Augmented 3D super-resolution of fluorescence-free nanoparticles using enhanced dark-field illumination based on wavelength-modulation and a least-cubic algorithm.

Peng Zhang,Seong Ho Kang,Suresh Kumar Chakkarapani,Kyungsoo Kim,Ning Fang,Seungah Lee

doi:10.1038/srep32863

Peng Zhang, Seong Ho Kang + Show 4 more

Open Access

https://doi.org/10.1038/srep32863

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Journal: Scientific Reports	Publication Date: Sep 13, 2016
Citations: 13	License type: CC BY 4.0

Affiliation: Kyung Hee University, Georgia State University

Abstract

Augmented three-dimensional (3D) subdiffraction-limited resolution of fluorescence-free single-nanoparticles was achieved with wavelength-dependent enhanced dark-field (EDF) illumination and a least-cubic algorithm. Various plasmonic nanoparticles on a glass slide (i.e., gold nanoparticles, GNPs; silver nanoparticles, SNPs; and gold nanorods, GNRs) were imaged and sliced in the z-direction to a thickness of 10 nm. Single-particle images were then compared with simulation data. The 3D coordinates of individual GNP, SNP, and GNR nanoparticles (x, y, z) were resolved by fitting the data with 3D point spread functions using a least-cubic algorithm and collation. Final, 3D super-resolution microscopy (SRM) images were obtained by resolving 3D coordinates and their Cramér-Rao lower bound-based localization precisions in an image space (530 nm × 530 nm × 300 nm) with a specific voxel size (2.5 nm × 2.5 nm × 5 nm). Compared with the commonly used least-square method, the least-cubic method was more useful for finding the center in asymmetric cases (i.e., nanorods) with high precision and accuracy. This novel 3D fluorescence-free SRM technique was successfully applied to resolve the positions of various nanoparticles on glass and gold nanospots (in vitro) as well as in a living single cell (in vivo) with subdiffraction limited resolution in 3D.

Highlights

Were based on modifications and encoding of the point spread function (PSF) in order to resolve the relative central position of the single emitter in the axial direction
An numerical aperture (NA) of 0.9 was determined to be optimal for enhanced dark-field (EDF) detection in our study (Supplementary Fig. 2), and an overly large NA value decreased the quality of the images dramatically
We developed a novel, easy, universal method to achieve 3D SRM imaging of fluorescence-free plasmonic nanoparticles with high precision and without any additional optical elements to modify the PSF

Summary

Introduction

Were based on modifications and encoding of the PSF in order to resolve the relative central position of the single emitter in the axial direction These 3D SRM techniques highly depend on the modification of conventional microscopy using additional optical elements such as cylindrical lenses[15,16,17,18,19,20], phase masks[21,22], multi-objective lenses[23], spatial light modulators[24,25], beam-splitters[26], adaptive optics devices[27,28], and multi-focus optical elements[29,30,31,32]. Compared with the commonly used least-square method in SRM, the least-cubic method makes it easier to find the center, especially in asymmetric cases This method uses direct PSF fitting based on wavelength-dependent EDF illumination detection in 3D and employs a novel least-cubic algorithm without any additional optical elements to enhance accuracy and feasibility

Methods

Results

Conclusion