Synthesis And Application Of Magnetic Resonance Imaging Contrast Agent Based On Chitosan Nanoparticles

With the rapid development of magnetic resonance imaging technology in the biomedical science,more and more attention is paid to new magnetic resonance imaging agent.At present,the main magnetic resonance imaging agents widely applied in clinical medicine are Gd-DTPA,Gd-HP-DO3A,Gd-DOTA and so on.The most widely used imaging agent is Gd-DTPA.However,Gd-DTPA is limited by the small molecular weight.Therefore,to synthesize and research the novel macromolecular magnetic resonance imaging contrast agent are the focuses of the researchers.During the last few years,to achieve good imaging results,the large molecules with good biocompatibility,such as antibodies,hormones,serum proteins,amino acids,dextran and polysaccharides,are used to modify small molecular contrast agents.Chitosan is a rare natural polysaccharide with positive charges,which has attracted considerable scientific interests in biomedical application because of its well-known biodegradability,biocompatibility,low toxicity,non-antigenic and renewable property.In this paper,spherical monodisperse chitosan nanoparticles were synthesized by chemical crosslinking method.The properties of chitosan nanoparticles were characterized by transmission electron microscopy(TEM),Dynamic Light Scattering(DLS),ZETA potential and infrared spectra.Morphology and size of chitosan nanoparticles were studied details at different concentrations,different reaction time and different crosslinking degree to obtain the 2-4nm spherical nanoparticles with good dispersity.Secondly,by modifying the small contrast agent with the chitosan nanoparticles,the water soluble macromolecular contrast agent was obtained.The ZETA potential of CS-DTPA nanoparticles was investigated under different pH condition.The properties of CS-Gd-DTPA was characterized by ZETA potential and infrared spectra.When the pH is neutral,the ZETA potential of CS-Gd-DTPA is 16.5 mV.Then we further investigated the biotoxicity and magnetic resonance imaging of CS-Gd-DTPA nanomaterial by incubating the nanoparticles with L02 cells,the results show that the nanomaterial have low cytotoxicity.In the end,MRI in vitro was tested by a 0.5 T magnetic resonance imaging(MRI)analyzer.The T1-weighted MR images and the T1 relaxation rate of CS-Gd-DTPA nanomaterial were obtained the at different concentrations of Gd.