Measuring vesicle loading with holographic microscopy and bulk light scattering

TL;DR

This paper introduces a label-free holographic microscopy technique combined with light scattering models to quantify vesicle loading, applicable to both cell-sized and nanoscale vesicles, without fluorescent or radioactive tracers.

Contribution

It presents a novel, tracer-free method for measuring vesicle loading using digital holographic microscopy and Lorenz-Mie scattering modeling, applicable across different vesicle sizes.

Findings

Successful measurement of vesicle refractive index and loading.

Method applicable to both cell-sized and nanoscale vesicles.

Provides a non-invasive alternative to traditional labeling techniques.

Abstract

We report efforts to quantify the loading of cell-sized lipid vesicles using in-line digital holographic microscopy. This method does not require fluorescent reporters, fluorescent tracers, or radioactive tracers. A single-color LED light source takes the place of conventional illumination to generate holograms rather than bright field images. By modelling the vesicle's scattering in a microscope with a Lorenz-Mie light scattering model, and comparing the results to data holograms, we are able to measure the vesicle's refractive index and thus loading. Performing the same comparison for bulk light scattering measurements enables retrieval of vesicle loading for nanoscale vesicles.