Glucose-responsive shape-memory cryogels

Boronic ester bonds can be reversibly formed between phenylboronic acid (PBA) and triol moieties. Here, we aim at a glucose-induced shape-memory effect by implementing such bonds as temporary netpoints, which are cleavable by glucose and by minimizing the volume change upon stimulation by a porous cryogel structure. The polymer system consisted of a semi-interpenetrating network (semi-IPN) architecture, in which the triol moieties were part of the permanent network and the PBA moieties were located in the linear polymer diffused into the semi-IPN. In an alkaline medium (pH = 10), the swelling ratio was approximately 35, independent ofCgluvaried between 0 and 300 mg/dL. In bending experiments, shape fixityRf≈ 80% and shape recoveryRr≈ 100% from five programming/recovery cycles could be determined.Rrwas a function ofCgluin the range from 0 to 300 mg/dL, which accords with the fluctuation range ofCgluin human blood. In this way, the shape-memory hydrogels could play a role in future diabetes treatment options.