PerspectiveChemistry

Thermally Responsive Pulsating Nanotubules

Science  21 Sep 2012:
Vol. 337, Issue 6101, pp. 1462-1463
DOI: 10.1126/science.1228178

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Summary

Thousands of years ago, Chinese medical doctors started to diagnose illness simply by feeling a pulse at a wrist with two fingers, knowing that the periodicity of the beating heart could be diagnostic (1). One of the ultimate scientific challenges would be to develop artificial analogs of cardiac muscle cell that pulsate autonomously. One approach has been to use noncovalent molecular assemblies (2) that pulsate in response to external stimuli. Essential issues to consider are what mechanism can be used to drive pulsation and how to visualize the resulting motion. Previous examples have featured “pulsating vesicles” that responded to pH and light as stimuli (3, 4). On page 1521 of this issue, Huang et al. (5) report a thermoresponsive nanotube that undergoes shrinkage and expansion upon heating and cooling, respectively, in water (5). By making use of this thermoinduced pulsation, the nanotube can push out guest molecules such as C60 from its hydrophobic interior.