# Subcellular nanoparticle trafficking investigated with label-free, live cell imaging

## TL;DR

The paper introduces a new imaging method to study how nanoparticles move inside cells without using labels, helping understand drug delivery processes.

## Contribution

A novel label-free, live cell imaging workflow combining holography and tomography is developed to study nanoparticle trafficking.

## Key findings

- Dynamic fluorescent holotomography enables long-term tracking of nanoparticle uptake and delivery in live cells.
- The method allows quantitative characterization of nanoparticle uptake without cell or organelle markers.
- Integration of holography and tomography improves understanding of nanoparticle-cell interactions over extended periods.

## Abstract

Nanoparticle drug delivery systems have significant potential to transform precision medicine due to their ability to encapsulate a wide range of cargo, improve systemic circulation time, and enhance targeted delivery. These delivery properties can be further modified by altering the surface chemistry of the nanoparticle carrier. However, a gap remains in our understanding of the cellular mechanisms underlying nanoparticle uptake, in addition to the subcellular trafficking kinetics. A comprehensive understanding of nanoparticle-cell interactions considering both the nanocarrier and the drug cargo has been challenging, in part due to technological limitations. Here, we present a robust imaging workflow to study long-term dynamics of nanoparticle delivery in live cells. We show that integration of holography and tomography enhances the study of live cells in a label-free environment and can be combined with intermittent fluorescence microscopy to assess nanoparticle uptake and delivery kinetics for up to 30 hours. We also describe a method to quantitatively characterize uptake of a library of fluorescently tagged lipid- and polymer-based nanoformulations without introducing cell or organelle markers. This application of dynamic fluorescent holotomography as a novel method to investigate nanoparticle uptake and cargo delivery highlights the expanding utility of multimodal, label-free, live imaging techniques.

Nanoparticle drug delivery systems have significant potential to transform precision medicine due to their ability to encapsulate a wide range of cargo, improve systemic circulation time, and enhance targeted delivery.