Abstract
Semiconductor quantum dots (QDs) have shown great promise as fluorescent probes for molecular, cellular and in vivo imaging. However, the fluorescence of traditional polymer-encapsulated QDs is often quenched by proton-induced etching in acidic environments. This is a major problem for applications of QDs in the gastrointestinal tract because the gastric (stomach) environment is strongly acidic (pH 1–2). Here we report the use of proton-resistant surface coatings to stabilize QD fluorescence under acidic conditions. Using both hyperbranched polyethylenimine (PEI) and its polyethylene glycol derivative (PEG-grafted PEI), we show that the fluorescence of core shell CdSe /CdS/ ZnS QDs is effectively protected from quenching in simulated gastric fluids. In comparison, amphiphilic lipid or polymer coatings provide no protection under similarly acidic conditions. The proton-resistant QDs are found to cause moderate membrane damage to cultured epithelial cells, but PEGylation (PEG grafting) can be used to reduce cellular toxicity and to improve nanoparticle stability. [Figure not available: see fulltext.]
Original language | English (US) |
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Pages (from-to) | 500-508 |
Number of pages | 9 |
Journal | Nano Research |
Volume | 2 |
Issue number | 6 |
DOIs | |
State | Published - Jun 2009 |
Externally published | Yes |
Keywords
- Nanoparticle
- gastrointestinal
- oral delivery
- polyethylene glycol (PEG)
- polyethylenimine (PEI)
- quantum dot
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- General Materials Science
- Condensed Matter Physics
- Electrical and Electronic Engineering