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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.


MTT cell viability assay of MCF7 cells incubated with various concentrations of NPs over a 12 h, b 24 h and c 48 h.
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Figure 8: MTT cell viability assay of MCF7 cells incubated with various concentrations of NPs over a 12 h, b 24 h and c 48 h.

Mentions: To further investigate the biocompatibility of the APTES-coated La(OH)3:Eu3+ NPs, these NPs were evaluated with human breast adenocarcinoma MCF7 cells as a model cell line. The cells were grown for intervals of 12, 24 and 48 h with a NP concentration range typically used in biological assays (0, 0.1, 1.0, 10 and 100 μg/mL). Cell proliferation was monitored with a MTT assay in which the reduction of a yellow tetrazolium salt in metabolically active cells forms purple formazan crystals [38]. The spectroscopic quantification of the formazan corresponds with cellular viability shown in Figure 8a–c. In this assay, no significant cytotoxicity was observed over the concentration entire range tested during the 48 h of the experiment. These results suggest that amine-functionalized La(OH)3:Eu3+ NPs may potentially serve as optical contrast agents for bioimaging.


Facile Synthesis of Amine-Functionalized Eu 3+ -Doped La(OH) 3 Nanophosphors for Bioimaging
MTT cell viability assay of MCF7 cells incubated with various concentrations of NPs over a 12 h, b 24 h and c 48 h.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 8: MTT cell viability assay of MCF7 cells incubated with various concentrations of NPs over a 12 h, b 24 h and c 48 h.
Mentions: To further investigate the biocompatibility of the APTES-coated La(OH)3:Eu3+ NPs, these NPs were evaluated with human breast adenocarcinoma MCF7 cells as a model cell line. The cells were grown for intervals of 12, 24 and 48 h with a NP concentration range typically used in biological assays (0, 0.1, 1.0, 10 and 100 μg/mL). Cell proliferation was monitored with a MTT assay in which the reduction of a yellow tetrazolium salt in metabolically active cells forms purple formazan crystals [38]. The spectroscopic quantification of the formazan corresponds with cellular viability shown in Figure 8a–c. In this assay, no significant cytotoxicity was observed over the concentration entire range tested during the 48 h of the experiment. These results suggest that amine-functionalized La(OH)3:Eu3+ NPs may potentially serve as optical contrast agents for bioimaging.

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.