It’s pretty amazing how living tissues can heal themselves, even after sustaining damage after damage. In their image, bioengineers have now developed a gel that can bind together in seconds if it gets cut.
The bond is strong enough to withstand repeated stretching (pictured, below) – making it suitable for medical sutures and targeted drug delivery (as well as industrial sealants).
Hydrogels are squishy, jello-looking, semi-solid materials similar to soft tissues. They’re made of linked chains of polymer molecules that are hydrophilic, which allows them to mimic the flexibility of materials with high water content (like in our bodies).
For years, scientists haven’t been able to create hydrogels that can rapidly repair themselves if damaged.
To create this self-healing hydrogel (pictured), a team led by Shyni Varghese from the University of California at San Diego turned to ‘dangling side chain’ molecules that extend like fingers on a hand, enabling them to grasp one another.
- Using computer simulations, they discovered that the self-healing ability depends on the length of the side chain molecules (the fingers).
- When 2 pieces of gels with optimal length fingers were placed together in acid, they stuck together instantly.
- By simply adjusting the pH levels, the gel pieces easily stuck (low pH) and unstuck (high pH).
"It is kind of like Velcro at the molecular level," says study researcher Ameya Phadke of UCSD.
Watch a video of the gummy material at work.
The hydrogel’s strength and flexibility in an acidic environment – like our stomachs – makes it ideal as an adhesive to heal stomach perforations or for controlled drug delivery to ulcers.
"You wouldn't have to keep taking the pill, you could just load this hydrogel with the drug and then it would just slowly diffuse the drug out at that site," Phadke explains.
Images: Joshua Knoff / UC San Diego Jacobs School of Engineering