Cellulose Nanocrystals Incorporating Fluorescent Methylcoumarin Groups

Fluorescent rod-shaped nanoparticles were prepared by attaching hydrazine- or amino-substituted fluorophores onto cellulose nanocrystals (CNC) to form hydrazone and Schiff-base compounds. The products 7-hydrazino-4-methylcoumarin (HMC)–CNC and 7-amino-4-methylcoumarin (AMC)–CNC were examined by ATR-IR, solid-state NMR, ultraviolet–visible absorbance, fluorescence spectroscopy, AFM, TEM, wide-angle XRD, elemental analysis, and X-ray photoelectron spectroscopy (XPS). Estimates of the amount of dye attached to the nanocrystals suggested that substitution was not confined to the reducing end of the nanocrystals. This provides a new route to fluorescent-tagged CNC in an aqueous one-step reaction.