Biogenic Guanine Crystals Are Solid Solutions of Guanine and Other Purine Metabolites
Noam Pinsk, Avital Wagner, Lilian Cohen, Christopher J. H. Smalley, Colan E. Hughes, Gan Zhang, Mariela J. Pavan, Nicola Casati, Anne Jantschke, Gil Goobes, Kenneth D. M. Harris, Benjamin A. Palmer
Abstract
(aka solid solutions and mixed crystals) of guanine, hypoxanthine, and sometimes xanthine. Guanine host crystals occlude homogeneous mixtures of other purines, sometimes in remarkably large amounts (up to 20% of hypoxanthine), without significantly altering the crystal structure of the guanine host. We find no correlation between the biogenic crystal morphology and dopant content and conclude that dopants do not dictate the crystal morphology of the guanine host. The ability of guanine crystals to host other molecules enables animals to build physiologically "cheaper" crystals from mixtures of metabolically available purines, without impeding optical functionality. The exceptional levels of doping in biogenic guanine offer inspiration for the design of mixed molecular crystals that incorporate multiple functionalities in a single material.