A “smart” flexible electric patch (ePatch) developed by a collaborative team from the Terasaki Institute for Biomedical Innovation promises to address the challenges posed by existing electrical field (EF) stimulation devices for wound healing and offers many uniquely advantageous features, the developers says.

The team chose silver nanowires as electrodes to provide antibacterial properties and also deliver high conductivity under strain. The electrodes are embedded in alginate, a gelatinous substance that maintains good moisture levels and biocompatibility and is presently used in absorbent surgical dressings. A chemical modification of the alginate and the addition of calcium, produces a material that increases electrode stability and function. 

Further modifications led to a flexible, precisely printable gel, or bio-ink that will produce a patch with customizable conformity to various wound shapes and sizes. Calcium added to the mix induces cell proliferation and migration to the wound site, which in turn would promote blood vessel formation.

“By careful selection of the materials and optimization of our gel formulation, we were able to develop a multifunctional, easy to make, and cost-effective e-Patch which will greatly facilitate and accelerate wound healing,” says TIBI researcher Han-Jun Kim, PhD, DVM.

Several experiments have validated the beneficial qualities of the e-Patch, the TIBI team says. Mechanical tests demonstrated that the e-Patch exhibited improved electrode stability and conductivity, and strain tests results showed good tolerance, on a level needed for normal skin deformation.

Tests conducted on cells cultured on the e-Patch showed that e-Patches pulsed with EF stimulation exhibited significantly faster cellular proliferation, migration, aggregation and alignment, as well as an increased secretion of growth factors.

Animal model studies on rats with open wounds were conducted and the results showed that significantly accelerated wound healing results were obtained with the e-Patch. Not only did the EF stimulated e-Patch exhibit more rapid progression of the wound-healing steps, but there was also a more directional healing process, resulting in minimal scarring, deposition of normal skin layers and hair growth following wound closure.

Other experiments confirmed the antibacterial properties of the silver nanowire electrodes used in the e-Patches and this property was shown to be independent of the amount of EF stimulation applied.

“Our ePatch offers an unprecedented combination of optimum features for accelerated wound healing,” says TIBI Director and CEO Ali Khademhosseini, Ph.D. “It is one of the many fine examples of the work that we do in our personalized biomaterials platform.”

PHOTO CAPTION: The Terasaki Institute for Biomedical Innovation has developed a flexible, printable ePatch which offers an unprecedented combination of optimum features for accelerated wound healing. CREDIT: Terasaki Institute for Biomedical Innovation (TIBI)