Receptor-mediated cellular uptake of folate-conjugated fluorescent nanodiamonds: a combined ensemble and single-particle study.
Fluorescent nanodiamonds (FNDs) are nontoxic and photostable nanomaterials, ideal for long-term in vivo imaging applications. This paper reports that FNDs with a size of approximately 140 nm can be covalently conjugated with folic acid (FA) for receptor-mediated targeting of cancer cells at the single-particle level. The conjugation is made by using biocompatible polymers, such as polyethylene glycol, as crosslinked buffer layers. Ensemble-averaged measurements with flow cytometry indicate that more than 50% of the FA-conjugated FND particles can be internalized by the cells (such as HeLa cells) through receptor-mediated endocytosis, as confirmed by competitive inhibition assays. Confocal fluorescence microscopy reveals that these FND particles accumulate in the perinuclear region. The absolute number of FNDs internalized by HeLa cells after 3 h of incubation at a particle concentration of 10 microg mL(-1) is in the range of 100 particles per cell. The receptor-mediated uptake process is further elucidated by single-particle tracking of 35-nm FNDs in three dimensions and real time during the endocytosis.
Zhang
Bailin
B
Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan.
Li
Yingqi
Y
Fang
Chia-Yi
CY
Chang
Cheng-Chun
CC
Chen
Chao-Sheng
CS
Chen
Yi-Ying
YY
Chang
Huan-Cheng
HC
D001672:Biocompatible Materials; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000378:metabolism*; D003432:Cross-Linking Reagents; D018130:Diamond; D004705:Endocytosis; D005456:Fluorescent Dyes; D058973:Folate Receptors, GPI-Anchored; D005492:Folic Acid / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D053758:Nanoparticles / Q000737:chemistry; D036103:Nanotechnology; D010316:Particle Size; D011956:Receptors, Cell Surface / Q000378:metabolism*
D001672:Biocompatible Materials; D002352:Carrier Proteins; D003432:Cross-Linking Reagents; D005456:Fluorescent Dyes; D058973:Folate Receptors, GPI-Anchored; D011956:Receptors, Cell Surface; D018130:Diamond; D005492:Folic Acid