Thermal cycler

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A Modern PCR Machine

The thermal cycler (also known as a thermocycler, PCR machine or DNA amplifier) is a laboratory apparatus most commonly used to amplify segments of DNA via the polymerase chain reaction (PCR).[1] Thermal cyclers may also be used in laboratories to facilitate other temperature-sensitive reactions, including restriction enzyme digestion or rapid diagnostics.[2] The device has a thermal block with holes where tubes holding the reaction mixtures can be inserted. The cycler then raises and lowers the temperature of the block in discrete, pre-programmed steps.

History

Baby Blue, a prototype automated thermal cycler built around 1986
A very early PCR machine which, rather than cycling through different temperatures, uses three different water baths at constant temperatures between which samples are moved with a robotic arm

The earliest thermal cyclers were designed for use with the

Peltier element is commonly used. Quality thermal cyclers often contain silver blocks to achieve fast temperature changes and uniform temperature throughout the block. Other cyclers have multiple blocks with high heat capacity, each of which is kept at a constant temperature, and the reaction tubes are moved between them by means of an automated process. Miniaturized thermal cyclers have been created in which the reaction mixture moves via channel through hot and cold zones on a microfluidic chip. Thermal cyclers designed for quantitative PCR
have optical systems which enable fluorescence to be monitored during reaction cycling.

Modern innovation

A Multi Bay PCR Machine

Modern thermal cyclers are equipped with a heated lid that presses against the lids of the reaction tubes. This prevents condensation of water from the reaction mixtures on the insides of the lids. Traditionally, a layer of mineral oil was used for this purpose. Some thermal cyclers are equipped with a fully adjustable heated lid to allow for nonstandard or diverse types of PCR plasticware.[3]

Some thermal cyclers are equipped with multiple blocks allowing several different PCRs to be carried out simultaneously. Some models also have a gradient function to allow for different temperatures in different parts of the block. This is particularly useful when testing suitable annealing temperatures for PCR primers.

References

  1. PMID 3203600
    .
  2. doi:10.1016/S0956-5663(02)00252-X
    .
  3. ^ "The Most "Advanced" Thermal Cycler Yet - Get Informed". Get Informed. 2014-09-29. Retrieved 2017-05-31.

External links

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