title: Interlaboratory round robin on cantilever calibration for AFM force spectroscopy.
abstract: Single-molecule force spectroscopy studies performed by Atomic Force Microscopes (AFMs) strongly rely on accurately determined cantilever spring constants. Hence, to calibrate cantilevers, a reliable calibration protocol is essential. Although the thermal noise method and the direct Sader method are frequently used for cantilever calibration, there is no consensus on the optimal calibration of soft and V-shaped cantilevers, especially those used in force spectroscopy. Therefore, in this study we aimed at establishing a commonly accepted approach to accurately calibrate compliant and V-shaped cantilevers. In a round robin experiment involving eight different laboratories we compared the thermal noise and the Sader method on ten commercial and custom-built AFMs. We found that spring constants of both rectangular and V-shaped cantilevers can accurately be determined with both methods, although the Sader method proved to be superior. Furthermore, we observed that simultaneous application of both methods on an AFM proved an accurate consistency check of the instrument and thus provides optimal and highly reproducible calibration. To illustrate the importance of optimal calibration, we show that for biological force spectroscopy studies, an erroneously calibrated cantilever can significantly affect the derived (bio)physical parameters. Taken together, our findings demonstrated that with the pre-established protocol described reliable spring constants can be obtained for different types of cantilevers.
authors.affiliation: Scanning Probe Microscopy, Radboud University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands.
authors.forename: Joost
authors.initials: J
authors.lastname: te Riet
authors.forename: Allard J
authors.initials: AJ
authors.lastname: Katan
authors.forename: Christian
authors.initials: C
authors.lastname: Rankl
authors.forename: Stefan W
authors.initials: SW
authors.lastname: Stahl
authors.forename: Arend M
authors.initials: AM
authors.lastname: van Buul
authors.forename: In Yee
authors.initials: IY
authors.lastname: Phang
authors.forename: Alberto
authors.initials: A
authors.lastname: Gomez-Casado
authors.forename: Peter
authors.initials: P
authors.lastname: Schön
authors.forename: Jan W
authors.initials: JW
authors.lastname: Gerritsen
authors.forename: Alessandra
authors.initials: A
authors.lastname: Cambi
authors.forename: Alan E
authors.initials: AE
authors.lastname: Rowan
authors.forename: G Julius
authors.initials: GJ
authors.lastname: Vancso
authors.forename: Pascal
authors.initials: P
authors.lastname: Jonkheijm
authors.forename: Jurriaan
authors.initials: J
authors.lastname: Huskens
authors.forename: Tjerk H
authors.initials: TH
authors.lastname: Oosterkamp
authors.forename: Hermann
authors.initials: H
authors.lastname: Gaub
authors.forename: Peter
authors.initials: P
authors.lastname: Hinterdorfer
authors.forename: Carl G
authors.initials: CG
authors.lastname: Figdor
authors.forename: Sylvia
authors.initials: S
authors.lastname: Speller
mesh_terms: D000465:Algorithms; D002138:Calibration; D008024:Ligands; D018625:Microscopy, Atomic Force / Q000295:instrumentation* / Q000379:methods*; D008962:Models, Theoretical; D013057:Spectrum Analysis / Q000295:instrumentation / Q000379:methods*; D055672:Static Electricity
chemical_list: D008024:Ligands