A prototype patch comfortably sticks inside the cheek to deliver insulin. (Credit: Adapted from ACS Applied Bio Materials 2022, DOI: 10.1021/acsabm.1c01161)

To deliver insulin in a less-invasive way, researchers have developed a prototype insulin-loaded patch that comfortably sticks to the inside of a person’s cheek. They used a polymer fiber mat that is activated by heat to release drugs attached to the cheek’s lining and deliver insulin.

They first soaked small squares of a nanofiber mat, made from electrospun fibers of poly(acrylic acid), β-cyclodextrin and reduced graphene oxide, in a solution with insulin for three hours. Then the team applied the insulin-loaded patches onto cheek linings and corneas from pigs. Heating the material with a near-infrared laser for 10 minutes to 122 °F activated the material and released insulin into the two types of membranes several times faster than through skin. In addition, the researchers placed the patches in vivo inside the cheeks of three insulin-dependent pigs.

The cheek linings showed no irritation or visual changes from the laser’s heat. As soon as the material was activated, the pigs’ blood sugar levels declined. Simultaneously, the animals’ plasma insulin levels increased, which the researchers say is proof-of-concept that this preliminary platform is efficient at getting insulin into the bloodstream. Finally, six human volunteers placed a placebo version of the patch inside their cheeks, saying that it felt comfortable over a two-hour period. The researchers say their next step is to conduct further preclinical studies of the prototype on animal models.

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