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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.


a Phase contrast image of NP-labeled HeLa cells. b Nanophosphor emission captured by FITC long-pass emission filter, which includes the red spectral region. c DAPI emission identifying cell nuclei. d overlay of b and c.
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Figure 7: a Phase contrast image of NP-labeled HeLa cells. b Nanophosphor emission captured by FITC long-pass emission filter, which includes the red spectral region. c DAPI emission identifying cell nuclei. d overlay of b and c.

Mentions: To visualize the luminescence of these NPs on the cellular level, La(OH)3:Eu3+ NP labeled HeLa cells were seeded on microscope cover slips and imaged with a fluorescence microscope (Figure 7a–d). In this in vitro fluorescence microscopy experiment, HeLa cells were stained with DAPI to identify the cell nucleus (Figure 7b, blue), while the NPs were visualized with a FITC excitation (420–490 nm)/emission (515 nm long pass) filter set (Figure 7c, green). The emission of the probes localization in the cell cytoplasm, likely within the endosomal or lysosomal compartments, demonstrates their ability to serve as optical imaging bioprobes. In addition, after incubation with the NPs, no changes in cell morphology or other visual signs of cytotoxicity were observed in the phase contrast images (Figure 7a).


Facile Synthesis of Amine-Functionalized Eu 3+ -Doped La(OH) 3 Nanophosphors for Bioimaging
a Phase contrast image of NP-labeled HeLa cells. b Nanophosphor emission captured by FITC long-pass emission filter, which includes the red spectral region. c DAPI emission identifying cell nuclei. d overlay of b and c.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 7: a Phase contrast image of NP-labeled HeLa cells. b Nanophosphor emission captured by FITC long-pass emission filter, which includes the red spectral region. c DAPI emission identifying cell nuclei. d overlay of b and c.
Mentions: To visualize the luminescence of these NPs on the cellular level, La(OH)3:Eu3+ NP labeled HeLa cells were seeded on microscope cover slips and imaged with a fluorescence microscope (Figure 7a–d). In this in vitro fluorescence microscopy experiment, HeLa cells were stained with DAPI to identify the cell nucleus (Figure 7b, blue), while the NPs were visualized with a FITC excitation (420–490 nm)/emission (515 nm long pass) filter set (Figure 7c, green). The emission of the probes localization in the cell cytoplasm, likely within the endosomal or lysosomal compartments, demonstrates their ability to serve as optical imaging bioprobes. In addition, after incubation with the NPs, no changes in cell morphology or other visual signs of cytotoxicity were observed in the phase contrast images (Figure 7a).

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.