Articles: 'Nanotech spy eyes life inside the cell' and 'Test-tube sperm get new genes'


Robert Karl Sto

Nanotech spy eyes life inside the cell
19:00 28 January 04

In Prey, Michael Crichton's tale of nanotech gone awry, a swarm of light-sensitive nanoparticles
swim through a human body, creating the ultimate medical imaging system.

In the real world, biochemists are hoping to go one step further, deploying viruses as "nano-
cameras" to get a unique picture of what goes on inside living cells and a greater understanding of
how viruses themselves work.

A team led by Bogdan Dragnea at Indiana University in Bloomington is exploiting the ability of
viruses laden with gold to break into cells, along with the viral shell's own telltale response
to laser light. Together these give an unprecedented picture of the chemical and physical
activity in cells.

Researchers currently study living cells using a technique called Raman spectroscopy. When laser
light bounces off some materials, most of the scattered light has the same wavelength as the
incident light. But a fraction called the Raman spectrum has an altered wavelength due to the
characteristic vibration of some molecules in the material.

This allows researchers to map the coarser features of a cell, such as its nucleus. But Raman
spectra are very weak. Introducing gold nanoparticles into cells enhances the Raman signal more than
fivefold, because electrons on the surface of the nanoparticle interact with and reinforce the
scattered light.

Unfortunately, the cell treats gold nanoparticles as foreign bodies and quickly clears them out. But
viruses are already able to avoid ejection. So Dragnea and his team decided to use them as Trojan
horses to smuggle the particles into living cells.

Read the rest at New Scientist:

Test-tube sperm get new genes
20:00 26 January 04

Growing sperm in a test tube may offer a powerful new way to genetically modify animals and
potentially correct human genetic diseases before conception.

The technology offers two advantages. Firstly, it creates GM animals in one generation rather than
two, unlike most conventional techniques.

Secondly, because the genes are spliced into laboratory-born sperm, it may allow scientists to do
sophisticated genetic manipulations in a wide range of animals. So far these have only been
possible in mice.

"The big deal here is that this opens up vast possibilities to tailor this technique for different
applications," says Shawn Burgess of the US National Institutes of Health in Bethesda, Maryland. But
experts say the technology will need to be improved further before it shows real promise.

Posted by Robert Karl Stonjek.