The goal of the proposed research is to enable rapid, high-resolution imaging of living cells using the Atomic Force Microscope (AFM). High-speed AFM imaging will enable the investigation of dynamic cellular functions such as migration. Understanding how cells move is important because cell movement plays a critical role, for example, in neovascularization of ischemic heart tissue, spread of cancer, and wound healing. Current instruments cannot provide high-resolution, three-dimensional, time-resolved images of critical cellular processes such as the formation of cytosketetal protrusions (e.g., lamellipodia with 110-160nm thickness) that mediate traction during cell migration. Atomic Force Microscopes (AFMs) have sufficient resolution to image such nano-scale processes. However, current AFM imaging of living cells (with imaging time in the minutes per frame) is too stow to investigate the dynamics of such cellutar processes. The proposed work aims to develop fast AFM systems (with imaging time in the seconds per frame) to overcome this present inability to image nano-scale cellular processes. The critical problem in rapid AFM imaging of cells is to precisely position the AFM probe over the cell surface at high-speeds (to prevent sample damage and distortion). We propose to address this problem by using novel model-based approaches to achieve precision positioning of the AFM probe at high speeds. Therefore, the proposed work will test the hypothesis that the time needed for AFM imaging of living cells can be substantially reduced (by two orders of magnitude without loss of spatial resolution or reduction in the area that can be imaged) by precisely positioning the AFM-probe, over the cell surface, during high-speed imaging. The two specific aims are: (1) develop, implement, and test model-based algorithms for precision positioning of AFM-probe at high speeds; and (2) comparatively evaluate the AFM-imaging time, with and without the use of precision positioning algorithms, when imaging human microvascular endothelial ceils (hmEC) from young and aged donors (at high resolution) during the migration of hmEC on type I collagen.
|Zou, Q; Leang, Kk; Sadoun, E et al. (2004) Control Issues in High-speed AFM for Biological Applications: Collagen Imaging Example. Asian J Control 6:164-178|