Facile and green fabrication of silk sericin films reinforced with bamboo-derived cellulose nanofibrils

Abstract

As the interest in the recycling of byproducts and resources derived from agriculture has increased, research on the application of sericin abandoned in the silk industry has been continuously carried out, but there is a limit due to the weak mechanical properties. Recently, nanocellulose has been attracting attention as an optimal reinforcing material to improve the deficient physical properties of natural polymers. In the present study, bamboo-derived cellulose nanofibrils (B-CNFs) were prepared and used as a facile reinforcer to improve the mechanical properties of the sericin film. B-CNF was prepared via simple and eco-friendly ultrasonic treatment and whole bio-nanocomposite film fabrication process conducted under aqueous solution condition. The prepared B-CNF was well distributed into the glycerol-plasticized sericin matrix without agglomeration until 10 wt% B-CNF loading, while agglomerated cellulose nanofibrils appeared after 20 wt% B-CNF loading. This uniform distribution of B-CNF not only greatly improved the properties of the sericin film but also affected the hydrophilic properties of bio-nanocomposite film. Moreover, the prepared B-CNF reinforced bio-nanocomposite films had notable antioxidant activity without any additional antioxidant ingredients. These findings support the potential use of B-CNF reinforced sericin films in active food packaging, drug delivery carriers, and in wound dressing materials. Silk and bamboo-derived natural polymeric raw materials and aqueous solvent-based film manufacturing processes will strongly provide cost efficiency and environmental friendliness and can be a suitable replacement of petroleum-based polymer industry and its related application fields.