Hyperlens for capturing sub-diffraction nanoscale single molecule dynamics

Abstract

Hyperlenses offer an appealing opportunity to unlock bioimaging beyond the diffraction limit with conventional optics. Mapping hidden nanoscale spatiotemporal heterogeneities of lipid interactions in live cell membrane structures has been accessible only using optical super-resolution techniques. Here, we employ a spherical gold/silicon multilayered hyperlens that enables sub-diffraction fluorescence correlation spectroscopy at 635 nm excitation wavelength. The proposed hyperlens enables nanoscale focusing of a Gaussian diffraction-limited beam below 40 nm. Despite the pronounced propagation losses, we quantify energy localization in the hyperlens inner surface to determine fluorescence correlation spectroscopy (FCS) feasibility depending on hyperlens resolution and sub-diffraction field of view. We simulate the diffusion FCS correlation function and demonstrate the reduction of diffusion time of fluorescent molecules up to nearly 2 orders of magnitude as compared to free space excitation. We show that the hyperlens can effectively distinguish nanoscale transient trapping sites in simulated 2D lipid diffusion in cell membranes. Altogether, versatile and fabricable hyperlens platforms display pertinent applicability for the enhanced spatiotemporal resolution to reveal nanoscale biological dynamics of single molecules.