Phytoglycogen is a glucose polymer that occurs naturally in the form of highly branched, compact nanoparticles. Because of their tree-like or dendrimeric structure, phytoglycogen nanoparticles have unique properties, such as a strong interaction with water, which makes them attractive for use in applications ranging from cosmetics to drug delivery. Many of these applications rely on the binding of small molecules onto phytoglycogen nanoparticles. Surface Plasmon Resonance (SPR) is a sensitive experimental technique, based on the resonant absorption of light within an ultrathin gold film, that can be used to measure the binding kinetics and affinities of small molecules. We have successfully created a stable phytoglycogen-functionalized gold surface, using 4-Mercaptophenylboronic Acid as a linker between the gold layer and phytoglycogen. This has allowed us to use SPR to measure the association constant between phytoglycogen and Concanavalin A to be 2.87±0.44×10^5 M-1 using the Langmuir adsorption model fit.