Using Neutron and X-ray Reflectivity to Investigate the Interfacial Structure of Cell Monolayers

Decades worth of scattering studies on model membrane systems, including lipid monolayers at the air-water interface and supported lipid bilayers on solid substrates, is motivated by their connection to the cell membrane. However, cell biology does not readily translate to physiology. Most biological interfaces are multi-cellular monolayers and monolayer biology is very different than single cell systems. Depending on the biological situation, cellular adhesion to interfaces is desirable or undesirable. In order to optimize material properties of biomedical devices, knowledge of whether cells stick or not stick to these materials is crucially important. Our prior studies utilized neutron reflectometry to study the cell membrane-substrate separation in cell monolayers, where the separation length is indicative of adhesion strength. We extend our work to x-rays because they provide a rich set of tools to probe the structure and interactions of cellular monolayers. X-rays can also overcome the low intensity, long collection times, and narrow Qz range limitations of neutrons. Applying x-ray scattering techniques to a true living cellular system will help us gain insight to parameters important for the improved design of medical devices.