Shear-thinning hydrogels can be injected into the body to carry drugs or cells to regenerate damaged tissue, but these hydrogels are vulnerable to degradation by mechanical stresses. Chemical engineers at the Massachusetts Institute of Technology (MIT) developed a gel that is made durable by a polymeric reinforcing network, which is activated when the gel is heated to body temperature (37 °C).

The research team, led by Bradley Olsen, an assistant professor of chemical engineering at MIT, worked with a protein hydrogel that consisted of loosely packed proteins held together by links between protein segments. Polymers attached to the ends of each protein are soluble in water and float freely in the gel at lower temperatures. When heated to body temperature, however, the polymers become insoluble, separate out of solution, and join together to form a reinforcing grid within the gel.

The researchers found that gels with this reinforcing network were significantly stiffer and much slower to degrade when exposed to mechanical stress. This offers a promising way to thwart the tendency of shear thinning materials to erode once in the body, said Jason Burdick, an associate professor of bioengineering at the University of Pennsylvania, in the MIT press release.

The gels can also be tuned to degrade over time, which would be useful for long-term drug release. The researchers are now working on ways to control this feature, as well as incorporating different types of biological functions into the gels, according to the release.