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3D visualization of additive occlusion and tunable full-spectrum fluorescence in calcite

View Article: PubMed Central - PubMed

ABSTRACT

From biomineralization to synthesis, organic additives provide an effective means of controlling crystallization processes. There is growing evidence that these additives are often occluded within the crystal lattice. This promises an elegant means of creating nanocomposites and tuning physical properties. Here we use the incorporation of sulfonated fluorescent dyes to gain new understanding of additive occlusion in calcite (CaCO3), and to link morphological changes to occlusion mechanisms. We demonstrate that these additives are incorporated within specific zones, as defined by the growth conditions, and show how occlusion can govern changes in crystal shape. Fluorescence spectroscopy and lifetime imaging microscopy also show that the dyes experience unique local environments within different zones. Our strategy is then extended to simultaneously incorporate mixtures of dyes, whose fluorescence cascade creates calcite nanoparticles that fluoresce white. This offers a simple strategy for generating biocompatible and stable fluorescent nanoparticles whose output can be tuned as required.

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FLIM analysis of GREEN/calcite composites.Samples prepared under (a–d) [Ca2+]=[CO32−]=10 mM and (e–h) 2.5 mM conditions were characterized by (a,e) optical and (b,f) CFM. (c,g) FLIM analysis of the same plane as that in the confocal image revealed regions of differing fluorescence lifetime. (d,h) Global fluorescence decays obtained from the regions of interest labelled in (c,g) yielded fluorescence lifetimes (d) 1=4.1 ns and 2=3.2 ns, and (h) 1=2.9 ns, 2=2.3 ns and 3=3.1 ns. Scale bars, 10 μm (a–c,e–g).
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f5: FLIM analysis of GREEN/calcite composites.Samples prepared under (a–d) [Ca2+]=[CO32−]=10 mM and (e–h) 2.5 mM conditions were characterized by (a,e) optical and (b,f) CFM. (c,g) FLIM analysis of the same plane as that in the confocal image revealed regions of differing fluorescence lifetime. (d,h) Global fluorescence decays obtained from the regions of interest labelled in (c,g) yielded fluorescence lifetimes (d) 1=4.1 ns and 2=3.2 ns, and (h) 1=2.9 ns, 2=2.3 ns and 3=3.1 ns. Scale bars, 10 μm (a–c,e–g).

Mentions: GREEN/calcite crystals were also investigated using FLIM to gain information about the local environment of the dye within the crystal lattice (Fig. 5). FLIM was conducted on GREEN/calcite crystals prepared from [Ca2+]=[CO32−]=10 (Fig. 5a–d) and 2.5 mM (Fig. 5e–h), with [GREEN]/[Ca2+]=0.02. Rhombohedral crystals formed under both sets of conditions, where the 10 mM samples were primarily (001) oriented (Fig. 5a). CFM micrographs revealed different patterns of dye distribution, where the crystals precipitated from 10 mM reagents exhibited more intense fluorescence at the centre of the crystal as compared with the vertices and edges, and an internal cross pattern (Fig. 5b). Those formed at 2.5 mM, in contrast, exhibit preferential location of the dye in one-half of the crystal only. In addition, the crystal shown in Fig. 5f shows that dye is concentrated beneath the small, new triangular faces formed at the crystal vertices.


3D visualization of additive occlusion and tunable full-spectrum fluorescence in calcite
FLIM analysis of GREEN/calcite composites.Samples prepared under (a–d) [Ca2+]=[CO32−]=10 mM and (e–h) 2.5 mM conditions were characterized by (a,e) optical and (b,f) CFM. (c,g) FLIM analysis of the same plane as that in the confocal image revealed regions of differing fluorescence lifetime. (d,h) Global fluorescence decays obtained from the regions of interest labelled in (c,g) yielded fluorescence lifetimes (d) 1=4.1 ns and 2=3.2 ns, and (h) 1=2.9 ns, 2=2.3 ns and 3=3.1 ns. Scale bars, 10 μm (a–c,e–g).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC5120221&req=5

f5: FLIM analysis of GREEN/calcite composites.Samples prepared under (a–d) [Ca2+]=[CO32−]=10 mM and (e–h) 2.5 mM conditions were characterized by (a,e) optical and (b,f) CFM. (c,g) FLIM analysis of the same plane as that in the confocal image revealed regions of differing fluorescence lifetime. (d,h) Global fluorescence decays obtained from the regions of interest labelled in (c,g) yielded fluorescence lifetimes (d) 1=4.1 ns and 2=3.2 ns, and (h) 1=2.9 ns, 2=2.3 ns and 3=3.1 ns. Scale bars, 10 μm (a–c,e–g).
Mentions: GREEN/calcite crystals were also investigated using FLIM to gain information about the local environment of the dye within the crystal lattice (Fig. 5). FLIM was conducted on GREEN/calcite crystals prepared from [Ca2+]=[CO32−]=10 (Fig. 5a–d) and 2.5 mM (Fig. 5e–h), with [GREEN]/[Ca2+]=0.02. Rhombohedral crystals formed under both sets of conditions, where the 10 mM samples were primarily (001) oriented (Fig. 5a). CFM micrographs revealed different patterns of dye distribution, where the crystals precipitated from 10 mM reagents exhibited more intense fluorescence at the centre of the crystal as compared with the vertices and edges, and an internal cross pattern (Fig. 5b). Those formed at 2.5 mM, in contrast, exhibit preferential location of the dye in one-half of the crystal only. In addition, the crystal shown in Fig. 5f shows that dye is concentrated beneath the small, new triangular faces formed at the crystal vertices.

View Article: PubMed Central - PubMed

ABSTRACT

From biomineralization to synthesis, organic additives provide an effective means of controlling crystallization processes. There is growing evidence that these additives are often occluded within the crystal lattice. This promises an elegant means of creating nanocomposites and tuning physical properties. Here we use the incorporation of sulfonated fluorescent dyes to gain new understanding of additive occlusion in calcite (CaCO3), and to link morphological changes to occlusion mechanisms. We demonstrate that these additives are incorporated within specific zones, as defined by the growth conditions, and show how occlusion can govern changes in crystal shape. Fluorescence spectroscopy and lifetime imaging microscopy also show that the dyes experience unique local environments within different zones. Our strategy is then extended to simultaneously incorporate mixtures of dyes, whose fluorescence cascade creates calcite nanoparticles that fluoresce white. This offers a simple strategy for generating biocompatible and stable fluorescent nanoparticles whose output can be tuned as required.

No MeSH data available.


Related in: MedlinePlus