Silk-based fibres vs collagen gel: major organic components of bivalve shells

• Main Author: Oluwatoosin Bunmi Adebayo Agbaje
• Format: Thesis
• Language: unknown
• Published: 2018
• Subjects: Other education not elsewhere classified; Bivalves > Anatomy; teacher education; biomineralisation; polyamino acid; Bivalves; solid state NMR; β pleated sheets; teaching presence; chitin; Biomineralization; Arctica islandica
• Online Access: https://doi.org/10.25949/19435865.v1; https://figshare.com/articles/thesis/Silk-based_fibres_vs_collagen_gel_major_organic_components_of_bivalve_shells/19435865

Biominerals are biogenic hierarchical nanocomposite materials consisting of mineral phases, such as calcite, aragonite or vaterite, and intimately intergrown with the organic macromolecules, including proteins, polysaccharides and lipids. There is a large diversity among biominerals, each with its structural motifs, inorganic crystal formation - shape, and micro- or macroscopic properties. For instance, shells of mollusc are formed with different ratios of inorganic-organic materials and different structural motifs resulting in a large variety of calcareous biocomposites with material properties outperforming those of their synthetic counterparts. Amongst all different shell microstructures, nacre is the most studied to date, while comparable knowledge is lacking for non-nacre shell structures such as homogeneous and crossed-lamellar structures. In this work both, nacre and non-nacre structures are investigated and compared for commonalities and differences. The aims are to characterise inorganic-associated macromolecules in shells of different bivalve species with different microstructures and to study the interface and the interactions between mineral and biomolecules. To achieve these aims, shells of 12 species from 7 molluscan families are studied. The calcareous shells are grouped into nacroprismatic (Hyriopsis cumingii, Cucumerunio novaehollandiae, Alathyria jacksoni, Pinctada maxima, Pinctada fucata martensii, Diplodon chilensis patagonicus), homogeneous (Arctica islandica) and crossed-lamellar (Tridacna gigas, Tridacna derasa, Fulvia tenuicostata, Callista disrupta, Callista kingii) based on their shell microstructures. Except for Pinctada shells that consist both calcitic and aragonitic layers, all shells are entirely aragonitic. A common phenomenon exists between the compositions of organics present in the nacreous layer of the studied nacroprismatic shells. Thermogravimetric analysis exhibits a total amount of organics in the range of 3.14 - 4.13 wt%. The amino acid composition reveals a high amount ...