Tannic acid (TA) exhibits unique adsorption capacity, while cellulose nanofiber (CNF) has excellent properties as immobilization carrier. In this study, to combine the excellent properties of both TA and CNF, tannic acid-immobilized cellulose nanofiber (TA-CNF) was prepared by esterification, using butane-1,2,3,4-tetracarboxylic acid (BTCA). The simple esterification method achieved immobilization of TA on cellulose nanofibrils, which was verified by attenuated total reflection Fourier transform infrared spectroscopy. The average fiber diameter of TA-CNF was 4.7 nm, as determined by atomic force microscopy characterization. The protein adsorption capacities of TA-CNF and TA-adsorbed CNF were compared, suggesting that the immobilization of TA on CNF is important for manifesting the protein adsorption capacity of TA. Since TA can adsorb various materials, besides proteins, TA-CNF may have the potential to expand the application of CNF as an immobilization carrier.
