Photopolymerizable precursors for degradable biomaterials based on acetal moieties

Abstract

In tissue engineering (TE), artificial biomaterials have emerged over the past decade as an alternative to autotransplants. The main characteristics of these materials include good biocompatibility as well as biodegradability. Up to now, most materials used in TE are based on polyesters, which are limited in their scope of application, especially as scaffolds, due to their undesirably slow degradation behavior under acidic conditions present, e.g. during the process of hydroxyapatite resorption during bone regeneration. Furthermore, the formation of acidic degradation products can lead to tissue inflammation or even necrosis. Therefore, alternatives to ester functionalities, which show enhanced degradability under acidic conditions, are of interest. Herein, we present the synthesis of linear and cyclic acetal-based monomers for photopolymerizable materials. The reactivity and mechanical properties of polymer networks derived from these monomers were investigated. Moreover, their degradation behavior compared to ester-based polymer networks was explored. Degradation studies of the model compounds showed that the synthesized acetals degrade 80 to 200 times faster than their ester counterparts. A subsequent in vitro degradation study of polymer networks based on these compounds confirmed the potential of acetals moieties in polymeric biomaterials for bone regeneration.