Mechanically Strong Metal–Organic Framework Nanoparticle-Based Double Network Hydrogels for Fluorescence Imaging
Li Tang, Liang Gong, Yue Xu, Shaoji Wu, Wu Wang, Bowen Zheng, Yijing Tang, Dong Zhang, Jianxin Tang, Jie Zheng
Abstract
Tough and multicolor-changing hydrogels have shown great potential in sensing devices, wearable electronics, and human–machine interfaces. However, most of these hydrogels are either mechanically weak or lack the multi-responsive color-change property. Here, we designed and fabricated gelatin/pHEAA hydrogels crosslinked by metal–organic framework (MOF) nanoparticles (NPs) and with a nanocomposite and double-network structure using a facile, one-pot method. The presence of vinyl-functional zeolitic imidazole framework-8 MOF NPs in hydrogels provided not only multiple chemical and physical interactions with polymer networks to strengthen their mechanical properties (a tensile strength of ∼2.4 MPa, a fracture strain of ∼14, and a fracture energy of ∼14.10 MJ/m3) but also UV-triggered multi-fluorescence changes ranging from primary red–green–blue to secondary yellow, magenta, cyan, and white colors. More importantly, MOF/gelatin/pHEAA hydrogels can be further fabricated to possess different fluorescence-responsive patterns for QR codes or potential information storage. This work provides a design concept and hydrogel systems for developing tough, multi-color-changing hydrogels for imaging and other optical applications.