Conventional Thermal Cyclers: Hot Machines For Cool Researchers

Size, speed, and flexibility are also important qualities to consider when searching for the perfect thermal cycler. A number of manufacturers are making powerful thermal cyclers with comparatively small footprints. Is space at a premium in your lab? Perhaps space isn’t so crucial, but your experiments involve running only a small number of samples? Check out the compact thermal cyclers, also known as personal thermal cyclers, offered by Bio-Rad and Techne, among others.

Techne claims that their personal thermal cycler, the TC-312, is the smallest and lowest-cost unit on the market today, saving you space (with a footprint of only 561 cm2) as well as money. It is available with two interchangeable block formats, a 25-well block for 0.2 ml samples, and a 20-well block for 0.5 ml samples. The TC-312 features a heating rate of up to 3.6 degrees C per second, and a cooling rate of 2.0 degrees C per second. In addition to being able to control the TC-312 with a computer (as with many thermal cyclers), the TC-312 model can be networked together with other Techne thermal cyclers, allowing up to 32 cyclers to be connected to one central computer. Furthermore, programming is made easier with their ready-to-go templates, and free software updates downloadable from Techne’s website.

Eppendorf is one of several manufacturers in the race to market the fastest thermal cyclers. But they aim to satisfy other demands as well, such as ease of use. “The Eppendorf Mastercycler ep family of thermal cyclers was designed from the ground up to be the most versatile and complete gradient PCR system on the market,” says Renee Davis, product manager at Eppendorf. “The Mastercycler ep utilizes control software with the highest ease of use to drive its advanced and proprietary Eppendorf technologies, including Impulse device-driven hotstart PCR, ESP electronic sample protection lid technology, and SteadySlope Triple Circuit gradient peltier design for the most direct transfer from gradient experiment to standard protocols.” Another useful feature, according to Davis, is that the Mastercycler ep models do not require specific tubes, plates, or brands of reagents.

The Mastercycler ep is available in three models—the ep gradient and ep 384 aluminum block models, and the ep S silver block “for those who seek ultra high speed—40 cycles in less than 25 minutes for some experiments,” comments Davis. The Mastercycler models also feature thermal gradient technology, with a gradient range of up to 20 degrees C for the gradient and 384 models, and up to 24 degrees C for the gradient S model. The gradient and 384 models have heating and cooling rates of about 4 and 3 degrees C per second, respectively, while the gradient S model has the fastest heating rate, at up to 6 degrees C per second, and cools at about 4.5 degrees C per second.

Eppendorf offers a personal card system that is especially useful for big labs or core facilities that use more than one Mastercycler machine. These chip-based memory cards extend the Mastercycler's 100-program internal memory, and allow you to transfer individual PCR protocols quickly and reliably from one Mastercycler machine to another.

Also a contender in the ultra fast PCR race is Analytik Jena, with their SpeedCycler. Analytik Jena’s Alexander Berka claims that the SpeedCycler attains a “speed that is up to ten times higher than that obtained with conventional thermal cyclers. A typical protocol allows PCR of 30 or 40 cycles to be run in less than 11 minutes.”

Several features underlie this fast performance, including high-speed temperature control with a fast heating rate of 10 degrees C per second, and a cooling rate of 6 degrees C per second. Contributing to the SpeedCycler’s higher speed is the more efficient heat transfer between the metal block and the sample, with Analytik Jena’s patented ultrathin-walled microtiter plate. The sample wells have walls that are ten times thinner than conventional wells, creating less resistance to heat transfer.

Berka claims that the SpeedCycler can give you higher-quality results. “Due to the enormously fast change of temperature (ramp rates) at maximum control accuracy, primer mismatching during the annealing process is efficiently prevented,” says Berka. “This results in amplification products of higher specificity.” The SpeedCycler is available with both 36-well and 96-well sample blocks, and can be motorized for automation using 96-well microtiter plates.

Neck-and-neck with the Mastercycler and the SpeedCycler in the race for the title of fastest is Applied Biosystems’ 9800 Fast Thermal Cycler, an important component of their 9800 Fast PCR System. This 96-well system can amplify genomic fragments under 500 bp in about 25 minutes (and in some cases—they claim—within about 10 minutes), with larger fragments up to 2 Kb amplifying in as little as 40 minutes. The system has a heating rate of about 5 degrees C per second and a cooling rate of 4.1 degrees C per second. Applied Biosystems’ GeneAmp Fa

The MBS cycler offers thermal gradient technology for its 0.2 and 0.5 ml format satellite blocks, with standard heating technology offered for its 384-well format blocks. It also features a heating rate of up to 3 degrees C per second, and a cooling rate of up to 2 degrees C per second.

Although the thermal cyclers discussed here by no means constitute a complete inventory of the machines on the market, they can give you an idea of the features that are available to you. Once you determine what kind of thermal cycler your lab needs, you are sure to find something out there that fits the bill.