“Let’s change our perspective”
A common way to create hydrogels is to take the material, dissolve it in water, and add gelling chemicals to swell the new liquid into a gel. Some materials simply dissolve in water, while others require researchers to tinker with the process or change the chemistry, but the core mechanism is the same. No water or hydrogel required.
However, semiconductors usually do not dissolve in water. Rather than finding time-consuming new means to force the process, Chicago’s PME team revisited the problem.
“We started thinking, ‘Okay, let’s change the perspective,’ and came up with the solvent exchange process,” Dai says.
Instead of dissolving the semiconductor in water, they dissolved it in an organic solvent that is miscible with water. Gels were then prepared from dissolved semiconductors and hydrogel precursors.
An important advantage of such solvent exchange-based methods is their wide applicability to different types of polymeric semiconductors with different functionalities.
“One plus one is greater than two”
The hydrogel semiconductor, patented by the team and commercialized through Chicago’s Polsky Center for Entrepreneurship and Innovation, is not a hybrid of semiconductor and hydrogel. This is one material that is both a semiconductor and a hydrogel.
“This is just one piece that has both semiconducting properties and a hydrogel design, which means this whole piece is exactly like any other hydrogel,” Wang said.
But unlike other hydrogels, this new material actually improved biological function in two areas, producing better results than hydrogels or semiconductors could achieve alone.
First, bonding the extremely soft material directly to tissue reduces the immune response and inflammation that typically occurs when implanting medical devices.
Second, because hydrogels are highly porous, new materials enable improved biosensing responses and stronger light modulation effects. The ability of biomolecules to diffuse and interact within the membrane greatly increases the number of interaction sites for the biomarker to be detected, improving sensitivity.
In addition to sensing, the response to light for therapeutic functions at tissue surfaces is also increased through more efficient transport of molecules. This could benefit features such as light-operated pacemakers and wound dressings, which can be illuminated and heated more efficiently to speed healing.
“It’s a combination of ‘one plus one is greater than two,'” Wang joked.
Citation: “Soft hydrogel semiconductors with enhanced biointeraction capabilities,” Dai et al., Science, October 24, 2024. DOI: 10.1126/science.adp9314
Funding: National Institutes of Health, Office of Naval Research, University of Chicago Startup Fund
—Adapted from a paper originally published by Pritzker Molecular Engineering.
