title: Light-induced actuating nanotransducers.
abstract: Nanoactuators and nanomachines have long been sought after, but key bottlenecks remain. Forces at submicrometer scales are weak and slow, control is hard to achieve, and power cannot be reliably supplied. Despite the increasing complexity of nanodevices 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 nanoactuation. Optically heating above a critical temperature [Formula: see text] = 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 [Formula: see text] their strong van der Waals attraction is overcome as the polymer expands, exerting nanoscale forces of several nN. This large force 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 toward rational design of diverse colloidal nanomachines.
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, United Kingdom; Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, United Kingdom; dt413@cam.ac.uk jjb12@cam.ac.uk.
authors.forename: Tao
authors.initials: T
authors.lastname: Ding
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, United Kingdom; Department of Physics, University of Bath, Bath, BA2 7AY, United Kingdom;
authors.forename: Ventsislav K
authors.initials: VK
authors.lastname: Valev
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, United Kingdom; Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Salmon
authors.affiliation: Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom.
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Forman
authors.affiliation: Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, CB3 0FS, United Kingdom;
authors.forename: Stoyan K
authors.initials: SK
authors.lastname: Smoukov
authors.affiliation: Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom.
authors.forename: Oren A
authors.initials: OA
authors.lastname: Scherman
authors.affiliation: Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom.
authors.forename: Daan
authors.initials: D
authors.lastname: Frenkel
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, United Kingdom; dt413@cam.ac.uk jjb12@cam.ac.uk.
authors.forename: Jeremy J
authors.initials: JJ
authors.lastname: Baumberg
keywords: colloidal; nanoactuator; nanomachine; pNIPAM; plasmonics