Other Uses for Hydrogels
A few weeks ago, I talked a lot about using hydrogels for drug delivery. Today I’m going to talk about two other uses for hydrogels: one commercial, one experimental.
Use in Electrodes
Biological signals tend to be of low voltage, (e.g, 0.5-4 millivolts for cardiac potential), which I suppose is a good thing for us. The downside is that potentials measured from other sources-often referred to as noise-interfere with the signal measurement. One of the problems with electrodes is that noise can occur if the electrodes slip out of place, or motion artifact.
Electrodes function by forming a series of opposite charges at the interface between the electrode and what it’s placed on. If the electrode moves, the charges on the other side of the interface are disrupted, and will have to redistribute to re-establish equilibrium. During that redistribution, a potential difference forms, which will be measured and considered part of the signal.
Hydrogels that contain electrolytes (such as chlorine ions) are used as an interface between electrodes and the skin. They keep the electrodes in place and reduce motion artifact.
Tissue engineering is exciting stuff. Can we grow skin, bone, or more complex body parts from cells? If we can, it would be a benefit to people with chronic wounds, burn patients, and (hopefully) people waiting for transplants. No doubt you’ve heard a lot about stem cells and the research done to get them to differentiate into a specific tissue type. One approach is to use a hydrogel as a scaffold, or support structure, for stem cells.
The properties of a hydrogel are similar to human tissues-they’re relatively soft and elastic. The premise is that the stem cells will take cues from the environment that will direct their differentiation. Additionally, hydrogels provide a 3-D environment more similar to the human body than the typical 2-D environment in which cell studies are performed.
Our lab has approached this by using superporous hydrogels as a scaffolding material. When the hydrogel is polymerized, the pores are created using sodium bicarbonate. The pores that are created interconnect and allow stem cells to infiltrate the structure and proliferate. One of the PhD students, Melanie, is currently working on this project. She’s using superporous hydrogels to differentiate human mesenchymal stem cells into bone tissue.
There’s way more than I could possibly say about the tissue engineering angle, but I’ll leave it at that for now.