Peptide Nanotube Reinforced Polymers: A System for Tunable, Composite Materials
Technical Report,01 Sep 2012,31 May 2013
Harvard Medical School Boston United States
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D,L-cyclic peptides DLCPs are peptides composed of alternating D and L amino acids that self-assemble into nanotubular stacks and microcrystalline aggregates. The goal of this proposal was to determine the suitability of these self-assembled structures for the mechanical reinforcement of polymeric materials used in the fabrication of implantable medical devices. Our results show that the high aspect ratio microcrystalline aggregates a.k.a. microneedles that come from the assembly process are capable of increasing the average stiffness of biodegradable polymers like poly-D,L-lactic acid PDLLA, a common polymer used in resorbable load bearing implants. Preliminary experiments also demonstrated that, for a particular sequence of DLCP cyclo-Gln-Leu4 the assembled microneedles do not exhibit any cytotoxicity toward sheep fibroblasts. Finally, nanomechanical characterization of the microneedles revealed that they were among the stiffest known proteinaceous substances in existence, suggesting their utility as mechanical reinforcers. However, significant challenges remain in rationally controlling the size and surface chemistry features of DLCP-derived microneedles, limiting the ease of their incorporation into biomedical implant devices.