Influence of active sites distribution on CaCO₃ formation under model biofilms at the air/water interface

Abstract

In an approach to understand the influence of structural parameters of interfaces on calcification in biomineralisation, the distribution of COOH groups as active sites in an inert matrix was varied using two–component lipid model monolayers. Octadecanoic acid and octadecyl succinic acid, respectively, were the active components, and methyl octadecanoate the inactive matrix. Surface pressure–area isotherms provide evidence for a different distribution of the active components in the matrix. Formation of solid calcium carbonate with two-component monolayers on subphases containing aqueous CaCO₃ was observed in situ by Brewster angle microscopy, where CaCO₃ domains appear bright. Striking differences in kinetics and extent of CaCO₃ formation are observed between monolayers containing octadecanoic acid and those containing octadecyl succinic acid of the same average surface density of COOH groups.

Acknowledgement: This work has been supported by the Deutsche Forschungsgemeinschaft (Mo 156/5). We thank the Fonds der Chemischen Industrie, Germany, for financial support.