Investigating Intracrystalline Composition and Structure of Biogenic Guanine Crystals

Organisms exhibit exceptional control over crystal nucleation, morphology, and the assembly of crystals into complex ultra-structures. While <i>inorganic</i> biominerals have been acknowledged for their remarkable material properties, such as superior damage resistance due to their composite structure, the composite nature biogenic <i>organic</i> crystals remains largely unexplored. It has recently been shown that biogenic guanine crystals are solid solutions in which guanine host crystals occlude mixtures of other purines (hypoxanthine and xanthine), without significantly altering the crystal structure of the host.¹ However, these dopants change the local structural properties of the crystals, resulting in the presence of nano-domains and defects which are important in dictating crystal formation, morphology, and molecular orientation. Our work focuses on utilizing synchrotron radiation characterization methods with nano-scale spatial resolution to reveal the local chemistry and structure of biogenic guanine crystals. Investigating the local composition, structure and textural properties of mature crystals may be used to retrospectively map the growth history of a crystal, e.g., to understand dynamic changes in the chemical environment of the growing crystal.<br/>[1] Pinsk, N. <i>et al.</i> Biogenic Guanine Crystals Are Solid Solutions of Guanine and Other Purine Metabolites. <i>J Am Chem Soc</i> <b>144</b>, 5180–5189 (2022).