RESUMO
Fourier transform infrared (FTIR) spectroscopy is widely used for molecular analysis. However, for the materials situated in an aqueous environment, a precondition for live biological objects such as cells, transmission-based FTIR is prevented by strong water absorption of mid-infrared (MIR) light. Reflection-based cellular assays using internal reflection elements (IREs) such as high-index prisms or flat plasmonic metasurfaces mitigate these issues but suffer from a shallow probing volume localized near the plasma membrane. Inspired by the recent introduction of high-aspect-ratio nanostructures as a novel platform for manipulating cellular behavior, we demonstrate that the integration of plasmonic metasurfaces with tall dielectric nanostructures dramatically enhances the sensing capabilities of FTIR spectroscopy. We also demonstrate the ability of a metal-on-dielectric metasurface to transduce intracellular processes, such as protein translocation to high-curvature membrane regions during cell adhesion, into interpretable spectral signatures of the reflected light.
Assuntos
Nanoestruturas , Nanoestruturas/química , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Humanos , Propriedades de Superfície , Adesão Celular , Metais/química , Membrana Celular/químicaRESUMO
The controllability of photonic setups is strongly related to how coherently their outputs react to changes in their inputs; such a generic concept is treated in the case of films comprising multilayers of tilted optical axes, under visible light. The optimized designs incorporate ordinary metals or semiconductors while being able to achieve practically all the combinations of reflected, transmitted and absorbed power within the passivity limits. Importantly, most of the proposed structures exhibit substantial robustness to manufacturing defects and are fabricable with various methods. Therefore, they can make indispensable pieces of integrated photonic systems by improving their light-controlling operation for applications ranging from steering and electrodynamic switching to filtering and optical signal processing.