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The thermal cycler: a perfect discovery

The thermal cycler or thermal sequencer is a device that allows the polymerase chain reaction (PCR) efficiently and quickly, through the automatic and cyclic realization of the temperature changes required for the amplification of a chain of deoxyribonucleic acid (DNA), from a thermostable enzyme. PCR allows a small number of DNA molecules to be amplified many times, exponentially.

ADN The development of the idea to put it into practice was the work of a peculiar Californian surfer and biochemist named Kary Mullis in 1983. This methodology is commonly used in medical and biological research laboratories, with a wide variety of applications, among them, the detection of the expression of genes and hereditary diseases, the identification of genetic fingerprints, the cloning of genes, the paternity tests, the DNA informatics and the diagnosis of infectious diseases, so it is considered that the creation of the thermal cycler was the perfect discovery for molecular biology.

The thermal cyclers are used for qualitative amplifications or to quantify the amount of amplified DNA. The results of these amplification techniques have a substantial impact on our society, so we must ensure that the thermal cyclers are accurate, accurate and uniform, in order to obtain reliable results.

What do these teams consist of?

The most common model consists of an electrical resistance block that distributes a homogeneous temperature through a plate during times that can be programmed, normally with temperature ranges from 4 ° C to 96 ° C. Since the reactions incubated in the apparatus are in aqueous solutions, they usually include a cover plate constantly heated to 103 ° C to avoid condensation of water in the lids of the tubes where the reaction occurs, and thus prevent the solutes from concentrating , which would modify the optimum conditions for the polymerizing enzyme and the thermodynamics of the primers. There are also other less popular technologies using hot air distribution in suspended tubes, achieving the same objective of efficiently transferring heat to the reaction so that the temperature cycles change. Then, in the thermal cycler, fast and continuous cycles are programmed to initiate the processes of separation and denaturation of the mold DNA chains at low temperatures, then at low temperatures the annealing of the primers so that the Taq polymerase acts after incorporating the dNTPs according to the to the template DNA during the PCR process.

Some types of thermal cyclers

Three-block touch screen PCR thermal cyclerSince its inception, this technology has been developed to adapt to different needs, for example there are thermal cyclers in which the cycles do not produce evaporation of the mixture (using drops of mineral oil), others that allow several programs to be carried out at the same time and others that allow working at different temperatures, and many others. But as far as the standard model is concerned, we will find as features a keyboard and screens which indicate the temperature, cycles and time.

For several years now several companies that manufacture and market these devices have changed the electrical resistance by Peltier technology taking advantage of the properties of semiconductors. This material offers better uniformity in the temperature and ramps of increase and decrease of the temperature much more pronounced, obtaining better results in the PCR processes. In the search to improve the precision, accuracy and homogeneity of the temperature, metals such as gold, silver and other alloys have also been introduced into the blocks of the wells, achieving stability and reproducibility in the tests. The current thermal cyclers are capable of rapid temperature changes, and thus perform the steps of DNA denaturation, alignment or binding of the primer with the complementary DNA sequence and extension of the DNA chain cyclically. In other words, the technology of the thermal cyclers has become very versatile in terms of the different needs of the experiments that arise over time.

Motivated by all this in Kalstein we put at your disposal an excellent range of thermal cyclers ranging from economic options to equipment of the most advanced technology, recognized for their reliability, precision and ease of use. That is why we invite you to take a look at our thermal cyclers available HERE

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This article was published on Tuesday 12 February, 2019.

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