Construction of a cellulose-based dual-responsive fluorescent probe for simultaneous pH and HClO detection and imaging in arthritic mice

pH and hypochlorous acid (HClO) are important active factors in living organisms and play a crucial role in the occurrence and progression of arthritis. Herein, a novel cellulose-based dual-responsive fluorescent probe was developed for highly sensitive and selective detect of pH and HClO. In the design, 4-(2-aminoethylamino) −1,8-naphthalimide and modified Nile red were grafted together onto a toluenesulfonyl actived cellulose to fabricate the cellulose-based probe. 4-(2-aminoethylamino) −1,8-naphthalimide was supplied as the pH-responsive part, and Nile red derivatives supplied as HClO-reponsive part, respectively. Upon decreasing solution pH, the cellulose-based probe exhibited 5-fold fluorescence enhancement at 560 nm. While, increasing of HClO concentrations resulted in remarkable fluorescence enhancement at 670 nm. The limit of detection (LOD) and limit of quantification (LOQ) for HClO were determined to be approximately 0.186 μM and 0.621 μM, respectively. The detection mechanism was explored by DFT calculation and HRMS analysis. Then it was successfully applied to detect pH and HClO within cells and zebrafish, and further validated in a mouse model of arthritis. The cellulose-based probe had demonstrated good biocompatibility, sensitivity, and prolonged fluorescence imaging capabilities (fluorescence stable for 3 h, over 50 % signal at 12 h). These results suggest the cellulose-based probe can potentially be used as a real-time monitoring tool for assessing clinical arthritis.