| This thesis focuses on the face-specific molecular adhesion to calcium oxalate monohydrate (COM) crystals, the principal crystalline in kidney stones. The primary technique used is atomic force microscopy (AFM), which allows visualizing the structure and growth of crystals, measuring the adhesion force between functional groups and crystal faces, and examining adhesion and binding of the molecules to crystals.; The microscopic events associated with crystal growth on the {lcub}100{rcub}, {lcub}12-1{rcub}, and {lcub}010{rcub} faces have been investigated. Each face exhibits hillocks with step sites that can be assigned to specific crystal planes, enabling direct determination of growth rates along specific crystallographic directions. The growth rates are found to depend on the degree of supersaturation. The addition of macromolecules with anionic side chains results in inhibition of hillock growth. The magnitude of this effect depends on the macromolecule structure & concentration, and the identity of the step site. The different profiles observed for three synthetic macromolecules, which have similar backbones but different side chains, argues that local binding of anionic side chains to crystal surface sites governs growth inhibition rather than any secondary polymer structure.; The dependence of adhesion force on the functional group-COM crystal face combinations has been identified. Tip-immobilized carboxylate and amidinium groups display the largest adhesion forces among all the functional groups examined, and the adhesive strength decreases as (100) > (12-1) > (010). The more adherent surface of COM, compared with its dihydrate form COD, corroborates the critical role of COM in stone formation. The influence of small molecules, synthetic polymers and native proteins on adhesion was examined. The introduction of these molecular additives, except osteopontin, result in a reduction in the adhesion force measured for all three faces. The extent of suppression, however, varies for molecule-crystal face combination. Curiously, osteopontin exhibits a unique behavior as it increased the adhesion force between the carboxylate tip and the (100) crystal face. 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. |
