Differential force microscope for long time-scale biophysical measurements
- 1 April 2007
- journal article
- research article
- Published by AIP Publishing in Review of Scientific Instruments
- Vol. 78 (4), 043711
- https://doi.org/10.1063/1.2727478
Abstract
Force microscopy techniques including optical trapping, magnetic tweezers, and atomic force microscopy (AFM) have facilitated quantification of forces and distances on the molecular scale. However, sensitivity and stability limitations have prevented the application of these techniques to biophysical systems that generate large forces over long times, such as actin filament networks. Growth of actin networks drives cellular shape change and generates nano-Newtons of force over time scales of minutes to hours, and consequently network growth properties have been difficult to study. Here, we present an AFM-based differential force microscope with integrated epifluorescence imaging in which two adjacent cantilevers on the same rigid support are used to provide increased measurement stability. We demonstrate displacement control over measurement times of and apply the instrument to quantify actin network growth in vitro under controlled loads. By measuring both network length and total network fluorescence simultaneously, we show that the average cross-sectional density of the growing network remains constant under static loads. The differential force microscope presented here provides a sensitive method for quantifying force and displacement with long time-scale stability that is useful for measurements of slow biophysical processes in whole cells or in reconstituted molecular systems in vitro.
Keywords
This publication has 30 references indexed in Scilit:
- Reversible stress softening of actin networksNature, 2007
- Reducing probe dependent drift in atomic force microscope with symmetrically supported torsion leversReview of Scientific Instruments, 2006
- Mechanical Processes in BiochemistryAnnual Review of Biochemistry, 2004
- Backtracking by single RNA polymerase molecules observed at near-base-pair resolutionNature, 2003
- Eliminating mechanical perturbations in scanning probe microscopyNanotechnology, 2002
- Multiple sensor stabilization system for local probe microscopesReview of Scientific Instruments, 2001
- Nanoscale Science of Single Molecules Using Local ProbesScience, 1999
- Short cantilevers for atomic force microscopyReview of Scientific Instruments, 1996
- Improvement of thermally induced bending of cantilevers used for atomic force microscopyScanning, 1995
- Noise reduction technique for scanning tunneling microscopyApplied Physics Letters, 1988