Low Stress Ion Conductance Microscopy of Sub-Cellular Stiffness

TL;DR

This paper introduces a novel microscopy technique using a glass nanopipet to measure subcellular stiffness with high resolution and minimal cell strain, revealing new insights into neuronal cell mechanics.

Contribution

The study presents a precise, contactless method for mapping cell stiffness at sub-100 nm resolution using nanopipet-based stress control and ion current measurements.

Findings

Neuronal cell body is significantly softer in the first 660 nm of compression.

Intracellular pressure around 120 Pa affects membrane-cytoskeleton attachment.

Method enables high-resolution, low-stress subcellular mechanical mapping.

Abstract

Directly examining subcellular mechanics whilst avoiding excessive strain of a live cell requires the precise control of light stress on very small areas, which is fundamentally difficult. Here we use a glass nanopipet out of contact with the plasma membrane to both exert the stress on the cell and also accurately monitor cellular compression. This allows the mapping of cell stiffness at a lateral resolution finer than 100 nm. We calculate the stress a nanopipet exerts on a cell as the sum of the intrinsic pressure between the tip face and the plasma membrane plus its direct pressure on any glycocalyx, both evaluated from the gap size in terms of the ion current decrease. A survey of cell types confirms that an intracellular pressure of approximately 120 Pa begins to detach the plasma membrane from the cytoskeleton and reveals that the first 660 +/- 90 nm of compression of a neuron cell body is much softer than previous methods have been able to detect.