Glucose-Responsive Microneedle Patch With Variable Crosslinking Density and Flexible Core-Shell Structure for Insulin Delivery

Developing glucose-responsive microneedle patches with features of simple preparation, high insulin loading, and safety has a great contribution to the treatment of diabetic patients. In this work, a novel glucose-responsive core-shell microneedle patch is prepared from biocompatible materials by a facile process. The exterior glucose-responsive shell is composed of polyvinyl alcohol (PVA) and e-polylysine modified with phenylboronic acid , and the inner flexible core is prepared by pure PVA loaded with insulin. The shell shows superior glucose-induced swelling and controlled insulin release ability due to the decomposition of borate ester bonds under the synergistic effect of glucose and water. The microneedle patch also features flexibility and high insulin loading capacity (36 IU cm(-2)). It shows high puncture efficiency (92%) and maintains a relatively complete morphology after being removed, enabling to reduce material residues in the skin. Moreover, the microneedle patch reveals a good hypoglycemic effect in diabetic rats, achieves a hypoglycemic rate similar to that of direct injection after swelling, and works effectively to prevent excess insulin transmission. The high glucose-responsive ability, simple preparation, high loading capacity, rapid hypoglycemic speed, high conformability to skin, and low component dissolution make this microneedle patch a suitable candidate for diabetic treatment.