Cholesterol Monohydrate Dissolution in the Presence of Bile Acid Salts
Abendan RS, Swift J. 2013. Cholesterol Monohydrate Dissolution in the Presence of Bile Acid Salts. Cryst. Growth Des. 13(8):3596–3602.
The molecular-level dissolution of cholesterol monohydrate single crystal (001) surfaces was systematically investigated in aqueous solutions of chenodeoxycholate (CDC) and ursodeoxycholate (UDC) using in situ atomic force microscopy (AFM). Dissolution via the layer-by-layer step retreat of monolayers was observed in solutions where the bile salt concentration exceeded the critical micelle concentration (cmc). Studies performed in CDC solution revealed markedly lower cmc values than in UDC. An abrupt transition from sporadic to continuous dissolution between 4–7 mM CDC was consistent with a previously proposed 2-step model for micelle formation. In contrast, cholesterol dissolution in UDC was apparent at 14 mM with no abrupt change in dissolution rate with increasing UDC concentration. Comparison with previous dissolution studies performed in aqueous ethanol (Cryst. Growth Des. 2005, 5, 2146–2153) reveal key differences in micelle-mediated versus bulk dissolution mechanisms.