ADSORPTION OF NATURALLY OCCURRING POLYMERS ONTO CALCIUM-OXALATE CRYSTAL-SURFACES

  • 1 January 1977
    • journal article
    • research article
    • Vol. 14  (4) , 278-283
Abstract
The adsorption of proteins and mucopolysaccharides on calcium oxalate crystals was measured by solution depletion. Anionic protein adsorption was sensitive to Ca2+ concentration. Adsorption of fibrinogen was anomalously large in the presence of 0.01 M Ca2+. Adsorption of cationic protein (histone) was sensitive to oxalate ion concentration. A small alteration in adsorption of protein as a result of pH or temperature change was also observed. Plots of adsorption vs. concentration were interpreted in terms of a Langmuir adsorption isotherm. The derived Langmuir adsorption parameters were used to investigate the contribution of protein, by physical adsorption, to the quantity of matrix in urinary stones. Physical adsorption accounted for the deposition of part but not all of the matrix in calcium oxalate stones. Physical adsorption of mucopolysaccharides by calcium oxalate crystals may explain the inhibition of growth and aggregation of calcium oxalate crystals seen with in vitro precipitation systems. Recalculation of published data indicated that adsorption of protein on dental enamel (calcium hydroxyapatite) resulted in approximately the same extent of surface coverage as adsorption on calcium oxalate crystals, but protein had a much lower affinity for dental enamel than for calcium oxalate crystals.

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