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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.

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a Nanophosphor (NP) size and morphology was evaluated by transmission electron microscopy (TEM). b Particle size distribution of NPs as determined by TEM. c XRD pattern of the NPs.
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Figure 2: a Nanophosphor (NP) size and morphology was evaluated by transmission electron microscopy (TEM). b Particle size distribution of NPs as determined by TEM. c XRD pattern of the NPs.

Mentions: The overall NP synthesis and functionalization process is illustrated in Figure 1. This straightforward procedure can be carried out with general chemistry laboratory equipment and utilizes relatively low-cost reagents. In this study, the size and morphology of the NPs produced by this process were analyzed by TEM. As shown in Figure 2a, NPs are roughly spherical in shape with a mean diameter of ~3.5 nm. Measurement of particle size with the NIH ImageJ image software package displayed good uniformity and narrow size distribution (Figure 2b) of the NPs, which are significant advantages of the synthesis procedure. The size of these NPs is on the order of biomacromolecules, such as cell-surface receptors or antigens, making them ideal for molecular imaging applications. In this size range, the NPs can also be taken up by cells via endocytotic vesicles, which are typically 40–60 nm in diameter [23]. Furthermore, the small size of these NPs opens the potential for in vivo applications by overcoming the size restriction of biological barriers [24,25] and allowing for clearance to minimize long-term toxicity [26,27].


Facile Synthesis of Amine-Functionalized Eu 3+ -Doped La(OH) 3 Nanophosphors for Bioimaging
a Nanophosphor (NP) size and morphology was evaluated by transmission electron microscopy (TEM). b Particle size distribution of NPs as determined by TEM. c XRD pattern of the NPs.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: a Nanophosphor (NP) size and morphology was evaluated by transmission electron microscopy (TEM). b Particle size distribution of NPs as determined by TEM. c XRD pattern of the NPs.
Mentions: The overall NP synthesis and functionalization process is illustrated in Figure 1. This straightforward procedure can be carried out with general chemistry laboratory equipment and utilizes relatively low-cost reagents. In this study, the size and morphology of the NPs produced by this process were analyzed by TEM. As shown in Figure 2a, NPs are roughly spherical in shape with a mean diameter of ~3.5 nm. Measurement of particle size with the NIH ImageJ image software package displayed good uniformity and narrow size distribution (Figure 2b) of the NPs, which are significant advantages of the synthesis procedure. The size of these NPs is on the order of biomacromolecules, such as cell-surface receptors or antigens, making them ideal for molecular imaging applications. In this size range, the NPs can also be taken up by cells via endocytotic vesicles, which are typically 40–60 nm in diameter [23]. Furthermore, the small size of these NPs opens the potential for in vivo applications by overcoming the size restriction of biological barriers [24,25] and allowing for clearance to minimize long-term toxicity [26,27].

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.


Related in: MedlinePlus