Cellulose nanocrystals (CNCs), a unique and promising natural material extracted from native cellulose, have attracted considerable attention owing to their physical properties and special surface chemistry. This review focuses on chemical conjugation strategies that can be used for preparation of fluorescent-molecule labeled CNCs and the development of biomaterials.Furthermore, their application in the detection of metal ions and future development prospects are discussed. We hope to provide a clear view of the strategies for surface fluorescent modification of CNCs and their application in detection of metal ions.

Conductive papers made from graphene and its derivatives are important for the development of electronic devices; however, elastomerbased matrices usually make it difficult for the conductive sheets to form continuous conductive networks. In this work, we used tunicate-derived cellulose nanocrystals (TCNC) instead of traditional elastomers as the matrix for polydopamine (PDA)-coated and reduced graphene oxide (GO) to prepare conductive paper, which, at a low concentration, were better for the formation of conductive networks from conductive sheets. It was found that the Young's modulus of the conductive paper produced via this strategy reached as high as 7 GPa. Meanwhile, owing to the partial reduction of GO during the polymerization of dopamine, the conductivity of the conductive paper reached as high as 1.3×10^-5 S/cm when the PDA-coated GO content was 1 wt%, which was much higher than the conductivity of pure GO (~4.60×10^-8 S/cm). This work provides a new strategy for preparing environmentally friendly conductive papers with good mechanical properties and low conductive filler content, which may be used to produce high-performance, low-cost electronic devices.

Cellulose nanocrystals (CNCs) have been widely applied in biomaterials and show great biocompatibility and mechanical strength. In this review, the chemical reactions applied in CNC surface modification and their application in CNC based biomaterials are introduced. Furthermore, the conjugation of different functional molecules and nanostructures to the surface of CNCs are discussed, with focus on the binding modes, reaction conditions, and reaction mechanisms. With this introduction, we hope to provide a clear view of the strategies for surface modification of CNCs and their application in biomaterials, thus providing an overall picture of promising CNC-based biomaterials and their production.