The Preparation And In Vitro Magnetic Resonance Signal Intensity Tests Of Ultrasmall Superparamagnetic Iron Oxide Nanoparticles

We studied the preparing methods of our own scientially authorized uhrasmall superparamagnetic iron oexide in the principle of Polymer template coprecipitation. We checked the structure of the magnetic products using transmissionelectron micrographies and the surface component characteristics using X-ray diffracted data and Fourier transform infrared spectrometer. The eligible products were selected for the magnetic resonance signal intensity tests. According to the different ration between Fe and PLA, the USPIO water solutions were divided into three groups of different formula. Each group was diluted into 2mg/Kg · BW of animal test dosage. Gd-DTPA(1:200) and saline were served as controls. Each group repeated eight times. The magnetic resonance imaging parameters were as follows: 1 5T Siemens superconductor scanner, head coil, T₁WI and T₂WI were finished. Accordingto the MR signal intensity characteristics, the reagent of high T₁WI signal intensity andlow T₂WI signal intensity was selected for next stage tests. According to differenthydrodynamic size, the USPIO were divided into five groups. The test methods and scanning parameters were the same with those of the former tests. For quantitative image analysis, signal intensity was measured with region of interest placement within the test tube. Region of interest size was chosen as two thirds the maximum diameter of each tube. All the data were analysed with SPSS 10.0software. The results showed that iron oxide nanoparticles whose core diameters were about 5nm were available after adding alkali into ferric chloride, ferrous chloride and polylactic acid. The transmissional electrometer results exhibited a well-dispersed property of the particles in water solution. The hydrodynamic diameters of the particles were accordant with design requests. After dilution to the in vivo tests concentrations, the magnetic resonance imaging and the signal intensity confirmed that the nanoparticles could shorten the T₁ relaxation time of the surrounding tissues significantly.