(656g) Hierarchical Self-Assembly of Peptide Amphiphiles Into Fibre Bundles Mediated by Cell-Binding Motif RGDS

The study of self-assembling peptide fibrous nanostructures was inspired by the natural biological system and is of great interest to many material designers for its extensive applications as scaffolds in tissue engineering, vehicles for drug delivery and even as templates for the mineralization of heavy metal nanoparticles. Various design strategies for self-assembling peptides into nanofibres have been explored. The design rules are either based on protein structures, in the form of alpha helices and beta-sheets, or based on peptide derivatives such as peptide amphiphiles and π-stacking systems. Among of them, the single-tail peptide amphiphiles (PA) discovered by Stupp and his c-workers is a versatile system with high degrees of control over the nanofibre’s structure and chemical functionality.

While peptide nanofibres and its application have been well investigated, fabrication of higher hierarchical order of such nanofibres has not received similar research attention. Only recently, two novel pathways of peptides self-assembly into aligned fibre bundles were reported by Stupp’s group. The pathways of X-ray irradiation or temperature elevation have been found to enable the formation of bundles of aligned nanofibres. In this work, we report a new pathway to form bundles of nanofibres by inducing and controlling inter-nanofibre interactions using the well-known bioactive sequence RGD. RGD has been found to bind to various types of integrins including α5β1, αVβ3, α8β1, αVβ1, αVβ6, and αIIbβ3and is frequently used to improve cell adhesion, cell proliferation, cell migration and cell differentiation. In our system, RGD as a cell binding sequence was found to take part in the structural thickening of the fibre bundles. The findings that RGDS type sequences function not only as bioactive motifs but also as key structural units in the lateral assembly of fibres could aid our understanding of fibrillogenesis in nature.