title: A fast analysis method to quantify nanoparticle uptake on a single cell level.
abstract: OBJECTIVE
  This study examines the absolute quantification of particle uptake into cells.
  
  
  METHODS
  We developed a novel method to analyze stacks of confocal fluorescence images of single cells interacting with nano-and micro-particles. Particle_in_Cell-3D is a freely available ImageJ macro. During the image analysis routine, single cells are reconstructed in 3D and split into two volumes - intracellular and the membrane region. Next, particles are localized and color-coded accordingly. The mean intensity of single particles, measured in calibration experiments, is used to determine the absolute number of particles.
  
  
  RESULTS
  Particle_in_Cell-3D was successfully applied to measure the uptake of 80-nm mesoporous silica nanoparticles into HeLa cells. Furthermore, it was used to quantify the absolute number of 100-nm polystyrene nanoparticles forming agglomerates of up to five particles; the accuracy of these results was confirmed by super-resolution, stimulated emission depletion microscopy.
  
  
  CONCLUSIONS
  Particle_in_Cell-3D is a fast and accurate method that allows the quantification of particle uptake into cells.
authors: Ludwig-Maximilians-University Munich, Department of Chemistry & Center for NanoScience, Butenandtstrasse 11, Gerhard-Ertl-Gebäude, 81377 Munich, Germany.
authors: Adriano A
authors: AA
authors: Torrano
authors: Julia
authors: J
authors: Blechinger
authors: Christian
authors: C
authors: Osseforth
authors: Christian
authors: C
authors: Argyo
authors: Armin
authors: A
authors: Reller
authors: Thomas
authors: T
authors: Bein
authors: Jens
authors: J
authors: Michaelis
authors: Christoph
authors: C
authors: Bräuchle
mesh_terms: D008962:Models, Theoretical; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size