Boronic Ester Cross-Linked Star Polyoxazoline Hydrogels with Self-Healing and Stimuli-Responsive Behavior

Self-healing and stimuli-responsive hydrogels are highly desirable in biomedicine. A promising strategy to achieve these properties is dynamic covalent cross-linking via boronic ester bonds between boronic acids and diols. However, most hydrogels using this mechanism are unstable under physiological conditions, which limits their biomedical applicability. Here, we present the synthesis and application of a star-shaped poly(2-methyloxazoline) functionalized with boronic acid derivatives, designed to form stable hydrogels in the presence of poly(vinyl alcohol) under physiological conditions. By tuning the overall polymer content, boronic acid/diol molar ratio, and molecular weight, hydrogel stiffness could be precisely adjusted. The resulting hydrogels exhibited rapid self-healing, high stretchability, injectability, and responsiveness to the pH value and glucose levels, as demonstrated by insulin release studies. Cytotoxicity and cell encapsulation experiments confirmed the cytocompatibility of the polymer and hydrogels.