A quicker, cheaper SARS virus detector -- one easily customizable for other targets

May 29, 2009
Antibody mimic protein is tailored to attach to nanowire base at one end, leaving biologically active area open for detection. Image: University of Southern California

Members of a USC-led research team say they've made a big improvement in a new breed of electronic detectors for viruses and other biological materials — one that may be a valuable addition to the battle against epidemics.

It consists of a piece of synthetic antibody attached to a nanowire that's attached to an electrical base, immersed in liquid.

If the the antibody binds to is present in the liquid, it will bind to these antibodies, immediately creating a sharply measurable jump in current through the nanowire.

The basic principle of nanotube and nanowire biosensors for protein detection was first demonstrated in 2001, but the new design by a team headed by Zhongwu Chou and Mark Thompson of the University of Southern California uses two new elements.

First, it takes advantage of bioengineered synthetic antibodies, much, much smaller versions of the natural substances that are designed to bind with a specific protein and only that protein.

Second, it uses indium oxide (In2O3) instead of silicon and other materials previously tried. Metal oxides, according to a new study published in ACSNano, do not, unlike silicon, develop "an insulating native oxide layer that can reduce sensitivity."

The result, according to the paper, is a device that can detect its target molecules with a sensitivity as great as the best alternative modes, do so more rapidly and without use of chemical reagents.

It is also potentially considerably cheaper than alternatives.

"We believe," the authors write, "that nanowire bisensor devices functionalized with engineered proteins … can have important applications ranging from disease diagnosis to homeland security."

Additionally, the system can be useful in basis research, in helping to establish certain important parameters for two-part biological systems like the antibody/target protein pair.

The protein the detects is the SARS (severe acute respiratory syndrome) virus n-protein, which infected more than 8,000 people in 2002-2003, killing nearly 10 percent of them.

Commercial systems using enzyme-linked immunosorbent assay (ELISA) now exist to test for SARS, but the new system has advantages in time, cost and portability.

The first step was the creation, by Richard Roberts and Mark Thompson, chemists, and their team of the synthetic antibody, including both the active area, design to interact with the protein and, at the other end, a chemical "hook" that would bind it to nanowire at this point and only this point. "This … strategy allows every bound [detector molecule] to retain full activity, a clear advantage over antibodies, which [in earlier biosensor designs] are often bound to nanowire surface via amine containing residues randomly distributed over the antibody surface."

The Zhou lab, which has specialized in nanowire and nanotube technology for years, performed the complex set of procedures to synthesize the wires, attaching

In tests, the group performed if anything better than predictions, showing a standard and low level of activity when no SARS protein was present, leaping quickly to a higher level when the protein was introduced, in response patterns that varied consistently according to concentration of the protein. Devices complete except for the detector molecule showed no response at all.

The response was complete in less than ten minutes, compared to hours needed for results from ELISA tests - which are basically present/not present tests with relatively little quantitative elements.

Next steps are to enable detection in more complex environment, such as Serum and whole blood, by integrating the nanobiosensor with micro systems such as microfluidics chips and micro filters.

Source: University of Southern California (news : web)

Explore further: Team finds electricity can be generated by dragging saltwater over graphene

add to favorites email to friend print save as pdf

Related Stories

Nano World: Nanowires help spot cancer

Sep 30, 2005

Arrays of silicon nanowires with biomolecular coatings can spot molecular traces of cancer far more accurately, quickly and specifically than technology currently available to doctors, experts told UPI's Nano World.

New test speeds up SARS detection

Aug 01, 2007

In the fight against epidemics, those battling on the front lines may be on the verge of a new weapon, thanks to a team of University of Alberta researchers.

Detecting Cancer with Silica Nanoparticles

Sep 18, 2006

Tumor necrosis factor-alpha is a widely accepted biomarker for cancer, but the minute amounts of this protein circulating in blood makes detecting the molecule and measuring its concentration accurately a technological challenge.

Researchers combine nanotubes and antibodies to detect cancer

Nov 17, 2005

By coating the surfaces of tiny carbon nanotubes with monoclonal antibodies, biochemists and engineers at Jefferson Medical College and the University of Delaware have teamed up to detect cancer cells in a tiny drop of water. ...

Chemical probes beat antibodies at own game

Apr 26, 2007

A new way of detecting biological structures could help in the fight against disease. The new method, developed by scientists at Oxford University, uses chemistry to assemble proteins into ‘protein probes’ ...

Scientists find nanowires capable of detecting individual viruses

Sep 22, 2004

Findings could point the way to ultra-powerful new diagnostic tools and bioterror detectors Harvard University scientists have found that ultra-thin silicon wires can be used to electrically detect the presence of single viruses, in real time, with near-p ...

Recommended for you

First direct observations of excitons in motion achieved

Apr 16, 2014

A quasiparticle called an exciton—responsible for the transfer of energy within devices such as solar cells, LEDs, and semiconductor circuits—has been understood theoretically for decades. But exciton ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

John_balls
not rated yet May 29, 2009
Sweeet!

More news stories

Thinnest feasible nano-membrane produced

A new nano-membrane made out of the 'super material' graphene is extremely light and breathable. Not only can this open the door to a new generation of functional waterproof clothing, but also to ultra-rapid filtration. The ...

Wiring up carbon-based electronics

Carbon-based nanostructures such as nanotubes, graphene sheets, and nanoribbons are unique building blocks showing versatile nanomechanical and nanoelectronic properties. These materials which are ordered ...

Hackathon team's GoogolPlex gives Siri extra powers

(Phys.org) —Four freshmen at the University of Pennsylvania have taken Apple's personal assistant Siri to behave as a graduate-level executive assistant which, when asked, is capable of adjusting the temperature ...

Better thermal-imaging lens from waste sulfur

Sulfur left over from refining fossil fuels can be transformed into cheap, lightweight, plastic lenses for infrared devices, including night-vision goggles, a University of Arizona-led international team ...