London Centre for Nanotechnology,
Keywords: DNA origami, Multivalency, integrin, EGF
Summary:DNA assembles according to precise base-pairing rules. This allows for the construction of DNA nanostructures (DNA origami) in which DNA is folded into various shapes with a high degree of positional order allowing for complex arrangements to be obtained. In addition, DNA origami can be employed as scaffolds to pattern multiple bioactive structures and nanostructures (e.g. peptides, antibodies, etc.) at the scale of individual molecules. Here we present a strategy for the fabrication of biomimetic nanoarrays, based on the use of DNA origami, that permit the multivalent investigation of ligand-receptor molecule interactions in cancer cell spreading, with nanoscale spatial resolution and single-molecule control. We employed DNA-origami to control the nanoscale spatial organization of integrin and epidermal growth factor (EGF)- binding ligands that modulate epidermal cancer cell behaviour. By organizing these multivalent DNA nanostructures in nanoarray configurations on nanopatterned surfaces, we demonstrated the cooperative behaviour of integrin- and EGF- ligands in the spreading of human cutaneous melanoma cells: this cooperation was shown to depend on both the number and ratio of the selective ligands employed. Notably, the multivalent biochips we have developed allowed for this cooperative effect to be demonstrated for the first time with single-molecule control and nanoscale spatial resolution. By and large, the platform presented here is of general applicability for the study, with molecular control, of different multivalent interactions governing biological processes, from the function of cell-surface receptors, to protein-ligand binding and pathogen inhibition.