期刊
JOURNAL OF MATERIALS CHEMISTRY
卷 18, 期 41, 页码 4949-4958出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/b810488c
关键词
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资金
- NRL
- ONR
- ARO
- NSF-IGERT [DGE-0504485]
- University of Massachusetts
We describe the design of new ligands made by coupling commercially available poly(ethylene glycol) methyl ether (mPEG, HO-PEG-OCH(3)) and thioctic acid (TA) via a stable amide bond to form TA-PEG-OCH(3) molecules. The ligands were obtained by a simple transformation of the hydroxyl group on the mPEG into an amine group, followed by attachment of TA via N, N'-dicyclohexylcarbodiimide (DCC) coupling. Following ring opening of the 1,2-dithiolane on the TA-PEG-OCH(3) to form a dihydrolipoic acid (DHLA) group, DHLA-PEG-OCH(3) was obtained. Cap exchange of nanoparticles with DHLA-PEG-OCH(3) provided dispersions in buffer solutions that were stable over a broad pH range (from 3 to 13 for CdSe-ZnS QDs and 2-13 for Au nanoparticles). Using DHLA-PEG-OCH(3) either neat or mixed with amine- or carboxyl-terminated ligands (DHLA-PEG-NH(2) or DHLA-PEG-COOH) allowed tuning of the surface functionalities of these nanoparticles. Microinjection of the ligand-exchanged QDs into live cells indicated that the newly capped QDs were stable and well dispersed in the cell cytosol for up to 32 h following delivery. The fluorescence distribution and its evolution over time of these DHLA-PEG-OCH(3)-QDs indicate improved intracellular stability and reduced non-specific interactions compared to nanocrystals capped with DHLA-PEG-OH.
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