SPRI kinetics of fibronectin deposition and serum protein adsorption. A) SPR difference image (630 nm, 56°) after fibronectin deposition onto areas of hexadecanethiol (indicated by the blue square) and PEG-thiol (indicated by the green rectangle). Grey scale values of image intensity display a conversion from reflectivity change (ΔR) to mass/area (ng/cm2). B) Kinetic measurements of fibronectin deposition onto hexadecanethiol regions compared to PEG-thiol regions obtained from averaging intensities over the hexadecanethiol and PEG areas, respectively. The observed fibronectin deposition isotherm onto hexadecanethiol fits a basic Langmuir model yielding an association constant ka = 2.7 × 104 s-1M-1. The solution concentration of fibronectin, C, was 25 μg/mL (= 53 nM). C) Kinetic measurements of relative serum deposition from cell culture medium containing 10% calf serum exposed to fibronectin coated regions compared to PEG coated regions for over 400 min at 37°C. D) 200 μm lines scans (colored magenta in A) on fibronectin coated and serum coated regions. The measured mass/area, in ng/cm2, was converted from SPRI reflectivity units using optical properties of globular proteins.