Functional AFM imaging of cellular membranes using functionalized tips.

The real-time visualization of specific binding sites on biological samples with high spatial resolution, in order of several nanometers, is an important undertaking in many fields of biology. During the past 5 years, simultaneous topography and recognition imaging (TREC) has become a powerful tool to quickly obtain local receptor nanomaps on complex heterogeneous biosurfaces, such as cells and membranes. In this chapter, we present the TREC technique and explain how to unravel the nano-landscape of cells of the immune system, such as macrophages. We describe the procedures for all steps of the experiment including tip functionalization with Fc fragments via flexible PEG-linker, sample preparation, and localization of Fcγ receptors on macrophages.