Careful structural characterization is essential at each step of the process. The traditional amide coupling agents EDC and NHS are still widely used for derivatizing HA, but we have found these reagents can give rise to poorly defined additional modifications of HA. We would therefore advocate using DMTMM in preference as activator as this reagent consistently gave very clean amide derivatives. CuAAC is one of the most widely used bioorthogonal reactions, and while it worked well for ligating the polymer and the azidefunctionalized glycans, it is important to appreciate that oxidative side reactions can lead to partial fragmentation of the glycopolymers. A comparison of SE (Table ) and SEC-MALS (Figure ) data highlighted further size selection of the glycopolymers upon attachment to the surface. It is thus most important to fully characterize and understand the films ultimately created including the sizes of the brushes, the mesh size, etc.