AVS 56th International Symposium & Exhibition
    Biomaterial Interfaces Tuesday Sessions
       Session BI-TuA

Paper BI-TuA9
In situ Characterization of Barnacle Primary Cement Interfaces by ATR-FTIR Spectroscopy

Tuesday, November 10, 2009, 4:40 pm, Room K

Session: Biofouling
Presenter: D.E. Barlow, U.S. Naval Research Laboratory
Authors: D.E. Barlow, U.S. Naval Research Laboratory
G Dickinson, Duke University Marine Laboratory
B. Orihuela, Duke University Marine Laboratory
D. Rittschof, Duke University Marine Laboratory
K.J. Wahl, U.S. Naval Research Laboratory
Correspondent: Click to Email
Understanding the chemistry of barnacle adhesion is of great interest in the areas of marine biofouling prevention and materials science of adhesives. Barnacles adhere to surfaces by a proteinaceous cement, for which most studies to date have been ex situ analyses of the protein composition. However, very little is currently known about the chemical structure and composition in the original, undisturbed cement interfaces of barnacles (primary cement interfaces) that provide the strong adhesion to substrates in marine environments. We will present a method that has been implemented for characterizing primary cement interfaces of barnacles using in situ attenuated total reflection - Fourier transform infrared spectroscopy (ATR-FTIR). Primary cement of the barnacle Balanus amphitrite (= Amphibalanus amphitrite) was characterized without any disruption to the original cement interface, after settling and growing barnacles directly on double side polished germanium wafers. High quality IR spectra were acquired of live barnacle cement interfaces, providing a spectroscopic fingerprint of cured primary cement in vivo with the barnacle adhered to the substrate. Additional spectra were also acquired of intact cement interfaces for which the upper portion of the barnacle had been removed leaving only the base plate and cement layer attached to the substrate. This allowed further characterization of primary cement interfaces that were dried or placed in D 2 O. The resulting spectra were consistent with a proteinaceous cement, and allowed analysis of the protein secondary structure and water content in the cement layer. The estimated secondary structure composition was primarily b-sheet, with additional a-helix, turn, and unordered components. The cement of live barnacles, freshly removed from seawater, was estimated to have a water content of 20% - 50% by weight. These results provide new insights into the chemical properties of the undisturbed barnacle adhesive interface. The ATR-FTIR method presented is also expected to be useful for in situ and in vivo studies of bioadhesives from other organisms.