Light-induced actuating nanotransducers
Proceedings of the National Academy of Sciences of the United States of America
National Academy of Sciences
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Ding, T., Valev, V., Salmon, A., Forman, C., Smoukov, S., Scherman, O., Frenkel, D., & et al. (2016). Light-induced actuating nanotransducers. Proceedings of the National Academy of Sciences of the United States of America, 113 (20), 5503-5507. https://doi.org/10.1073/pnas.1524209113
Nanoactuators and nanomachines have long been sought after, but key bottlenecks remain. Forces at sub-micron scales are weak and slow, control is hard to achieve, and power cannot be reliably supplied. Despite the increasing complexity of nano-devices such as DNA Origami and molecular machines, rapid mechanical operations are not yet possible. Here, we bind temperature-responsive polymers to charged Au nanoparticles, storing elastic energy that can be rapidly released under light control for repeatable isotropic nano-actuation. Optically heating above a critical temperature =32°C using plasmonic absorption of an incident laser, causes the coatings to expel water and collapse within a microsecond to the nanoscale, millions of times faster than the base polymer. This triggers a controllable number of nanoparticles to tightly bind in clusters. Surprisingly, by cooling below their strong van der Waals attraction is overcome as the polymer expands, exerting nanoscale forces of several nN. This large force/weight depends on van der Waals attractions between Au cores being very large in the collapsed polymer state, setting up a tightly compressed polymer spring which can be triggered into the inflated state. Our insights lead towards rational design of diverse colloidal nanomachines.
nanoactuator, nanomachine, plasmonics, pNIPAM, colloidal
This research is supported by UK Engineering and Physical Sciences Research Council grants EP/G060649/1 and EP/L027151/1, and ERC grants LINASS 320503 and EMATTER 280078. VKV acknowledges support from The Royal Society through the University Research Fellowships.
European Research Council (320503)
European Research Council (280078)
External DOI: https://doi.org/10.1073/pnas.1524209113
This record's URL: https://www.repository.cam.ac.uk/handle/1810/254997