Adhesion at calcium oxalate crystal surfaces and the effect of urinary constituents

Xiaoxia Sheng, Taesung Jung, Jeffrey A. Wesson, Michael D. Ward

Research output: Contribution to journalArticle

Abstract

Kidney stones, aggregates of microcrystals, most commonly contain calcium oxalate monohydrate (COM) as the primary constituent. The aggregation of COM microcrystals and their attachment to epithelial cells are thought to involve adhesion at COM crystal surfaces, mediated by anionic molecules or urinary macromolecules. Identification of the most important functional group-crystal face adhesive combinations is crucial to understanding the stability of COM aggregates and the strength of their attachments to epithelial cell surfaces under flow in the renal tubules of the kidney. Here, we describe direct measurements of adhesion forces, by atomic force microscopy, between various functional groups and select faces of COM crystals immersed in aqueous media. Tip-immobilized carboxylate and amidinium groups displayed the largest adhesion forces, and the adhesive strength of the COM crystal faces decreased in the order (100) > (121) > (010), demonstrating that adhesion is sensitive to the structure and composition of crystal faces. The influence of citrate and certain urinary proteins on adhesion was examined, and it was curious that osteopontin, a suspected regulator of stone formation, increased the adhesion force between a carboxylate tip and the (100) crystal face. This behavior was unique among the various combinations of additives and COM crystal faces examined here. Collectively, the force measurements demonstrate that adhesion of functional groups and binding of soluble additives, including urinary macromolecules, to COM crystal surfaces are highly specific in nature, suggesting a path toward a better understanding of kidney stone disease and the eventual design of therapeutic agents.

Original languageEnglish (US)
Pages (from-to)267-272
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume102
Issue number2
DOIs
StatePublished - Jan 11 2005

Keywords

  • Atomic-force microscopy
  • Kidney stone
  • Protein

ASJC Scopus subject areas

  • General

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