Sustainable, Insoluble, and Photonic Cellulose Nanocrystal Patches for Calcium Ion Sensing in Sweat

Abstract

Self‐assembly of cellulose nanocrystals (CNCs) is invaluable for the development of sustainable optics and photonics. However, the functional failure of CNC‐derived materials in humid or liquid environments inevitably impairs their development in biomedicine, membrane separation, environmental monitoring, and wearable devices. Here, a facile and robust method to fabricate insoluble hydrogels in a self‐assembled CNC–polyvinyl alcohol (PVA) system is reported. Due to the reconstruction of inter‐ or intra‐molecular hydrogen bond interactions, thermal dehydration makes an optimized CNC/PVA photonic film form a stable hydrogel network in an aqueous solution rather than dissolve. Notably, the resulting hydrogel exhibits superb mechanical performance (stress up to 3.3 Mpa and tough up to 0.73 MJ m−3) and reversible conversion between dry and wet states, enabling it convenient for specific functionalization. Sodium alginate (SA) can be adsorbed into the CNC photonic structure by swelling dry CNC/PVA film in a SA solution. The prepared hydrogel showcases the comprehensive properties of freezing resistance (−20°C), strong adhesion, satisfactory biocompatibility, and highly sensitive and selective Ca2+ sensing. The material could act as a portable wearable patch on the skin for the continuous analysis of calcium trends during different physical exercises, facilitating their development in precision nutrition and health monitoring.

Recognizing chiral amino acids with a dual-optical-response system

“…We speculated that such a pitch change was enabled by a double effect, the system charge and the interaction between His molecules and the system. 29,36–38…”

Biomimetic Mechanically Robust Chiroptical Hydrogel Enabled by Hierarchical Bouligand Structure Engineering

“…To highlight the mechanical performance of our chiroptical hydrogels, we compared our hydrogel with previously reported photonic hydrogels, − ,− PVA hydrogels, ,,− and the natural hydrogel (Figure g,h, Table S5). Obviously, the mechanical properties of our hydrogel are one-to-three orders higher than those of these photonic hydrogels in all aspects of strength, modulus, and toughness (Figure S18, Table S4).…”

Recent advances in cellulose nanocrystals-based sensors: a review

“…156 In another methodology reported by Li et al EISA-assisted tunicate CNCs/PVA films were prepared, and their sodium alginate-based hydrogels were prepared for calcium ion sensing in sweat. 157 Li et al have reported a free radical copolymerization method to prepare CNCs-based sensing probes. They used these sensors for strain response monitoring.…”