Time-resolved measurements of changes in the size and shape of nanobiological objects and layers are crucial to understand their properties and optimize their performance. Optical sensing is particularly attractive with high throughput and sensitivity, and label-free operation. However, most state-of-the-art solutions require intricate modeling or multiparameter measurements to disentangle conformational or thickness changes of biomolecular layers from complex interfacial refractive index variations. Here, we present a dual-band nanoplasmonic ruler comprising mixed arrays of plasmonic nanoparticles with spectrally separated resonance peaks. As electrodynamic simulations and model experiments show, the ruler enables real-time simultaneous measurements of thickness and refractive index variations in uniform and heterogeneous layers with sub-nanometer resolution. Additionally, nanostructure shape changes can be tracked, as demonstrated by quantifying the degree of lipid vesicle deformation at the critical coverage prior to rupture and supported lipid bilayer formation. In a broader context, the presented nanofabrication approach constitutes a generic route for multimodal nanoplasmonic optical sensing.
Bibliographical noteFunding Information:
This research has received funding from the Knut and Alice Wallenberg Foundation project 2016.0210, from the Swedish Foundation for Strategic Research Framework project RMA15-0052, and the Polish National Science Center project 2017/25/B/ST3/00744. F.A.A.N. acknowledges support from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Grant Agreement No. 101028262. Part of this work was carried out at the MC2 cleanroom facility at the Chalmers Materials Analysis Laboratory, under the umbrella of the Chalmers Excellence Initiative Nano. A part of the TOC figure is modified from free-licensed resources from Freepik ( www.freepik.com ).
© 2022 The Authors. Published by American Chemical Society.
- nanoplasmonic sensors
- supported lipid bilayer