Abstract
The magnetic tweezer technique has become a versatile tool for unfolding or folding of individual molecules, mainly DNA. In addition to single molecule analysis, the magnetic tweezer can be used to analyze the mechanical properties of cells and extracellular matrices. We have established a magnetic tweezer that is capable of measuring the linear and non-linear viscoelastic behavior of a wide range of soft matter in precisely controlled environmental conditions, such as temperature, CO2 and humidity. The magnetic tweezer presented in this study is suitable to detect specific differences in the mechanical properties of different cell lines, such as human breast cancer cells and mouse embryonic fibroblasts, as well as collagen matrices of distinct concentrations in the presence and absence of fibronectin crosslinks. The precise calibration and control mechanism employed in the presented magnetic tweezer setup provides the ability to apply physiological force up to 5 nN on 4.5 µm superparamagnetic beads coated with fibronectin and coupled to the cells or collagen matrices. These measurements reveal specific local linear and non-linear viscoelastic behavior of the investigated samples. The viscoelastic response of cells and collagen matrices to the force application is best described by a weak power law behavior. Our results demonstrate that the stress stiffening response and the fluidization of cells is cell type specific and varies largely between differently invasive and aggressive cancer cells. Finally, we showed that the viscoelastic behavior of collagen matrices with and without fibronectin crosslinks measured by the magnetic tweezer can be related to the microstructure of these matrices.
Highlights
The magnetic tweezer technique has become a versatile tool for unfolding or folding of individual molecules, mainly DNA
Due to the strong influence of external parameters on cellular m echanics[21,22], the employment of a surrounding incubation chamber with precisely controlled environmental conditions is a major improvement compared to earlier implementations of the magnetic tweezer setup
MCF-7 human breast cancer cells, PINCH-1 cells carrying a Lox-P-flanked PINCH-1 gene (PINCH-1fl/fl cells), and PINCH-1 knock-out cells (PINCH-1−/−) mouse embryonic fibroblasts were cultured in high glucose (4.5 g/l) DMEM supplemented with 10% fetal bovine serum (FBS) and 1% P/S56
Summary
The magnetic tweezer technique has become a versatile tool for unfolding or folding of individual molecules, mainly DNA. The precise calibration and control mechanism employed in the presented magnetic tweezer setup provides the ability to apply physiological force up to 5 nN on 4.5 μm superparamagnetic beads coated with fibronectin and coupled to the cells or collagen matrices. These measurements reveal specific local linear and non-linear viscoelastic behavior of the investigated samples. The aim of this study was to demonstrate that the presented setup is suitable to probe differences in the non-linear viscoelastic properties between different cell lines as well as different models for extracellular matrices. Due to the strong influence of external parameters on cellular m echanics[21,22], the employment of a surrounding incubation chamber with precisely controlled environmental conditions is a major improvement compared to earlier implementations of the magnetic tweezer setup
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
