Norwegian researchers have developed the world's first sensor capable of measuring individual particles in a blood sample. This new innovation could cause a sensation in the medical world.
Our blood contains several hundred different proteins that can give us a picture of our general health - and provide information about the condition of our heart or the presence of cancer. Currently, when we give our doctor a blood sample for a 'full check', it can only be analysed for five or six indicators, such as blood percentages, blood sugar and infections. For other test results, the sample must be sent to a central laboratory for analysis. It can often take as long as a week before the results come back.
Four years ago, SINTEF began a joint project with Stanford University in the USA and the University of Oslo (UiO). The aim was to build a sensor that could improve sensitivity a million fold, making it possible to measure individual particles in the blood, including proteins at extremely low concentrations, as well as DNA and RNA (ribonucleic acid) molecules.
Their work has been able to proceed thanks to internal funding from SINTEF's own Medical ACTION project, government SIP funding (the Strategic Institute Programme), and assistance from the Norwegian University of Science and Technology (NTNU), the University of Bergen (UiB), the University of Zurich and the German research organisation Fraunhofer. The researchers have also been able to use the Norwegian NorFab laboratories.
The result is a new nano-particle sensor developed in MiNaLab in Oslo.
The sensor comprises a thin silicon membrane - about three hundred times thinner than a single hair. It is perforated with hundreds of small holes arranged in a regular pattern.
'We call these structures photonic crystals. The same structures occur naturally in the wings of some butterflies,' says Ib-Rune Johansen at SINTEF ICT. Like his colleagues Jon Olav Grepstad and Michal Mielnik, he believes that they are not exaggerating when they claim that this is "the ultimate bio-sensor - at the cutting edge of nanotechnology".
One of the properties of the crystal is that it amplifies parts of the light spectrum.
'When we are looking for particles in blood samples, we illuminate the photonic crystal from behind. That way, we can amplify the intensity of light within the membrane by many hundred fold. The crystal is impervious to light: all light is reflected and nothing gets through. Viewed from behind, therefore, the crystal looks like the dark night sky. However, each particle that is captured becomes trapped in a hole in the membrane and allows some light to leak through - giving it the appearance of a star in the sky,' says Johansen.
'Our breakthrough came with this opportunity to see these microscopic particles,' he tells us.
Early cancer diagnosis
Currently, medical laboratories measure proteins to detect imbalances in the body that occur when an infection is present. The new sensor can take these analyses much further.
SINTEF's chemists are trying to attach receptors to the wall of each of the perforations in the membrane (biofunctionalisation). When blood is pumped through, the receptors trap very specific molecules, depending on what the scientists are looking for. Because the sensor/membrane has many perforations, they can specify a wide range of different proteins. It will thereby be possible to detect illnesses such as prostate and ovarian cancer in their very early stages.
Two challenges overcome