DNA Sequencing Requires Precise Temperature Control for Better Yield and Purity

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The Challenge
Think about how time consuming it would be to communicate the written word without the printing press, copy machine, newspaper and book publishing equipment. Before these inventions, each copy had to be individually hand written. Now apply that same thought process to the benefit of PCR to DNA sequence amplification. Using recombinant technology this traditionally took days or sometimes weeks. PCR now allows for amplification (hundreds of millions copies) over hours. To that end, the DNA sequencing process involves multiple PCR cycles which involves specific temperature shifts for specific dwell times. The PCR process depends on many factors including precise temperature and control. Our customer, whom offers DNA sequencing technology to many fields, needed a better heating profile of the three primary heating shifts; Denature, Anneal, and Extend for better yield and purity. Most damaging was the incomplete reactions from thermal runaway in one or more shifts during the many cycles on their current equipment.

The Solution
The Chromalox team had to first work with customer to thoroughly understand the equipment, process, software, and end products. With that knowledge, a Kapton® heater design was offered to individually accommodate the specific needs of each of the three thermal heating process shifts. First, a Kapton® heater design that addressed the ‘Denature’ shift for high temperature using a controlled heat profile @ ±3°F. Second, this Kapton® heater design was more complicated since it involved the ‘Anneal’ shift that had to be adjustable to the specific needs of different melting temperature of a given primer-template hybrid. And third, a Kapton® design to satisfy the ‘Extend’ heat shift for DNA synthesis by DNA polymerase.  In addition to the customer’s original expectations-request, all Kapton® heater designs included thermal sensors, amplifier interface, microprocessors, and software interface to the existing automated equipment.

The Benefits
The customer has now greatly enhanced the purity and yield of their end product. First, we eliminated the thermal deviations which previously resulted in incorrect examinations. Second, the sensors worked flawlessly which resulted in better signals and amplification; thereby enhanced control. And finally, the way the Kapton® heaters were positioned allowed for better multi ‘Sensor-Controller-Microprocessor’ interface. This is another example of how Chromalox collaborates with customers towards solving problems with new innovative world class cost saving solutions to exceed expectations.