In-Paper Self-Assembly of Cellulose Oligomers for the Preparation of All-Cellulose Functional Paper

Paper has gained increasing attention as a sustainable, inexpensive, and portable material for a wide variety of applications and has been functionalized by chemical or physical modification methods. Nevertheless, simple and convenient modification methods are still required. In this study, we demonstrate a new strategy for noncovalently modifying cellulose paper via the heterogeneous nucleation-based self-assembly of functional cellulose oligomers in paper. Efficient and stable modification was simply achieved by the stepwise impregnation of paper with aqueous alkaline solutions of the oligomers and then with aqueous acid solutions. The chemically reactive all-cellulose paper was prepared by using cellulose oligomers with a terminal azido group. When alkynylated biotin was immobilized on azidated paper via Huisgen cycloaddition reactions, anti-biotin immunoglobulin G was successfully detected with a high signal-to-background ratio. The long-term functional stability and reusability of azidated paper were also demonstrated. The in-paper self-assembly of functional cellulose oligomers using aqueous solutions would conveniently construct various sustainable all-cellulose paper-based devices.