Self-Assembly and Collagen-Stimulating Activity of a Peptide Amphiphile Incorporating a Peptide Sequence from Lumican

The self-assembly and bioactivity of a peptide amphiphile (PA) incorporating a 13-residue sequence derived from the last 13 amino acids of the C-terminus of lumican, C₁₆-YEA­LRV­ANE­VTLN, attached to a hexadecyl (C₁₆) lipid chain have been examined. Lumican is a proteoglycan found in many types of tissue and is involved in collagen fibril organization. A critical aggregation concentration (cac) for the PA was determined through pyrene fluorescence measurements. The structure of the aggregates was imaged using electron microscopy, and twisted and curved nanotapes were observed. In situ small-angle X-ray scattering and fiber X-ray diffraction reveal that these tapes contain interdigitated bilayers of the PA molecules. FTIR and circular dichroism spectroscopy and fiber X-ray diffraction indicate that the lumican sequence in the PA adopts a β-sheet secondary structure. Cell assays using human dermal fibroblasts show that below the cac the PA displays good biocompatibility and also stimulates collagen production over a period of 3 weeks, exceeding a 2-fold enhancement for several concentrations. Thus, this PA has promise in future biological applications, in particular, in tissue engineering