CS can also establish molecular interactions with dispersed particles (e.g., Dox-loaded PCL-PEI NPs) through its amino and hydroxyl groups. At pH 7.4 these interactions ensured the structural integrity of the hybrid hydrogel, whereas at pH 6, protonation of the two components occurred, resulting in an unstable and fluid system from which NPs were easily released. Acidic pH values also led to the destabilization of NPs, causing the release of Dox (up to 30% in 12 h), while it did not exceed 10% under neutral conditions. In a similar manner, multiple interactions (e.g., hydrogen bonding, cation-π, thiol-π) between silver-lignin NPs (Ag@Lig NPs) and thiol-functionalized HA (HA-SH) ensured self-assembly and stabilization of a hybrid hydrogel for chronic wound management. To be noted that no gelation occurred in absence of HA modification, revealing the key role of the non-covalent reticulation (Figure ). As above discussed, it is quite common to formulate CS hydrogels in presence of β-GP.