Nanomachines are still far from reality, despite intense interest. One of the key issues is how to move them through water, and how they can switch functions on and off. Since they cannot be tethered electrically, light is a promising way to power, orient, drive and switch them. We have been combining soft materials such as DNA and polymers with light-active materials to create new capabilities.
Current work:
DNA origami optical nanocavities
By using short synthesised sections of DNA to knit together a long DNA strand, we create a variety of nano-architectures. Using ‘DNA origami’ tiles, we assemble a gold nanoparticle above a gold mirror, to trap light in the nanogap. Dye molecules placed in specific locations give drastically increase light-matter coupling in this tight nanocavity for light. We find amplified optical forces enough to move the metal atoms around. [1,2]
DNA origami optical nanocavities
Combining hinged DNA origami plates with gold nanoparticles and thermo-responsive polymers allows creation of optically and thermally driven nano-tweezers. When incident light heats the nanoparticle above 32degrees, the clamp closes. A wide variety of functional nanomachines are now in prospect. [3]
Optically driven jellyfish
Selectively coating carefully grown ‘skeletons’ of carbon nanotube forests with a thermo-responsive polymer ‘muscle’, we are able to switch these micro-jellyfish by light, inducing motion. This combination allows a scalable system that can be driven into different configurations at high speeds. [4]
Metal-insulator switching of polymers
By coating nanoparticles with thin layers of conducting polymer which can be switched using external potential, the optical properties of the nanocavity can be controlled in real time. This is the basis of a novel electrochromic switch. [5]
Electrochromic switched nanocavities
Conducting polymers can be switched between oxidation state by adding or removing electrons. Placing these in the plasmonic gap that traps light, allows the optical properties to be spectrally shifted in real time. Using vibrational spectroscopy at the same time allows the state of the electrons in the polymer to be tracked. [6]
Optically actuating nano-switches
By coating gold nanoparticles with a thermoresponsive polymer, we create colloids that can be switched by light that locally heats them above their transition temperature. The polymer coating collapses in size by repelling water, and assembles reversibly with surrounding nanoparticles. This switches the colour, as well as driving large forces that provide motion. [7]
Key papers:
- Amplified Plasmonic Forces from DNA Origami-Scaffolded Single Dyes in Nanogaps, Nano Lett (2023); DOI 10.1021/acs.nanolett.3c01016
- Quantum electrodynamics at 300K coupling a single vibrating molecule with a plasmonic nanocavity, Nature Comm. 10:1049 (2019); DOI: 10.1038/s41467-019-08611-5
- Thermo-responsive Actuation of a DNA Origami Flexor, Adv.Func.Mat. 1706410 (2018); DOI 10.1002/adfm.201706410
- Kinetics of Light-Responsive CNT/PNIPAM Hydrogel Microactuators, Small (2023); DOI: 10.1002/smll.202305034
- Metal to insulator transition for conducting polymers in plasmonic nanogaps, Nature Light Sciences & App (2024); DOI: 10.1038/s41377-023-01344-7
- In-Situ Spectro-Electrochemistry of Conductive Polymers…, ACS Nano (2022); DOI: 10.1021/acsnano.2c09081
- Actuating Single Nano-oscillators with Light, Adv.Opt.Mat. 6, 1701281 (2018); DOI 10.1002/adom.201701281
Current people involved:
JJB, Sara Rocchetti, Thieme Schmidt, Yuhang Zhang, Yuling Xiong