Nanocellulose-based carbon sphere immobilized AgNPs for antibacterial cellulosic paper

Silver nanoparticles (AgNPs) tend to leak from matrix easily, resulting in cumulative toxicity. Consequently, it is especially necessary to immobilize AgNPs and improve their biosafety. In this study, thiol-modified cellulose nanocrystal (CNC) was mixed with AgNPs to prepare carbon sphere-encapsulated AgNPs nanocomposite (Ag@TMCS) by one-step hydrothermal, which was then mixed with pulp to fabricate antibacterial paper (Ag@CS-P). Due to the coating of carbon spheres and the fixation of paper fiber, the cumulative release rate of Ag⁺ from Ag@CS-P in 14 days was only 1.97 %. This inner immobilization strategy endowed the paper with excellent antibacterial activity and biocompatibility without damaging cell viability. Furthermore, with varying addition of Ag@TMCS, the tensile strength of Ag@CS-P increased from 34.23 MPa to 43.74 MPa, and the elongation at break increased from 5.33 % to 8.05 %. At the same time, the solubility (7.14–3.71 %) and swelling (124.89–109.88 %) of the Ag@CS-P were reduced. This was due to the filling of Ag@TMCS, which made the structure of the paper more compact. Collectively, the incorporation of Ag@TMCS not only endowed the paper with antimicrobial properties but also enhanced its mechanical strength. This study provides new ideas for the safe application of AgNPs and expands the potential use of antibacterial paper in biomedical and food packaging fields.