Adsorption differences of acidic, neutral and alkaline amino acids onto nano/micron COM and COD crystals

摘要

In this study, the adsorption differences of different kinds of amino acids (acidic L-glutamic acid (L-Glu), neutral L-threonine (L-Thr) and alkaline L-histidine (L-His)) onto calcium oxalate monohydrate (COM) and calcium oxalate dihydrate (COD) crystals with sizes of 50 nm, 100 nm, 1 μm, 3 μm and 10 μm were investigated using spectrophotometry. The study of adsorption differences of amino acids on calcium oxalate has rarely been conducted; hence, we studied it with different pH values onto COM and COD crystals. The amount of adsorbed amino acids was determined using the depletion method and the centrifugation method was applied. At pH=7.3, COM crystals mainly adsorbed acidic L-Glu and have less adsorption to L-Thr and L-His, while COD mainly adsorbed alkaline L-His. Results of this study showed that when the size of crystal increases, the adsorption amount of crystals decreased. This was attributed to the decreases of specific surface area of larger crystals. The adsorption amount of COM was greater than that of COD with the same size because the specific surface area of COM is greater than COD. Our results help to further illustrate the formation mechanism of calcium oxalate stones and provide inspiration for inhibiting its recurrence.