Holographic microscopy for the three-dimensional exploration of light scattering from gold nanomarkers in biological media

TL;DR

This paper demonstrates a high-resolution holographic microscopy technique for 3D imaging of gold nanomarkers in live cells, enabling precise localization and discrimination from cellular background signals.

Contribution

It introduces a novel 3D reconstruction method combined with digital holography to accurately locate gold nanomarkers in biological media.

Findings

Gold nanomarkers produce distinct bright scattering patterns

The method effectively discriminates nanomarkers from cellular structures

3D images are longitudinally undistorted and highly resolved

Abstract

The 3D structure of light scattering from dark-field illuminated live 3T3 cells marked with 40 nm gold nanomarkers is explored. For this purpose, we use a high resolution holographic microscope combining the off-axis heterodyne geometry and the phase-shifting acquisition of the digital holograms. Images are obtained using a novel 3D reconstruction method providing longitudinally undistorted 3D images. A comparative study of the 3D reconstructions of the scattered fields allows us to locate the gold markers which yield, contrarily to the cellular structures, well defined bright scattering patterns that are not angularly titled and clearly located along the optical axis. This characterization is an unambiguous signature of the presence of the gold biological nanomarkers, and validates the capability of digital holographic microscopy to discriminate them from background signals in live cells.