Thiol-functionalised SPR chips were used to generate PSPMA brushes of 10 and 30 nm, high and low density, following the same process than for silicon/gold substrates. SPR assays were carried out in PBS on a Biacore 1K+ (Cytiva), in triplicate. The flow rate of injections/running buffer was maintained constant throughout the experiment at a value of 10 µL min -1 . A change of 10 4 RU corresponding to 1 µg cm -2 of binding capacity was considered, based on the literature . Brush-coated SPR chips were mounted on plastic sensor chip supports, docked, and left to equilibrate with PBS until a stable baseline was obtained. A set of protein concentrations ranging from 1 to 10 µg mL -1 was prepared by serial dilutions, with the solvent matching the running buffer to reduce RI drifts. All injections were carried out incrementally, starting from the lowest concentration. Upon equilibration, 50 µL of protein solution was injected for 5 min, followed by a washing step with running buffer for 10 min. Prior to each subsequent injection, regeneration with 2 M NaCl and further equilibration were performed.