“…In addition, they have been classified based on their applications, such as in sensors, catalysts, drug delivery systems, wound dressings, and tissue engineering (Song et al, 2015;Vashist et al, 2018). They are also classified according to the type of incorporated nanomaterials, which is the more common type of classification (Sharma et al, 2018;Vashist et al, 2018;Rafieian et al, 2019). Frequently reported nanofillers in NC hydrogels are silica such as nano-clay (Jin et al, 2018) and fumed silica (Kehr et al, 2013), carbon in the form of carbon nanotubes, graphene (Servant et al, 2014) and graphene oxide (GO) (Rasoulzadeh and Namazi, 2017;Tarashi et al, 2019), metal and metal oxide nanoparticles (Tan et al, 2019) such as gold, silver, iron oxide, titanium oxide (TiO 2 ), nanohydroxyapatite, alumina and zirconia, and polymeric nanoparticles such as nano-scaled cellulose (NSC) (Dutta et al, 2019), including cellulose nanofibers, nanocrystals, and nanowhiskers.…”