Ripping off the bandaid just got a whole lot harder thanks to a researcher supported by UBC.
Dr. Zhenwei Ma, a UBC Killam Postdoctoral Fellow and research fellow at Harvard Universty, collaborated with scholars worldwide to study how adhesive bandages, also known as bioadhesives, can be controlled using sound waves.
With applications in drug delivery, cancer treatment and daily clinical use, improving bioadhesives will transform how the healthcare industry treats patients and even our day-to-day lives.
A sticky situation
Bioadhesives are an essential in emergency rooms and first aid kits but they have their share of challenges. Most current bioadhesives are not ideal for wet skin and can easily become compromised to lose their stickiness.
Published this summer in Science, Ma’s work on ultrasound-mediated bioadhesion aims to create tougher bioadhesives. The tougher the bioadhesive, the more resistant it is to cracks forming between the skin and the adhesive itself. This reduces the bioadhesive’s ability to stick and can be an issue for common adhesives like Band-Aids.
To better understand bioadhesives, Ma said we should “think of adhesives not as a single material, but like a material system.” There are three main components to an adhesive system: the biological tissue, the adhesive and in this specific case, a double network hydrogel.
The double network hydrogel — developed by Ma and his colleagues at McGill University and the University of Zurich — is special due to stretchy and stiff networks that make it more resilient towards physical damage.
Although the double network hydrogel is flexible and resilient and body’s surfaces are often quite tough, the adhesive itself can be a limitation. Some adhesives in circulation today use chemical reactions which can be toxic to the human body.
“One key motivation of my work is to get rid of the chemical reactions and how we can use purely physical methods to achieve equivalent or even better controllability of the formed adhesion on biological tissues,” Ma said.
According to Ma, the resilience of the ultrasound-mediated bioadhesive systems will “solve some of the fundamental problems of existing adhesives used in the operating rooms because they usually cannot form very strong adhesion with wet biological tissues.”
Sound and bubbles
Ultrasound is used for imaging in hospitals and clinics, but a lesser-known application is in adhesion.
When ultrasonic waves are immersed in liquid they induce cavitation, which is the rapid formation and collapse of vapour bubbles within a liquid. These bubbles play an essential role in bioadhesion because they can be selectively placed and used to actively push the adhesive into the outermost layer of the skin.
“A lot of materials that are not adhesive become more adhesive, just by simply pushing them into the [target], like some biological tissues,” Ma said. “We unlock the potential of materials to be adhesives by using ultrasound.”
In addition to creating cavitation bubbles, ultrasound also generates heat. This property is used in the removal process of bioadhesives. Gelatin, a thermo-sensitive polymer present in the hydrogel, is a liquid above a certain temperature and a gel below.
Ma explained changing temperature allows for temporary adhesion onto the hydrogel. When it is time for removal, ultrasound is applied again, the temperature is increased, the gelatin melts and the bioadhesive may be taken off.
Though he has a background in chemical and mechanical engineering from McGill, Ma’s current research interest lies in health care applications.
“For my PhD studies, I’m more interested in the mechanics side, especially how we can use materials and mechanics to solve clinical challenges,” he said.
“I think what we’re doing is very interdisciplinary and transdisciplinary.”
The big question
Ma has demonstrated adhesion to the skin, aorta and the inner skin of the cheeks and lips, opening the door for broader clinical applications like surgery, drug delivery and cancer treatment.
“I’m really excited to actually integrate our adhesive technologies with other minimally invasive surgical procedures for a wide range of applications and in the clinics in general,” Ma said.
Ma explained many drugs are delivered through the veins, meaning they can end up almost anywhere in the body and carry a risk for systemic toxicity. The local nature of ultrasound-mediated bioadhesion can minimize the potential risk of toxicity across the body, while maximizing the effectiveness of the drug.
For Ma, the potential for ultrasound-mediated bioadhesion extends to new research opportunities, namely in treating cancer. Ultrasound-mediated bioadhesives can be used in cancer treatment to locally deliver drugs to inoperable tumors.
“I’m personally very excited about [ultrasound-mediated bioadhesion] for its application for cancer therapy,” Ma said. As a researcher, Ma is excited to have his work touch the lives of those in health care.
“To better design a treatment strategy for the patients, that’s what I’m hoping for.”
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