At the National Institute of Biomedical Imaging and Bioengineering (NIBIB) and Tufts University a team has developed a microfluidic chip that mimics human tissue for use in drug testing applications. The chip is based on a silk gel that overcomes the limitations of polydimethylsiloxane (PDMS), a silicon material widely used to host living cells within microfluidic devices. As an example, PDMS has problems handling lipids, absorbing them instead of letting them move freely along with other nearby compounds and so not applicable with lipid-based compounds. Additionally, PDMS is not biodegradable and so a small device based on it can’t easily be used as an implantable. Silk, on the other hand, just needed a bit of engineering to make a candidate that overcomes many of PDMS’s limitations.
Silk can be used to replicate tissues of different softness, is stable yet can degrade completely given enough time, and can be made transparent to make it easy to work with. Mixing it with a gel already containing live cells and shaping it inside a mold, the researchers created a device with channels running through it that is also partially alive. Valves were added that regulate the flow of fluids through the channels using an air pressure mechanism.
Silk is a lot more forgiving than PDMS, requiring moderate temperatures during production of the device and offering excellent biocompatibility if implanted into the body. That last part is yet to be attempted, but the researchers believe there’s great potential for such technology to be eventually translated for tissue regeneration applications.