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

Abstract

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.

Exploring Biases in Atom Probe Tomography Compositional Analysis of Minerals

“…2015, Pérez‐Huerta et al . 2016, 2019, Pérez‐Huerta and Laiginhas 2018), phosphates (Gordon et al . 2012, 2015, Santhanagopalan et al .…”

“…2016, Pérez‐Huerta et al . 2019, 2020), metamorphism (Peterman et al . 2019) and the study of extra‐terrestrial materials (Heck et al .…”

Chitosan as a Canvas for Studies of Macromolecular Controls on CaCO3Biological Crystallization

“…In the first, authors studied nucleation of CaCO 3 onto chitin itself, in various forms, or chitin that had been partially degraded. As presented in Table , calcite is the dominant polymorph to crystallize in the presence of any form of chitin (substrate, , gel, − or nanofiber − ). In studies where chitin was treated with yatalase, a chitinolytic enzyme, a change in morphology was observed from rhombohedral to roughened or rounded rhombohedra.…”

“…In studies where chitin was treated with yatalase, a chitinolytic enzyme, a change in morphology was observed from rhombohedral to roughened or rounded rhombohedra. The authors suggested that partial degradation of chitin increases the mechanical strength of biomineral features (e.g., an organism’s shell) through small crystal defects and lattice distortions. − …”

Functional analyses of chitinolytic enzymes in the formation of calcite prisms in Pinctada fucata

“…Parameters were following; laser pulse energy = 150 and 1300 pJ, detection rate = 2%, base temperature = 50 K. Three dimensional reconstructions from data of ion distributions were performed using the CAMECA IVAS software platform (details in [28]).…”