Physical Properties Of Nanoparticles Research Articles

Nanotechnologies in medicine

Mutated genes, misfolded proteins and pathogenic viruses or bacteria can lead to cell malfunction or miscommunication at the nanoscale level. These molecules and infectious agents are nanometer in size and may be present in biological systems that are protected by nanometers-sized barriers. The chemical and physical properties of nanoparticles appear to govern the transport of molecules to specific biological compartments and the interactions between molecules. Since nanomaterials are similar in scale to biological molecules and systems they can be engineered to have various functions. Nanotechnology is potentially useful for medical applications, such as in vitro and in vivo diagnosis, transport of diagnostic or therapeutic agents through biological barriers, molecular identification and imaging evaluation of diseases.

Synthesis of Silver Nanoparticles Using Complexing Agent Method: Comparing the Effect of Ammonium Hydroxide and Nitric Acid on Some Physical Properties of Nanoparticles

Silver nanoparticles were prepared using complexing agent method in which citric acid was used as the complexing agent. The effect of ammonium hydroxide and nitric acid addition on size, morphology, purity and surface area of nanoparticles were studied and compared. XRD, TEM, EDAX and BET were used for the characterization of synthesized nanoparticles. Addition of ammonium hydroxide led to smaller size of the silver nanoparticles. However, lower purity of nanoparticles was obtained when ammonium hydroxide was added to the mixture. However, the morphology of nanoparticles in both conditions is same. Also the experimental studies of nanoparticles surface areas show their tracking by size as we expected. These effects can be explained by the role of ammonium hydroxide and nitric acid on the direction of equilibrium reaction and affecting the solubility of silver citrate.

Potential integration of cadmium lab chip with immunoassay using quantum dot/antibody probe for detection of microcystin-LR

Quantum dots (QDs) were used to detect quickly pathogenic microorganisms in sea water. The size is an important parameter that determines the chemical and physical properties of nanoparticles. In order to measure the size of water soluble nanoparticles, QDs, field-flow fraction (FFF) was used. Different sized water-soluble nanoparticles were effectively separated. As an indirect measurement of target analyte, instead of conventional fluorescent optical methods, we measured amount of cadmium ions using anodic stripping voltammetry since major component of core-shell CdSe/ZnS QDs used for immunoassay of cyanobacterial hepatotoxin microcystin-LR was cadmium. In addition, we developed a lab chip (LC) to measure electrochemically cadmium in water. For our further research, it will be integrated with immunoassay method to develop portable lab chip monitoring system QDs for the detection of cyanobacterial hepatotoxin microcystin-LR. The quantum dots-antibody (QD/Ab) and QD-labeling methods were simple, sensitive...

The effect of [Fe3+]/[Fe2+] molar ratio and iron salts concentration on the properties of superparamagnetic iron oxide nanoparticles in the water/ethanol/toluene system

In this study, we developed a convenient one-pot method with sodium oleate as both the surfactant and precipitant to synthesize pure magnetite nanoparticles in the water/ethanol/toluene system. The initial molar ratio of [Fe3+]/[Fe2+] and the concentration of iron salts were changed in order to systematically investigate their influences on the chemical and physical properties of nanoparticles, such as the crystal structure, morphology, particle sizes, dispersion and magnetism. Samples were determined by XRD, XPS, FTIR, DLS, and VSM. The oleate coating steadily existed on the surface of the nanoparticles to profit them of excellent monodispersibility and stability in non-polar solvents with very narrow size distribution and extremely approximate mean diameters of ~7 nm. Particles consisted mainly of magnetite with a little or no maghemite phase with the molar ratio of [Fe3+]/[Fe2+] decreasing from 2:1 to 1:1, but they all exhibited superparamagnetism at room temperature. After the optimization, pure magnetite nanoparticles could be prepared with the saturation magnetization successfully increasing to 75 emu/g(Fe), when the molar ratio of [Fe3+]/[Fe2+] was 1.5:1 and the concentration of iron precursors was 95 mM.

Formation and strain distribution of Ni/NiO core/shell magnetic nanoparticles fabricated by pulsed laser deposition

Nucleation and growth lead to substantial strain in nanoparticles embedded in a host matrix. The distribution of strain field plays an important role in the physical properties of nanoparticles. Magnetic Ni/NiO core/shell nanoparticles embedded in the amorphous Al2O3 matrix were fabricated by pulsed laser deposition. The results from a high-resolution transmission electron microscope also revealed that the core/shell nanoparticles consist of a single crystal Ni core with a faced-centered cubic structure (Space Group FM-3M) and polycrystalline NiO shell with a trigonal/rhombohedral structure (Space Group R-3mH). The growth strain of Ni/NiO core/shell nanoparticles embedded in the Al2O3 matrix was investigated. Finite element calculations clearly indicate that the NiO shell incurs large compressive strain. The compressive strain existing at the NiO shell area enables the shell material at the interface to adapt to the lattice parameters of Ni core. This process results in a relatively good crystallinity near the interface, which may be associated with the higher exchange coupling between the ferromagnetic Ni core and antiferromagnetic NiO shell.

Influence of nanoparticles on the dynamics of miscible Hele-Shaw flows

In this study, we have made an attempt to address how the nanoparticle flows may affect the hydrodynamic instability around a miscible front. In order to explore the role of nanoparticles in such flows, a linear stability analysis was performed to examine the impact of nanoparticle addition for an already unstable miscible displacement. The growth rates of the temporal modes of the instability are determined for different profiles or physical properties of nanoparticles. The results reveal that the diffusion of either the carrier fluids or nanoparticles initially has destabilizing effects, but demonstrates stabilizing effects at longer times, as the cutoff spectrum is initially shifted to larger wavenumbers, but shifted back later. It was found that deposition of nanoparticles into the medium stabilizes the miscible front, such that the maximum growth rates and cutoff wavenumbers increase continuously.

Characterization of TiO2Synthesized in Acidic Conditions at Low Temperature by Sol-gel Method

Titanium dioxide (), which is one of the most basic materials in our daily life, plays a key role for environment purification. We synthesized nanoparticles by the hydrolysis reactions of titanium tetraisopropoxide using as a peptizing agent or as a chelating agent in the sol-gel method. The powder consisted of a rod shape or a spherical shape according to the concentration and kind of acid. The physical properties of nanoparticles were investigated with X-ray diffraction, SEM, BET analysis, and UV-Vis spectrophotometer.

DIRECTIONAL SUPERPARAMAGNETISM AND PHOTOLUMINESCENCE IN CLUSTERS OF MAGNETITE AND CADMIUM SELENIDE NANOPARTICLES

ZnO microcrystals, Ca2Nb3O10 nanoplates, and LiMo3Se3 nanowires were used to chemically assemble CdSe and magnetite nanoparticles into discrete nanostructures. The CdSe-containing clusters exhibit directional and polarized light emission properties, which are modulated by the one- and two-dimensional morphology of the clusters. Clusters of Fe3O4 nanoparticles are superparamagnetic and contain one or two hard magnetic axes, depending on the cluster shape. The ability to control the physical properties of nanoparticles via assembly is of academic and practical interest. Nanostructures with directional emissive and magnetic properties could find applications in light emitting devices, as optical probes, and as magnetic sensors and actuators.

Effect of various formulation parameters on the properties of polymeric nanoparticles prepared by multiple emulsion method

This work evaluates and interprets underlying mechanisms behind various aspects related to preparation and physical characteristics of polymeric nanoparticles (NP). These were prepared from different biodegradable polymers according to a water-in-oil-in-water emulsion solvent evaporation method. Polymers used were poly(lactic-co-glycolic) acid (PLGA), poly (lactic acid) (PLA), (PLA-PEG-PLA) triblock and (PLA-PEG-PLA)n multi-block co-polymers. A model DNA, as an example of a hydrophilic drug, was encapsulated in the internal aqueous phase. The primary emulsion was prepared using a high shear turbine mixer. The secondary emulsion was prepared by high-pressure homogenization. Surface morphology and internal structure were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Influence of process variables on the physical properties of NP has been studied. Release of DNA was evaluated. In addition, changes occurring to NP porosity and surface area during degradation were followed. Nanoparticle size was ranging between 200–700 nm, according to the preparation conditions. Homogenizing pressure, concentration of the emulsifying agent used, polymer concentration and type and the concentration of a cryoprotectant had variable effects on NP size, surface area and porosity. Batches of NP where no emulsifying agent was added were obtained successfully. The release rate of the DNA from NP was mainly dependent on porosity, which varied significantly among used polymers. The preparation technique was efficient in encapsulating the model DNA and will be used for plasmid encapsulation in a future work.

The Nucleation of a Nanoparticle of Silicon Dioxide in a Closed Domain. Computer Experiment

The method of molecular dynamics is used to study SiO2 clusters located in cavities of spherical, cylindrical, and cubic shape. The effect of the elastically stressed state of the cell boundaries on the physical properties of nanoparticles contained in them is investigated. Given the same pattern of application of external forces, a nanoparticle in a spherical cell experiences a stronger compression than in clusters surrounded by envelopes of other geometries. The clusters assume the shape of the cavity in which they were contained. The effect of compressive forces results in the breakage of Si–O bonds and in the subsequent oxygen enrichment of the cluster surface. The behavior of nanoparticles after the elimination of the stimulation by the cavity boundaries is treated. It is only for a cluster of spherical geometry that a significant number of Si–O bonds is restored. For other clusters, the evaporation of oxygen atoms is observed.