Micro bubble dynamics in DNA solutions

Micro bubble generation and its subsequent dynamic behavior in single-stranded DNA (ssDNA) solutions are presented in this paper. A micro vapor bubble was generated in ssDNA using a micro bubble actuator, which is capable of producing periodic and stable single vapor bubbles under pulse heating. The growth and collapse of the micro vapor bubble were visualized by a high-speed CCD camera, and the bubble dynamics was investigated at different ssDNA concentrations and under various pulse widths. It was observed that an increase in the ssDNA concentration led to an increase of the electric power required for incipient bubble nucleation. Based on thermodynamics considerations and a simple model for nucleus formation in ssDNA solution, an analysis of bubble nucleation work was carried out and the results are consistent with experimental data. It is found that the bubble dynamics in ssDNA solutions is different from that in DI water, and an obvious retardation effect on the motion of the micro bubble was observed at high ssDNA concentrations. Based on Zimm's model, the effect of ssDNA macromolecules on the total viscosity of the solution is revealed. The present study indicates that polymer properties can significantly influence bubble nucleation and the subsequent evolution of bubble dynamics, owing to hydrodynamic intermolecular interactions of polymer macromolecules.