Halogen-Mediated Partial Oxidation of Polyvinyl Alcohol for Tissue Engineering Purposes

Abstract

Partial oxidation of polyvinyl alcohol (PVA) with potassium permanganate turned out to be an efficient method to fabricate smart scaffolds for tissue engineering, endowed with biodegradation and protein delivery capacity. This work considered for the first time the use of halogens (bromine, chlorine and iodine) as less aggressive agents than potassium permanganate to perform controlled PVA oxidation, in order to prevent degradation of polymer molecular size upon chemical modification. Oxidized PVA solutions were chemically characterized (i.e., dinitrophenylhydrazine assay, viscosity measurements, molecular size distribution) before preparing physically cross-linked hydrogels. Scaffolds were assessed for their mechanical properties and cell/tissue biocompatibiliy through cytotoxic extract test on IMR-90 fibroblasts and subcutaneous implantation into BALB/c mice. According to chemical investigations, bromine and iodine allowed for minor alteration of polymer molecular weight. Uniaxial tensile tests demonstrated that oxidized scaffolds had decreased mechanical resistance to deformation, suggesting tunable hydrogel stiffness. Finally, oxidized hydrogels exhibited high biocompatibility both in vitro and in vivo, resulting neither to be cytotoxic nor to elicit severe immunitary host reaction in comparison with atoxic PVA. In conclusion, PVA hydrogels oxidized by halogens were successfully fabricated in the effort of adapting polymer characteristics to specific tissue engineering applications.

Bioactivated Oxidized Polyvinyl Alcohol towards Next-Generation Nerve Conduits Development

“…Since OxPVA development by partial oxidation, there was a consciousness of the great potential associated with this new synthetic polymer showing tunable mechanical behavior, swelling properties and biodegradability [ 5 , 14 ]. Additionally, another interesting feature related to the introduction of carbonyls in the OxPVA backbone is the possibility for its functionalization.…”

Synthesis of micrometer-sized poly(vinyl acetate) particles through microsuspension iodine transfer polymerization: effect of iodine species in a water medium

“…Meanwhile, PVA also tends to be oxidized by iodine radicals at high temperature. 36,37 Although the hydrolysis of PVAc carried out with a acid catalyst in a pure water system is inhibited, 38 the PVA dispersant was regarded as one of the reasons for the side reactions, in which the high amount of hydroxyl groups (-OH) of PVA dispersant relative to iodine groups (-I) existed. A portion of PVA is degraded into ketone and aldehyde specimens by reacting with free iodine radicals (Scheme 1(b)).…”

Biomaterials for Regenerative Medicine in Italy: Brief State of the Art of the Principal Research Centers

“…Halogens such as bromine, chlorine, and iodine are less aggressive than potassium permanganate and perform controlled PVA oxidation, which prevents polymer molecular size degradation upon chemical modification. Halogen oxidized PVA hydrogels exhibited high biocompatibility in vitro as well as in vivo, resulting in neither cytotoxic nor inducing severe host immune reactions compared to non-toxic PVA ( Figure 1 ) [ 17 ]. Oxidized PVA was cross-linked with a decellularized intestinal wall to develop a composite scaffold for intestinal restoration.…”