title: Minimizing pulling geometry errors in atomic force microscope single molecule force spectroscopy.
abstract: In atomic force microscopy-based single molecule force spectroscopy (AFM-SMFS), it is assumed that the pulling angle is negligible and that the force applied to the molecule is equivalent to the force measured by the instrument. Recent studies, however, have indicated that the pulling geometry errors can drastically alter the measured force-extension relationship of molecules. Here we describe a software-based alignment method that repositions the cantilever such that it is located directly above the molecule's substrate attachment site. By aligning the applied force with the measurement axis, the molecule is no longer undergoing combined loading, and the full force can be measured by the cantilever. Simulations and experimental results verify the ability of the alignment program to minimize pulling geometry errors in AFM-SMFS studies.
authors.affiliation: Department of Mechanical Engineering and Materials Science, Center for Biologically Inspired Materials and Materials Systems, Pratt School of Engineering, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Monica
authors.initials: M
authors.lastname: Rivera
authors.forename: Whasil
authors.initials: W
authors.lastname: Lee
authors.forename: Changhong
authors.initials: C
authors.lastname: Ke
authors.forename: Piotr E
authors.initials: PE
authors.lastname: Marszalek
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Cole
authors.forename: Robert L
authors.initials: RL
authors.lastname: Clark
mesh_terms: D016477:Artifacts; D003198:Computer Simulation; D004279:DNA, Viral / Q000737:chemistry; D003911:Dextrans / Q000737:chemistry; D018625:Microscopy, Atomic Force; D012984:Software; D013057:Spectrum Analysis / Q000379:methods*; D013499:Surface Properties
chemical_list: D004279:DNA, Viral; D003911:Dextrans