期刊
ACS APPLIED MATERIALS & INTERFACES
卷 12, 期 1, 页码 151-162出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.9b16150
关键词
PEGylation; cationic liposomes; paclitaxel delivery; bicelles; discoidal micelles; cryogenic electron microscopy
资金
- National Institutes of Health [R01GM130769, DGE 1144085]
- National Science Foundation [DMR-1807327]
- Simons Foundation [SF349247]
- NIH National Institute of General Medical Sciences [GM103310]
- University of California, Santa Barbara
- University of California, Office of the President
Poly(ethylene glycol) (PEG) is a polymer used widely in drug delivery to create stealth nanoparticles (NPs); PEG coatings suppress NP detection and clearance by the immune system and beneficially increase NP circulation time in vivo. However, NP PEGylation typically obstructs cell attachment and uptake in vitro compared to the uncoated equivalent. Here, we report on a cationic liposome (CL) NP system loaded with the hydrophobic cancer drug paclitaxel (PTX) in which PEGylation (i.e., PEG-CLPTX NPs) unexpectedly enhances, rather than diminishes, delivery efficacy and cytotoxicity to human cancer cells. This highly unexpected enhancement occurs even when the PEG-chains coating the NP are in the transition regime between the mushroom and brush conformations. Cryogenic transmission electron microscopy (TEM) of PEG-CLPTX NPs shows that PEG causes the proliferation of a mixture of sterically stabilized nanometer-scale vesicles and anisotropic micelles (e.g., bicelles). Remarkably, the onset of bicelles at sub-monolayer concentrations of the PEG coat has to our knowledge not been previously reported; it was previously thought that PEG-lipid in this composition regime was incorporated into vesicles but did not alter their shape. Confocal microscopy and flow cytometry reveal significantly greater PTX cell uptake from stabilized PEG-CLPTX NPs (vesicles and bicelles) in contrast to bare CLPTX NPs, which can aggregate in cell medium. This underscores the ability of steric stabilization to facilitate NP entry into cells via distinct size-dependent endocytic pathways, some of which cannot transport large NP aggregates into cells. This study highlights the value of understanding how PEGylation alters NP shape and structure, and thus NP efficacy, to design next-generation stealth drug carriers that integrate active cell targeting strategies into NPs for in vivo delivery.
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