PURPOSE: Plasmonic photothermal cancer therapy by gold nanorods (GNRs) emerges as a promising tool for cancer treatment. The goal of this study was to design cationic oligoethylene glycol (OEG) compounds varying in hydrophobicity and molecular electrostatic potential as ligand shells of GNRs. Three series of ligands with different length of OEG chain (ethylene glycol units = 3, 4, 5) and variants of quaternary ammonium salts (QAS) as terminal functional group were synthesized and compared to a prototypical quaternary ammonium ligand with alkyl chain - (16-mercaptohexadecyl)trimethylammonium bromide (MTAB). METHODS: Step-by-step research approach starting with the preparation of compounds characterized by NMR and HRMS spectra, GNRs ligand exchange evaluation through characterization of cytotoxicity and GNRs cellular uptake was used. A method quantifying the reshaping of GNRs was applied to determine the effect of ligand structure on the heat transport from GNRs under fs-laser irradiation. RESULTS: Fourteen out of 18 synthesized OEG compounds successfully stabilized GNRs in the water. The colloidal stability of prepared GNRs in the cell culture medium decreased with the number of OEG units. In contrast, the cellular uptake of OEG+GNRs by HeLa cells increased with the length of OEG chain while the structure of the QAS group showed a minor role. Compared to MTAB, more hydrophilic OEG compounds exhibited nearly two order of magnitude lower cytotoxicity in free state and provided efficient cellular uptake of GNRs close to the level of MTAB. Regarding photothermal properties, OEG compounds evoked the photothermal reshaping of GNRs at lower peak fluence (14.8 mJ/cm2) of femtosecond laser irradiation than the alkanethiol MTAB. CONCLUSION: OEG+GNRs appear to be optimal for clinical applications with systemic administration of NPs not-requiring irradiation at high laser intensity such as drug delivery and photothermal therapy inducing apoptosis.

• Keywords
• cellular uptake, gold nanorods, oligoethylene glycol, photothermal stability, quaternary ammonium salts,
• MeSH
• Biological Transport MeSH
• HeLa Cells MeSH
• Hydrophobic and Hydrophilic Interactions MeSH
• Colloids MeSH
• Quaternary Ammonium Compounds chemistry   MeSH
• Humans MeSH
• Ligands MeSH
• Nanotubes chemistry   MeSH
• Polyethylene Glycols chemistry   MeSH
• Drug Stability MeSH
• Temperature * MeSH
• Gold chemistry   metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Colloids MeSH
• Quaternary Ammonium Compounds MeSH
• Ligands MeSH
• Polyethylene Glycols MeSH
• Gold MeSH

BACKGROUND: Poly-l-lysine (PLL) enhances nanoparticle (NP) uptake, but the molecular mechanism remains unresolved. We asked whether PLL may interact with negatively charged glycoconjugates on the cell surface and facilitate uptake of magnetic NPs (MNPs) by tumor cells. METHODS: PLL-coated MNPs (PLL-MNPs) with positive and negative ζ-potential were prepared and characterized. Confocal and transmission electron microscopy was used to analyze cellular internalization of MNPs. A colorimetric iron assay was used to quantitate cell-associated MNPs (MNPcell). RESULTS: Coadministration of PLL and dextran-coated MNPs in culture enhanced cellular internalization of MNPs, with increased vesicle size and numbers/cell. MNPcell was increased by eight- to 12-fold in response to PLL in a concentration-dependent manner in human glioma and HeLa cells. However, the application of a magnetic field attenuated PLL-induced increase in MNPcell. PLL-coating increased MNPcell regardless of ζ-potential of PLL-MNPs, whereas magnetic force did not enhance MNPcell. In contrast, epigallocatechin gallate and magnetic force synergistically enhanced PLL-MNP uptake. In addition, heparin, but not sialic acid, greatly reduced the enhancement effects of PLL; however, removal of heparan sulfate from heparan sulfate proteoglycans of the cell surface by heparinase III significantly reduced MNPcell. CONCLUSION: Our results suggest that PLL-heparan sulfate proteoglycan interaction may be the first step mediating PLL-MNP internalization by tumor cells. Given these results, PLL may facilitate NP interaction with tumor cells via a molecular mechanism shared by infection machinery of certain viruses.

• Keywords
• glycoconjugate, heparan sulfate proteoglycan, magnetic nanoparticles, poly-l-lysine, tea catechin,
• MeSH
• Cell Membrane metabolism   MeSH
• Dextrans chemistry   metabolism   MeSH
• Human Umbilical Vein Endothelial Cells MeSH
• Glioma drug therapy   pathology   MeSH
• HeLa Cells MeSH
• Heparan Sulfate Proteoglycans chemistry   metabolism   MeSH
• Humans MeSH
• Magnetite Nanoparticles administration & dosage   chemistry   MeSH
• Magnetic Fields MeSH
• Cell Line, Tumor MeSH
• Polylysine chemistry   metabolism   pharmacokinetics   MeSH
• Polysaccharide-Lyases metabolism   MeSH
• Microscopy, Electron, Transmission MeSH
• Iron metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Dextrans MeSH
• Heparan Sulfate Proteoglycans MeSH
• heparitinsulfate lyase MeSH Browser
• Magnetite Nanoparticles MeSH
• Polylysine MeSH
• Polysaccharide-Lyases MeSH
• Iron MeSH