PVAc/PVA microspheres for embolization, chemoembolization, and local drug delivery: structure-property relationships...

Poly(vinyl acetate)/poly(vinyl alcohol) (PVAc/PVA) microspheres have emerged as promising biomaterials for embolization, chemoembolization, and localized drug delivery. Commercial PVA-based microspheres have demonstrated substantial clinical utility but are generally permanently implanted hydrogels with relatively fixed structural and functional characteristics.This review critically examines the PVAc/PVA microsphere platform developed by the MatNuc research group in the context of current PVA-based embolic and chemoembolic technologies. The platform is based on suspension polymerization of vinyl acetate followed by controlled alkaline saponification, enabling systematic modulation of morphology, size, porosity, degree of hydrolysis, degradation-related behavior, and ionic functionality within a unified polymeric framework. Three complementary families have been developed:smooth microspheres (S-Ms) for embolization, porous microspheres (T-Ms) for localized drug delivery with potential chemoembolic applications, and sulfonated porous microspheres (SP-Ms) for ion-exchange drug delivery.The relationships between synthesis, structure, physicochemical properties, mechanical behavior, degradation-related behavior, drug loading, release kinetics, and biological performance are critically discussed. Experimental studies demonstrate effective embolization with S-Ms, controlled loading and release of doxorubicin and irinotecan with T-Ms while preserving drug bioactivity, significant antitumor efficacy following intratumoral administration of doxorubicin-loaded T-Ms, and enhanced ion-exchange interactions for cationic and zwitterionic compounds with SP-Ms. The review considers their distinct degradation-related behavior, including progressive mass loss consistent with hydrolytic alteration in S-Ms and T-Ms and degradation-related chemical evolution involving sulfonated functionalities in SP-Ms. Future directions are discussed, highlighting the potential of structurally tunable PVAc/PVA microspheres and the main scientific, manufacturing, and regulatory challenges for clinical translation.