Early Stages of Crystallization of Calcium Carbonate Revealed in Picoliter Droplets

Stephens, Christopher J.; Kim, Yi‐Yeoun; Evans, Stephen D.; Meldrum, Fiona C.; Christenson, Hugo K.

doi:10.1021/ja200309m

Cited by 107 publications

(111 citation statements)

References 30 publications

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“…Arrays of picolitre droplets formed on patterned self-assembled monolayers (SAMs) in contrast have provided an opportunity to study heterogeneous nucleation in confined volumes. 12 As an elegant way of producing droplets under highly controlled conditions, microfluidic systems are also beginning to be explored as platforms for the study of crystal nucleation and growth in general. 13 They provide excellent spatial and temporal control of temperature, pressure, pH, and reagent concentration and can be used to generate segmented flows, allowing the formation of monodisperse, pL-volume droplets at kHz rates.…”

Section: Introductionmentioning

confidence: 99%

Calcium carbonate polymorph control using droplet-based microfluidics

2012

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Calcium carbonate (CaCO 3 ) is one of the most abundant minerals and of high importance in many areas of science including global CO 2 exchange, industrial water treatment energy storage, and the formation of shells and skeletons. Industrially, calcium carbonate is also used in the production of cement, glasses, paints, plastics, rubbers, ceramics, and steel, as well as being a key material in oil refining and iron ore purification. CaCO 3 displays a complex polymorphic behaviour which, despite numerous experiments, remains poorly characterised. In this paper, we report the use of a segmented-flow microfluidic reactor for the controlled precipitation of calcium carbonate and compare the resulting crystal properties with those obtained using both continuous flow microfluidic reactors and conventional bulk methods. Through combination of equal volumes of equimolar aqueous solutions of calcium chloride and sodium carbonate on the picoliter scale, it was possible to achieve excellent definition of both crystal size and size distribution. Furthermore, highly reproducible control over crystal polymorph could be realised, such that pure calcite, pure vaterite, or a mixture of calcite and vaterite could be precipitated depending on the reaction conditions and dropletvolumes employed. In contrast, the crystals precipitated in the continuous flow and bulk systems comprised of a mixture of calcite and vaterite and exhibited a broad distribution of sizes for all reaction conditions investigated.

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Section: Introductionmentioning

confidence: 99%

Calcium carbonate polymorph control using droplet-based microfluidics

2012

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“…However, no evidence for a direct transformation of ACC into calcite had been obtained, which led to the suggestion that this mechanism is unlikely 8. A recent study of the transformation of ACC in picoliter droplets on SAMs, in contrast, indicated a direct transformation of ACC into calcite 4d. The hypothesis that ACC crystallization is initiated at the ACC/water interface was also supported by another recent study, which showed that ACC dehydrates before crystallizing, even in solution, and that the loss of the final water fraction coincides with crystallization 15a.…”

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confidence: 99%

The Effect of Additives on the Early Stages of Growth of Calcite Single Crystals

et al. 2017

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As crystallization processes are often rapid, it can be difficult to monitor their growth mechanisms. In this study, we made use of the fact that crystallization proceeds more slowly in small volumes than in bulk solution to investigate the effects of the soluble additives Mg2+ and poly(styrene sulfonate) (PSS) on the early stages of growth of calcite crystals. Using a “Crystal Hotel” microfluidic device to provide well‐defined, nanoliter volumes, we observed that calcite crystals form via an amorphous precursor phase. Surprisingly, the first calcite crystals formed are perfect rhombohedra, and the soluble additives have no influence on the morphology until the crystals reach sizes of 0.1–0.5 μm for Mg2+ and 1–2 μm for PSS. The crystals then continue to grow to develop morphologies characteristic of these additives. These results can be rationalized by considering additive binding to kink sites, which is consistent with crystal growth by a classical mechanism.

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“…The sizes of the confined reaction environments, which vary among vesicles within the emulsion used for this study (21), can have a significant impact on both enzymatic activity (21) and mineralization (35). Such variable effects, in combination with the heterogeneous distribution of metal impurities, may contribute to the compositional chemical diversity of the crystalline phases.…”

Section: Resultsmentioning

confidence: 99%

Evolutionary selection of enzymatically synthesized semiconductors from biomimetic mineralization vesicles

Bawazer

Izumi

Kolodin

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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The way nature evolves and sculpts materials using proteins inspires new approaches to materials engineering but is still not completely understood. Here, we present a cell-free synthetic biological platform to advance studies of biologically synthesized solid-state materials. This platform is capable of simultaneously exerting many of the hierarchical levels of control found in natural biomineralization, including genetic, chemical, spatial, structural, and morphological control, while supporting the evolutionary selection of new mineralizing proteins and the corresponding genetically encoded materials that they produce. DNA-directed protein expression and enzymatic mineralization occur on polystyrene microbeads in waterin-oil emulsions, yielding synthetic surrogates of biomineralizing cells that are then screened by flow sorting, with light-scattering signals used to sort the resulting mineralized composites differentially. We demonstrate the utility of this platform by evolutionarily selecting newly identified silicateins, biomineralizing enzymes previously identified from the silica skeleton of a marine sponge, for enzyme variants capable of synthesizing silicon dioxide (silica) or titanium dioxide (titania) composites. Mineral composites of intermediate strength are preferentially selected to remain intact for identification during cell sorting, and then to collapse postsorting to expose the encoding genes for enzymatic DNA amplification. Some of the newly selected silicatein variants catalyze the formation of crystalline silicates, whereas the parent silicateins lack this ability. The demonstrated bioengineered route to previously undescribed materials introduces in vitro enzyme selection as a viable strategy for mimicking genetic evolution of materials as it occurs in nature. directed evolution | in vitro compartmentalization | DNA shuffling | metal oxide nanoparticles | self-assembly

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Early Stages of Crystallization of Calcium Carbonate Revealed in Picoliter Droplets

Cited by 107 publications

References 30 publications

Calcium carbonate polymorph control using droplet-based microfluidics

Calcium carbonate polymorph control using droplet-based microfluidics

The Effect of Additives on the Early Stages of Growth of Calcite Single Crystals

Evolutionary selection of enzymatically synthesized semiconductors from biomimetic mineralization vesicles

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