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Smart bandage releases medication when it senses heat 

What's New? | April 11, 2022 | By:

A microscopic image of the nanofibers used in a heat-activated wound dressing. Photo: Empa. 

While antibiotics are very effective at treating infected wounds, it is generally agreed that they should be used only when necessary. Not only can antibiotics cause unwanted side effects, but their overuse may contribute to the development of antibiotic-resistant bacteria. A new experimental bandage has been designed with this mind, dispensing medication only when it detects the heat of an infection.

Unfortunately, because conventional wound dressings are opaque, it’s impossible to see if the wound beneath them is becoming infected. As a result, antibiotics are often preemptively applied to a wound before it gets covered, to keep it from getting infected. Even then, it can still develop an infection after absorbing the initial application of antibiotics.

Seeking a more effective alternative, scientists at the Swiss Federal Laboratories for Materials Science and Technology (Empa) developed the new material. It incorporates a fine membrane of nanofibers, which are made of a blend of the polymer PMMA (polymethyl methacrylate) and a biocompatible polymer known by the trade name Eudragit. An antiseptic, octenidine dihydrochloride, is encapsulated within those fibers.

As long as the wound surface remains at the normal skin temperature range of 32 to 34 ºC (89 to 93 ºF), the polymer blend stays solid, keeping the medication trapped inside. If infection-related inflammation causes the wound surface temperature to increase to at least 37 ºC (99 ºF), however, the polymer transitions to a softer state, releasing some of the bacteria-killing octenidine into the infected tissue.

Once the infection has been treated and the wound cools back down, the polymer firms up again, retaining what’s left of the antiseptic. The dressing can therefore perform up to five separate octenidine deployments, before its entire payload of medication is used up. The scientists are now trying to reduce the temperature increase which is required to activate the material, and they’re exploring the use of other medications. 

A paper on the research, which is being led by Qun Ren and Fei Pan, was recently published in the journal ACS Applied Bio Materials.

Source: Empa and

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