I’ve just read a fascinating article in December 16th edition of Chemical & Engineering News* by Louisa Dalton which describes a new technique to sample cell material without killing the cell.
This new method, developed by biomolecular engineer, Nader Pourmand, and colleagues at the University of California, Santa Cruz, is able to withdraw approximately 50 femtolitres from the cell using a computer guided scanning ion conductance microscope. The computer guides a glass nanotube to the cell membrane where it is pushed 1 micrometre into the cell. A negative voltage across the tip of the pipette alters the surface tension between the cytoplasm and a solution in the pipette causing approximately 50 femtolitres of cytoplasm to be withdrawn from the cell.
This method allows cytoplasm to be withdrawn from different parts of a cell, with the cell remaining viable even after 10 punctures. The utility of this technique has been demonstrated by using it to extract and subsequently sequence, cytoplasmic messenger RNA from human cancer cells and mitochondrial DNA from fibroblasts.
This new technique opens the way to dynamic monitoring of cells. According the to the C&EN article “It permits many different types of measurements, such as single cell diagnostic tests or drug testing.”
* unfortunately this article currently appears to be behind a paywall.