Multiphoton-Absorption-Induced-Luminescence (MAIL) Imaging of Tumor-Targeted Gold Nanoparticles

• Published in: Bioconjugate chemistry 2010-11, Vol.21 (11), p.1968-1977
• Main Authors: Dowling, Matthew B, Li, Linjie, Park, Juhee, Kumi, George, Nan, Anjan, Ghandehari, Hamid, Fourkas, John T, DeShong, Philip
• Format: Article
• Language: English
• Subjects: Cell Line; Cell Survival - drug effects; Cells; Endothelial Cells - drug effects; Endothelial Cells - metabolism; Gold; Gold - analysis; Gold - chemistry; Gold - metabolism; Humans; Luminescence; Metal Nanoparticles - analysis; Metal Nanoparticles - chemistry; Molecular Imaging - methods; Nanoparticles; Particle Size; Peptides, Cyclic - chemical synthesis; Peptides, Cyclic - chemistry; Peptides, Cyclic - metabolism; Polypeptides; Proteins; Serum Albumin, Bovine - pharmacology; Sodium Azide - pharmacology; Surface Properties; Tumors
• ISSN: 1043-1802; 1520-4812
• DOI: 10.1021/bc100115m

We demonstrate that multiphoton-absorption-induced luminescence (MAIL) is an effective means of monitoring the uptake of targeted nanoparticles into cells. Gold nanoparticles (AuNPs) with diameters of 4.5 and 16 nm were surface-functionalized with monocyclic RGDfK, an RGD peptide analogue that specifically targets the αvβ3 integrin, a membrane protein that is highly overexpressed in activated endothelial cells during tumor angiogenesis. To determine whether cyclic RGD can enhance the uptake of the functionalized AuNPs into activated endothelium, human umbilical vein endothelial cells (HUVECs) were used as a model system. MAIL imaging of HUVECs incubated with AuNPs demonstrates differential uptake of AuNPs functionalized with RGD analogues: RGDfK-modified nanoparticles are taken up by the HUVECs preferentially compared to AuNPs modified with linear RGD (GRGDSP) conjugates or with no surface conjugates. The luminescence counts observed for the AuNP-RGDfK conjugates are an order of magnitude greater than for AuNP-GRGDSP conjugates. Transmission electron microscopy shows that, once internalized, the AuNP-RGDfK conjugates remain primarily within endosomal and lysosomal vesicles in the cytoplasm of the cells. Significant aggregation of these particles was observed within the cells. MAIL imaging studies in the presence of specific uptake inhibitors indicate that AuNP-RGDfK conjugate uptake involves a specific binding event, with αvβ3 integrin-mediated endocytosis being an important uptake mechanism.