title: Membrane-based actuation for high-speed single molecule force spectroscopy studies using AFM.
abstract: Atomic force microscopy (AFM)-based dynamic force spectroscopy of single molecular interactions involves characterizing unbinding/unfolding force distributions over a range of pulling speeds. Owing to their size and stiffness, AFM cantilevers are adversely affected by hydrodynamic forces, especially at pulling speeds >10 microm/s, when the viscous drag becomes comparable to the unbinding/unfolding forces. To circumvent these adverse effects, we have fabricated polymer-based membranes capable of actuating commercial AFM cantilevers at speeds >or=100 microm/s with minimal viscous drag effects. We have used FLUENT, a computational fluid dynamics (CFD) software, to simulate high-speed pulling and fast actuation of AFM cantilevers and membranes in different experimental configurations. The simulation results support the experimental findings on a variety of commercial AFM cantilevers and predict significant reduction in drag forces when membrane actuators are used. Unbinding force experiments involving human antibodies using these membranes demonstrate that it is possible to achieve bond loading rates >or=10(6) pN/s, an order of magnitude greater than that reported with commercial AFM cantilevers and systems.
authors.affiliation: Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.
authors.forename: Krishna
authors.initials: K
authors.lastname: Sarangapani
authors.forename: Hamdi
authors.initials: H
authors.lastname: Torun
authors.forename: Ofer
authors.initials: O
authors.lastname: Finkler
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhu
authors.forename: Levent
authors.initials: L
authors.lastname: Degertekin
mesh_terms: D001323:Autoantibodies / Q000737:chemistry; D003198:Computer Simulation; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry / Q000276:immunology; D008567:Membranes, Artificial; D018625:Microscopy, Atomic Force / Q000379:methods*; D011108:Polymers / Q000737:chemistry; D011485:Protein Binding; D012984:Software; D013057:Spectrum Analysis / Q000379:methods*; D014783:Viscosity; D014867:Water; D014992:Xylenes / Q000737:chemistry
chemical_list: D001323:Autoantibodies; D007074:Immunoglobulin G; D008567:Membranes, Artificial; D011108:Polymers; D014992:Xylenes; D014867:Water; C011055:parylene