showed no significant differences compared to undoped gels. When determining the optimal NP concentration, it is also essential to consider the potential disruption they may cause in the network formed by the physical or chemical bonds between polymer chains. For instance, is has been shown that: (i) the spatial organization of COL fibers was disturbed increasing the amount of silica NPs and (ii) silica-coated magnetic NPs could widen the distance between PVA chains resulting in a diminution of the elastic properties of the hybrid hydrogels. In another example, when maleimide-containing Au NPs were introduced into furanmodified CS hydrogels (HG CS-Fu) at the highest concentration (i.e., 510 × 10 -9 M), their reinforcing effect was counterbalanced by an interference on the hydrophobic interactions between CS chains. Hence, the modulus of this composite material was similar to that of noncrosslinked hydrogels (Figure ). Figure HG CS-Fu-Au510, respectively. Adapted with permission. Copyright 2016 Wiley-VCH.