Influence of different kind external fields on DNA yield at isolation on silica from model solutions. Effect of ultrasound

The effect of 2.65 MHz focused ultrasound on M. tuberculosis DNA yield with the use of commercial silica microcolumns and magnetic particles from the model solutions was studied over an ultrasound intensity range from 1.2 to 3.0 W/cm2. The study revealed that in both cases DNA yields are linearly proportional to the ultrasound intensity but upon reaching maximum values, the yields are inversely related to the intensity. In either case the DNA yield peaks 82 % at intensity of 2.0 W/cm2. Hence isolation of DNA outperforms by a factor of 2 as compared with the absence of ultrasound; it is 10 % greater than the DNA yield at optimal temperature 70 oC. Visual observation and photo-, video-recording offer a clear view of acoustic field structure as well acoustic streaming patterns with time, at ultrasound processing of magnetic particles as the intensity increases. Consideration is being briefly given to some physic effects on DNA microcolumn adsorption in the course of the liquid passage through porous media during ultrasound processing. Using the literature data and electrophoresis the possibility of DNA fragmentation/destruction is assessed under the test conditions. It was not until about 3.0 W/cm2 that plasmid destruction has been going with the time period in excess of 1 minute. It is concluded that choosing between the adsorption systems involved is basically determined by convenience in operation and availability rather than the system performance.