Self-oscillating polymer chain

We report a novel rhythmic phenomenon of a single polymer chain between the elongated coil state and the folded compact state under thermodynamically open conditions. It is shown that a T4 DNA molecule (166 kbp) in poly(ethylene glycol) (PEG) solution exhibits rhythmic conformational change at the focus of a continuous wave (CW) Nd:YAG laser beam (1064 nm), where the laser beam plays dual roles: trapping a molecular chain and making a temperature gradient around the focus. The conformational oscillation is discussed in terms of the limit-cycle oscillation of a single polymer chain driven through the dissipation of the photon energy.