title: Detection of single photoluminescent diamond nanoparticles in cells and study of the internalization pathway.
abstract: Diamond nanoparticles are promising photoluminescent probes for tracking intracellular processes, due to embedded, perfectly photostable color centers. In this work, the spontaneous internalization of such nanoparticles (diameter 25 nm) in HeLa cancer cells is investigated by confocal microscopy and time-resolved techniques. Nanoparticles are observed inside the cell cytoplasm at the single-particle and single-color-center level, assessed by time-correlation intensity measurements. Improvement of the nanoparticle signal-to-noise ratio inside the cell is achieved using a pulsed-excitation laser and time-resolved detection taking advantage of the long radiative lifetime of the color-center excited state as compared to cell autofluorescence. The internalization pathways are also investigated, with endosomal marking and colocalization analyses. The low colocalization ratio observed proves that nanodiamonds are not trapped in endosomes, a promising result in prospect of drug delivery by these nanoparticles. Low cytotoxicity of these nanoparticles in this cell line is also shown.
authors.affiliation: Laboratoire de Photonique Quantique et Moléculaire, UMR CNRS 8537, Cachan, France.
authors.forename: Orestis
authors.initials: O
authors.lastname: Faklaris
authors.forename: Damien
authors.initials: D
authors.lastname: Garrot
authors.forename: Vandana
authors.initials: V
authors.lastname: Joshi
authors.forename: Frédéric
authors.initials: F
authors.lastname: Druon
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Boudou
authors.forename: Thierry
authors.initials: T
authors.lastname: Sauvage
authors.forename: Patrick
authors.initials: P
authors.lastname: Georges
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Curmi
authors.forename: François
authors.initials: F
authors.lastname: Treussart
mesh_terms: D018130:Diamond / Q000737:chemistry*; D011992:Endosomes / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D049449:Luminescence; D053758:Nanoparticles / Q000032:analysis / Q000737:chemistry*; D010777:Photochemistry
chemical_list: D018130:Diamond