We deployed in situ spectroscopic ellipsometry (SE) to quantify the surface density of mucin like structures. SE is sensitive to the thickness and refractive index of surface adlayers, and enables label-free quantitation of the biomolecular mass per unit surface area (i.e., the areal mass density, AMD). Brushes of mucin-like glycopolymers were formed as described above for the QCM-D analyses, with all binding steps instead monitored by SE (Figures ).