Zebra mussel is inspiration for human body super glue

The zebra mussel has a bad reputation as being an invasive species but a Waterloo researcher is using the maligned mussel as inspiration for developing sticky synthetic adhesives that he hopes will be used in the human body some day.

“We do not copy nature. We’re just inspired by it,” says Boxin Zhao, a professor in Waterloo’s Department of Chemical Engineering. “We ask, ‘What’s the chemistry and how do we use it?' ”

New super glue conducts electricity

Recently, Zhao’s team published a research paper about a unique way to use the adhesive chemistry of zebra mussels in polymers. The team discovered a way to vastly improve the glue’s electrical conductivity. A conductive glue has medical applications because it could one day be used as a platform for biomedical sensors or for human tissue engineering, says Zhao.

He uses the zebra mussel as inspiration because it produces glue-like fibres that, once they cure and harden, are nearly impossible to remove - even underwater.

Photo credit: Vitalii Hulai/Thinkstock/Getty Images

Earlier glue bonds underwater

His team has already developed an innovative super glue that can strongly bond things underwater, which could be useful for surgeons looking to bond tissues inside the wet environment of the human body.

Zhao is one of several researchers around the world who are taking a good look at the zebra mussel because of its ability to stick to rocks, wood, metal and other creatures. “We call it molecular glue because we’re working at a molecular level,” he says.

Dopamine is key to improving conductive glue

For two years, Zhao and his team of graduate and undergraduate students tried to add dopamine - a “sticky” biomolecule, that mimics the components of mussel adhesive protein - to a polymer called polypyrrole. The goal was to create a new, water-based, environmentally friendly, permanent molecular adhesive that would help conduct electricity too.

One problem they experienced was that once the very active molecule was added to water and exposed to air, it kept oxidizing and didn’t work. Too many dopamine molecules acted as an insulator as well, which inhibited electrical conductivity.

The trick was to find a dopamine sweet spot.

Luckily, the team’s persistence paid off. Zhao discovered that if they added less dopamine, rather than more, two very surprising things happened: the adhesion level increased, but so did the electrical conductivity with a remarkable improvement of almost two orders of magnitude.

At this time, Zhao says he’s not completely certain why using less dopamine works so well, but the results could have far-reaching practical applications. The glue could be used to engineer human organs and tissues because of it can serve as a template for cell adhesion and growth.

Super glues are on path of commercialization

Looking at two little jars in Zhao’s lab on the first floor of Engineering 6, it’s hard to imagine their contents – an inky black solution in which molecules are dispersed – could lead to such incredible opportunities down the road. But Zhao has already blazed a path to commercialization with other research projects and knows the impact his molecular glue could have.

Partnering with the Waterloo Commercialization Office (WatCo), Zhao has filed patent applications for the waterproof super glue that covers Canada, the U.S., China and numerous other countries. He believes his team is the first one to use dopamine, a neuron transmitter, to create a conductive polymer; a provisional patent application was just filed for this technology.

Zhao has the infamous zebra mussel to thank, even if its chemistry acted only as a launch pad to insight.