Smartdetect

Fast detection of pathogens in food

Monday 01 Feb 16

Contact

Yi Sun
Groupleader, Associate Professor
DTU Health Tech
+4526 67 39 98

Contact

Anders Wolff
Associate Professor
DTU Bioengineering
+4545 25 63 05
Rapid in-field detection of pathogens in food is now possible thanks to a newly developed portable Lab-on-a-Chip-system called SMARTDETECT. The system provides all the functions of an analytical laboratory in a chip and can be employed directly on the production line to screen for harmful bacteria in food at considerably reduced time and cost.

Considering the pace of today’s food processing and global distribution network, a fast and accurate screening of food products is essential. Rapid in-field detection of pathogens expedites the timely release of products for retail distribution and mitigates foodborne diseases and economic loss.

In collaboration with academia and industry, researchers at DTU Nanotech have developed a new portable Lab-on-a-Chip platform suitable for simultaneous detection of several pathogens at the point of need  in food processing industries e.g. in slaughterhouses.  

Combining nanotechnology and molecular biology

 

Two newly developed technologies are essential, to performing a fast and reliable screening of pathogens.

The first is a new molecular method called “Direct solid-phase polymerase chain reaction”. Polymerase chain reactions (PCR reactions) serve to amplify a piece of DNA to facilitate detection. Unlike the conventional liquid-phase PCR, the new method makes it possible, to simultaneously perform dozens of different PCR reactions at several separate locations on a solid substrate with minimized interference. In this way, the new “Direct solid-phase polymerase chain reaction” allows DNA of several different bacteria or subspecies to be amplified at the same time.

Associate Professor, Yi Sun, explains: “We use a special inhibitor-resistant enzyme and because of this enzyme, the raw samples can be handled directly. We do not need the tedious sample preparation procedures”. This development has been performed in collaboration with DTU Food.

During the solid-phase PCR, fluorescence signals are generated from each of the different PCR reactions. To efficiently detect all these signals and thereby identify the presence of pathogens, the second technology, an optical detection method based on a concept called 'Super Critical Angle Fluorescence' (SAF), is brought into play. This technology is highly sensitive and it is multiplexed, enabling simultaneous detection of optical signals from multiple points.

 

Using an advanced microfabrication technique, researchers at DTU Nanotech have incorporated a cone-shaped SAF micro-optic array into a polymeric microchip. By collecting light at a super critical angle, that is the direction to which the majority of fluorescence light emits, the SAF structure works as a high-quality lens, dramatically increasing the sensitivity by nearly 50 times.

 

Genomic DNA 

If pathogens are present in the sample, their DNA will be captured by the specific DNA probes immobilized on the surface of the SAF array. During solid-phase PCR, millions of copies of pathogen DNA will be generated, and the PCR products will be labeled with fluorescent dye (the yellow “stars”) and detected through the SAF array. 

 

30 targets detected simultaneously

While the two technologies have demonstrated prestigious characteristics on their own, combining the two in an integrated system results in even higher impacts. Researchers at DTU Nanotech and DTU Food have succeeded in performing direct solid-phase PCR on the surface of the cone-shaped SAF array embedded in a microfluidic chamber. They showed that ultra-sensitive, rapid (0.5-1 hr instead of 2 days) and multiplexed (30 targets) pathogen detection could be achieved on a low-cost and portable microfluidic system. 

Associate Professor Anders Wolff says that “the chip-based portable laboratory completely eliminates the need for transport of samples to a central laboratory and we believe it will fundamentally change the paradigm for microbiological diagnostics and set new standards for the detection of harmful bacteria in food production”.

Innovation potential

The portable system also has great potential in other areas where the duration of the analysis is critical, such as intensive care units in hospitals and outbreaks of infectious diseases in both animals and humans. Based on the technologies developed in this project, a large research project SMARTDIAGNOS has been funded by EU Horizon 2020 for developing the next generation platform for sepsis diagnosis. 

Two departments from DTU (DTU Nanotech and DTU Food) and three other industrial partners (Dianova, Scandinavian MicroBio Systems, Danish Crown) are involved in the SMARTDETECT project which is funded by the Danish Innovation Fund and will run from 2013 to 2016.

Read more about the BioLabChip group.