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.