(629c) Using Confocal Microscopy as a Novel Technique to Study Lung Surfactant Adsorption to the Air-Water Interface

Lung surfactant (LS) is a mixture of lipids and proteins that lines the air-liquid interface of the alveolar walls. It modulates the surface tension in the lungs which greatly reduces the mechanical work of breathing and also prevents the collapse of the alveoli upon expiration. Blood serum leaking into the alveoli as a result of trauma can lead to LS inhibition, which is one characteristic of acute respiratory distress syndrome (ARDS). One mode of LS inhibition, as observed during ARDS, is the competitive adsorption of albumin to the air-liquid interface of the alveoli which blocks LS from forming a functional monolayer. The addition of polyethylene glycol (PEG) and chitosan, two hydrophilic polymers, to the liquid subphase has been shown to reverse albumin's deleterious effects on LS in vitro. The ability of confocal microscopy to optically section a sample and simultaneously image multiple dyes provides an ideal tool to study LS adsorption. We present here a way to employ confocal microscopy to image our system in order to simultaneously determine the relative lateral and axial concentrations of surfactant, polymer, and albumin. As a result of the new technique, we have directly visualized the fundamentally differing mechanisms between PEG and chitosan in reversing albumin's inhibition of LS.