Packaging-ejection phase transitions of a polymer chain: Theory and Monte Carlo simulation

We theoretically study packaging-ejection phase transitions of a flexible polymer chain, translocating through a spherical cavity. Based on the Flory model for coil-globule transitions of a single flexible polymer, we derive the free energy of the polymer chain through a spherical cavity. Depending on the size of the cavity, the attractive interaction between the polymer and cavity, solvent quality, and the length of the polymer chain, we find continuous and discontinuous phase transitions between a packaged state and an ejected one of the polymer chain. These results suggest a possibility of the control of DNA packing and ejection. We also perform a Monte Carlo simulation to confirm the theoretical results. (C) 2009 American Institute of Physics. [doi:10.1063/1.3225140]