Photoluminescent diamond nanoparticles for cell labeling: study of the uptake mechanism in mammalian cells

TL;DR

This study demonstrates that photoluminescent nanodiamonds can be effectively used for intracellular cell labeling, primarily entering cells via clathrin-mediated endocytosis, with potential applications in targeted biomolecule delivery.

Contribution

It reveals the uptake mechanism of photoluminescent nanodiamonds in mammalian cells, showing predominant clathrin-mediated endocytosis and intracellular localization patterns.

Findings

Nanodiamonds enter cells mainly through clathrin-mediated endocytosis.

Larger nanoparticles localize in endocytic vesicles, smaller ones are free in cytosol.

Photoluminescent nanodiamonds enable long-term cellular tracking.

Abstract

Diamond nanoparticles (nanodiamonds) have been recently proposed as new labels for cellular imaging. For small nanodiamonds (size <40 nm) resonant laser scattering and Raman scattering cross-sections are too small to allow single nanoparticle observation. Nanodiamonds can however be rendered photoluminescent with a perfect photostability at room temperature. Such a remarkable property allows easier single-particle tracking over long time-scales. In this work we use photoluminescent nanodiamonds of size <50 nm for intracellular labeling and investigate the mechanism of their uptake by living cells . By blocking selectively different uptake processes we show that nanodiamonds enter cells mainly by endocytosis and converging data indicate that it is clathrin mediated. We also examine nanodiamonds intracellular localization in endocytic vesicles using immunofluorescence and transmission electron microscopy. We find a high degree of colocalization between vesicles and the biggest nanoparticles or aggregates, while the smallest particles appear free in the cytosol. Our results pave the way for the use of photoluminescent nanodiamonds in targeted intracellular labeling or biomolecule delivery