title: Unbinding molecular recognition force maps of localized single receptor molecules by atomic force microscopy.
abstract: Atomic force microscopy is a technique capable to study biological recognition processes at the single-molecule level. In this work we operate the AFM in a force-scan based mode, the jumping mode, where simultaneous topographic and tip-sample adhesion maps are acquired. This approach obtains the unbinding force between a well-defined receptor molecule and a ligand attached to the AFM tip. The method is applied to the avidin-biotin system. In contrast with previous data, we obtain laterally resolved adhesion maps of avidin-biotin unbinding forces highly correlated with single avidin molecules in the corresponding topographic map. The scanning rate 250 pixel s(-1) (2 min for a 128 x 128 image) is limited by the hydrodynamic drag force. We are able to build a rupture-force distribution histogram that corresponds to a single defined molecule. Furthermore, we find that due to the motility of the polymer used as spacer to anchor the ligand to the tip, its direction at rupture does not generally coincide with the normal to the tip-sample, this introduces an appreciable error in the measured force.
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Sotres
authors.forename: Anabel
authors.initials: A
authors.lastname: Lostao
authors.forename: Linda
authors.initials: L
authors.lastname: Wildling
authors.forename: Andreas
authors.initials: A
authors.lastname: Ebner
authors.forename: Carlos
authors.initials: C
authors.lastname: Gómez-Moreno
authors.forename: Hermann J
authors.initials: HJ
authors.lastname: Gruber
authors.forename: Peter
authors.initials: P
authors.lastname: Hinterdorfer
authors.forename: Arturo M
authors.initials: AM
authors.lastname: Baró
mesh_terms: D001360:Avidin / Q000737:chemistry*; D001710:Biotin / Q000737:chemistry*; D008024:Ligands; D018625:Microscopy, Atomic Force / Q000379:methods*; D010316:Particle Size; D011108:Polymers / Q000737:chemistry*; D013314:Stress, Mechanical
chemical_list: D008024:Ligands; D011108:Polymers; D001360:Avidin; D001710:Biotin