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A reflecting diffraction grating has
been etched onto the backside of a standard cantilever for atomic force
microscopy, and the diffracted light has been used to monitor the angular
position of the cantilever. It is shown experimentally that for small angles of
incidence and for large reflection angles, the force sensitivity can be
improved by few times when an appropriate detection scheme based on the
position sensitive (duolateral) detector is used. The first demonstration was
performed with a one micron period amplitude diffraction grating onto the
backside of an Al-coated cantilever etched by a focused ion beam milling for
the experiments in air and an analogous 600 nm-period grating for the
experiments in air and in water.
The cell mechanical features are largely regulated by actin cytokeleton. By analyzing the mechanical features, it is possible to evaluate the characteristics of the complicated actin cytoskeleton in diverse cell types. In this study, we examined the sub-membrane mechanical structures of normal fibroblasts TIG-1 cells, and cervical cancer Hela cells using local elasticity mapping method of atomic force microscope. Especially we aimed at clarifying the regulatory mechanisms of sub-membrane actin structures in these cells by activation of actomyosin formation using calyculin A. This technique revealed that TIG-1 and Hela cells bore clearly different sub-membrane mechanical structures. TIG-1 cells had aligned stiff filamentous structures, whereas Hela cells had crooked and relatively soft filaments. The surface stiffness of TIG-1 cells increased slightly by actomyosin formation due to stiffness increase of the aligned filamentous structures. On the other hand, the surface stiffness of Hela cells increased by actomyosin formation due to upregulation of the apical actin filaments. Therefore, the structural and regulatory differences of the apical actin filaments could be demonstrated by atomic force microscopy elasticity mapping analysis.