After 30 years, what’s next for PCR?
In the 80s, saying you were doing “PCR” was enough for everybody to know what kind of experiment you were performing. Today, the “PCR family” has gained so many new members that it can be confusing to decipher which type of PCR you’re using.
Developed in 1983 by Kary Mullis, polymerase chain reaction, or PCR for short, began as a way to copy specific DNA fragments using an amplification enzyme and specific primers. Very quickly this technique achieved world domination and its use became routine to in every lab to clone genes, diagnose diseases or identify genetic fingerprints.
In the fast-changing world of today, it’s hard to imagine how a simple technique not only managed to stay popular for over 30 years, but its use is still increasing. Not surprisingly then that PCR is referred to by many as the “gold standard” in the lab.
One of the ways PCR has managed to maintain its “throne” has been through many technological advances – such as speciality enzymes and digital PCR – developed over the years to solve specific problems associated with the technique or to improve its performance. And, undoubtedly, this is the best way to move forward.
The need for speed
Nowadays, the main improvement researchers are looking for is speed. PCR can be used in a multitude of diagnostic procedures, but currently patients need to wait days or even weeks for the results. Improvements have increased the speed of standard bench top thermal cyclers, but the current system is still far too slow to be of any practical use in a clinical setting. However, as technology moves forward with more automated systems developed to deliver in real time, it’s anticipated that waiting times will drop dramatically.
Continuous flow PCR
One of the most interesting and innovative ways to increase speed is through continuous flow PCR. These systems cleverly rely on different heating zones with the PCR mixture passing along microfluidic channels. This approach can significantly reduce the time needed for the reaction, as surface area is increased and the solution can reach thermal equilibrium in a matter of seconds.
One of the challenges still to overcome, however, is potential degradation of polymerase around the walls of the microfluidic channels. Research teams worldwide are working on new materials with increased hydrophobicity, as well as new heating and cooling systems, to avoid this problem and increase the system’s efficiency.
Fast PCR could save lives
These fast PCR systems in the hands of clinicians and health care workers could literally save lives, as part of a standard diagnostic test done in just a few minutes. In addition, PCR tests run in a simple low power handheld device would significantly reduce costs and simplify the procedure. It’s easy to see potential applications of such systems in areas with poor resources and medical facilities. Lack of electricity, clean water or transportation would not be limiting factors to use this all-in-one technique, with sample preparation, amplification and interpretation of the results done in the same device. This is the future of PCR.