Crystal defects induced by chitin and chitinolytic enzymes in the prismatic layer of Pinctada fucata

Kintsu, Hiroyuki; Okumura, Taiga; Negishi, Lumi; Ifuku, Shinsuke; Kogure, Toshihiro; Sakuda, Shohei; Suzuki, Michio

doi:10.1016/j.bbrc.2017.05.088

Cited by 33 publications

(22 citation statements)

References 32 publications

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“…Inspired by the sandwich-like structure of nacre [7,8], considerable effort has been devoted to in vitro biomimetic mineralization experiments in an effort to fabricate composite materials that are similar to nacre or to reveal the mechanism of biomineralization. The most common approach for these experiments is to use various substrates, such as chitin [15][16][17], collagen, silk fibroin [18][19][20], fibrous protein, gelatin [21][22][23][24], and nacre [25][26][27], to modulate the formation of CaCO 3 polymorphs. Furthermore, nacre protein with or without chitin has been used to induce CaCO 3 growth for an improved understanding of the interactions between crystals and proteins [6,[28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Gelatinous Siphon Sheath Templates the Starfruit-Shaped Aragonite Aggregate Growth

Huang

Zhang

Tan

2019

Journal of Nanomaterials

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Biomimetic synthesis of aragonite with various templates in vitro is an important way to understand the biomineralization process and synthesize nacre-like materials. Herein, we used the siphon sheath from the bivalve Lutraria sieboldii as the substrate for the formation of calcium carbonate. We found that the inner layer of the sheath, which is composed of approximately 40% protein and 60% β-chitin, induced the formation of nearly pure aragonite by the transformation of amorphous calcium carbonate (ACC). More surprisingly, unique starfruit-shaped aragonite aggregates were observed on the substrate and were constructed from many adhered, oriented aragonite tablets. We consider that the acid-rich protein from the inner layer of the siphon sheath triggers the formation of ACC, and the swollen β-chitin regulates the transformation of ACC into aragonite by lattice matching and stereochemical recognition. The various surface adhesion energies of the crystal, the change in growth rates on different crystallographic facets, and the hexagonal features of the aragonite tablets led to the formation of starfruit-shaped aragonite aggregates.

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Section: Introductionmentioning

confidence: 99%

Gelatinous Siphon Sheath Templates the Starfruit-Shaped Aragonite Aggregate Growth

Huang

Zhang

Tan

2019

Journal of Nanomaterials

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“…The location of the organic network correlates with the location of the crystal defects, indicating that the organic network affects the formation of the crystal defects. Our previous report clarified chitin and chitinolytic enzyme as the components of this organic network (Kintsu et al 2017), in which we indicated that the chitin treated by chitinolytic enzymes may induce the formation of crystal defects.…”

Section: Introductionmentioning

confidence: 76%

Chitin Degraded by Chitinolytic Enzymes Induces Crystal Defects of Calcites

et al. 2018

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Mollusk shells have unique microstructures and mechanical properties such as hardness and flexibility. Calcite in the prismatic layer of P. fucata is extremely tough due to small crystal defects and localized organic networks inside calcites. Electron microscopic observations have suggested that such crystal defects are caused by the organic networks during calcite formation. Our previous work reported that the chitin which is the main component of organic networks and chitinolytic enzymes that bind to chitin were identified. In this article, to investigate the effects of chitin and chitinolytic enzymes on the formation of calcites, calcites were synthesized in chitin gel after treatment with chitinolytic enzymes. Chitin fibers seemed to become smooth and loosened after degradation. The crystal defects became larger as the chitin fibers became more degraded by chitinolytic enzymes in a dose-dependent manner. These results suggest that the shape of chitin fiber, which is regulated by the degradation of chitinolytic enzymes, contributes to the formation of small crystal defects.

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“…Single calcite crystals were grown in the presence of chitin hydrogel and chitin nanofibers [6] ( Figure 1a). For the calcite precipitation in chitin hydrogel, the hydrogel was prepared as follows [6]: 2 mg of chitin (nacalai) was added to 100 mL of methanol saturated with calcium chloride dehydrate (Kanto Chemical, Tokyo, Japan), and stirred for several hours. Two liters of 10 mM calcium chloride solution was added to the chitin solution under vigorous stirring, then the precipitated chitin hydrogel was washed 3 times with a 10 mM calcium chloride solution to remove the methanol.…”

Section: Methodsmentioning

confidence: 99%

“…This plate was put into desiccator filled with the gas of 5 g of ammonium carbonate (Kanto Chemical), followed by the calcium carbonate crystallization in the chitin hydrogel for 24 h. Chitin hydrogel was then dissolved with 50% sodium hypochlorite to collect the calcium carbonate crystals. For the crystallization of calcite using the chitin nanofiber, the procedure was as follows [6]: 1.1% (w/v) chitin nanofiber in 0.5% acetic acid solution was prepared and the resulting chitin nanofiber solution was neutralized with a solution of 1 M NaOH, 10 mM calcium chlorite. Calcium carbonate was then crystallized in the chitin nanofiber solution using the same method described above.…”

Section: Methodsmentioning

confidence: 99%

“…The analysis of the intra-crystalline fraction has been traditionally difficult because of the (sub-) nanometric size of individual components [2]. Recently, synthetic carbonate systems, especially single calcite crystals, have been used to study the incorporation of organic components (i.e., peptide or polysaccharides) and their effect on the formation of crystal defects, mechanical properties, and the incorporation of chemical impurities (e.g., [3][4][5][6]). However, the characterization of the distribution of such organics inside crystals is very challenging.…”

Section: Introductionmentioning

confidence: 99%

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Atom Probe Tomography (APT) Characterization of Organics Occluded in Single Calcite Crystals: Implications for Biomineralization Studies

Pérez‐Huerta

Suzuki

Cappelli

et al. 2019

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Occlusion of organic components in synthetic calcite crystals has been recently used as a model to understand the role of intra-crystalline organics in biominerals. However, the characterization of the distribution of both types of organics inside these calcite crystals is very challenging. Here, we discuss the potential of using the technique of atom probe tomography (APT) for such characterization, focusing on the analysis of chitin incorporation in single crystals. Additionally, APT has at least the same spatial resolution as TEM tomography, yet with the advantage of obtaining quantitative chemical data. Results show that chitin, either after degradation with yatalase or in the form of nanofibers, forms discrete clusters (2 to 5 nm) in association to water and hydronium molecules, rather than forming a 3D network inside crystals. Overall findings indicate that APT can be an ideal technique to characterize intra-crystalline organic components in abiogenic and biogenic carbonates to further advance our understanding of biomineralization.

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Crystal defects induced by chitin and chitinolytic enzymes in the prismatic layer of Pinctada fucata

Cited by 33 publications

References 32 publications

Gelatinous Siphon Sheath Templates the Starfruit-Shaped Aragonite Aggregate Growth

Gelatinous Siphon Sheath Templates the Starfruit-Shaped Aragonite Aggregate Growth

Chitin Degraded by Chitinolytic Enzymes Induces Crystal Defects of Calcites

Atom Probe Tomography (APT) Characterization of Organics Occluded in Single Calcite Crystals: Implications for Biomineralization Studies

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