After surface functionalization the substrate is washed with the same buffer and restabilized in PBS. BSA (1% in PBS) is then injected to fill pockets left unfunctionalized by the BPT, the sensor is washed with PBS afterwards. Neutravidin (10µg/mL in PBS) is flown for 20 minutes and the surface is again washed with PBS. A constant flow rate of 10 µL/min was maintained all throughout the experiment. All SPR measurements in this work were carried out with the 670 nm laser wavelength which has a spot size of 0.5 mm in diameter (from which the angular shift is averaged). The surface coverage of the organic molecules immobilized on the sensor is proportional to the angular shift at a given wavelength and, as a generic rule of thumb, the conversion from angle shift to mass per surface area is obtained using the equivalent units: 1mdeg = 0.8 ng/cm 2 at 670 nm.