Sharif Digital Repository

Arrays of ZnO nanorods were synthesized on ZnO seed layer/glass substrates by a hydrothermal method at a low temperature of 70 °C. The effect of pH > 7 of the hydrated zinc nitrate-NaOH precursor on the morphology and topography (e.g. size, surface area and roughness), the optical characteristics (e.g. optical transmission and band-gap energy), hydrophilicity and antibacterial activity of the grown ZnO nanostructure and nanorod coatings were investigated. For pH = 11.33 of the precursor (NaOH concentration of 0.10M), a fast growth of ZnO nanorods on the seed layer (length of ∼1 νm in 1.5 h) was observed. The fast growth of the ZnO nanorods resulted in a significant reduction in the optical... 

Herein, a novel Pt-APA composite (APA = pyridinium bromide salt) based on magnetic graphene oxide was synthesized and used as an effective catalyst. In this way, Fe3O4 nanoparticles are grown on graphene oxide (GO) nanosheets by a simple and practical method which creates a unique nanostructure (Fe3O4/GO) through dispersing uniformly among graphene nanosheets. The resulted Pt-APA composite was obtained via adding PtCl2 to an ethanol solution of Fe3O4/GO and α-keto stabilized pyridinium ylide in related conditions. The synthesized nanocomposite structure was identified using field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive... 

The synergistic effect of nano titanium dioxide (10 and 30 nm) and nano silver (10 nm) as antibacterial agents were investigated on UV curable clear coating. Antibacterial and physical-mechanical properties of coating were optimized using experimental design in response surface method. Twenty different samples of nano Ag and nano TiO2 were prepared in this method. Antibacterial properties on Gram-negative bacteria (Escherichia coli) were investigated. The results revealed that using equal amounts of two sizes of nano TiO2 promote the antibacterial activity of nano Ag. So, the coating shows strong activity against E. coli. Physical-mechanical properties such as surface hardness, abrasion... 

Rhamnolipids (RLs) produced by the opportunistic human pathogen Pseudomonas aeruginosa are considered as potential candidates for the next generation of surfactants. Large-scale production of RLs depends on progress in strain engineering, medium design, operating strategies, and purification procedures. In this work, the rhlAB genes extracted from a mono-RLs-producing strain of P. aeruginosa (ATCC 9027) were introduced to an appropriate safety host Pseudomonas putida KT2440. The capability of the recombinant strain was evaluated in various media. As a prerequisite for optimal medium design, a set of 32 experiments was performed in two steps for screening a number of macro-nutritional... 

TiO2-based photocatalysts are seen as the most common agents for the photodegradation of bacteria. In this study, AgCl/TiO2, hydroxyapatite(Hp)/AgCl/TiO2, AgI/TiO2, and Hp/AgI/TiO2 were prepared by the deposition-precipitation method on P25 TiO2 nanoparticles and were characterized by XRD, SEM, FT-IR, EDX and BET methods. The prepared composites showed high efficiency for the inactivation of Escherichia coli (E. coli) bacteria under visible light and in dark media with different catalyst amounts of 12 and 24 mg, respectively. In less than 30 min, AgI/TiO2, prepared by the combination of cationic surfactant and PVPI2, disinfected 1 × 107 colony-forming units of E. coli completely. However,... 

Background. Autoimmune process and immunosuppressive therapy of pemphigus vulgaris would predispose the patients to infections. Aim. We aimed to study the prevalence of infection and pathogenic agents in pemphigus vulgaris patients admitted to dermatology service. Material and methods. This retrospective study was conducted on 155 pemphigus vulgaris patients (68 males, 87 females) admitted to dermatology service between 2009 and 2011. In this study, the diagnosis of pemphigus vulgaris was confirmed by light microscopic and direct immunofluorescence findings. Data were collected through a questionnaire. Results. Of 155 pemphigus vulgaris patients, 33 had infection at admission and 9 acquired... 

In this research, response surface methodology (RSM) was applied to study the effects of Na-Montmorillonite (Na-MMT) and glycerol on some functional properties of corn starch films. Films were prepared by casting method according to central composite design (CCD). Originally image processing technique was used in order to estimate transparency of the films. It was found that Na-MMT absorbed UV light from 216 to 266. nm. No antimicrobial activities were observed against Escherichia coli and Staphylococcus aureus. Contact angle analysis revealed hydrophilicity of starch films decreased utilizing nanoparticles and increased with plasticizer content. Increase in glycerol content decreased... 

The adverse effect of graphene-titanium oxide composite films (containing sheet-like surface morphology) on Caenorhabditis elegans nematodes (as a model for minuscule animals) was investigated in a solar light-induced photocatalytic process. X-ray photoelectron spectroscopy demonstrated photocatalytic reduction of the chemically exfoliated graphene oxide sheets included in the TiO 2 film. Furthermore, formation of TiC and Ti-O-C bonds in the composite film (obtained through annealing at 450 °C in air) resulted in a substantial delay in the recombination rate of the photoexcited electron-hole pairs and more efficient photocatalytic processes. The composite film showed a type of... 

Zeolite-based Ag/AgBr and Ag/AgBr/TiO 2 photocatalysts were prepared by sol-gel and deposition methods and were characterized. Their photocatalytic activities were evaluated by inactivation of Escherichia (E.) coli and the photodegradation of Acid Blue 92 and potassium permanganate. The composites containing Ag/AgBr showed the antibacterial activity in the dark by releasing Ag ions into the medium. The results for inactivation of E. coli indicated that Ag/AgBr/TiO 2 modified photocatalyst had better antibacterial activity than Ag/AgBr/zeolite, while zeolite and TiO 2/zeolite did not show any antibacterial activity under visible light and dark conditions. Photodecolarization rate was affected... 

In the current study, for the first time, photochemical facile green synthesis of salep capped silver nano-wedges was reported via the wet chemical synthesis procedure. Sunlight-UV as an available reducing agent caused mild reduction of silver ions to the silver nano-wedges. Salep as an effective capping/shaping polysaccharide bioresource material was used in the reaction medium and caused creation of flower-like self-assembled structures of the silver nano-wedges. The formation of silver nano-wedges and their flower-like self-assembled structures was confirmed by SEM technique. Further investigations were carried out using UV-vis, FTIR, GPC and XRD data. The prepared silver nano-wedges... 

Vertical copper oxide nanoflakes were synthesized on a Cu foil through oxidation in alkaline conditions. X-ray photoelectron spectroscopy showed that after exposing the nanoflakes to an Escherichia coli bacterial suspension, the outermost surface of the nanoflakes was chemically reduced through the glycolysis process of the bacteria. Current-voltage (I-V) characteristics of the nanoflakes (measured perpendicular to surface of the Cu foil by using conductive atomic force microscopy) indicated that electrical resistivity of the nanoflakes increased about one order of magnitude after exposure to the bacterial suspension. The nanoflakes reduced by the bacterial suspension could also be... 

Multi-component photocatalysts based on apatite-coated Ag=AgBr=TiO 2 were prepared by the deposition method. The effects of various kinds of apatites, with hydroxyl and fluoro substituents, on photocatalytic activity were investigated. The antibacterial processes in the dark, and under visible light, on two types of bacteria indicate that the multi-composites can inhibit the growth of bacteria by two different mechanisms. TEM images and optical microscopic data demonstrate that by attaching the nanosize catalyst to the outer membrane of the cell, the bacteria could not derive nourishment from surrounding media, i.e. this component acts as bacteria-static. The mechanism for deactivation of... 

Graphene oxide platelets synthesized by using a chemical exfoliation method were deposited on anatase TiO2 thin films. Postannealing of the graphene oxide/TiO2 thin films at 400 °C in air resulted in partial formation of a Ti-C bond between the platelets and their beneath thin film. By using atomic force microscopy and X-ray photoelectron spectroscopy analyses, UV-visible light-induced photocatalytic reduction of the graphene oxide platelets of the annealed graphene oxide/TiO2. thin films immersed in ethanol was studied for the different irradiation times. After 4 h of photocatalytic reduction, the vertical space between the platelets decreased from about 1.1 to less than 0.8 nm and the... 

The most important issue during synthesis of nanoparticles (NPs) is to avoid particle agglomeration and adhesion. There have been several attempts to use special substances such as organic surfactants, polymers and stable ligands for this purpose. In this study, silver NPs were synthesised with and without gelatin macromolecules, as a green natural biopolymer, which resulted in NPs with varying shapes and sizes. The effect of morphological characteristics on the antibacterial and antifungal properties of the synthesised NPs were studied, by comparing Gram-negative (Escherichia coli) versus Gram-positive (Staphylococcus aureus) bacteria as well as fungi (Candida albicans) by calculation of... 

The present study deals with the feasibility of a microfluidic microbial electrolysis cell (MEC) as an efficient biohydrogen generator for medical usage for the first time. The evaluation of nickel in microfluidic MEC as an alternative for conventional electrodes indicates successful performance in the improvement of bioenergy production. The maximum biohydrogen production rate and produced power density of 2.2 μW cm−2 and 1.4 μl H2 μl substrate−1 day−1 were obtained, respectively. It is considered a promising technology for medical usage due to the following factors: significant biohydrogen generation, low consumption of expensive materials, simple construction, and utilization of human... 

In this study, anti-leukemic enzyme L-asparaginase (E.C.3.5.1.1) from Escherichia coli ATCC 11303 was modified by the microencapsulation technique onto calcium alginate beads. Using response surface methodology (RSM), a three-level full factorial design, the values of concentration of sodium alginate, concentration of calcium chloride, and enzyme loading were investigated to obtain the highest residual L-asparaginase (L-ASNase) activity % (immobilized enzyme activity/free enzyme activity). The effects of the studied factors on immobilization were evaluated The predicted values by the model were close to the experimental values, indicating suitability of the model. The results presented that... 

A composite coating containing silver, fluoride and hydroxyapatite (Ag-FHA) was developed on titanium substrate by sol-gel method. Triethylphosphite, hydrated calcium nitrate, ammonium fluoride and silver nitrate were used respectively, as P, Ca, F and Ag precursors with a Ca:P ratio 1.67 and concentration of silver was 0.3 wt%. Coatings were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and atomic absorption spectrometry (AAS). Potentiodynamic polarization measurements in simulated body fluid proved corrosion protection caused by both Ag-FHA coatings. Antibacterial activity of coatings against... 

In recent years, applications of dielectrophoresis-based platforms have been recognized as effective and dependable approach to separate cells and bioparticles, suspended in different carrier fluids, based on particle size and electrical properties. In this study, a microfluidic device was fabricated by an unprecedented electrode pattern, and several experiments were performed to enrich samples including either of yeast, Escherichia coli, or latex particles. A chemical deposition-based method was employed for fabrication of microelectrodes, inducing nonuniform electric field required for dielectrophoresis-based separation. One major advantage of our employed method is low fabrication cost,... 

Titanium dioxide is prepared by sol gel method from titanium tetraisopropoxide (TTIP) as precursor and likewise zinc oxide is prepared by sol gel method from zinc acetate dehydrate (ZAD) as precursor. The composite sols are prepared in three different molar ratios 90TiO2:10ZnO, 70TiO2:30ZnO and 50TiO2:50ZnO. Thin film deposition is carried out by dip coating technique. Crystal structure, surface morphology and photocatalytic activity of the prepared nanocomposite thin films are investigated. The antibacterial activity of the prepared nanocomposite thin film against E-coli ATCC 25922 bacteria is examined by placing the thin film in standard aqueous E-coli medium under UV light for 1, 2, 3 and... 

Silver nanoparticles (NPs) stored in pore-arrays (pa) SU-8 photoresist layer were utilized as an antibacterial nanocomposition against E. coli bacteria. The pa-SU-8 matrix was fabricated by an optical interference lithography method resulting in small pores with a diameter of ∼50 nm and a depth of ∼100 nm. The Ag NPs were deposited on the soft polymeric matrix at different drying temperatures of 50 and 90 °C. X-ray photoelectron spectroscopy showed that the deposited silver NPs were substantially in the metallic state, independent from the drying condition. However, the concentration of the immobilized Ag NPs on the film surface increased (by a factor of 2.5) at the higher drying...