Effect of Microwaves on DNA and Proteins

The Rolling Circle Amplification (RCA) is an enzymatic synthesis method of deoxyribonucleic acid (DNA) strands with repeated sequence of a circulate template-DNA. Microwave heating technology is applied to organic and inorganic chemistry to produce useful effects such as rapid heating, selective heating, decreased reaction times, and improved product yield. However, the mechanisms underlying the thermal or non-thermal effects, i.e., reaction-promoting effects, of MW chemistry are still unclear. We focus on the molecular perspective to investigate the effect of MWs via a DNA amplification reaction that utilizes enzymes. The microwave reaction temperature was strictly controlled using a microwave applicator optimized for enzymatic-scale reactions. We show that microwave heating facilitated the synthesis of repetitive DNA through RCA using the four DNA polymerases. Analysis of the temperature profiles of each RCA component subjected to microwave heating revealed the selectivity heating of buffer components compared with primers, template DNA, dNTP, and RNase-free water. Further, we showed the relation between the microwave power loss and RCA components via dielectric measurements, cavity resonator feature measurement, and electromagnetic simulation. The buffer containing ions of the RCA components was selectively heated via microwave irradiation in the TM010 cavity resonator.