Microneedle patch penetrates biofilms to treat chronic wounds

Chronic wounds such as diabetic foot ulcers can be very difficult to treat, partially because of antibiotic-resistant "biofilms" that form over the affected tissue. A new type of microneedle patch, however, has been shown to deliver medication through such films.

Bacterial bioflms are made up of colonies of bacteria that stick together by building up a slimy polymer matrix. Unfortunately, topically applied antibiotics and other medications have difficulty penetrating that matrix, so they can't reach the infected tissue underneath.

As a result, doctors will often peel off the biofilms before treating the wounds. Not only is this painful to the patient, but some healthy tissue will often come off along with the biofilm, setting back the healing process. With these limitations in mind, scientists at Indiana's Purdue University have developed a biodegradable polymer composite patch with an array of tiny medication-laden "microneedle" studs on its underside.

When the patch is applied to a chronic wound, those microneedles penetrate the biofilm and absorb fluid from the tissue underneath. This causes them to harmlessly dissolve, releasing their medication into that tissue. The patient feels no discomfort as this is happening, since the needles are short enough that they don't reach any nerve endings. Once the process is complete, the patch is removed, leaving the biofilm – and the rest of the wound – intact.

In lab tests performed on samples of pig skin with chronic wounds, the microneedle patch was successfully able to deliver calcium peroxide through biofilms and into the underlying tissue, with the needles dissolving in less than five minutes. Calcium peroxide produces oxygen that both kills bacteria and promotes the growth of new tissue.