Researchers at University of California, San Diego have engineered a new hydrogel that binds to other pieces of itself like Velcro, but at a molecular level. The same quality allows the hydrogel to rapidly self-heal when a certain pH level is reached in its aqueous environment, which in turn makes the process externally controllable by changing the pH.
Hydrogels hold promise for a multitude of applications in medicine because they have physical properties similar to soft tissue, but their normally fragile nature has been a roadblock. By attaching so called “dangling side chain” molecules to the hydrogel, two pieces of the material can now grab onto each other and become one.
More from the UCSD announcement:
To design the side chain molecules of the hydrogel that would enable rapid self-healing, [team leader Shyni] Varghese and her collaborators performed computer simulations of the hydrogel network. The simulations revealed that the ability of the hydrogel to self-heal depended critically on the length of the side chain molecules, or fingers, and that hydrogels having an optimal length of side chain molecules exhibited the strongest self-healing. When two cylindrical pieces of gels featuring these optimized fingers were placed together in an acidic solution, they stuck together instantly. Varghese’s lab further found that by simply adjusting the solution’s pH levels up or down, the pieces weld (low pH) and separate (high pH) very easily. The process was successfully repeated numerous times without any reduction in the weld strength.
Ameya Phadke, a fourth year PhD student in Varghese’s lab said the hydrogel’s strength and flexibility in an acidic environment – similar to that of the stomach – makes it ideal as an adhesive to heal stomach perforations or for controlled drug delivery to ulcers. Phadke will present related research on April 12, 2012 at Research Expo, the annual research and networking event of the Jacobs School of Engineering at UC San Diego.
Press release: Smart, self-healing hydrogels open far-reaching possibilities in medicine, engineering
Study abstract in PNAS: Rapid self-healing hydrogels
(hat tip: Gizmag)