Physicists from Novosibirsk are on the way to designing a biological sensor for easy and cheap diagnostics of various pathologies, as well as detection of tiniest amounts of hazardous substances in gas and liquid media.

Just imagine – only one drop of blood, and a special biological sensor tells you whether your organism needs repair or not. The analysis will be extremely accurate and cost much less, than common blood analysis in a medical laboratory. Similar biological sensors can also be used for detecting single molecules of hazardous substances, like poisoning gases or explosives, in various environments.

These biosensors will be based upon silicon nanowire transistors, which are currently being developed and improved in the Institute of Semiconductor Physics (Siberian branch of Russian academy of sciences). Semiconductor nanowires change their electronic properties, when contacting with biological molecules, thus they can be used as very sensitive biological sensors. Silicon nanowires are easier to synthesize, than their carbon relatives, and their properties can be easily changed, if required.

Russian physicists from Siberia worked with silicon nanowire transistors since 2000, and in 2004 the think-tank expanded, when researchers from Moscow decided to participate in the project. First silicon nanowire sensor in the laboratory was built in 2007.

Electronic biochip is a combination of chips with a small hole for a biological fluid – a solution with particles to be analyzed – to enter the chip. Sensor’s nanowires are covered with antibodies, for instance, to a flu virus, or to some tumor marker proteins, or to heart attack markers, etc. These antibodies only interact with specific antigens, and this interaction is very strong, so it changes electronic properties of a particle. Connection of two large biological molecules – an antigen and an antibody – changes surface potentials, respectively, and this change can be detected by a sensitive field transistor.

Same principle works in optical biosensors, which are designed to detect viruses of hepatitis B and C. Complex compounds, formed by an antigen and an antibody, increase refraction coefficient inside the sensor, thus deflecting a laser beam for some certain angle and signaling that marker proteins of hepatitis are present in patient’s blood. However, optical biosensors require higher concentration of markers in blood, than electronic biochips, for normal operation.

Abovementioned sensors have many applications, for example, they can be used for recording an encephalogram, since cerebral cortex also has a difference of potentials, which can be detected by means of biological sensors. Moreover, field transistors are similar to cell membranes, where difference in electric potentials affects membrane permeability.  

In near future no one will be surprised by coexistence of organic and electronic systems in one organism. Science fiction harbours many ideas, which later become reality with help and scientists and engineers.

Source: Sibkray.ru

Anna Kizilova