Imaging Living Chondrocyte Surface Structures With AFM Contact Mode

In its most established mode of operation, named constant force contact mode, atomic force microscopy (AFM) has been applied to image the 2D and 3D architecture of surfaces. Any deflection of the tip as a result of surface topography is recorded. The microscope reconstructs an image of the surface from the x, y , and z scan data to develop a 3D illustration of any surface at the micro- and nanometer level. The production of high-resolution images of a wide variety of biological samples at near-native conditions and the possibility to measure very low local forces is proving to be a powerful tool for cell analysis (1 ,2 ). In contrast with electron microscopy observations in particular, AFM improves biological studies involving imaging by also monitoring dynamic processes. However, the investigation of soft biomaterials with this special method is still challenging. This chapter reviews practical details of imaging two cell lines: human chondrocytes and human osteosarcoma. However, characteristics described are not unique to this type of cell. Principally, all types of adherently growing cells can be investigated with the techniques described here. Force curve analysis, as a backdrop for the understanding of the received images (1 ), will be introduced in detail in Subheading 3.4 . Further sections explore how AFM can be used as a helpful tool in observations of the cell surface and the physical interactions that occur there, like adhesion or friction, and their influence on the active cell. In Subheading 7. common artifacts and troubles are described, along with the practical instructions.