Activation of Integrin Function by Nanopatterned Adhesive Interfaces

TLDR

The study investigates how the spatial arrangement of single integrins on cell‑adhesive surfaces influences cell adhesion and signaling. They fabricated rigid gold nanodot arrays (<8 nm diameter) with cyclic RGDfK peptides, spaced at 28–85 nm intervals, to allow one integrin per dot. When the nanodot spacing is ≥73 nm, cells exhibit limited attachment, spreading, and reduced focal adhesions, indicating that integrin clustering is constrained; the 58–73 nm range appears to be a universal scale for integrin clustering and activation across cell types.

Abstract

To study the function behind the molecular arrangement of single integrins in cell adhesion, we designed a hexagonally close-packed rigid template of cell-adhesive gold nanodots coated with cyclic RGDfK peptide by using block-copolymer micelle nanolithography. The diameter of the adhesive dots is < 8 nm, which allows the binding of one integrin per dot. These dots are positioned with high precision at 28, 58, 73, and 85 nm spacing at interfaces. A separation of > or = 73 nm between the adhesive dots results in limited cell attachment and spreading, and dramatically reduces the formation of focal adhesion and actin stress fibers. We attribute these cellular responses to restricted integrin clustering rather than insufficient number of ligand molecules in the cell-matrix interface since "micro-nanopatterned" substrates consisting of alternating fields with dense and no nanodots do support cell adhesion. We propose that the range between 58-73 nm is a universal length scale for integrin clustering and activation, since these properties are shared by a variety of cultured cells.