To impart unique characteristics to hybrid hydrogels, additional materials have been studies as dispersed phase. They comprise (i) carbon-based materials, such as nanotubes , graphene oxide sheets and graphene quantum dots (QDs); (ii) phosphate minerals including hydroxyapatite (HAP) and whitlockite (WKT) NPs; (iii) metal-organic frameworks (iv) cellulose nanocrystals (CNCs) and (v) conductive NPs made of polypyrrole (PPy) or poly (3,4-ethylenedioxythiophene) (PEDOT) NPs. Their incorporation resulted in hybrid hydrogels with improved drug loading efficiency and/or control on release. For instance, the dispersion of carbon nanotubes in a CS matrix led to a stiffer network, which efficiently slowed down the release rate of methotrexate loaded in the hydrogel. In another example, the electrostatic interactions of bone morphogenetic protein-2 (BMP-2) with dispersed HAP and WKT NPs, ensured a more sustained drug release over four weeks, with a significant lower burst release compared to pristine HA hydrogel. It is noteworthy that these phosphate minerals also provided mechanical reinforcement of the hydrogel by enhancing its crosslinking density, and endowed the hybrid materials with osteoconductive and biomineralization capabilities, driving their use in the regeneration of bone tissue. While PPy and PEDOT NPs were primarily used as conductive agents, the latter also exibithed intersting phortothermal properties.