'Living' PEGylation on gold nanoparticles to optimize cancer cell uptake by controlling targeting ligand and charge densities.
We report and demonstrate biomedical applications of a new technique--'living' PEGylation--that allows control of the density and composition of heterobifunctional PEG (HS-PEG-R; thiol-terminated poly(ethylene glycol)) on gold nanoparticles (AuNPs). We first establish 'living' PEGylation by incubating HS-PEG₅₀₀₀-COOH with AuNPs (∼20 nm) at increasing molar ratios from zero to 2000. This causes the hydrodynamic layer thickness to differentially increase up to 26 nm. The controlled, gradual increase in PEG-COOH density is revealed after centrifugation, based on the ability to re-suspend the pellet and increase the AuNP absorption. Using a fluorescamine-based assay we quantify differential HS-PEG₅₀₀₀-NH₂ binding to AuNPs, revealing that it is highly efficient until AuNP saturation is reached. Furthermore, the zeta potential incrementally changes from -44.9 to +52.2 mV and becomes constant upon saturation. Using 'living' PEGylation we prepare AuNPs with different ratios of HS-PEG-RGD (RGD: Arg-Gly-Asp) and incubate them with U-87 MG (malignant glioblastoma) and non-target cells, demonstrating that targeting ligand density is critical to maximizing the efficiency of targeting of AuNPs to cancer cells. We also sequentially control the HS-PEG-R density to develop multifunctional nanoparticles, conjugating positively charged HS-PEG-NH₂ at increasing ratios to AuNPs containing negatively charged HS-PEG-COOH to reduce uptake by macrophage cells. This ability to minimize non-specific binding/uptake by healthy cells could further improve targeted nanoparticle efficacy.
Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, USA. hongweic@umich.edu
Hongwei
H
Chen
Hayley
H
Paholak
Masayuki
M
Ito
Kanokwan
K
Sansanaphongpricha
Wei
W
Qian
Yong
Y
Che
Duxin
D
Sun
D001692:Biological Transport; D045744:Cell Line, Tumor; D016503:Drug Delivery Systems; D005909:Glioblastoma / Q000188:drug therapy / Q000378:metabolism; D006046:Gold / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008264:Macrophages / Q000378:metabolism; D053758:Nanoparticles / Q000737:chemistry / Q000378:metabolism*; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism*; D011092:Polyethylene Glycols / Q000737:chemistry / Q000378:metabolism*
D009842:Oligopeptides; D011092:Polyethylene Glycols; D006046:Gold; C047981:arginyl-glycyl-aspartic acid