ORIENTED GROWTH OF CALCIUM-OXALATE MONOHYDRATE CRYSTALS BENEATH PHOSPHOLIPID MONOLAYERS

Oriented calcium oxalate crystals have been grown beneath phospholipid monolayers at the air-solution interface from supersaturated calcium oxalate solutions. Mature calcium oxalate crystals grown beneath zwitt erionic dipalmitoylphosphatidylcholine (DPPC) monolayers exhibit the c haracteristic morphology of calcium oxalate monohydrate (COM) crystals with the elongated ((1) over bar 01) crystal face preferentially orie nted parallel to the plane of the monolayer. Calcium oxalate crystals grown beneath negatively-charged dimyristoylphosphatidylserine (DMPS) monolayers also show a preferential orientation with respect to the mo nolayer; they do not, however, exhibit the characteristic COM morpholo gy. Raman spectroscopy strongly suggests that the crystals grown benea th either DPPC or DMPS monolayers are the monohydrate phase of calcium oxalate; therefore, differences in crystal morphology are not due to differences in the crystalline phase. Dimyristoylphosphatidylethanolam ine (DMPE), dimyristoylphosphatidic acid (DMPA), eicosanoic acid (C-20 ), and eicosanol (C-20-OH) monolayers have also been studied to help e lucidate the mechanisms of interaction between the lipid monolayers an d the calcium oxalate crystals. We discuss the roles of lattice matchi ng, hydrogen bonding, stereochemistry and electrostatics on crystal or ientation and morphology. (C) 1998 Elsevier Science B.V.