Measurement of interaction force between nanoarrayed integrin αvβ3 and immobilized vitronectin on the cantilever tip

Protein nanoarrays containing integrin αvβ3 or BSA were fabricated on ProLinker™-coated Au surface by dip-pen nanolithography (DPN). An atomic force microscope (AFM) tip coated with ProLinker™ was modified by vitronectin. We measured the interaction force between nanoarrayed integrin αvβ3 or BSA and immobilized vitronectin on the cantilever tip by employing tethering-unbinding method. The unbinding force between integrin αvβ3 and vitronectin (1087 ± 62 pN) was much higher than that of between BSA and vitronectin (643 ± 74 pN). These results demonstrate that one can distinguish a specific protein interaction from non-specific interactions by means of force measurement on the molecular interactions between the nanoarrayed protein and its interacting protein on the AFM tip.