STEM Gels Act Like Stem Cells for New Materials

Chemists at Carnegie Mellon University have further developed a polymeric material inspired by the body’s stem cells, called STEM gels. Using techniques, including one developed at Carnegie Mellon, the researchers were able to create a platform that can be controlled using light. Their research, which has implications for the 3D printing of novel materials, was featured on the cover of the April Issue of Trends in Chemistry.

In materials science, there is an always increasing demand for new materials that can reliably perform certain functions and contain novel properties. This has become increasingly true with the rapid growth and adoption of additive and subtractive manufacturing techniques, including 3D printing.  

Structurally tailored and engineered macromolecular (STEM) gels, like their biological namesake, exist in an undifferentiated state. Researchers are able to use controlled radical polymerization techniques (CRP) to introduce new functionalities to the materials. For example, STEM gels that can be programmed to diffuse nutrients or drugs show promise as materials for the development of artificial tissue. The gels are also able to be layered to create new materials, making them ideal for use in 3D printing.

In the Trends in Chemistry article, Julia Cuthbert, a chemistry doctoral candidate working in the lab of J.C. Warner University Professor of Natural Sciences Krzysztof Matyjaszewski, gives an overview of existing research into the creation of STEM gels, including her work and that of her colleagues at Carnegie Mellon.

The Carnegie Mellon and University of Pittsburgh researchers created a STEM gel that incorporates latent active sites into its primary network. The researchers were able to incorporate polymer chains, proteins and inorganic particles into the network using two CRP techniques: atom transfer radical polymerization (ATRP), which was discovered and pioneered by Matyjaszewski, and reversible addition fragmentation chain transfer polymerization (RAFT). The molecules attached to the latent sites are what allow the STEM gels to differentiate into materials with unique properties. 

The researchers were further able to control the properties of the STEM gels by attaching a photo-responsive moiety to the latent sites, which allows them to control the gels’ properties using only light. By eliminating the need for a catalyst to turn the functional materials “on” or “off,” the process is much more environmentally friendly.

The researchers will continue to study and develop STEM gels for their use in additive and subtractive manufacturing.

Additional study authors include: Tomasz Kowalewski, from Carnegie Mellon’s Department of Chemistry and Anna C. Balazs from University of Pittsburgh’s Department of Chemical Engineering.

The research was funded by the U.S. Department of Energy (ER15998).