Self-Assembly of Palmitoyl Lipopeptides Used in SkinCare Products.

The self-assembly of three cosmeticallyactive peptide amphiphilesC16-GHK, C16-KT, and C16-KTTKS (C16denotes a hexadecyl, palmitoyl chain) used in commercialskin care products is examined. A range of spectroscopic, microscopic,and X-ray scattering methods is used to probe the secondary structure,aggregate morphology, and the nanostructure. Peptide amphiphile (PA)C16-KTTKS forms flat tapes and extended fibrillar structureswith high β-sheet content. In contrast, C16-KT andC16-GHK exhibit crystal-like aggregates with, in the caseof the latter PA, lower β-sheet content. All three PA samplesshow spacings from bilayer structures in small-angle X-ray scatteringprofiles, and all three have similar critical aggregation concentrations,this being governed by the lipid chain length. However, only C16-KTTKS is stained by Congo red, a diagnostic dye used todetect amyloid formation, and this PA also shows a highly alignedcross-β X-ray diffraction pattern consistent with the high β-sheetcontent in the self-assembled aggregates. These findings may provideimportant insights relevant to the role of self-assembled aggregateson the reported collagen-stimulating properties of these PAs. [ABSTRACT FROM AUTHOR]