Intracrystalline inclusions within single crystalline hosts: from biomineralization to bio-inspired crystal growth

Abstract

Many crystals in nature exhibit fascinating mechanical, optical, magnetic and other characteristics. One of the reasons for this phenomenon has to do with the presence of specific organic molecules that are tightly associated with the mineral. Over the years, some organic crystals have been found to be located within the lattices of their singlecrystalline biogenic hosts. A number of questions remain unanswered: for example, how do these molecules become incorporated and what is their function? In this review we survey the gradual refinement of the above mentioned finding in biogenic crystals, with the object of tracing the acquisition of our fundamental knowledge in this field during the last 50 years. We highlight the progress made in understanding the function and significance of this intracrystalline organic matter, from the earliest observations of this phenomenon in a biological system to the highly promising recent achievements in bio-inspired material synthesis, where intracrystalline molecules have been used in many studies to synthesize numerous synthetic nanohybrid composites with fascinating new properties.Boaz Pokroy is an associate professor in the Department of Materials Science and Engineering at the Technion-Israel Institute of Technology, Israel, where he earned all of his degrees. Previously, he was a postdoctoral fellow and Fulbright Scholar in the laboratory of Prof. Joanna Aizenberg at the School of Engineering and Applied Sciences at Harvard University and Bell Labs. Pokroy's research focuses on biomineralization and bio-inspired surface engineering. He studies the structure of biominerals on the atomic, nano-, and mesoscales using state-of-the-art high-resolution characterization techniques such as high-resolution synchrotron diffraction and aberration-corrected transmission electron microscopy. Based on the strategies that organisms use to produce natural materials, his lab also develops novel bio-inspired materials, such as semiconductors whose bandgap can be tuned by the incorporation of intracrystalline biological molecules; controlling the short-range order of nano-amorphous materials; and fabrication of superhydrophobic/superoleophobic surfaces for various applications.

In vivoandin vitroanalysis of starmaker activity in zebrafish otolith biomineralization

“…Second, nonmineralization-related proteins present in endolymph (8,42) could have been trapped inside the developing otolith. Examples of organic macromolecule occlusion were previously shown for shells (43)(44)(45)(46), coccoliths (47), and sea urchin spines (48). Third, it should be noted that proteomics is very sensitive, and despite rigorous purification steps, the presence of some proteins may reflect contamination from other zebrafish tissues.…”

Anisotropic Lattice Distortions in Biogenic Minerals Originated from Strong Atomic Interactions at Organic/Inorganic Interfaces

“…[20]), is a "younger" and less studied subject, than inter-crystalline organics. [20]), is a "younger" and less studied subject, than inter-crystalline organics.…”

“…[50] Another important observation comes from laboratory experiments, in which calcite crystals are grown from solutions containing organic macromolecules. [20] The next question regards the specific mechanism standing behind the development of lattice distortions in biogenic calcium carbonate. [60,61] Calcite crystals, grown in the presence of purified caspartin at two different concentrations, 3 and 5 μg ml -1 , revealed expanded lattice parameters, which were found to increase with protein concentration up to Δc/c ≈ 0.1%.…”

Interplay between Calcite, Amorphous Calcium Carbonate, and Intracrystalline Organics in Sea Urchin Skeletal Elements

“…29 Organic molecules are attached to specific crystallographic planes and, hence, facilitate the formation of single crystals of different shapes (see e.g. brief review 30 ). For example, it was shown that proteins in P. lividus sea urchin spines are preferentially adsorbed on calcite planes parallel to the c-axis (hk0-planes), 23 whereas proteins from sponge spicules and from calcitic prims of mollusk shells are mostly attached to the (001)-planes.…”