Nanowire Could be Next Big Diagnositc Tool

[Guest guest]

(This looks promising. Actually, the technology that would permit

the detection of genes this way would be a big improvement. It would

permit detection without the necessity of PCR amplification

procedures.)

Tiny Nanowire Could Be Next Big Diagnostic Tool For Doctors

12/16/2003

Source: American Chemical Society

A tiny nanowire sensor — smaller than the width of a human hair,

1,000 times more sensitive than conventional DNA tests, and capable

of producing results in minutes rather than days or weeks — could

pave the way for faster, more accurate medical diagnostic tests for

countless conditions and may ultimately save lives by allowing

earlier disease detection and intervention, Harvard scientists say.

In preliminary laboratory studies demonstrating the capability of the

new sensor, the researchers showed that it has the potential to

detect the gene for cystic fibrosis more efficiently than

conventional tests for the disease. CF is the most common fatal

genetic disease among people of European origin.

One of a growing number of promising diagnostic tools that are based

on nanotechnology, the silicon sensor represents the first example of

direct electrical detection of DNA using nanotechnology, according to

the researchers. The sensor and the detection of the CF gene will be

described in the Jan. 14 issue of the journal Nano Letters, a peer-

reviewed publication of the American Chemical Society, the world's

largest scientific society.

" This tiny sensor could represent a new future for medical

diagnostics, " says study leader M. Lieber, Ph.D., a professor

of chemistry at Harvard and one of the leading researchers in

nanotechnology.

" What one could imagine, " says Lieber, " is to go into your doctor's

office, give a drop of blood from a pin prick on your finger, and

within minutes, find out whether you have a particular virus, a

genetic disease, or your risk for different diseases or drug

interactions. "

With its high sensitivity, the sensor could detect diseases never

before possible with conventional tests, he says. And if all goes

well in future studies, Lieber predicts that an array of sensors can

ultimately be configured to a handheld PDA-type device or small

computer, allowing almost instant test results during a doctor's

visit or possibly even at home by a patient. It could potentially be

used to screen for disease markers in any bodily fluid, including

tears, urine and saliva, he says.

The sensor also shows promise for early detection of bioterrorism

threats such as viruses, the researcher says.

An experimental version of the technology consists of a thin plate

about the size of a small business card containing the tiny nanowire

sensor. A working prototype device suitable for testing of human

blood or other body fluids could be five years away, Lieber

estimates.

To demonstrate the effectiveness of the sensor device, the

researchers grafted nucleic acids, the building blocks of DNA, to a

silicon nanowire. The nucleic acids were specifically designed to

recognize a particular mutation site in the cystic fibrosis gene that

is responsible for most fatal cases of the genetic disease. The

researchers then exposed the nanowire to fragments of the cystic

fibrosis gene, some with the lethal mutation and some without it.

The researchers found that they could successfully distinguish

between the two types of gene fragments, even down to extremely low

levels that would have been missed by conventional DNA sensors,

according to Lieber.

Unlike conventional DNA detection methods that require a complex

procedure called PCR amplification to view the results, the nanowire

sensor does not need such sophisticated and expensive techniques,

which could ultimately speed up genetic testing while reducing costs.

Lieber recently helped start a company, NanoSys, Inc., that is now

developing nanowire technology and other nanotechnology products. His

associate in this study is Jong-in Hahm, Ph.D., a former postdoctoral

fellow in his research group who is currently an assistant professor

at Penn State University.