Smart Polymers Perform Nano-Acrobatics
One result of the new research is that scientists will now be able to exploit the COMPcc portion of a polymer to wrap around a Vitamin D molecule in order to stimulate its tissue-regenerating power. Genetically engineered copolymers have applications in everything from artificial therapeutics, biocatalysts, scaffolds, and cells for medicine, to sustainable energy and environmental remediation.Credit: New York University
Researchers are finding remarkable ways in which bioengineered paired macromolecules can be made to self-assemble, disassemble, and more -- and then biodegrade when they’ve finished their work. The key to these macromolecules -- called block copolymers -- is their ability to self-assemble when exposed to discrete external stimuli. Self-assembly can occur as a function of temperature or pH, for example. And it is not necessarily a permanent change; it can be reversed. Genetically engineered copolymers have applications in everything from artificial therapeutics, biocatalysts, scaffolds, and cells for medicine, to sustainable energy and environmental remediation. For four years, Jin Kim Montclare and researchers at the Polytechnic Institute of New York University have been developing block copolymers from scratch using recombinant DNA and putting them through biochemical hoops. The group’s work, published recently in the journal ChemBioChem, involves block copolymers comprising elastin alternating with COMPcc. The former is a pentapeptide whose amino-acid constituents can assemble into a beta spiral structure as a function of temperature, pH, or salinity. COMPcc, which stands for “cartilage oligomeric matrix protein coil coiled,” is a pentamer arranged as five helixes that can contort into an arrangement that produces a hydrophobic core the way one might create a cylindrical cavity by stacking garden hoses on a deck -- thus the odd “coiled coil” nomenclature. COMPcc has the ability to bind small water-insoluble molecules such as Vitamin D within its hydrophobic core. The possibilities are manifold. “That central pore can potentially bind chemicals that are hard to deliver as drugs because they are normally not water soluble,” says Montclare. For example COMPcc can bind to Vitamin D, a non-dissolving molecule that happens to have profound implications for regenerative tissue and serves as a signaling hormone for the promotion of tissue differentiation into cartilage and bone. And COMPcc can “live” in a copolymer with elastin, synthetics, or other coiled coil-based materials that self-assemble into gels or more organized forms like scaffolding, which can be used for tissue regeneration.
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