The new chip is the next stage in the evolution of express diagnostics

Specialists from IBM (Zurich, Switzerland) and the University of Basel (Switzerland) Luc Gervais and Emmanuel Delamarche have developed a single-stage diagnostic test for performing tests directly at the patient's bedside. Compared to traditional laboratory tests, the new test, made on the basis of an innovative silicon chip, requires a smaller sample volume and less processing time. In addition, it is portable, easy to use and allows you to diagnose a large number of diseases, including diseases of the cardiovascular system, which are one of the leading causes of death worldwide. The speed of obtaining results and their accuracy is so high that the analysis of a small sample of the patient's blood or serum, carried out immediately after a heart attack, will allow doctors to immediately diagnose a heart attack and take measures necessary to save the patient's life.

According to the article "Towards one-step point-of-care immunodiagnostics using capillary-driven microfluidics and PDMS substrates" published in the December issue of the journal Lab on a Chip, the principle of operation allowing the new test to analyze small samples of serum or blood for the presence of protein markers of various diseases is based on the use of capillary forces. These forces ensure the tendency of the liquid to increase the level in thin capillaries, or, in other words, its "suction" into thin elongated cavities. A clear example of the action of capillary forces is the gradual wetting of a towel, one edge of which is lowered into a container with water.

The main part of the new device is a microfluidic chip measuring 1×5 centimeters, made of a silicon composition similar to the material used for the production of computer chips. It is permeated with microchannels, the speed of fluid passage through which can vary from 15 seconds to several minutes, depending on the difficulty of detecting markers.

The functioning of the chip, which has become the result of almost three years of research work, takes place in four stages:

• A sample with a volume of 1 microliter is placed on a chip using a pipette, where capillary forces begin to act on it.
• Capillary forces push the liquid through complex cellular structures, which prevents the formation of conglomerates and bubbles.
• The sample passes through a zone on which a microscopic amount (70 picoliters) of antibodies labeled with fluorescent dyes binding the markers contained in the sample is applied. Such a small amount of antibodies ensures their instant dissolution in the sample and extremely effective binding to the marker contained in it.
• The most important fourth stage takes place in the so-called "reaction compartment", 30 microns wide and 20 microns deep. At this stage, markers connected to labeled antibodies bind to the compartment surface. Exposure to a directional beam of red light allows you to register labeled markers using an extremely sensitive portable sensor. Based on the brightness of the registered glow, doctors can draw conclusions about the concentration of the analyzed marker in the sample and take therapeutic measures appropriate to the patient's condition.

Another important innovation is the capillary pump that ensures the operation of the device, having a depth of 180 microns and containing a complex complex of microstructures, the task of which is to pump liquid through the device for a given time with a uniform flow rate. This pump ensures the accuracy, portability and ease of use of the new diagnostic test. IBM specialists have developed a library of capillary pumps, which allows you to conduct tests that require different volumes of samples, or different testing times, without changing the design of the entire device.

Following IBM's Open Collaboration strategy, the developers tested their development together with academic and clinical partners.

According to Thierry Leclipteux, chief executive officer and head of the scientific department of the Belgian company Coris BioConcept, the new microfluidic chip is the next stage in the evolution of devices designed for diagnostics at the bedside. Together with IBM, Coris BioConcept plans to continue working on improving the test, which, in addition to medical purposes, can be used to detect chemical and biological toxic substances.

Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of R&D Mag: One-step chip may revolutionize disease diagnostics.

27.11.2009