by Santina Russo
working on the microscope.
His method measures cellular signaling molecules
in a completely new way.
Credit: ETH Zurich / Tilman Schlotter
They secrete signaling molecules - ions, proteins and nucleic acids - that are picked up by adjacent cells, which in turn pass on the signal to other cells.
Our muscles, digestive system and brain are only able to function thanks to this type of communication.
And this is the only way in which our immune system can recognize pathogens or infected cells and react accordingly - again, by sending out signals to mobilize the immune defenses.
If something goes wrong with this signaling between cells, it can lead to diseases such as cancer or autoimmune disorders.
The methods were not sensitive enough to use on individual cells, meaning that the signaling molecules from individual cells were submerged into the average of the total cell population:
The new method, which was recently published (Localized Detection of Ions and Biomolecules with a Force-controlled Scanning Nanopore Microscope) in the scientific journal Nature Nanotechnology, is different.
Morteza Aramesh and his colleagues used what is known as a fluid force microscope, equipped with a special cantilever tip.
What is new is that a
tiny sensor is placed on the tip of the cantilever. It consists of a
silicon nitride pore just a few nanometres in size, which registers
when a cell releases molecules.
The new nanopore sensor has such a small diameter that it can be positioned precisely over one of these transport proteins and thus intercept the molecules flowing through it.
The nanopore sensor is able to measure the ionic current, which changes when ions or larger biomolecules, such as proteins or nucleic acids, flow through the pore.
Different signaling molecules can then be identified depending on the nature and duration of the change in ionic current.
So far, they have been able to distinguish between individual signaling molecules, such as ions and certain proteins.
The biophysicists now plan to develop their nanosensor further in order to identify other signaling molecules in the future.
Nonetheless, the method
can already be used to localize transport proteins in a living cell.
Inside the cell, it is then possible to analyze what is eliminated from the cell nucleus.
They provide insight into which proteins a cell is currently producing - a key factor in the onset of many diseases.
It can not only differentiate between diseased and healthy cells, but can also be used in the development of stem cells or to determine whether cells in the lab behave in the same way as in the body.
The new method is likely to help answer many other questions in the future.