Fabrication of an Electrochemical Sensor Based on Gold Nanoparticles/Carbon Nanotubes as Nanocomposite Materials: Determination of Myricetin in Some Drinks

In this paper, the electrochemical behavior of myricetin on a gold nanoparticle/ethylenediamine/multi-walled carbon-nanotube modified glassy carbon electrode (AuNPs/en/MWCNTs/GCE) has been investigated. Myricetin effectively accumulated on the AuNPs/en/MWCNTs/GCE and caused a pair of irreversible redox peaks at around 0.408 V and 0.191 V (vs. Ag/AgCl) in 0.1 mol L⁻¹ phosphate buffer solution (pH 3.5) for oxidation and reduction reactions respectively. The heights of the redox peaks were significantly higher on AuNPs/en/MWNTs/GCE compare with MWCNTs/GC and there was no peak on bare GC. The electron-transfer reaction for myricetin on the surface of electrochemical sensor was controlled by adsorption. Some parameters including pH, accumulation potential, accumulation time and scan rate have been optimized. Under the optimum conditions, anodic peak current was proportional to myricetin concentration in the dynamic range of 5.0×10⁻⁸ to 4.0×10⁻⁵ mol L⁻¹ with the detection limit of 1.2×10⁻⁸ mol L⁻¹. The proposed method was successfully used for the determination of myricetin content in tea and fruit juices.     

PIA and rSesC Mixture Arisen Antibodies Could Inhibit the Biofilm-Formation in Staphylococcus aureus

Background:Staphylococcus aureus as a causative agent of hospital-acquired infections has been considered as the primary concern in biomaterial-related infections (BAIs).Methods:Following the purification of polysaccharide intercellular adhesion (PIA) as an efficient macromolecule in biofilm formation in the native condition, recombinant S. epidermidis surface-exposed rSesC protein, with the most homology to clumping factor A (ClfA) in S. aureus was cloned and expressed in a prokaryotic host as well. Fourier transform infrared spectrometry (FTIR) and Western blotting procedure analyzed purified PIA and protein, respectively. Then, the immune response was evaluated by measuring total IgG titers. Moreover, the capacity of Anti-biofilm forming activity of arisen antibodies to a biofilm-forming S. aureus strains was assessed by the semi-quantitative micro-plate procedure.Results:Data showed that the total IgGs were boosted in mice immunized sera. By performing an inhibition assay, the biofilm inhibitory effect of secreted antibodies to test strain was observed. Arisen antibodies against the mixture significantly were more potent than PIA and rSesC, when comparing individual antigens in a biofilm inhibition assay.Conclusion:immunization of mice with mentioned antigens especially a mixture of them, could eliminate the biofilm formation process in S. aureus. Hopefully, this study corresponds to the suggestion that the immunization of mice with PIA and rSesC candidate vaccines could protect against S. aureus infection.Key Words: PIA, Purification, Staphylococcus aureus, rSesC, Vaccine candidates     

Identification of Trichomonas Vaginalis Genotypes Using by Actin Gene and Molecular Based Methods in Southwest of Iran

Background:Trichomonas vaginalis (T. vaginalis) is a sexually transmitted protozoan parasite and the causative agent of trichomoniasis. The genetic characterization of T. vaginalis isolates shows notable genetic variation in this parasite. In the present study, we aimed to identify the T. vaginalis genotypes based on analyzing of actin gene in women specimens referred to health centers of Ilam city, southwest Iran.Methods:A total of 1765 female samples were collected from gynecology clinics in the city of Ilam. DNA was extracted from positive samples and nested polymerase chain reaction (Nested PCR) was used to amplify the actin gene. Then, partial sequencing and genotyping of the actin gene was performed. A phylogenetic tree was drawn using the detected genotypes of T. vaginalis and reference sequences.Results:Twenty-one of the 1765 urine and vaginal samples were positive for T. vaginalis. All infected individuals were married and their age in years was between 25 to 34. Further, the majority of infected women had cervical lesions, patchy erythema, and white color discharge. According to sequencing analysis, the isolates were identified as genotype G (n= 8) and genotype E (n= 2).Conclusion:From the collected samples, we were able to distinguish at least two genotypes (G and E) of T. vaginalis. However, lesser is known about these genotypes in the city of Ilam. Further studies with a higher number of isolates should be performed in order to understand the implications of these results in this region.Key Words: Actin gene, Genotypes, Ilam, Iran, Trichomonas vaginalis     

Genetic Diversity and Chemical Polymorphism of Some Thymus Species

To ascertain whether there are chemical and genetic relationships among some Thymus species and also to determine correlation between these two sets of data, the essential‐oil composition and genetic variability of six populations of Thymus including: T. daenensis ?elak. (two populations), T. fallax Fisch . & C.A.Mey ., T. fedtschenkoi Ronniger , T. migricus Klokov & Des .‐Shost ., and T. vulgaris L. were analyzed by GC and GC/MS, and also by randomly amplified polymorphic DNA (RAPD). Thus, 27 individuals were analyzed using 16 RAPD primers, which generated 264 polymorphic scorable bands and volatiles isolated by distillation extraction were subjected to GC and GC/MS analyses. The yields of oils ranged from 2.1 to 3.8% (v/w), and 34 components were identified, amounting to a total percentage of 97.8–99.9%. RAPD Markers allowed a perfect distinction between the different species based on their distinctive genetic background. However, they did not show identical clustering with the volatile‐oil profiles.     

Structural and Electrochemical Study of Al2O3 and TiO2 Coated Li1.2Ni0.13Mn0.54Co0.13O2 Cathode Material Using ALD

Nanolayers of Al₂O₃ and TiO₂ coatings were applied to lithium‐ and manganese‐rich cathode powder Li_1.2Ni_0.13Mn_0.54Co_0.13O₂ using an atomic layer deposition (ALD) method. The ALD coatings exhibited different surface morphologies; the Al₂O₃ surface film appeared to be uniform and conformal, while the TiO₂ layers appeared as particulates across the material surface. In a Li‐cell, the Al₂O₃ surface film was stable during repeated charge and discharge, and this improved the cell cycling stability, despite a high surface impedance. The TiO₂ layer was found to be more reactive with Li and formed a Li_xTiO₂ interface, which led to a slight increase in cell capacity. However, the repetitive insertion/extraction process for the Li⁺ ions caused erosion of the surface protective TiO₂ film, which led to degradation in cell performance, particularly at high temperature. For cells comprised of the coated Li_1.2Ni_0.13Mn_0.54Co_0.13O₂ and an anode of meso‐carbon‐micro‐beads (MCMB), the cycling stability introduced by ALD was not enough to overcome the electrochemical instability of MCMB graphite. Therefore, protection of the cathode materials by ALD Al₂O₃ or TiO₂ can address some of the capacity fading issues related to the Li‐rich cathode at room temperature.     

Inferring species boundaries using acoustic and morphological data in the ground cricket genus Gymnogryllus (Orthoptera: Grylloidea: Gryllinae)

An important function of song production by male crickets is to attract conspecific females. These sound signals can be used to infer species boundaries as they can provide indirect evidence for reproductive isolation. However, many studies of orthopteran diversity in South-east Asia are based mainly on morphology and only occasionally acoustics. As such, there is a lack of information on how acoustic data can be congruent with morphological data when used to delineate species. Crickets of the genus Gymnogryllus (Grylloidea, Gryllidae), are such an example. Gymnogryllus are relatively speciose, but their calling songs have not been studied. We collected specimens and calling songs of five Gymnogryllus species from South-east Asia. The acoustic parameters of the calls, along with male tegminal venation and morphology genitalia, were compared. All data types showed congruency in distinguishing G. sylvestris and G. leucostictus from each other and from the other species. Inferring species boundaries for G. angustus, G. malayanus, and G. unexpectus using acoustics and tegminal morphometry proves to be more challenging. While acoustics, tegminal morphometry, and genital morphology are likely to be useful for inferring species of Gymnogryllus from different species groups, greater coverage of taxa is needed to resolve taxonomy of closely related Gymnogryllus.     

PEGylated Single-Walled Carbon Nanotubes as Nanocarriers for Cyclosporin A Delivery

Single-walled carbon nanotubes (SWCNTs) have attracted the attention of many researchers due to their remarkable physicochemical features and have been found to be a new family of nanovectors for the delivery of therapeutic molecules. The ability of these nanostructures to load large amounts of drug molecules on their outer surface has been considered as the main advantage by many investigators. Here, we report the development of a PEGylated SWCNT-mediated delivery system for cyclosporin A (CsA) as a potent immunosuppressive agent. The available OH group in the CsA structure was first linked to a bi-functional linker (i.e., succinic anhydride) in order to provide a COOH terminal group. CsA succinylation process was optimized by using the modified simplex method. The resulting compound, CsA–CO–(CH₂)₂–COOH, was then grafted onto the exterior surface of SWCNTs, previously PEGylated with phospholipid–PEG₅₀₀₀–NH₂ conjugates, through the formation of an amide bond with the free amine group of PEGylated SWCNTs. Drug loading, stability of the PEGylated SWCNT–CsA complex, and in vitro release of the drug were evaluated. Loading efficiencies of almost 72% and 68% were achieved by UV spectrophotometry and elemental analysis methods, respectively. It was observed that 57.3% of cyclosporine was released from CsA–Pl–PEG₅₀₀₀–SWCNTs after 3 days. In this investigation, we conjugated CsA to an amine-terminated phospholipid–polyethylene glycol chain attached on SWCNTs via a cleavable ester bond and demonstrated the possible potential of PEGylated SWCNT-based systems for CsA delivery.