Qiongya Li, Chenchen He, Cunli Wang, Yuxiao Huang, Jiaqi Yu, Chunbo Wang, Wei Li, Xin Zhang, Fusheng Zhang,* and Guangyan Qing*

Small 2023, 2207932.

A research group led by Prof. Qing Guangyan from the Dalian Institute of Chemical Physics (DICP), Chinese Academy of Sciences recently reported a sustainable, insoluble, and chiral photonic cellulose nanocrystal patch for calcium ion (Ca2+) sensing in sweat. This study provides a new idea for the functionalization of cellulose nanocrystals (CNC). The study was published in Small on Apr 13th.

    Under the advocacy of a low-carbon circular economy, CNC has been rapidly developed as a bio-based material. Its wide application in electronics, bioplastics, energy, and other fields is expected to accelerate the sustainable development of various fields. CNC can spontaneously organize into a chiral nematic liquid crystal structure to produce brilliant photonic structural colors, which is of great significance for the development of sustainable optics and optical sensing.

    However, the functional failure of such materials in wet or liquid environments inevitably impairs their development in biomedicine, membrane separation, environmental monitoring, and wearable devices. Therefore, it is very important to make CNC stable in a liquid environment and realize functional application by simple and effective means.

    Here, the authors developed a simple and efficient method to fabricate insoluble CNC-based hydrogels. Utilizing intermolecular hydrogen bond reconstruction, thermal dehydration enables the optimized CNC composite photonic film to form a stable hydrogel network in an aqueous solution. The hydrogel can be reversibly switched between dry and wet states, which is convenient for specific functionalization. The introduction of functionalized molecules by adsorption swelling in a liquid environment resulted in a hydrogel with freeze resistance (–20°C), strong adhesion, good biocompatibility, and high sensitivity to Ca2+.

    “This work is expected to facilitate the application of sustainable cellulose sensors to monitor other metabolites (i.e., glucose, urea, and vitamins, etc.),” said Prof. Qing. “And lay the foundation for digitally controlled hydrogel systems operating in environmental monitoring, membrane separations, and wearable devices.”