By John Toon
When someone you know is wearing an unfamiliar hat, you might not recognize him. Georgia Tech researchers are using just such a disguise to sneak biomaterials containing peptide-signaling molecules into living animals.
When biomaterials are introduced into the body, they normally stimulate an immune system response immediately. But the researchers used molecular cages like hats to cover binding sites on the peptides that are normally recognized by cell receptors, preventing recognition by the animal’s cells. The cages were designed to detach and reveal the peptides when they encounter specific wavelengths of light.
So, when the disguised peptides are needed to launch biological processes, the researchers shine ultraviolet light onto the molecules through the skin, causing the “hat” structures to come off. That allows cells and other molecules to recognize and interact with the peptides on the surface of the biomaterial.
This light-activated triggering technique has been demonstrated in animal models, and if it works in humans, it could help provide more precise timing for processes essential to regenerative medicine, cancer treatment, immunology, stem cell growth, and a range of other areas. The research represents the first time biological signals presented on biomaterials have been activated by light through the skin of a living animal.
“Many biological processes involve complex cascades of reactions in which the timing must be very tightly controlled,” said Andrés García, a Regents Professor in the George W. Woodruff School of Mechanical Engineering at Georgia Tech. “With this technique, we can deliver a drug or particle with its signal in the ‘off’ position, then use light to turn the signal ‘on’ precisely when needed.”
Supported by the National Science Foundation and the National Institutes of Health, the research was reported in the journal Nature Materials. It resulted from collaboration with scientists from the Max-Planck Institute.