterial and mechanical properties of BC/GO‐Ag composite are further investigated.     

Application of induced pluripotent stem cell and embryonic stem cell technology to the study of male infertility

Stem cells (SCs) are classes of undifferentiated biological cells existing only at the embryonic, fetal, and adult stages that can divide to produce specialized cell types during fetal development and remain in our bodies throughout life. The progression of regenerative and reproductive medicine owes the advancement of respective in vitro and in vivo biological science on the stem cell nature under appropriate conditions. The SCs are promising therapeutic tools to treat currently of infertility because of wide sources and high potency to differentiate. Nevertheless, no effective remedies are available to deal with severe infertility due to congenital or gonadotoxic stem cell deficiency in prepubertal childhood. Some recent solutions have been developed to address the severe fertility problems, including in vitro formation of germ cells from stem cells, induction of pluripotency from somatic cells, and production of patient‐specific pluripotent stem cells. There is a possibility of fertility restoration using the in vitro formation of germ cells from somatic cells. Accordingly, the present review aimed at studying the literature published on the medical application of stem cells in reproductive concerns.     

Development of a biodegradable coating formulation based on the biological characteristics of the Iranian Ultra-filtrated cheese

Type and concentration of edible components, are two main factors which can be affected the chemical, microbial, quality, sensory properties and storage life of coated cheese. In this work, to optimize the concentrations of chitosan and Natamycin for coating Iranian white UF cheese response surface methodology was used. The effects of main edible coating components, chitosan (0.5–2.5%, w/w) and Natamycin (5–20 ppm) on pH, TSS, bacterial total count, yeast and mould population and starter of coated cheese were studied up to 3 weeks after storage at 4?±?2 °C. The obtained results indicated that the second-order polynomial models could be successfully generated with high coefficient of determination (R²?≥?0.9153) using experimental data for all the studied response variables. The optimum concentrations of chitosan and Natamycin were obtained at 1.6% w/w and 18.5 ppm, respectively which the predicted values for pH, TSS, bacterial total count, yeast and mould population and starter were 4.5, 37%, 12 cfu, 14 cfu and 346 cfu, respectively. The verification test was done at obtained optimum concentrations of the main edible components and the statistical analysis indicated insignificant (p?>?0.05) differences between the predicted and experimental values of the response variables.     

Development of a localized surface plasmon resonance-based gold nanobiosensor for the determination of prolactin hormone in human serum

A localized surface plasmon resonance immunoassay has been developed to determine prolactin hormone in human serum samples. Gold nanoparticles were synthesized, and the probe was prepared by electrostatic adsorption of antibody on the surfaces of gold nanoparticles. The pH and the antibody-to-gold nanoparticle ratio, as the factors affecting the probe functions, were optimized. The constructed nanobiosensor was characterized by dynamic light scattering. The sensor was applied for the determination of prolactin antigen concentration based on the amount of localized surface plasmon resonance peak shift. A linear dynamic range of 1–40 ng ml⁻¹, a detection limit of 0.8 ng ml⁻¹, and sensitivity of 10 pg ml⁻¹ were obtained. Finally, the nanobiosensor was applied for the determination of prolactin in human control serum sample.     

Potassium permanganate–glutaraldehyde chemiluminescence system catalyzed by gold nanoprisms toward selective determination of fluoride

Gold and silver nanoparticles (NPs) are shown to exert a positive effect on the chemiluminescence (CL) reaction of permanganate aldehydes. Interestingly, between various shapes examined, Au nanoprisms have the highest beneficial effect. This effect is even more notable in the presence of sodium dodecyl sulfate (SDS) surfactant. UV‐vis spectra and transmission electron microscopy were used to characterize the NP shapes and sizes. Furthermore, it was observed that iron(III) ions can slightly increase CL emission of this system. This intensification is very effective in the presence of fluoride ions (F^–). These observations form the basis of the method for the high sensitive determination of F^– in the 6–1200 nmol L^–1 concentration range, with a detection limit of 2.1 nmol L^–1. The proposed method has good precision and was satisfactorily used in the selective determination of low concentrations of fluoride ion in real samples. Copyright © 2015 John Wiley & Sons, Ltd.