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Biomedical and Pharmaceutical Sciences


A number of cyclic peptides, including [FR]4, [FK]4, [WR]4, [CR]4, [AK]4, and [WK]n (n = 3-5) containing L-amino acids were synthesized using solid-phase peptide synthesis. We hypothesized that an optimal balance of hydrophobicity and charge could generate self-assembled nanostructures in aqueous solution by intramolecular and/or intermolecular interactions. Among all the designed peptides, [WR]n (n = 3-5) generated self-assembled vesicle-like nanostructures at room temperature as shown by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), and/or Dynamic light scattering (DLS). This class of peptides represents the first report of surfactant-like cyclic peptides that self-assemble into nanostructures. A plausible mechanistic insight of self-assembly of [WR]5 was investigated by molecular modeling studies. Modified [WR]5 analogues, such as [WMeR]5. [WR(Me)2]5, [WMeR(Me)2]5,and [WdR]5 exhibited different morphologies than [WR]5 as shown by TEM observations. [WR]5 exhibited significant stabilizing effect for generated silver nanoparticles and glyceraldehyde-3-phosphate dehydrogenase activity. These studies established a new class of surfactant-like cyclic peptides that self-assembled into nanostructures and could have potential applications for stabilizing of silver nanoparticles and protein biomolecules.