发布时间：2008/08/22 09:04 下载：44 次
Many physiological behaviors such as heartbeat and brainwaves exhibit rhythmical oscillations. Unlike conventional stimuli-responsive materials which act in an equilibrium state,1,2 such a living system works in a nonequilibrium state. No doubt,biomimetic systems with rhythmical action can not only help
us to understand nonequilibrium thermodynamics and phenomena in life but find applications in nanodevices, biomaterials and drug delivery. In the past years, self-oscillating polymer gels,3 free polymer chains,4 and immobilized macromolecules5
have been prepared. These materials work in a closed system driven by the Belousov-Zhabotinsky reaction, so the oscillation amplitude decays with time. In parallel, oscillations of some polymer gels6,7 and DNA8 have also been achieved in an open system driven by the Landolt reaction, whose amplitude holds a constant due to the continuous input. Obviously, the latter is more analogous to a physiological system, namely, the oscillation has invariant amplitude under a constant input.