where 𝑁𝑁 is the total number of tethered receptor on the surface (𝑁𝑁 = 𝑆𝑆 𝑐𝑐 𝐴𝐴 where 𝑆𝑆 𝑐𝑐 is the surface coverage shown in Fig. and 𝐴𝐴 = 1 𝑐𝑐𝑚𝑚 2 ). The calculation of the Flory radius is possible only in presence of a polymer trapped in a good solvent which is not the case of the smallest tether employed. For this specific case we considered that the 4-ATP is a molecule whose main degree of freedom is the rotation around the vertical axis (virtually connecting SH and NH2) which depicts an ellipsoid with the major axis measuring 0.58 nm and the minor 0.47 nm (the latter is considered in Table ). Regarding the APT, if the distance between tethers is less than the Flory radius, we can consider them to be immobilized at high density thus displaying a brush-like conformation. Comparing the figures, we determined that the tether density was high enough to stretch the tethers and make them assume a brush-like conformation for all the tethers analysed (APT-400 to APT-10k). Nevertheless, a mixed brush/mushroom conformation cannot be completely ruled out. Evolution of AuNP density as function of tether length for fixed receptor density is shown in Fig. . This was obtained by normalizing the AuNP density shown in Fig. , by the receptor densities (𝛿𝛿 𝑟𝑟𝑟𝑟𝑐𝑐𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟 in molecule/cm 2 ) shown in Fig. , and following the equation,