Thermoresponsive Nanoparticle Systems in Plasmonic Applications

Thermoresponsive nanoparticle systems integrate temperature-sensitive polymers with metallic nanostructures to achieve active control over plasmonic properties. By grafting or embedding polymers such as poly(N-isopropylacrylamide) (PNIPAM) onto gold or silver cores, the hybrid materials undergo reversible volume and refractive-index changes upon heating or cooling. These structural transformations modulate the coupling between nanoparticles or between nanoparticles and underlying substrates, resulting in tunable shifts of the localised surface plasmon resonance (LSPR). Such dynamic modulation enables applications in biosensing, where temperature-driven contraction of a hydrogel corona concentrates analytes at plasmonic hotspots for enhanced detection sensitivity, as well as in colourimetric indicators, optical switches and microactuators. The ability to programme rapid and reversible optical responses across the visible and near-infrared spectrum has fostered on-chip integration of responsive nanophotonic devices, wearable temperature sensors and fluidic pumps. Recent advances focus on optimising response times, refining transition temperatures through copolymer composition, and engineering nanostructure geometries to amplify field intensities while maintaining biocompatibility and scalability.

Research from Nature Portfolio

Researchers have demonstrated a tunable plasmonic nanoantenna device constructed from bowtie nanoantenna arrays coated with a submicrometre thermosensitive hydrogel. The device leverages the strong field enhancement of coupled plasmonic dimers and the rapid swelling–collapse transition of the hydrogel to achieve resonance wavelength shifts exceeding 16 nm in under 250 ms. Submicrometre hydrogel thickness ensures fast ionic diffusion, while the bowtie geometry maximises local field concentration. This approach highlights the potential for integrating responsive hydrogels with intricate nanostructures to fabricate compact, temperature-sensing optics and lays ground for future tunable metasurfaces.

Thermoresponsive Nanoparticle Systems in Plasmonic Applications publication trend

The graph below shows the total number of articles in thermoresponsive nanoparticle systems in plasmonic applications across all publications each year (not limited to Nature Index journals).

Technical terms

Localised Surface Plasmon Resonance (LSPR): Collective oscillation of conduction electrons in a nanoparticle excited by light, producing strong local field enhancement.

Poly(N-isopropylacrylamide) (PNIPAM): A thermosensitive polymer exhibiting a reversible coil–globule transition near physiological temperatures.

Hydrogel: A water-swollen polymer network that can expand or contract in response to stimuli such as temperature or pH.

Core–shell nanoparticle: A nanoparticle comprising a metallic core and a polymer shell, enabling coupled optical and responsive properties.

Responsive polymer: A polymer that undergoes a reversible change in conformation or volume when exposed to an external stimulus.

References

1. Plasmonic nanomaterials with responsive polymer hydrogels for sensing and actuation. Chemical Society Reviews (2022).
2. Tunable Optical Nanoantennas Incorporating Bowtie Nanoantenna Arrays with Stimuli-Responsive Polymer. Scientific Reports (2015).
3. Light-Programmed Bistate Colloidal Actuation Based on Photothermal Active Plasmonic Substrate. Research (2023).
4. The Importance of Excess Poly(N‑isopropylacrylamide) for the Aggregation of Poly(N‑isopropylacrylamide)-Coated Gold Nanoparticles. ACS Nano (2016).
5. Active Control of SPR by Thermoresponsive Hydrogels for Biosensor Applications. The Journal of Physical Chemistry C (2013).