Protein nanoarrays containing integrin alpha(v)beta(3) or BSA were fabricated on Pro Linker (TM)-coated Au surface by dip-pen nanolithography (DPN). An atomic force microscope (AFM) tip coated with ProLinker (TM) was modified by vitronectin. We measured the interaction force between nanoarrayed integrin alpha(v)beta(3) or BSA and immobilized vitronectin on the cantilever tip by employing tethering-unbinding method. The unbinding force between integrin alpha(v)beta(3) 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. (C) 2007 Elsevier Inc. All rights reserved.