Hiroyuki Mayama

Self-oscillating polymer chain

Abstract 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.

Self-oscillating polymer chain in a laser field

We have investigated the dynamical behaviour of the rhythmic conformational change between the folded compact state and the unfolded state in a single polymer chain under thermodynamically open conditions. It is shown that the spontaneous rhythmic change in the conformation of a single polymer chain (T4DNA, 166 kbp, contour length: 56 μm) is generated using a focused continuous wave (CW) Nd:YAG laser beam (wavelength λ = 1064 nm), where the focused laser beam plays a dual role, both trapping a polymer chain at the focus and creating a temperature gradient around the focus. Furthermore, the whole process of the rhythmic conformational change: the course of melting, nucleation and growth between the folded and unfolded states has been clarified. The rhythmic change in the conformation is discussed in terms of the limit-cycle oscillation driven by the dissipation of the photon energy.

Nonlinear dynamics in a laser field: spontaneous oscillation of mesoscopic soft matter

Abstract Experimental studies on the utilization of a laser to create a thermodynamically open system in a mesoscopic scale have been performed, where the laser has the roles to generate attractive and scattering forces on an optically trapped object. We have succeeded in the observation of various novel oscillatory phenomena under laser illumination. In this paper, we present the results of new experiments on the cyclic oscillation of a single giant molecule and periodic bursting in a cluster of micrometer sized beads.