Preparation Of Contrast Agents In Magnetic Resonance Imaging By Laser Pyrolysis

Compound magnetic nano-particles usually consist of a magnetic core and polymer shell.They have been used in an increasing number of biosciences and biotechnology such as bioseperation,drug delivery,MRI contrast enhancement and so on.All those functions mentioned above are mainly related to magnetic and polymer property.Currently,about one-third of MRI scans are in need of administration of a contrast agent to improve the contrast of signals.Therefore,it is of great scientific significance and diagnostic value to synthesize and study new types compound magnetic nano-particles as MRI contrast agent.Fe₃O₄/Dextran compound nano-particles had been prepared by chemical coprecipitation in different conditions.The amount of Dextran had been investigated,the time and the temperature affluence on the compound nano-particles,and the morphologies, microstructures were investigated too.The result confirmed that the core of the nano-particles diameter was 10nm and the thickness of dextran layer at the outside of the Fe₃O₄ was from 2.5 to 3 nm,the average particle size was 16 nm,and the saturation magnetization was 46emu.g^-1.At the room temperature,Fe₃O₄/Dextran compound nano-particles have super paramagnetic without remnant magnetism and coercive force.By mean of dc arc-discharge to produce Fe/Dextran compound nano-particles.The time and the way of the distribution affluence on the performance characterization of the compound nano-particles had been investigated.The result confirmed that saturation magnetization of the compound nano-particles was up to 100 emu.g^-1,and which affect application of the compound nano-particles as contrast agents in the field of the medicine.Fe/Dextran compound nano-particles had been prepared by laser in different conditions.The time decentralized approach and pH value on the compound nano-particles had been investigated,and the morphologies,microstructures and characteristics were analyzed too.The result confirmed that saturation magnetization of the compound nano-particles was up to 60 emu.g^-1.After 3 months,the saturation magnetization was up to 56 emu.g^-1 and which still had super paramagnetic.The solution of the Fe/Dextran compound nano-particles had stable existence in the PH value from 4 to 13.According to the analysis of FT-IR Spectrum,it approved that the acting force between Dextran and Fe particle was physisorption not of chemical bonding.In contrast finally,it can be seen that Fe/Dextran compound nano-particles used by laser was the most fit for making superparamagenetic contrast agents in biotechnology.