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A comparative study of non-covalent encapsulation methods for organic dyes into silica nanoparticles.

Auger A, Samuel J, Poncelet O, Raccurt O - Nanoscale Res Lett (2011)

Bottom Line: Nevertheless, the behaviour and effect of such luminescent molecules appear to have been much less studied and may possibly prevent the encapsulation process from occurring.Mainly, the photophysical characteristics of the dyes are retained upon their encapsulation into the silica matrix, leading to fluorescent silica nanoparticles.This feature article surveys recent research progress on the fabrication strategies of these dye-doped silica nanoparticles.

View Article: PubMed Central - HTML - PubMed

Affiliation: CEA Grenoble, Department of Nano Materials, NanoChemistry and NanoSafety Laboratory (DRT/LITEN/DTNM/LCSN), 17 rue des Martyrs, 38054 Grenoble Cedex 9, France. aurelien.auger@cea.fr.

ABSTRACT
Numerous luminophores may be encapsulated into silica nanoparticles (< 100 nm) using the reverse microemulsion process. Nevertheless, the behaviour and effect of such luminescent molecules appear to have been much less studied and may possibly prevent the encapsulation process from occurring. Such nanospheres represent attractive nanoplatforms for the development of biotargeted biocompatible luminescent tracers. Physical and chemical properties of the encapsulated molecules may be affected by the nanomatrix. This study examines the synthesis of different types of dispersed silica nanoparticles, the ability of the selected luminophores towards incorporation into the silica matrix of those nanoobjects as well as the photophysical properties of the produced dye-doped silica nanoparticles. The nanoparticles present mean diameters between 40 and 60 nm as shown by TEM analysis. Mainly, the photophysical characteristics of the dyes are retained upon their encapsulation into the silica matrix, leading to fluorescent silica nanoparticles. This feature article surveys recent research progress on the fabrication strategies of these dye-doped silica nanoparticles.

No MeSH data available.


Excitation and emission spectra of aqueous solutions of (left) fluorescein and silica nanoparticles doped with fluorescein 1 h, and (right) rhodamine B and silica nanoparticles doped with rhodamine B 1g.
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Figure 4: Excitation and emission spectra of aqueous solutions of (left) fluorescein and silica nanoparticles doped with fluorescein 1 h, and (right) rhodamine B and silica nanoparticles doped with rhodamine B 1g.

Mentions: Furthermore, fluorescein and rhodamine B were successfully encapsulated by the method 1. The fluorescence data, excitation and emission wavelengths, observed for sample 1 h were identical to those recorded for a solution of free fluorescein in water as illustrated in Figure 4. Indeed, the fluorescence maximum, at 513 nm upon an excitation at 488 nm for sample 1 h, indicated that the fluorescein had been encapsulated into the silica nanoparticles. A freshly prepared solution of fluorescein into water also exhibited maxima excitation and emission wavelengths at 486 and 513 nm, respectively. The same phenomena were observed for the sample 1g consisting of rhodamine B encapsulated into silica nanoparticles. Both, the aqueous solutions of free rhodamine B and of sample 1g displayed maxima excitation and emission wavelengths at 555 and 577 nm, respectively. A slight shift and different shapes in the excitation band of the fluorescein was observed which is attributed to the incorporation of the fluorescent dye and its interaction with the silica network. Those results indicated that the silica encapsulation by microemulsion was suitable for encapsulation of hydrophilic chromophores and was consistent with the literature [15,51-54]. It was therefore decided after those fluorescence measurements (Figure 4) that no better encapsulation could be achieved by other processes and no further investigation of those two dyes were tested. It was also important to notice that non-covalent encapsulation of those dyes has been reported earlier on in the literature [52].


A comparative study of non-covalent encapsulation methods for organic dyes into silica nanoparticles.

Auger A, Samuel J, Poncelet O, Raccurt O - Nanoscale Res Lett (2011)

Excitation and emission spectra of aqueous solutions of (left) fluorescein and silica nanoparticles doped with fluorescein 1 h, and (right) rhodamine B and silica nanoparticles doped with rhodamine B 1g.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211415&req=5

Figure 4: Excitation and emission spectra of aqueous solutions of (left) fluorescein and silica nanoparticles doped with fluorescein 1 h, and (right) rhodamine B and silica nanoparticles doped with rhodamine B 1g.
Mentions: Furthermore, fluorescein and rhodamine B were successfully encapsulated by the method 1. The fluorescence data, excitation and emission wavelengths, observed for sample 1 h were identical to those recorded for a solution of free fluorescein in water as illustrated in Figure 4. Indeed, the fluorescence maximum, at 513 nm upon an excitation at 488 nm for sample 1 h, indicated that the fluorescein had been encapsulated into the silica nanoparticles. A freshly prepared solution of fluorescein into water also exhibited maxima excitation and emission wavelengths at 486 and 513 nm, respectively. The same phenomena were observed for the sample 1g consisting of rhodamine B encapsulated into silica nanoparticles. Both, the aqueous solutions of free rhodamine B and of sample 1g displayed maxima excitation and emission wavelengths at 555 and 577 nm, respectively. A slight shift and different shapes in the excitation band of the fluorescein was observed which is attributed to the incorporation of the fluorescent dye and its interaction with the silica network. Those results indicated that the silica encapsulation by microemulsion was suitable for encapsulation of hydrophilic chromophores and was consistent with the literature [15,51-54]. It was therefore decided after those fluorescence measurements (Figure 4) that no better encapsulation could be achieved by other processes and no further investigation of those two dyes were tested. It was also important to notice that non-covalent encapsulation of those dyes has been reported earlier on in the literature [52].

Bottom Line: Nevertheless, the behaviour and effect of such luminescent molecules appear to have been much less studied and may possibly prevent the encapsulation process from occurring.Mainly, the photophysical characteristics of the dyes are retained upon their encapsulation into the silica matrix, leading to fluorescent silica nanoparticles.This feature article surveys recent research progress on the fabrication strategies of these dye-doped silica nanoparticles.

View Article: PubMed Central - HTML - PubMed

Affiliation: CEA Grenoble, Department of Nano Materials, NanoChemistry and NanoSafety Laboratory (DRT/LITEN/DTNM/LCSN), 17 rue des Martyrs, 38054 Grenoble Cedex 9, France. aurelien.auger@cea.fr.

ABSTRACT
Numerous luminophores may be encapsulated into silica nanoparticles (< 100 nm) using the reverse microemulsion process. Nevertheless, the behaviour and effect of such luminescent molecules appear to have been much less studied and may possibly prevent the encapsulation process from occurring. Such nanospheres represent attractive nanoplatforms for the development of biotargeted biocompatible luminescent tracers. Physical and chemical properties of the encapsulated molecules may be affected by the nanomatrix. This study examines the synthesis of different types of dispersed silica nanoparticles, the ability of the selected luminophores towards incorporation into the silica matrix of those nanoobjects as well as the photophysical properties of the produced dye-doped silica nanoparticles. The nanoparticles present mean diameters between 40 and 60 nm as shown by TEM analysis. Mainly, the photophysical characteristics of the dyes are retained upon their encapsulation into the silica matrix, leading to fluorescent silica nanoparticles. This feature article surveys recent research progress on the fabrication strategies of these dye-doped silica nanoparticles.

No MeSH data available.