Marlow’s extensive experience developing and integrating reliable thermoelectric (Peltier) devices into polymerase chain reaction (PCR) thermal cycling modules remains a valued advantage for Marlow’s medical industry customers. Medical professionals use PCR thermal cycling modules for DNA amplification.
What is PCR:
The polymerase chain reaction (PCR) technique is used primarily in molecular biology. A DNA polymerase amplifies a piece of DNA by in vitro enzymatic replication. As the PCR progresses, the DNA generated is itself used as a template for replication. This sets in motion a chain reaction during which the DNA template exponentially amplifies. With PCR, researchers can amplify a single or few copies of a piece of DNA across several orders of magnitude, generating millions or more copies of the DNA piece.
PCR Thermal Cycler:
The Thermal Cycler (also known as a Thermocycler, PCR Machine or DNA Amplifier) is a laboratory apparatus used to amplify segments of DNA via the polymerase chain reaction (PCR) process. The device has a thermal block with holes where tubes holding the PCR reaction mixtures can be inserted. The cycler then raises and lowers the temperature of the block in discrete, pre-programmed steps.
Almost all PCR applications employ a heat-stable DNA polymerase, such as Taq polymerase, an enzyme originally isolated from the bacterium Thermus aquaticus. The PCR is commonly carried out in a reaction volume of 10-200 μl in small reaction tubes (0.2-0.5 ml volumes) in a thermal cycler. The thermal cycler heats and cools the reaction tubes to achieve the temperatures required at each step of the reaction. Thermal cyclers make use of the Peltier effect which permits both heating and cooling of the block holding the PCR tubes simply by reversing the electric current. Thin-walled reaction tubes permit favorable thermal conductivity to allow for rapid thermal equilibration. The thermal cycling steps are necessary to physically separate the strands of the DNA double helix and then duplicate them through polymerase synthesis. The separation of the double helix strand takes place at the elevated temperature cycle and is referred to as DNA Melting. The single DNA strand is used as template during DNA synthesis. DNA synthesis takes place at the lower temperature cycle. Repetition of the thermal cycle from the low to high temperature results in the repetitive growth (amplification) of the DNA sample. The DNA polymerase selectively amplifies the target DNA. The selectivity of PCR results from the use of primers that are complementary to the DNA region targeted for amplification under specific thermal cycling conditions.
Applications:
Marlow’s thermoelectric devices operate as the heart of PCR thermal cycler modules. They are used in the diagnostic testing of sophisticated genetic organisms and genetic-based diseases. Marlow supplies thermoelectric equipment to companies who develop, manufacture and market fully-integrated systems and tests for genetic analysis in the pharmaceutical, clinical, food, agricultural, environmental, industrial and bio-threat markets.
PCR Performance:
Reproducibility, accuracy and speed define the primary requirements of any PCR application. PCR reaction modules driven by Marlow thermoelectric devices are unparalleled in their ability to fulfill these requirements. Unsurpassed temperature uniformity, heating/cooling rates, control range and reliability make the Marlow thermoelectric devices the perfect choice for your reaction module needs. Marlow has a selection of XLT series devices ready for your PCR application. To get the most from your reaction module, you may consider a customized design to optimize the performance for your specific application and control scheme. Marlow thermoelectric coolers maintain superb uniformity and performance with module uniformity of +/- 0.5°C and typical ramp rates of eight degrees C/sec. Our devices will operate to high thermal cycle counts with minimal performance degradation. The outstanding performance of the Marlow XLT series devices make them the number one choice for PCR applications that require the combination of; 1) fast thermal ramp rates, 2) controls supporting real-time detection and 3) the ability to perform multiple cycling protocols simultaneously for detection of multiple targets in a single run.
