Controlled Growth of Gold Nanoparticles in Aerosol-OT/Sorbitan Monooleate/Isooctane Mixed Reverse Micelles

Inorganic nanoparticles based contrast agents for X-ray computed tomography

Nanomaterials have gained considerable attention and interest in the development of new and efficient molecular probes for medical diagnosis and imaging. Heavy metal nanoparticles as such are excellent absorber of X-rays and can offer excellent improvement in medical diagnosis and X-ray imaging. Substantial progress has been made in the synthesis protocol and characterization studies of these materials but a major challenge still lies in the toxicological studies, which are rather incomplete. The worst known cases were those associated with Thorotrast (suspension of ThO(2) nanoparticles) which resulted in many deaths over years. Properly protected nanomaterials conjugated or coated with biocompatible materials can be used for the fabrication of various functional systems with multimodality, targeting properties, reduced toxicity and proper removal from the body. This review aims mainly to provide the advances in the development of inorganic nanoparticle based X-ray contrasting agents with an overview of methods of their preparation, functionalization and applications in medical diagnosis.

Biopharmaceutical applications of nanogold

The application of nanogold in biopharmaceutical field is reviewed in this work. The properties of nanogold including nanogold surface Plasmon absorption and nanogold surface Plasmon light scattering are illustrated. The physical, chemical, biosynthesis methods of nanogold preparation are presented. Catalytic properties as well as biomedical applications are highlighted as one of the most important applications of nanogold. Biosensing, and diagnostic and therapeutic applications of gold nanoparticles are evaluated. Moreover, gold nanoparticles in drugs, biomolecules and proteins' delivery are analyzed. Gold nanoparticles for the site-directed photothermal applications are reviewed as the most fruitful research area in the future.

Population Balance Models and Monte Carlo Simulation for Nanoparticle Formation in Water-in-Oil Microemulsions: Implications for CdS Synthesis

We address controlled CdS nanoparticle formation by tuning experimental synthesis conditions. To this end, a bivariate population balance equation (PBE) model has been developed based on time scale analysis, to explain the mechanism of nanoparticle formation in self-assembled templates. It addresses the process of mixing two water-in-oil (w/o) microemulsions, each containing a pre-dissolved reactant in the microemulsion drops. Brownian collision and coalescence of two water drops of nanometer size results in mixing and exchange of reactant molecules, leading to chemical reaction. The water insoluble reaction product nucleates to form a nanoparticle in an individual drop, which subsequently grows internally by consuming the excess product and by coalescence-exchange with other drops. Finite rates of nucleation and coalescence-exchange are accounted for in the PBE, while the rates of reaction and internal growth of nanoparticles are found to be instantaneous. Experimentally proven binomial redistribution of reactant and product molecules upon drop coalescence is implemented in the present work. This results in a very good prediction of experimental data of the mean aggregate number (MAN) and hence size of CdS nanoparticles. Both our model and Monte Carlo (MC) simulation quantitatively capture the reported variation of MAN with molar excess of Cd2+ concentration and microemulsion drop size. Our results together with previous experimental data establish that usage of stoichiometrically five times or more of excess Cd2+ concentration can cause surface adsorption and desirable enhanced emission intensity of CdS nanoparticles, without altering particle size. We also propose a simplified and computationally efficient univariate PBE model. The univariate model gives very fast (in minutes) and accurate estimates (for low reactant concentrations) of the number and mean size of CdS nanoparticles. Time-scale analysis offers a good a priori choice of the appropriate model based on range of reactant concentrations.

Controllable synthesis, characterization and catalytic properties of WO(3)/ZrO(2) mixed oxides nanoparticles

Tungsten-promoted zirconia (WO(3)/ZrO(2)) nanoparticles were synthesized in reverse micelles of water/sodium bis(2-ethylexyl) sulfosuccinate/isooctane, which were compared with WO(3)/ZrO(2) prepared by incipient wetness impregnation and sol-gel method. The control of particle size was achieved by varying the process variables, such as water-to-surfactant molar ratio and reagent concentration. Their sizes, appearances, crystal structures, and thermochemical behavior were characterized by UV-vis, TEM, XRD and TG-DTA. NH(3)-TPD and Hammett indicator measurement were also employed to study the acidity of samples. The results revealed that samples prepared in reverse micelles had higher percentages of T-ZrO(2) and greater acid strength than those of other samples. The alkylation of butene with isobutane on WO(3)/ZrO(2) was carried out in a fixed-bed reactor. Samples synthesized in reverse micelles had better reaction performance than others. A parallel relationship could be drawn between the catalytic activity and the acid amounts as well as the acid strength of the catalysis.