Scientists at the New York University Polytechnic School of Engineering say they have made a major advance in the development of proteins that form specialized fibers used in medicine and nanotechnology. For as long as scientists have been able to create new proteins that are capable of self-assembling into fibers, their work has taken place on the nanoscale.
For the first time, this achievement has been realized on the microscale—a leap of magnitude in size that presents significant new opportunities for using engineered protein fibers, according to Jin Kim Montclare, Ph.D., an associate professor of chemical and biomolecular engineering at the NYU School of Engineering. He led a group of researchers who published the results (“Engineered Coiled-Coil Protein Microfibers”) of successful trials in the creation of engineered microfiber proteins in Biomacromolecules.
Many materials used in medicine and nanotechnology rely on proteins engineered to form fibers with specific properties. For example, the scaffolds used in tissue engineering depend on engineered fibers, as do the nanowires used in biosensors. These fibers can also be bound with small molecules of therapeutic compounds and used in drug delivery.
Dr. Montclare and her collaborators began their experiments with the intention of designing nanoscale proteins bound with the cancer therapeutic curcumin. They successfully created a novel, self-assembling nanoscale protein, including a hydrophobic pore capable of binding small molecules. To their surprise, after incubating the fibers with curcumin, the protein not only continued to assemble, but did so to a degree that the fibers crossed the diameter barrier from the nanoscale to the microscale, akin to the diameter of collagen or spider silk.
“This was a surprising and thrilling achievement,” said Dr. Montclare, explaining that this kind of diameter increase in the presence of small molecules is unprecedented. “A microscale fiber that is capable of delivering a small molecule, whether it be a therapeutic compound or other material, is a major step forward.”
She explained that biomaterials embedded with small molecules could be used to construct dual-purpose scaffolds for tissue engineering or to deliver certain drugs more efficiently, especially those that are less effective in an aqueous environment.
Using microscopy, the team was able to observe the fibers in three dimensions and to confirm that the curcumin, which fluoresces when bound to structural protein, was distributed homogeneously throughout the fiber.
“Unlike previously designed coiled-coil fibers, these engineered protein microfibers can bind the small molecule curcumin throughout the assembly, serving as a depot for encapsulation and delivery of other chemical agents within protein-based 3D microenvironments, wrote the investigators.
The research team believes they can devise even larger fibers. The next step, according to Dr. Montclare, is developing proteins that can assemble on the milliscale, creating fibers large enough to see with the naked eye. “It’s even possible to imagine generating hair out of cell assembly,” she maintains.