Our bodies are busy places. Neurons fire constantly. Cells glean energy from food, and our immune systems ward off intruders. Each reaction or change is triggered by a biochemical signal. When this intricate communication system breaks down, so can crucial functions — from immunity to mobility. Materials chemists are now working to create synthetic materials that are dynamic enough to fix or replicate the damaged communications and, ultimately, repair our bodies.
One of those scientists is Mohit Kumar, a postdoctoral associate at the Advanced Science Research Center (ASRC) at The Graduate Center.
“Materials in biology often function only when needed, and degrade when their job is over,” Kumar says. “Creating synthetic analogs that can also change over time is a big challenge.”
In the July cover story of Nature Chemistry, Kumar and co-authors from CUNY and the University of California, Irvine, describe how they can use different chemical signals to “program” molecules to combine and arrange themselves into different nanostructures with properties that change over time.
Some of these nanomaterials conduct electricity. The team hopes that once they perfect the materials, researchers could use them in brains to help misfiring neurons by sending electrical impulses to the neuronal cells.
The team started with a base molecule they designed themselves. By adding different types of amino acids — the building blocks of proteins — to the mix, they found they could chemically prompt the individual molecules to come together and fashion different types of materials.
When combined with glutamic acid, the molecules assembled themselves into tiny fibers, about 16,000 times narrower than a human hair. The nanofibers were able to conduct electricity until they decayed over the course of several weeks, like miniature, transient electric wires.
By using leucine instead of glutamic acid, the team was also able to signal the molecules to assemble into electricity-conducting nanotubes with their own distinct behaviors. Being able to control the material’s composition by adding different amino acids is an important step toward creating nanostructures that can appropriately interface with biological materials that have specific functions.
“Our paper is a first demonstration of nanoscale versions of electronic wires that can be built up and broken down in response to simple chemical signals,” says Einstein Professor of Chemistry Rein Ulijn (GC/Hunter) the director of the ASRC Nanoscience Initiative and one of the paper’s co-authors.
Though the research is still in an early stage, the idea of programming molecules to take different shapes that can or cannot conduct electricity, via an amino acid “code,” holds promise. The team plans to fine-tune their control over the materials’ lifetimes and improve electrical conductivity, in the hopes of eventually integrating these materials with biological systems.
“A long-term goal is to take this to the level of neuronal cells and use this in a living brain,” Kumar says.