Regensburg 2010 – scientific programme
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BP: Fachverband Biologische Physik
BP 5: Posters: Biopolymers and Biomaterials
BP 5.2: Poster
Monday, March 22, 2010, 17:15–20:00, Poster B1
Probing the components of nacre by contact angle measurements — •Malte Launspach, Fabian Heinemann, and Monika Fritz — Pure and Applied Biomineralisation, Biophysics Institute, University Bremen, Germany
Nacre of some molluscs is a highly structured polymer/mineral composite, which has been brought to perfection by evolution over millions of years. Densely packed mineral platelets are interdispersed by a few nanometer of organics. The order and the dimension of the platelets lead to astonishing mechanical properties. Soluble and insoluble proteins are involved in the formation of the aragonite platelets; some are attached to a chitin core - the organic matrix. Here the surface energy properties are probed by contact angle measurements to quantify the adhesive strength between the mineral and organic phase and to investigate the relevance of the organic matrix during platelet formation. Measurements were conducted with a home-made device. The demineralised insoluble organic matrix in a native state and after enzymatic treatment were probed as well as the (001) surface of geological aragonite. The (001) surface of aragonite is not a cleavage plane and had to be processed in a special way. The surface free energy of the organic matrix was calculated using semi-empirical approaches. Three different models yield a total surface free energy between 40 and 44 mJ/m2 for the native matrix and a value between 51 and 59 mJ/m2 after enzymatic treatment. In the case of the minerals the obtained values could not be used for further calculations since the influence of the preparation process was to dominant.