Visualizing the 3D Internal Structure of Calcite Single Crystals Grown in Agarose Hydrogels

Crystal Growing Kit For single crystals to remain intact, there is a limit to the size and number of defects that can be included before the underlying lattice is destroyed. Biological crystals, however, are known to include large macromolecules. H. Li et al. (p. 1244 ; see the Perspective by Hollingsworth ) used electron tomography to study the crystallization of calcium carbonate inside an agarose gel, observing that the crystals physically entrapped the agarose macromolecules. To accommodate the curvature induced by the polymer chains, both high- and low-energy facets formed at the fiber-crystal interfaces. Thus, physical interactions alone may be sufficient for the incorporation of macromolecules in biological crystals and it may be possible to grow unusually shaped single crystals.