Optically Active Dispersions of DNA: Evolution of the Particles

The kinetics of generation of the circular dichroism signals characteristic of the cholesteric liquid-crystalline dispersions of DNA are compared with the results of their detailed study using confocal microscopy. Three processes of the dispersed particle evolution have been experimentally confirmed (characteristic time intervals are given in the parentheses): (1) growth due to the attachment of DNA molecules (tens of seconds); (2) coalescence accompanied by the rearrangement of cholesteric layers (minutes); and, finally, (3) aggregation resulting in the formation of large clusters of irregular shape that has a threshold dependence on the concentration of the nucleic acid (hours). It has been suggested that the latter have no “integral” optical activity.