Fluorescence Interferometry of Neuronal Cell Adhesion on Microstructured Silicon.
Dieter Braun and Peter Fromherz, Physical Review Letters 81:5241-5244 (1998)
 

Description:

One of the great hopes of emerging nanoscience is that man-made devices will finally be able to function with the basic building blocks of nature.  The technology and science finally exists to probe and understand nature at the nanometer scale, the length scale of individual cells and even DNA, the tiny things that govern life of all types.

Trying to interface silicon electronics with biological neurons requires an understanding of how the two interact.  The separation of cell membranes from a surface of silica was measured with nanometer precision taking advantage of the fluorescence of an organic dye in the standing modes of light above silicon. For neural cells from a rat brain we found about 105 nm of separation on a surface coated with laminin (a protein) and about 60 nm with fibronectin (a different protein). No areas of close adhesion were seen within a lateral resolution of 400 nm. The wide homogeneous cleft raises the question about the nature of the attractive and repulsive forces in cell adhesion.

This image shows a fluorescence micrograph of a rat neuron on a silicon wafer with square steps of oxide coated with laminin (a protein). The membrane was stained with dye. The checkerboard pattern originates from the lower membrane of the cell. (The scale bar is only: 10 μm). Left inset: Unit cell of the chip. The height (enhanced x2) of the 16 steps of oxide increases from 20 nm to 320 nm in the order of the numbers. Right inset: Micrograph of a unit cell in white light with Newton-type interference colors.

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