[Preparation and property study of ion-exchange embolic microspheres for delivering pingyangmycin]

To develop and study the properties of ion-exchange polyvinyl alcohol-acrylic acid microspheres (PVA-AA-Ms) for embolization.

The PVA-AA-Ms were produced by the method of inverse suspension polymerization. The morphology and particle size were determined by optical microscope; FT-IR was used to investigate the special functional groups of PVA-AA-Ms; the carboxyl content of PVA-AA-Ms was measured by chemical titration; the compression elasticity was examined by texture analyzer (TA-plus). Pingyangmycin (bleomycin A(5)) was used as model drug to prepare drug-loaded PVA-AA-Ms. Drug loading and entrapment efficiency were measured through UV-spectrophotometer; in vitro drug release characteristic was detected by constant temperature vibration dialysis assay.

The PVA-AA-Ms were round and integrated. The average diameter of PVA-AA-Ms was 500 microm with a range of 150-1 000 microm. The carboxyl vibration was demonstrated by FT-IR and the content of carboxyl was 8.905 mmol/g. PVA-AA-Ms were mechanically stable with appropriate elasticity. Drug loading and entrapment efficiency were 30 g/L and 99.4%, respectively. The drug release rate was slow in phosphate buffer solution (PBS), 88.3% of the drug was released after 24 h and the t(50) was 2.19 h.

PVA-AA-Ms prepared in this study were supposed to be suitable for clinical embolization according to the physicochemical properties. The high carboxyl content of PVA-AA-Ms which allowed them to load cationic drugs (e.g., drug with amino group) through ion-exchange mechanism brought broad prospects for combination of embolization and chemotherapy.