Al Fin: Probing the Cell With Many Fingers

Eric Drexler talks about nanobots that roam the human body, looking for problems in cells--then jumping into the cell to repair any damage or dysfunction. Developing these "cell repair machines" will take some time. In the meantime, we need to learn different ways to probe the inner and outer workings of cells.

For example, we may want to develop a tiny nano-voltmeter to monitor the internal electric field of cells:

"The basic idea behind this field of research is to follow cellular processes---both normal and abnormal---by monitoring physical properties inside the cell. There's a long history of research on the chemistry happening inside the cell, but now we're getting interested in measuring the physical properties, because physical and chemical processes are related," said Kopelman, who is the Richard Smalley Distinguished University Professor of Chemistry, Physics and Applied Physics.

With a diameter of about 30 nanometers, the spherical device is 1,000-fold smaller than existing voltmeters, Kopelman said. It is a photonic instrument, meaning that it uses light to do its work, rather than the electrons that electronic devices employ.

Kopelman's former postdoctoral fellow Katherine Tyner, now at the U.S. Food and Drug Administration, used the nano-voltmeter to measure electric fields deep inside a cell---a feat that until now was impossible. Scientists have measured electric fields in the membranes that surround cells, but not in the interior, Kopelman said.

With the new approach, the researchers don't simply insert a single voltmeter; they're able to deploy thousands of voltmeters at once, spread throughout the cell. Each unit is a single nano-particle that contains voltage-sensitive dyes. When stimulated with blue light, the dyes emit red and green light, and the ratio of red to green corresponds to the strength of the electric field in the area of interest.

Eurekalert

Clever, no? Or perhaps researchers could use X-rays to take snapshots of the cell in action:

A research team led by Jue Chen, an associate professor of biological sciences, obtained a snapshot of the tiny protein gate complex that opens and closes pathways through the protective cellular membrane. The gates, operated by small protein machines that push them open and closed, bring nutrients into the cell and flush out waste.

The Purdue-led team was the first to achieve an image of the middle step of the process, capturing the molecular interactions as material passes through the membrane.

...The research team used X-ray crystallography to obtain a picture of a special protein, called an ABC transporter protein, as it moved material through the cellular membrane. The work was published in last week's issue of Nature.

Purdue

But there are many more approaches (many fingers) used to probe cells:

Etc.

Labels: cell biology, LEDs, Nanotechnology