Rapid identification of blood poisoning
Does the patient have blood poisoning? In order to find out, the doctor takes a blood sample and sends it to a central laboratory for testing. Valuable time is lost, which could cost the patient his or her life. In future, doctors will be able to analyse blood in their surgery and results will be available within twenty minutes. This is made possible by a biochip developed by scientists at the Fraunhofer Institute for Physical Measurement Techniques IPM in Freiburg.
“To analyse the biochip we have also designed a fully automated device to carry out all the examination steps,” explains Dr. Albrecht Brandenburg, group manager at the IPM. “All the doctor has to do is place the sample in the apparatus and wait for the results.”
While the doctor waits, the device is busy: first, it prepares the blood sample. Red blood cells are separated from the blood and the plasma that remains in the test tube is guided onto the biochip. The immune system of patients suffering from sepsis reacts by producing certain proteins. The biochip uses these proteins in its diagnosis: antibodies are positioned on the chip, which fit into the proteins like a key in a lock. If sepsis-related proteins are present in the blood, the antibodies fish them out of the fluid and bind them to the chip. But how does the apparatus know if proteins have been captured? "The chip is rinsed with a solution containing the appropriate antibodies, which have been labelled with a fluorescent dye," explains IPM scientist Dr. Manuel Kemmler. "These bind to the proteins - i.e. antibodies, proteins and labelled antibodies are all securely linked to each other and to the surface of the chip. The dye lights up when the chip is illuminated." The apparatus sees many small illuminated spots that show that the protein was in the blood. If the patient is healthy, the chip remains dark.
The researchers can even test for different proteins at the same time in one cycle. This is done by placing various different capture molecules on the chip, to which specific molecules in the blood attach. A sophisticated selection of proven protein markers allows the scientists to obtain additional crucial information about the severity and cause of the illness.
Together with colleagues from a university hospital, the researchers have already successfully tested prototypes of the device and the biochip. Each biochip can only be used once - so they have to be affordable. "We predict that in the long run, with production on a large enough scale, it will cost no more than a euro to produce a single chip," says Brandenburg. There are various possible applications: other conditions such as heart attacks or cancers can also be investigated. The chip can also be used for doping- and urine testing as well as the quality assessment of foods.