title: Bimodal atomic force microscopy imaging of isolated antibodies in air and liquids.
abstract: We have developed a dynamic atomic force microscopy (AFM) method based on the simultaneous excitation of the first two flexural modes of the cantilever. The instrument, called a bimodal atomic force microscope, allows us to resolve the structural components of antibodies in both monomer and pentameric forms. The instrument operates in both high and low quality factor environments, i.e., air and liquids. We show that under the same experimental conditions, bimodal AFM is more sensitive to compositional changes than amplitude modulation AFM. By using theoretical and numerical methods, we study the material contrast sensitivity as well as the forces applied on the sample during bimodal AFM operation.
authors.affiliation: Instituto de Microelectrónica de Madrid, CSIC, Isaac Newton 8, 28760 Tres Cantos, Madrid, Spain.
authors.forename: N F
authors.initials: NF
authors.lastname: Martínez
authors.forename: J R
authors.initials: JR
authors.lastname: Lozano
authors.forename: E T
authors.initials: ET
authors.lastname: Herruzo
authors.forename: F
authors.initials: F
authors.lastname: Garcia
authors.forename: C
authors.initials: C
authors.lastname: Richter
authors.forename: T
authors.initials: T
authors.lastname: Sulzbach
authors.forename: R
authors.initials: R
authors.lastname: Garcia