Entropic Trapping of DNA During Gel Electrophoresis: Effect of Field Intensity and Gel Concentration

Abstract

We present an experimental study of single-stranded DNA electrophoresis in polyacrylamide gels. We demonstrate the existence of an entropic trapping regime, situated between the Ogston and reptation regimes, in which the mobility scales as ${1/M}^{1+\gamma }$, where $M$ is the DNA molecular size. The exponent $\gamma >0\mathrm{}$ increases for denser gels but decreases for higher fields. Entropic trapping disappears for electric fields $E$ exceeding a critical size-dependent value $E^{*}\left(M\right)$. We also present various estimates of the gel's mean pore size. Finally, we propose a phase diagram describing the observed DNA migration regimes.