QTraps promise fast, accurate detection and analysis

QTraps bound to a control cell under a fluorescent microscope.

QTraps not only have a catchy name but they also present a novel way of isolating a compound, cell or virus by combining an antibody with a magnetic bead and a quantum dot, known as a Qdot.

The first target of a research project underway with investment from the Foundation for Research, Science and Technology, is developing a device that can detect and purify noroviruses.

Noroviruses cause an intestinal flu-like illness, are highly contagious and a major cause of outbreaks of infection in closed and crowded environments such as hospitals, nursing homes and cruise ships.

The recent outbreak at Dunedin hospital is an example of just how infectious they can be. They spread primarily through consuming food or water contaminated by faecal matter or through close contact with infected people.

IRL biochemist, Keryn Johnson says the device under development could, for example, be used to test whether shellfish have been exposed to faecal waste and therefore present a norovirus risk.

“Existing technologies have a key limitation in that they can’t always disable inhibitors within the shellfish that mask the virus. Ours will be more accurate and much faster.”

IRL’s solution is an all-in-one ‘target/capture/see’ solution designed to work with complex mixes where ‘you are effectively trying to find a needle in a haystack’ says Keryn Johnson.

"It combines an antibody to target the cell or virus, a magnetic bead to separate it and a Qdot to see it, using a unique self-assembly approach.

"Current systems only allow you to do two of those things at once. As well as making it a one-step process, our technology is switchable so you can put an antibody on and take it off and use pretty much any antibody you like.

"For example, our technology would allow you to capture cells from animal tissue, purify them, get rid of the magnetic bead and put them back in the animal.”

The IRL team began working on the concept two years ago, combining knowledge gained during an enzyme inhibiting project for Crop & Food Research with other technology used to immobilise antibodies in protein purification.

The team has achieved proof of concept with the recently announced funding from the Foundation enabling it to work with ESR on detecting noroviruses from environmental samples.

An existing system, called reverse transcription-PCR, can detect noroviruses but Keryn Johnson says it is not foolproof and take between six and eight hours to deliver a result.

“We are able to label an antibody with a Qdot in 30 minutes but want to produce Qdot-labelled antibodies even faster. We are developing a miniature analytical system that uses QTraps for fast and accurate diagnosis, and is portable and easy to use. We also aim to produce Qdot-labelled antibodies, ready for use in testing regimes.”

The QTrap research is part of a wider IRL programme in fast fluidic microanalysis, led by Mike Arnold, which has received funding of $9 million over six years from the Foundation for Research, Science and Technology.

Mike Arnold says as well as detecting harmful viruses and contaminants, the technology offers significant potential to quantify beneficial organisms in biological materials from industry.

“Once the technology is fully proven, it offers a method for New Zealand’s primary industries to quickly and accurately quantify the nutritional benefits of food, providing the scientific proof of efficacy that international markets demand.”