Yuqiang Huang

Synthesis of MRI contrast agent by coating superparamagnetic iron oxide with chitosan

Ultrasuperpara magnetic iron oxide (USPIO) nanoparticles were synthesized with iron chloride using a sonochemical method. The size of the USPIO nanoparticles was controlled by ultrasonic exposure time and power. The USPIO nanoparticles had a narrow size distribution, a perfect magnetite crystal structure, and high saturation magnetization. The magnetic resonance imaging (MRI) contrast agent was prepared by coating the USPIO and dispersing it with biocompatible chitosan. In vivo testing in New Zealand white rabbits confirmed the effectiveness of the USPIO nanoparticles as a MRI contrast agent.

Control of iron nanoparticles size and shape by thermal decomposition method

Iron nanoparticles were prepared by thermal decomposition under 180/spl deg/C with 0.256M iron pentacaronyl and 0 M-0.085M oleylamine as a surfactant. Sizes of the synthesized iron nanoparticles are from 4.8nm to 10.9nm depending on the decomposition times in the range from 10 to 60min. The surfactant concentration is a key factor for controlling the size and shape of iron nanoparticles. The synthesized iron particles without surfactant are flocculated to be clusters of 20-50nm. In the case of using 0.0425M surfactant, the obtained particles are almost sphere. While oleylamine concentration was added up to 0.085M, several iron nuclei are agglomerated together regularly. It is confirmed that the synthesized iron particles are amorphous, but the surface of the particles is easily oxidized and to be spinel structured iron oxide by HRTEM.

Effect of surfactants on the size and shape of cobalt nanoparticles synthesized by thermal decomposition

Cobalt nanoparticles with various morphologies were synthesized by thermal decomposition of cobalt acetate in the presence of various surfactants at 260°C. A combination of surfactants consisting of sufficient amount of oleic acid together with polyvinylpyrrolidone and oleylamine resulted in well-dispersed cubic cobalt nanoparticles of ∼25nm in average size. When 1,2-dodecanediol was added as a reducing agent to the surfactant mixture, triangular-prism-shaped nanoparticles of ∼50nm in average size were synthesized. Furthermore, an injection of trioctylphosphine into the reactor as an additional surfactant decreased the particle size to ∼10nm. The XRD pattern of the prism-like particles corresponded to hexagonal close-packed crystalline phase of cobalt.

Synthesis of nano-size magnetite coated with chitosan for MRI contrast agent by sonochemistry

Superparamagnetic iron oxide (SPIO) nanoparticles have been developed for clinical applications in magnetic resonance imaging (MRI) contrast enhancement. The particles were synthesized by a sonochemistry to control the particle size and get hold of narrow size distribution. The properties of such particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), VSM, and PSA. The in-vivo test was carried out with two New Zealand white rabbit to validate MR image enhancement effect and physiological toxicity. In this study, the hydro-particle size were controlled in the range 40/spl sim/80 nm at the ultrasonic exposure time for 60 min and ultrasonic power 30%. Magnetization curves of the magnetic particles at different ultrasonic exposure time showed that the particles behaved with superparamagnetism and the magnetization values increased with decreasing ultrasonic exposure time. It is for no other reason than that the crystal size became smaller at long ultrasonic exposure time. The prepared particles have a perfect crystal structure to ensure that the clear image can be gained in diagnoses. Such particles coated with chitosan can be used in medical diagnostic techniques and allow the noninvasive visualization by enhancement of T2 MRI images.

Preparation of nanometric CuxFe1−xOFe2O3 for treatment of tumor

The nanometric particles possess some physical and chemical properties different from the bulk. The water-based magnetic fluids with nanometric CuxFe1−xOFe2O3 particles were prepared by the two-step method, in which the x value varied from 0.1 to 0.4. The experiment results showed the magnetization decreased with increasing x values. The copper element was partly coprecipitated with iron oxides. These phenomena are ascribed to excess ammonia water in the precipitation. The decanoic acid and the nonanoic acid were selected as the first and second surfactants. The optimal reaction temperatures for the first and second surfactants were 80 and 60 °C respectively with the holding time of 30 min.

Preparation and properties of novel iron nanoparticles

Iron nanoparticles are synthesized by thermal decomposition with iron pentacarbonyl as precursor under N/sub 2/ atmosphere. Particle size, shape and magnetization as a function of various experimental conditions are investigated by transmission electron microscopy, X-ray diffraction and vibrate sample magnetometer methods.

Preparation of nanometric Cu/sub x/Fe/sub 1-x/OFe/sub 2/O/sub 3/ and design of a magnetic field system for treatment of tumor

The water-based magnetic fluids with nanometric Cu/sub x/Fe/sub 1-x/OFe/sub 2/O/sub 3/ particles were prepared by the two-step method, in which the x value varied 0.1 to 0.4. The magnetization decreased with increasing x values. Also, an external magnetic field system was designed for drug delivery, with which the spatial magnetic flux distribution was analyzed.