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Facile Synthesis of Amine-Functionalized Eu 3+ -Doped La(OH) 3 Nanophosphors for Bioimaging

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ABSTRACT

Here, we report a straightforward synthesis process to produce colloidal Eu3+-activated nanophosphors (NPs) for use as bioimaging probes. In this procedure, poly(ethylene glycol) serves as a high-boiling point solvent allowing for nanoscale particle formation as well as a convenient medium for solvent exchange and subsequent surface modification. The La(OH)3:Eu3+ NPs produced by this process were ~3.5 nm in diameter as determined by transmission electron microscopy. The NP surface was coated with aminopropyltriethoxysilane to provide chemical functionality for attachment of biological ligands, improve chemical stability and prevent surface quenching of luminescent centers. Photoluminescence spectroscopy of the NPs displayed emission peaks at 597 and 615 nm (λex = 280 nm). The red emission, due to 5D0 → 7F1 and 5D0 → 7F2 transitions, was linear with concentration as observed by imaging with a conventional bioimaging system. To demonstrate the feasibility of these NPs to serve as optical probes in biological applications, an in vitro experiment was performed with HeLa cells. NP emission was observed in the cells by fluorescence microscopy. In addition, the NPs displayed no cytotoxicity over the course of a 48-h MTT cell viability assay. These results suggest that La(OH)3:Eu3+ NPs possess the potential to serve as a luminescent bioimaging probe.

No MeSH data available.


Fluorescence images of HeLa cell pellets containing ~106 cells, control (left) and NP labeled (right), acquired with a conventional bioimaging system (Xenogen IVIS Illumina).
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Figure 6: Fluorescence images of HeLa cell pellets containing ~106 cells, control (left) and NP labeled (right), acquired with a conventional bioimaging system (Xenogen IVIS Illumina).

Mentions: Fluorescence labeling and optical detection of molecular interactions has become an indispensable tool in biology. To demonstrate the efficacy of the amine-functionalized La(OH)3:Eu3+ NPs to serve as a luminescent probe under biological conditions, an in vitro imaging experiment was performed with human cervical cancer HeLa cells. In this assay, cells were labeled with APTES-coated NPs via charge interaction between the positive amine terminal groups and negatively charged cell membrane. In addition, non-specific uptake of NPs was likely due to the high incubation concentration (100 μg/mL) and extended incubation times (4 h). After the NP incubation, the cells were washed, cleaved, and centrifuged. The resulting cell pellet containing ~ 106 cells and a control sample w/o NPs were imaged with the IVIS Illumina imaging system (Figure 6). The successful fluorescent labeling of the cells with NPs was observed by the red emission in comparison with control cells.


Facile Synthesis of Amine-Functionalized Eu 3+ -Doped La(OH) 3 Nanophosphors for Bioimaging
Fluorescence images of HeLa cell pellets containing ~106 cells, control (left) and NP labeled (right), acquired with a conventional bioimaging system (Xenogen IVIS Illumina).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211300&req=5

Figure 6: Fluorescence images of HeLa cell pellets containing ~106 cells, control (left) and NP labeled (right), acquired with a conventional bioimaging system (Xenogen IVIS Illumina).
Mentions: Fluorescence labeling and optical detection of molecular interactions has become an indispensable tool in biology. To demonstrate the efficacy of the amine-functionalized La(OH)3:Eu3+ NPs to serve as a luminescent probe under biological conditions, an in vitro imaging experiment was performed with human cervical cancer HeLa cells. In this assay, cells were labeled with APTES-coated NPs via charge interaction between the positive amine terminal groups and negatively charged cell membrane. In addition, non-specific uptake of NPs was likely due to the high incubation concentration (100 μg/mL) and extended incubation times (4 h). After the NP incubation, the cells were washed, cleaved, and centrifuged. The resulting cell pellet containing ~ 106 cells and a control sample w/o NPs were imaged with the IVIS Illumina imaging system (Figure 6). The successful fluorescent labeling of the cells with NPs was observed by the red emission in comparison with control cells.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Here, we report a straightforward synthesis process to produce colloidal Eu3+-activated nanophosphors (NPs) for use as bioimaging probes. In this procedure, poly(ethylene glycol) serves as a high-boiling point solvent allowing for nanoscale particle formation as well as a convenient medium for solvent exchange and subsequent surface modification. The La(OH)3:Eu3+ NPs produced by this process were ~3.5 nm in diameter as determined by transmission electron microscopy. The NP surface was coated with aminopropyltriethoxysilane to provide chemical functionality for attachment of biological ligands, improve chemical stability and prevent surface quenching of luminescent centers. Photoluminescence spectroscopy of the NPs displayed emission peaks at 597 and 615 nm (λex = 280 nm). The red emission, due to 5D0 → 7F1 and 5D0 → 7F2 transitions, was linear with concentration as observed by imaging with a conventional bioimaging system. To demonstrate the feasibility of these NPs to serve as optical probes in biological applications, an in vitro experiment was performed with HeLa cells. NP emission was observed in the cells by fluorescence microscopy. In addition, the NPs displayed no cytotoxicity over the course of a 48-h MTT cell viability assay. These results suggest that La(OH)3:Eu3+ NPs possess the potential to serve as a luminescent bioimaging probe.

No MeSH data available.