Seeing single cells clearly

Compiled by BioPhotonics staff

A new investigative tool that allows scientists to observe DNA, proteins and viruses could make significant research inroads to improve drug discovery, further studies of host cell-pathogen interactions and refine analysis of stem-cell differentiation.

The technique, called electrochemical impedance microscopy (EIM), can peer into single cells and view intracellular processes with clarity, helping scientists to explore subtle features in basic and applied research. These include cell adhesion, apoptosis and electroporation, a process that introduces DNA or drugs into cells. The method builds upon the advantages of an existing technology, electrochemical impedance spectroscopy (EIS), which applies an AC voltage to an electrode, measuring the current response as a change in impedance.

EIS allows subtle phenomena that occur at the electrode’s surface to be imaged, including molecular binding events, and when modified, can be used to study cell spreading, adhesion, invasion, toxicology, mobility and other cellular processes. The noninvasive technique also does not require fluorescent labeling particles or dyes, which often interfere with normal cellular functioning.

Although EIS has proved attractive, it does not provide good spatial resolution, according to scientists at Arizona State University. EIM, on the other hand, allows for submicron spatial resolution of biological phenomena. Using specialized video cameras to record rapid cellular events, the scientists studied apoptosis, enabling better understanding of its cellular mechanisms, which is critical for cancer research and the design of cancer therapies. The technique also has made it possible to observe electroporation, which can be used to insert a molecular probe to monitor a cell’s interior or to introduce a cell-altering drug or segment of coding DNA.

Further work will be conducted to refine the label-free, noninvasive microscopy technique. The research findings appeared in the journal Nature Chemistry, Jan. 23, 2011 (doi: 10.1038/nchem.961).