Green bio-synthesis of Ni/montmorillonite nanocomposite using extract of Allium jesdianum as the nano-catalyst for electrocatalytic oxidation of methanol

In this work,synthesis of Ni nanoparticles was carried out successfully by water extract of Allium jesdianum as a biochemical reducing agent in the presence of montmorillonite clay(MMT)as a natural solid support for the first time.Then the electrochemical activity of the synthesized nanocomposite was investigated in methanol electrocatalytic oxidation.MMT with high cation exchange capacity and nano layer structure was exposed to ion exchange conditions in nickel solution.Then Ni^2+ion exchanged form was used in this process as a source of ions and also capping agent.Water extract of Allium jesdianum used as a reducing agent due to abundant availability of phenolic and flavonoid contents.The synthesized Ni/MMT nanocomposite was characterized using UV–Vis spectroscopy(UV–Vis),Fourier Transform Infrared Spectroscopy(FT-IR),X-ray diffraction(XRD),Scanning Electron Microscopy(SEM),Transmission electron microscopy(TEM)and Energy-dispersive X-ray spectroscopy(EDX).The surface of prepared modified electrode has been characterized using SEM to evaluate the morphology,showing uniform dispersion of Ni nanoparticles with mean diameter of 12 to 20 nm.The modified carbon paste electrode was then used in methanol electrocatalytic oxidation reaction.Methanol oxidation on the proposed modified electrode surface occurs at 0.6 V and 0.3 V in alkaline and acidic medium respectively.Also,the results showed the better performance of modified electrode toward methanol electrocatalytic oxidation in comparison with carbon paste electrode that is modified by ion exchanged MMT.Charge transfer coefficients and apparent charge transfer rate constant for the modified electrode in the absence of methanol in alkaline medium were respectively found as:αa=0.53,αc=0.37 and ks=1.6×10^-1 s^-1.Also,the average value of catalytic rate constant for the electrocatalytic oxidation of methanol by the prepared nano-catalyst was estimated to be about 0.9 L·mol^-1·s^-1 by chronoamperometry technique.The prepared electrode was also effective for electrocatalytic oxidation of ethanol and formaldehyde in alkaline medium.

Green synthesis of functional metallic nanoparticles by dissimilatory metal-reducing bacteria“Shewanella”:A comprehensive review

The biosynthesis strategy of nanoparticles has attracted much attention due to the mild synthesis condi-tions,environmental-friendly properties,and low costs.Biosynthesized nanoparticles(bio-NPs)not only show excellent physicochemical properties,but also exhibit high stability,enlarged specific surface area,and excellent biocompatibility,which are crucial for industrial,agricultural,and medical fields.She-wanella,a kind of dissimilatory metal-reducing bacteria,is regarded as a typical biosynthesis-functional bacteria class with wide distribution and strong adaptability.Thus,in this paper,functional bio-NPs by Shewanella were reviewed to provide a comprehensive view of current research progress.The biosynthetic mechanisms of Shewanella are summarized as the Mtr pathway(predominant),extracellular polymeric substance-induced pathway,and enzyme/protein-induced pathway.During the biosynthesis process,bio-logical factors along with the physicochemical parameters highly influenced the properties of the resul-tant bio-NPs.Till now,bio-NPs have been applied in various fields including environmental remediation,antibacterial applications,and microbial fuel cells.However,some challenging issues of bio-NPs by She-wanella remain unsolved,such as optimizing suitable bacterial strains,intelligently controlling bio-NPs,clarifying biosynthesis mechanisms,and expanding bio-NPs applications.

Construction of a plasmid for human brain-derived neurotrophic factor and its effect on retinal pigment epithelial cell viability

Several studies have investigated the protective functions of brain-derived neurotrophic factor（BDNF） in retinitis pigmentosa. However, a BDNF-based therapy for retinitis pigmentosa is not yet available. To develop an efficient treatment for fundus disease, an eukaryotic expression plasmid was generated and used to transfect human 293 T cells to assess the expression and bioactivity of BDNF on acute retinal pigment epithelial-19（ARPE-19） cells, a human retinal epithelial cell line. After 96 hours of co-culture in a Transwell chamber, ARPE-19 cells exposed to BDNF secreted by 293 T cells were more viable than ARPE-19 cells not exposed to secreted BDNF. Western blot assay showed that Bax levels were downregulated and that Bcl-2 levels were upregulated in human ARPE-19 cells exposed to BDNF. Furthermore, 293 T cells transfected with the BDNF gene steadily secreted the protein. The powerful anti-apoptotic function of this BDNF may be useful for the treatment of retinitis pigmentosa and other retinal degenerative diseases.