Impact of order and disorder in RGD nanopatterns on cell adhesion.

We herein present a novel platform of well-controlled ordered and disordered nanopatterns positioned with a cyclic peptide of arginine-glycine-aspartic acid (RGD) on a bioinert poly(ethylene glycol) background, to study whether the nanoscopic order of spatial patterning of the integrin-specific ligands influences osteoblast adhesion. This is the first time that the nanoscale order of RGD ligand patterns was varied quantitatively, and tested for its impact on the adhesion of tissue cells. Our findings reveal that integrin clustering and such adhesion induced by RGD ligands is dependent on the local order of ligand arrangement on a substrate when the global average ligand spacing is larger than 70 nm; i.e., cell adhesion is "turned off" by RGD nanopattern order and "turned on" by the RGD nanopattern disorder if operating at this range of interligand spacing.