Simultaneous control of degradation and mechanical properties of in situ forming and fast dissolving polyaspartamide hydrogels by graft architecture

Abstract

Polyaspartamide, derived from polysuccinimide (PSI), has the advantage of conveniently presenting desired functional groups by ring-opening addition of amine-based nucleophiles to the succinimidyl ring moieties of PSI. In this study, polyaspartamide presenting amine groups with controllable grafting density and length could be synthesized using diamines with varying length of poly(ethylene glycol) linker. This namely poly(2-hydroxyethyl aspartamide)-g-amino-poly(ethylene glycol) (PHEA-PEGAm) was then used to develop in situ forming hydrogels by Schiff base formation with aldehyde- containing alginate (Alg-ALD). The mechanical properties of the resulting Alg-PHEA hydrogel can be controlled over a wide range by adjusting the graft architecture (e.g. graft length and density). Remarkably, the hydrogel were shown to undergo facile degradation and complete dissolution in physiological conditions, regardless of mechanical properties, by the expedited hydrolysis through the action of remaining amine groups, which was also heavily influenced by the graft architecture. In addition, the rate of degradation could be further controlled by additional ionic crosslinking of alginate. The potential application as an injectable drug delivery system was demonstrated by measuring drug release kinetics and monitoring degradation ex vivo