NANOSCALE
Year:2015 | Volume:2 | Issue:1|Papers Count:8

Surface plasmon resonance (SPR) sensors are an optical platform capable of highly sensitive and specific measuring of biomolecular interactions in real-time. This label-free technology can quantify the kinetics, affinity and concentration of surface interactions. SPR sensors have been used to detect bacterial pathogens in clinical and food-related samples. SPR-based immunosensors that coupled with a specific antigen-antibody reaction, have become a promising tool for the quantification of bacteria as it offers sensitive, specific, rapid, and label-free detection. In this paper, we evaluated application of a SPRbased immunosensor for detection of Vibrio cholera causative agent of cholera by a dual channel Surface plasmon resonance device. At first a Self Assembled Monolayer (SAM) of 11-Mercaptoundecanoic acid was formed on sensor chip and after that antibody againstVibrio cholera was immobilized on chip covalently. Then different dilutions of Vibrio cholera cultures was passed on immobilized antibody and the response of SPR was recorded. The specificity of this Nano biosensor was studied by interaction of some non-Vibrio cholera bacteria.

LaFe0.6Co0.4O3 perovskite is a candidate material for a carbon monoxide gas sensor. The synthesis of cobalt doped lanthanum ferrite perovskite nanoparticles via chemical route using ammonium hydroxide (NH4OH) and sodium hydroxide (NaOH) as the precipitation agent and calcination at different temperatures is reported. Presence of crystallized particles in orthorhombic lattice was confirmed with phase analysis using X-ray diffraction (XRD). Field emission scanning electron microscopy (FESEM) observations revealed that smaller mean particle size obtained by using NH4OH precipitant. Lowering the calcination temperature, from 900 to 800oC, leads to a significant morphological change of nanoparticles and decrement in mean particle size. Raman analysis revealed that the sample synthesized by NaOH has a larger ratio of Co2+/Co3+ and thus more oxygen vacancies.

Size is one of the most important physical factors of nanoparticles (NPs). The size of the NPs can be effective in application of particles, especially in designing of drug delivery systems. NPs size could regulate blood half-life, immunogenicity and toxicity of them. So determination factors affecting the size can be very helpful in various applications. In this study the influence of various factors, including chitosan concentration, pH and reaction time (as independent variables), on the self-assembled NPs were investigated. Artificial neural networks were used to study the relationship between the independent and dependent variables. The results showed that chitosan concentration is the most important factor and has a direct effect on size. pH and reaction time have slight effect on size. Increasing pH would decrease the size but increasing pH would lead to increasing size. In total for preparation of chitosan/albumin NPs in desired size, polymer concentration, pH and reaction time must be adjusted.

Citrate colloidal silver nanoparticles were synthesized with 17 nm by Lee and Meisel technique. TiO2-Ag/MWCNTs nanocomposites were synthesized by sol-gel method. The size of colloidal silver nanoparticles were estimated under 20 nm by Dynamic Light Scattering (DLS) and Zeta analyzer. By Raman spectroscopic methodology different loading of MWCNTs into TiO2-Ag matrix were scanned in which it is an effective factor in shifting Raman frequencies bands. G band (1583 cm-1) that is one of the main bands of MWCNTs in above matrix, was analyzed and evaluated according to the shift of this band as a function of different loading percentages of MWCNTs. According to the amount of shifting of this band, the compressive strain of MWCNTs in the matrix was calculated that is more remarkable than the amount of the reported values in similar works.

In this paper, we study the electronic transport of an infinite ladder network that a part of it is twisted by using Green’s function method at the tight-binding approach. For this purpose, we insert the effects of orbital overlapping of the neighbor atoms as well as the effect of twisting, in the tight-binding parameters of the twisted part. Moreover, due to the symmetric considerations of the system Hamiltonian, the under consider problem reduces to the problem of the two simple chains. The numerical results show that the conductance dramatically depends on amount of twisting and the coefficient of variation of orbital overlapping strength. Increasing of twisting in the center ladder causes the decreasing of its energy window and consequently the resonance region becomes smaller.

In this study for comparing the thermal conductivity of magnetic nanofluids with other nanofluids, three sample nanofluids prepared. Functionalized nanofluids, nanofluids with surface active substance and magnetic nanofluids using hybrid carbon nanotube-iron oxide for weight percentages under 1% in distilled water as a base fluid. First functionalized nanofluids, multi-walled carbon nanotubes functionalized with carboxyl functional group was pickling, then preparing nanofluids with Sodium dodecyl sulfate (SDS) surfactant then magnetic nanoparticles was synthesized with hybrid Fe2O3-CNT for the first time .The thermal conductivity coefficient were measured by KD2pro device. The results showed that with enhancement of temperature and weight percentage the thermal conductivity coefficient were increased. Magnetic nanofluids showed higher thermal conductivity in comparison with functionalized and nanofluids with surfactant SDS.

Oil contaminations are a problem that Iran, as a country having oil reserves, faces it. These contaminations mostly occur in aquatic ecosystems and cause death of many aquatic organisms, their entrance in food chain, and health problems in human societies. Many solutions have been proposed for this problem and using nanoparticles has been introduced as a new approach. In this project, iron oxide nanoparticles have been synthesized in order to be used in separating petroleum from water. These nanoparticles are biocompatible and could be directed and recovered by magnetism. Based on our experiments, nanoparticles were successful in separating petroleum from water. Furthermore, the recovered petroleum was analyzed by Gas Chromatography and showed no significant change. According to the results of current investigation, the separated petroleum could be recovered and returned to the economic cycle of the country and inhibit the loss of national wealth.

Hybridization of graphene is a common method to create highly conductive composites with high adsorptive surfaces. In this study, we synthesized graphene/TiO2 hybrid by simple and fast microwave method under reaction of graphene oxide and n-butyl-ortho-titanate in water/ethanol solvent. First, graphite oxide was prepared by modified Hummer’s method. Then, we used n-butyl-ortho-titanate, water/ ethanol mixture and graphene oxide to create titania nanoparticles on graphene oxide via hydrolysis. Microwave irradiation used to create graphene/TiO2 hybrid by reducing graphene oxide into graphene. Presence of Ti-O-C bonds confirms creation of graphene/TiO2 hybrid. The synthesized hybrid shows enhanced photocatalytic functionality by degradation of methylene blue under UV light illumination. Characterization has been done by XRD, UV-Vis and FTIR analysis.