Kidney stone formation in the urinary tract is a global health issue with few effective treatments available due to a poor understanding of the biomineralization mechanisms. Calcium oxalates are the most common components in renal stones (up to 70 – 80 %), with the monohydrate phase (CaC2O4.H2O, COM) being the most stable and accounting majority of the oxalate part. This mineral phase has been studied extensively before via XRD analysis and to a lesser extent using 13C and 43Ca solid-state NMR. Here we report for the first time a selective 17O-isotopic enrichment of COM mineral using mechanochemistry. Excellent 17O enrichment can be achieved separately in the oxalate (up to 20 %) and water (up to 10 %) oxygens, enabling to study independently oxalate and water molecules at an atomic scale resolution within the COM structure. The examination of the 17O NMR is accompanied by GIPAW calculations in order to help with the oxygen assignment. A great resolution is achieved in all oxygen sites, with two and up to eight sites for water and oxalate oxygens, respectively.

Oxygen-17 isotopic enrichment of calcium oxalate monohydrate phase

ACS Spring Meeting 2021

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