Plasma-activated nanocellulose for sustainable Pickering emulsions: Enhanced stability and antibacterial performance

Nanocellulose-based Pickering emulsions represent renewable and biocompatible alternatives to molecular surfactant systems, yet their limited surface functionality and bioactivity restrict practical applications. In this study, a green and tunable gas-liquid discharge plasma pretreatment was developed to activate TEMPO-oxidized cellulose nanofibers (TOCNFs). The approach establishes a structure-activity relationship linking plasma parameters with TOCNF surface chemistry and emulsion performance. Physicochemical analyses indicate that plasma treatment increased the surface polarity and charge of TOCNFs, thereby improving their colloidal dispersibility. This enhanced dispersibility facilitates more efficient interfacial adsorption during emulsification and supports the formation of a robust fibrillar network. Specifically, an intermediate plasma treatment time of 10 minutes yielded the highest zeta potential and smallest particle size for P-TOCNFs. This optimal dispersion state thus contributed to the enhanced emulsion stability and antibacterial performance. The synergistic effects of high energy electrons and reactive oxygen species (ROS) conferred intrinsic bioactivity in a treatment-dependent manner. Importantly, these emulsions acted as reservoirs for plasma-derived reactive species, retaining their antibacterial functionality that was well preserved even after 14 days of storage. This work offers a novel plasma-based platform for advanced formulations in food, pharmaceutical, and biomedical sectors.