Waveguide evanescent field fluorescence microscopy: high contrast imaging of a domain forming mixed lipid Langmuir-Blodgett monolayer mimicking lung surfactant.

Waveguide evanescent field fluorescence (WEFF) microscopy is a new development that allows the imaging of contact regions between biological cells and their substratum, as well as imaging of ultrathin films such as monomolecular Langmuir-Blodgett (LB) films. Mixed-lipid monolayer systems mimicking lung surfactant were fabricated on waveguides using the LB technique and imaged by both WEFF and standard wide field epi-fluorescence microscopy. These two technologies were compared with respect to contrast, photobleaching, and sensitivity. It was found that WEFF microscopy produced images with a much higher contrast, lower photobleaching, and higher sensitivity. In addition, fine structures in the lipidic domains were observed for the first time.