接枝微球CPVA-g-PSSS的制备及其对5-氟尿嘧啶载药及体外结肠定位释药特性研究

在具有生物相容性的交联聚乙烯醇(CPVA)微球表面,采用铈盐-羟基氧化还原引发体系,实施了对苯乙烯磺酸钠(SSS)的表面引发接枝聚合,制得了接枝有聚阴离子的接枝微球CPVA-g-PSSS,采用红外光谱(FTIR)、扫描电子显微镜(SEM)及zeta电位测定等法,对接枝微球的化学结构及物理化学特性进行了表征.在此基础上重点考察分析了接枝微球CPVA-g-PSSS对5-氟尿嘧啶(5-FU)的吸附(载药)性能与吸附机理,考察探索了载药微球在不同pH介质中的释放行为.实验结果表明,羟基-铈盐氧化还原引发体系可有效地引发SSS在CPVA微球的表面接枝聚合,在适宜的反应条件下,可制得PSSS接枝度为16.1 g/100g的接枝微球CPVA-g-PSSS.在酸性介质中,受强静电相互作用的驱动,接枝微球CPVA-g-PSSS对5-FU分子表现出很强的吸附能力,吸附容量达105 mg/g,可实现有效载药.载药微球的释药行为具有强烈的pH依赖性,在pH=1的介质中,基本不释药;而在pH=7.4的介质中,则发生突释,表现出良好的结肠定位释放行为.

PREPARATION OF GRAFTED MICROSPHERES CPVA-g-PSSS AND STUDIES ON THEIR CHARACTER OF DRUG CARRYING AND COLON-SPECIFIC DRUG DELIVERY FOR 5-FLUOROURACIL

The graft-polymerization of sodium 4-styrene sulfonate(SSS) was performed on the surfaces of crosslinked polyvinyl alcohol(CPVA) microspheres using cerium salt-hydroxyl group redox initiation system,and the grafted microspheres CPVA-g-PSSS,on which the strong anionic polyelectrolyte PSSS was grafted,was obtained.The chemical structure and physicochemistry characters of CPVA-g-PSSS microspheres were adequately characterized by infrared spectrum(FTIR),scanning electron microscope(SEM) and determination of zeta potential.On this basis,the adsorption property of CPVA-g-PSSS microspheres for 5-fluorouracil(5-FU),namely the drug carrying ability,was mainly investigated and the adsorption mechanism was discussed.The in vitro release behavior of the drug-carried microspheres was also examined.The experimental results show that cerium salt-hydroxyl group redox initiation system can effectively initiate the graft polymerization of SSS on CPVA microspheres,and under the suitable conditions,the grafting degree of PSSS can reach 16.1 g/100g.In the acidic medium,the grafted microspheres CPVA-g-PSSS exhibit very strong adsorption ability for 5-FU by driving of electrostatic interaction.The adsorption capacity can get up to 105 mg/g,displaying the high efficiency of drug-loading.The in vitro release behavior of the drug-carrying microspheres is highly pH-dependent.In the medium of pH=1,the drug is not released,while in the medium of pH=7.4,the burst release phenomenon will be produced,displaying an excellent colon-specific drug delivery behavior.