Microneedle Array Patch Pierces Bacterial Biofilms

A flexible polymer composite microneedle array bypasses biofilm in chronic wounds to deliver both oxygen and bactericidal agents simultaneously.

The polymeric microneedles, developed at Purdue University (Lafayette, IN, USA) and Virginia Polytechnic Institute and State University (Virginia Tech; Blacksburg, USA), are manufactured by ultraviolet (UV) polymerization of flexible polyethylene terephthalate, which conformably attaches to the human body. Containing calcium peroxide and polyvinylpyrrolidone, the microneedle array can effectively elevate oxygen levels from 8 to 12 ppm, as well as provide strong bactericidal effects on both liquid and biofilm bacteria cultures, commonly found in dermal wounds.

Results from an ex-vivo assay study on a porcine wound model showed successful insertion of the biodegradable microneedles into the tissue, while also providing effective bactericidal properties against both Gram-positive and Gram-negative microbes within the complex tissue matrix. The microneedles also demonstrated high levels of cytocompatibility, with less than 10% of apoptosis throughout six days of continuous exposure to human dermal fibroblast cells. The study was published on July 19, 2021, in ACS Applied Bio Materials.

“Bacteria biofilm acts as a shield, hindering antibiotics from reaching infected cells and tissues. The traditional method to bypass biofilm is for physicians to peel it off, which is painful to patients and doesn't discriminate unhealthy tissue from healthy tissue,” said senior author Rahim Rahimi, PhD, of the Purdue School of Materials Engineering. “A flexible microneedle array can provide a better approach for increasing the effectiveness of topical tissue oxygenation as well as the treatment of infected wounds with intrinsically antibiotic resistant biofilms.”

Chronic non-healing wounds, such as diabetic foot ulcer (DFU), are colonized by bacteria that often develop into biofilms that act as a physicochemical barrier to therapeutics and tissue oxygenation, leading to chronic inflammation and tissue hypoxia. Although wound debridement and vigorous mechanical abrasion techniques are often used by clinicians to manage and remove biofilms from wound surfaces, such methods are highly nonselective and painful.

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