Structure and Properties in Synthetic MSUM and the Corresponding Biomaterial

Abstract

At the MRS Fall 2014 Meeting, Symposium E, we reported on morphologies, fragmentation, and hardness in synthetic hydrogen urate monohydrate (monosodium urate monohydrate, MSUM, or MSU) crystals. We are now presenting further characterization results, including some from the biomaterial that forms in humans with gout disease: The fanning of radiating blades (needles) in spherulitic grains of synthetic MSUM was examined by microscopy techniques. These and previous data are consistent with an interpretation in terms of the crystallographic parameters in the unit cell, and the presence of dislocation arrays at low angle boundaries. The kinetics of such branched growth is here related to thermodynamic properties and super-saturation levels. Secondary nucleation is an additional mechanism leading to more complex morphologies. Differences in overall growth rates, under conditions of either branched or single needle growth, are considered in relation to gout. Novel powder XRD and solid state NMR data show, respectively, preferred orientation in the biomaterial, and the potential of NMR for identifying and characterizing MSUM in specific environments, helping to resolve pending questions in gout. Present results are anticipated to be useful for designing bio-inspired and bio-mimetic materials, regarding morphologies, overall growth rates, and mechanical properties.