Problem
Diagnostics in the field of genetic mutations (e.g. for the early detection of cancer) is intended to recognise genetic changes before the clinical symptoms of their presence become visible. Therefore, the decisive parameter of successful techniques for the detection of small genetic variants is their sensitivity. Here, for example, native nucleic acid electrophoresis, known as SSCP, is used. The most important physical conditions that influence ssDNA conformers and SSCP patterns are: pH, ionic strength, as well as temperature. However, temperature control during electrophoresis is a major problem due to the heat generated by the current flow. However, it is important because it has been proven to increase the mutation detection rate. A multi-temperature SSCP device has been developed, the DNA Pointer System, which performs genetic analyses by electrophoretic separation and under sequentially changing gel temperature.
An electrophoresis gel is pressed onto the heat exchanger. To ensure even heat distribution in the gel, electrophoretic glass plates must be precisely bonded to the heat exchanger. In the system's predecessor model, glass plates were manually inserted into the electrophoresis chamber and held in place by two clamping cam levers. To improve device handling and, above all, safe temperature control during electrophoresis, a suitable linear bearing solution was to be found instead of cam levers.
Solution
One of the main components of the latest version of the DNA Pointer System are
drylin SHT lead screw linear systems in combination with a
NEMA 23 stepper motor from the drylin E product portfolio, which is controlled by a microprocessor system.
The use of the drylin E system made it possible to press the electrophoretic glass plates with the polyacrylamide gel onto the heat exchanger automatically, precisely and evenly. It significantly improved the quality of the electrophoretic separation of analysed samples compared to the previous version of the DNA Pointer System. Improved temperature control directly influenced the results of the SSCP procedure and led to a more reproducible and sensitive detection of mutated genetic variants in the analysed genes. Following the evaluation tests, consideration is now being given to retrofitting the drylin system in some pre-series appliances.
