16 June 2011

Christian Mittermayr: “Rapid detection of pathogens in water supply networks increases public security”

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An integrated, automated and highly sensitive measurement device based on a nanobiological sensors to simultaneously monitor the presence of several viruses or dangerous bacteria in water can guarantee the safety and quality of drinking water  

Dr. Christian Mittermayr from Lambda GmbH is the Coordinator of the EU research project DINAMICS, involving major European stakeholders from the relevant branches, end users and production system suppliers, ICT providers, SMEs and academic and research institutes.

Which are the achievements of your research efforts?
The prime deliverable is an exploitable lab-on-a-chip device for detection of pathogens in water using on-the-spot recognition and detection based on the nanotechnological assembly of DNA.

Can you better explain how the new measurement device based works?
The biosensors produced for the DINAMICS project contain the DNA of a specific bacteria. The DNA is integrated onto the plastic surface and then its parts are integrated into a microchip. This microchip can then detect the different bacteria. Each line, each band of DNA attaches exactly to a bacteria we want to find in the water. Then, the microchip is read with a scanner. With this biochip, we can prove the presence of bacteria in drinking water in order to insure safety against bioterrorism attacks. When the detector measures a signal higher than a threshold, the system automatically reports that a pathogen has been found.

Where could this system be set up?
The system must be set up in various locations, after treatment by water purification stations, in order to guarantee safety. On location, this system will filter a sample of water to get rid of impurities. Purified, the water will be reduced and will contain only biological organisms. At the next step, each pathogen DNA found in the sample will be isolated and copied to increase its concentration in order to be more easily identified. The polymerase chain reaction (PCR) is a biochemical copy-machine that doubles the amount of DNA in each reaction cycle. After 30-40 cycles the amount of DNA is increased about one billionfold. The PCR does not amplify the whole genome of a bacterium but only a small part of the gemome usually several hundred bases. At the end of the process, this highly concentrated water sample will be introduced with the microchip of the system to check correspondance of pathogen’s DNA.

How do the amplified DNA bind to the biosensor?
The amplified DNA bind to the biosensor in a microfluidic cartridge. The binding reaction is also called DNA-hybridization and is a very specific reaction. The biosensor is DNA deposited on a polymer surface. The DNA of the biosensor matches the DNA of the pathogen 100%. There are several sensor areas each with a different DNA sequence that matches a different pathogen. The location of biosensor tells us which pathogen is present in the probe.

What happens next?
After the pathogen DNA has been bound to the sensor it is marked by an enzyme that generates light. The light is detected by a photodiode (similar to a digital camera, but with less pixels). This light is projected onto different photodiodes. This shows us where and what type of bacteria has attached to it. Then, using the signal that we can read with our equipment, we get two results: first, we can detect the type of bacteria present in the solution, and secondly, by amplifying the signal, we can determine its concentration in the water. When the detector measures a signal higher than a threshold, the system automatically reports that a pathogen has been found.

Which kind of pathogens can be detected by the system?
We can introduce three types of organisms: viruses, bacteria or unicellular organisms. These unicellular organisms can also be found in nature, like pathogens. So they can be used for specific purposes. A lot of pathogens could be injected into drinking water by terrorists.

Is this system ready for use?
The methods of molecular analysis currently used require a water sample to be taken and brought to a laboratory. That takes hours. And what's more, once in the lab, we still need about a day to determine the results. Our goal is to bring our laboratory to the water so the time it takes to analyze the sample is significantly reduced, down to an hour at best.

Which will be benefits for end-users?
By enabling rapid detection of bioterrorism agents at very low concentrations, public security will be increased. As fast as an alarm is sent via SMS, email or other predefined channels, the authorities will take action according to a national or local action plan. Besides that, the know-how developed within the project can also be easily transferred to different sensing applications such as medical diagnostics, or pharmaceutical manufacturing.

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