(235e) Peptide Stereocomplexes As Dynamic Elements of Biomaterials

Blending complementary stereoregular macromolecules brings about remarkable transformations in the thermomechanical properties, stability, and morphology of materials, ranging from synthetic semi-crystalline polymers to biomolecules like peptides and proteins. In the context of biomaterials, blending mirror image peptides (i.e., d- and l-peptides) can markedly increases stiffness and proteolytic stability of hydrogel-forming peptide fibers. Yet, recently, we discovered that blends of rapidly assembling d- and l-pentapeptides designed for neural tissue engineering produced softer gels than those from the individual components. Transmission electron microscopy revealed morphological differences between the blends and individual component peptides that explain the differences in mechanical properties. Whereas the individual component peptides form nanoscale fibers that entangle to form hydrogels, the d- and l-peptide blends formed micron-scale plates. In contrast, d- and l-peptide blends reported to yield stiffer hydrogels than the constituent peptides retain a nanofibrous morphology. Therefore, these findings suggest that peptide sequence dictates the morphology and mechanics of biomaterials generated from stereochemistry-driven assembly. Going forward, continuing to parse out the connections between sequence and materials properties of peptide stereocomplexes is needed to accelerate the development of these highly tunable biomaterials building blocks.