磁性N-羧甲基壳聚糖造影剂的制备及性能

采用简单经济(与传统微乳法、热分解法等比较)的方法制备出一种磁性N-羧甲基壳聚糖造影剂。首先对壳聚糖的氨基进行羧甲基化制备N-羧甲基壳聚糖,然后在其链上采用原位生成Fe3O4纳米粒子的方法制备出磁性N-羧甲基壳聚糖,并对其进行了表征及性能的测试。热重分析结果表明,Fe3O4的生成量与N-羧甲基壳聚糖中羧甲基的含量有关,其生成量随着羧甲基含量的增加而增加,但当羧甲基的含量增加到一定程度时,Fe3O4的生成量达到某一峰值。透射电镜结果表明,生成的Fe3O4纳米粒子的粒径约为5～10 nm。磁共振成像结果显示,该磁性N-羧甲基壳聚糖的横向弛豫率为82.82 mmol/(L.s),高于超顺磁性氧化铁作为磁共振成像造影剂时R2需大于62 mmol/(L.s)的最低标准,可作为潜在的磁共振成像阴性造影剂。

Preparation and Properties of Magnetic N-Carboxymethyl Chitosan as Contrast Agent

Magnetic N-carboxymethyl chitosan as a kind of potential magnetic resonance imaging contrast agent was synthesized through a simple and economic route(compared with such traditional methods as microemulsion and thermal decomposition).N-Carboxymethyl chitosan was first synthesized through the process of carboxymethylation of chitosan.Then,Fe3O4 nanoparticles were obtained by in situ reaction in the chains of N-carboxymethyl chitosan.The characterization and performance test of the magnetic N-carboxymethyl chitosan were carried out.The results of TGA show that the generation amount of Fe3O4 was related to the contents of carboxymethyl groups in N-carboxymethyl chitosan.It increased unceasingly along with the increase of the contents of carboxymethyl groups.But the generation amount of Fe3O4 reached a peak when the contents of catboxymethyl groups increased to a certain degree.The results of TEM indicated that the average grain size of the Fe3O4 nanoparticles was about 5～10 nm.The MRI depicted that the magnetic N-carboxymethyl chitosan provided a high transversal relaxation rate of 82.82 mmol/(L·s).It was higher than the minimum standard of R2,which was more than 62 mmol/(L·s),when superparamagnetic iron oxide was used as magnetic resonance imaging contrast agent.The magnetic N-carboxymethyl chitosan could be used as a kind of potential magnetic resonance imaging negative contrast agent.