Combining Atomic Force Microscopy with Micropipette Techniques for Cell Mechanical Measurements

Introduction

Topography, roughness, and mechanical properties of biomaterials are crucial parameters affecting cell adhesion/motility, morphology and mechanics as well as the proliferation of stem/progenitor cells [1-4]. Nanomechanical analysis of cells and tissue slices increasingly gains in importance in different fields of cell biology, like cancer research [5] and developmental biology [6]. Atomic Force Microscopy (AFM) is a powerful, multipurpose technology suitable not only for imaging a wide range of different samples with nanometer-scale resolution under controlled environmental conditions, but also for mapping mechanical and adhesive properties of sample/cell systems and tissues.

Atomic force microscopy is not a high throughput technique as optical readout methods can be. However, the JPK NanoWizard® AFM can be seamlessly combined with methods such as fluorescence, confocal, TIRF, STED microscopy for high-content analyses [e.g. 7,8] showing that the JPK NanoWizard® AFM is versatile when combined with other single-cell techniques. For a better understanding of how cells react on externally applied mechanical stimuli, some researchers have tried to connect fluorescence microscopy with AFM and micropipette related technologies like simple manipulation (e.g. [9]), aspiration, injection, and patch clamp for electric physiological investigation. The simultaneous combination of different single cell technologies results to several technical challenges. In this report, we will describe how inverted microscopy can be equipped with micropipette aspiration and AFM indentation measurements on suspended mammalian cells.