title: Mechanistic aspects of fluorescent gold nanocluster internalization by live HeLa cells.
abstract: We have studied cellular uptake of ultrasmall fluorescent gold nanoclusters (AuNCs) by HeLa cells by confocal fluorescence microscopy in combination with quantitative image analysis. Water solubilized, lipoic acid-protected AuNCs, which had an overall hydrodynamic diameter of 3.3 nm and emitted fluorescence in the near-infrared region at ∼700 nm, were observed to accumulate on the cell membrane prior to internalization. The internalization mechanisms were analyzed using inhibitors known to interfere with specific pathways. Cellular uptake of AuNCs is energy-dependent and involves multiple mechanisms: clathrin-mediated endocytosis and macropinocytosis appear to play a significant role, whereas the caveolin-mediated pathway contributes only to a lesser extent. Co-labeling of different cell organelles showed that intracellular trafficking of AuNCs mainly follows through endosomal pathways. The AuNCs were ultimately transferred to lysosomes; they were completely excluded from the nucleus even after 24 h.
authors: Institute of Applied Physics and Center for Functional Nanostructures, Karlsruhe Institute of Technology, Wolfgang-Gaede-Strasse 1, 76131 Karlsruhe, Germany.
authors: Linxiao
authors: L
authors: Yang
authors: Li
authors: L
authors: Shang
authors: G Ulrich
authors: GU
authors: Nienhaus
mesh_terms: D003287:Contrast Media; D006046:Gold / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry*; D008856:Microscopy, Fluorescence / Q000379:methods*; D010316:Particle Size; D013347:Subcellular Fractions / Q000737:chemistry* / Q000648:ultrastructure*
chemical_list: D003287:Contrast Media; D006046:Gold