Functional extension of high-speed AFM for wider biological applications.

High-speed atomic force microscopy (HS-AFM) has been established and used, which can visualize biomolecules in dynamic action at high spatiotemporal resolution without disturbing their function. Various studies conducted in the past few years have demonstrated that the dynamic structure and action of biomolecules revealed with HS-AFM can provide greater insights than ever before into how the molecules function. However, this microscopy has still limitations in some regards. Recently, efforts have been carried out to overcome some of the limitations. As a result, it has now become possible to visualize dynamic processes occurring even on live cells and perform simultaneous observations of topographic and fluorescent images at a high rate. In this review, we focus on technical developments for expanding the range of objects and phenomena observable by HS-AFM as well as for granting multiple functionalities to HS-AFM.