Interfacing cell-based assays in environmental scanning electron microscopy using dielectrophoresis

Development of the dielectrophoretic (DEP) live cell trapping technology and its interfacing with the environmental scanning electron microscopy (ESEM) is described. DEP microelectrode arrays were fabricated on glass substrate using photolithography and lift-off. Chip-based arrays were applied for ESEM analysis of DEP-trapped human leukemic cells. This work provides proof-of-concept interfacing of the DEP cell retention and trapping technology with ESEM to provide a high-resolution analysis of individual nonadherent cells.

Single cell stiffness measurement at various humidity conditions by nanomanipulation of a nano-needle

This paper presents a method for single cell stiffness measurement based on a nano-needle and nanomanipulation. The nano-needle with a buffering beam was fabricated from an atomic force microscope cantilever by the focused ion beam etching technique. Wild type yeast cells (W303) were prepared and placed on the sample stage inside an environmental scanning electron microscope (ESEM) chamber. The nanomanipulator actuated the nano-needle to press against a single yeast cell. As a result, the deformation of the cell and nano-needle was observed by the ESEM system in real-time. Finally, the stiffness of the single cell was determined based on this deformation information. To reveal the relationship between the cell stiffness and the environmental humidity conditions, the cell stiffness was measured at three different humidity conditions, i.e. 40, 70 and 100%, respectively. The results show that the stiffness of a single cell is reduced with increasing humidity.