A new type of shape-memory polymer (SMP) that changes its shape in response to exposure to enzymes and is compatible with living cells could represent a medical breakthrough.
SMPs typically require external stimuli, such as a change in temperature or exposure to light, to trigger shape-shifting behavior. The material developed by researchers at the College of Engineering and Computer Science at Syracuse University in New York, in collaboration with Bucknell University (Lewisburg, PA), eliminates the need for external triggers by responding directly to cellular activity.
|Professor James Henderson (left) and PhD candidate Shelby L. Buffington. Image courtesy Syracuse University.|
SMPs are soft, rubbery, “smart” materials that can change shape and hold it indefinitely, reverting back to their original morphology when triggered to do so. Cardiovascular stents are among the biomedical applications: They can adopt one shape to facilitate surgical insertion and expand once they are positioned in a blood vessel in response to the warmth of the patient’s body.
“The enzymatic sensitivity of the material [developed at Syracuse University] allows it to respond directly to cell behavior,” biomedical engineering PhD candidate Shelby L. Buffington explained to Matt Wheeler, who authored an article about the research on the university website. “For instance, you could place it over a wound, and as the tissue remodeled and degraded it, the SMP would slowly pull the wound closed. It could be adapted to play a role in treating infections and cancer by adjusting the material’s chemistry.”
The material is produced using dual electrospinning, in which a high-voltage current is applied to two needle tips pumping two separate polymer solutions. The voltage draws out the polymer fibers, which are blended into a fiber polymer mat. The proper combination of fibers gives the material its shape-memory properties.
The researchers detailed the material’s properties, shape-memory performance and cytocompatibility in a paper published in Acta Biomaterialia. The experiments successfully demonstrated that the SMP’s original shape could be recovered through a degree of reversal, or degradation, of the shape-fixing phase.
They are now examining the material in cancer and macrophage cell cultures. With additional research, they hope to uncover practical uses for the material using a lower concentration of enzymes, produced by less extreme cellular activity.
“We anticipate that the materials we’re developing could have broad applications in healthcare," said Professor James Henderson, who is part of the research team. "For example, our SMPs could be used in drugs that only activate when the target cells or organ are in the desired physiological state; in scaffolds that guide tissue regeneration in response to the behavior of the regenerating tissue itself; and in decision-making biosensors that guide patient treatment more effectively. We’re very excited to have achieved these first enzymatically responsive SMPs,” said Henderson.