"Muscle shirt" may soon take on a whole new meaning if new research out of Washington University in St. Louis pans out. A team has found a way to use bacteria to produce synthetic muscle proteins, which can then be spun into fibers to make clothing, protective gear and biomedical implants and prosthetics.
Humans are great at making artificial materials for whatever job we need them for, but oftentimes nature’s several-billion-year head start means the work has already been done, with a better result. Muscles are one example – artificial muscles made of materials like polymers, rubber and carbon fiber have proven strong, but can be tricky to make and are often outperformed by their natural counterparts anyway. So for the new study, the researchers decided to use this to our advantage.
“We wondered, ‘Why don’t we just directly make synthetic muscles?’” says Fuzhong Zhang, lead author of the study. “But we’re not going to harvest them from animals – we’ll use microbes to do it.”
Natural muscles are composed of three main proteins, and the team focused on one of these – titin, which acts like a spring, giving muscle its elasticity. The problem is that titin is actually the largest known protein, which makes it tricky to assemble artificially.
To get around that, the researchers engineered bacteria that can construct the larger proteins from small segments. Then, the titin can be converted into fibers 10 micrometers wide, using a wet-spinning technique.
The end result is fibers that are tough and strong, but still flexible, and able to dissipate mechanical energy as heat. That could make it a useful material for protective gear such as bulletproof vests – in fact, the researchers claim that it’s even tougher than Kevlar in that regard. And because it’s made of the same protein as natural muscle fibers, the new material should be biocompatible, making it suitable for sutures and other uses in the body.
“Its production can be cheap and scalable,” says Zhang. “It may enable many applications that people had previously thought about, but with natural muscle fibers.”
In future work, the team says that the protein-assembling bacteria could be put to work making other types of polymers for a range of other applications.
The research was published in the journal Nature Communications.