AVS 58th Annual International Symposium and Exhibition
    Marine Biofouling Focus Topic Monday Sessions
       Session MB-MoM

Invited Paper MB-MoM5
Probing Molecular Details of Marine Bioadhesion with In Situ Infrared Spectroscopy

Monday, October 31, 2011, 9:40 am, Room 105

Session: Interfacial Aspects of Marine Biofouling
Presenter: Jim McQuillan, University of Otago, Dunedin, New Zealand
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The critical step which triggers biofouling at interfaces is the initial adhesion of an invading species to a solid substrate. Of less importance in what occurs thereafter is growth of the species under the infuence of nutrients and with the protection of its more sheltered environment. Understanding the factors determining the propensity of species to adhere to substrates is the key to developing new strategies aiming to more effectively inhibit the development of biofouling in many contexts.

Much of the thinking about biofilm formation and the adhesion of biological species to surfaces has been extrapolated from macroscopic observations about the aggregation of colloids. This has been largely based on the interplay between attractive dispersion forces and repulsive electrostatic forces and has given rise to adhesion descriptions in terms of reversible and irreversible stages. A major advance has been the use of in situ atomic force microscopy (AFM) to measure forces during adhesion of microbes to substrates and evaluate their environmental influences. Nevertheless, this approach is unable to provide in situ molecular details of the chemical components which are suspected to play major roles in adhesion processes.

Vibrational spectroscopy is powerful to reveal the identity and environmental details of molecules in wet interface environments. Vibrational sum frequency spectroscopy and infrared spectroscopy are increasingly thus employed. However, attenuated total reflection infrared (ATR-IR) spectroscopy has the advantages of relative simplicity and greater general familiarity in spite of its use for wet surface situations having only recently been recognised. The ATR-IR approach employs total internal reflection at a high index refraction crystal such as ZnSe or diamond resulting in an evanescent wave sampling a few micrometers of material.

In this talk I will outline the principles of the ATR-IR method and how we have adapted them for studies of initial settling of live marine organisms settling onto surfaces under controlled temperature and environment conditions. Observations from recently published work on the settling of Perna canalicula mussel larvae and Undaria pinnatifida kelp spores will be presented and prospects for breakthrough studies of the settling and propagation of the feshwater diatom Didymosphenia geminata, invasive to New Zealand, will also be discussed.