Fluorescent PVP-g-chitosan polymer probes for the recognition of 4-nitrophenol

Natural polymer chitosan has many advantages, but the poor solubility limits its application. In this study, chitosan derivatives soluble in DCM, DMF, DMSO, H 2 O and other solvents were developed by introducing side chains into chitosan (CS). In addition, the fluorescent group on the side chain makes the chitosan derivative have the ability to detect 4-nitrophenol (4-NP). Firstly, a chain transfer agent containing C  C (N3-NS) was synthesized with naphthalimide as the fluorescence unit. Then, using AIBN as initiator, an extensively soluble polymer with fluorescent moiety TP-NVP was synthesized by reversible addition-fragmentation chain transfer polymerization (RAFT) method using monomer N -vinyl pyrrolidone (NVP). Finally, the C  C of TP-NVP was used to react with –NH 2 on CS to prepare PVP-g-chitosan, so that more CS was “pulled” by TP-NVP into the solvent. The solubility of the synthesized CS-PVP probe can be adjusted by adjusting the amount of NVP, up to 17.6 mg/mL. At the same time, the synthesized CS-PVP had a good detection effect on 4-NP, and the detection limit (LOD) was 0.054 μM. The HOMO-LUMO energy level of the probe was calculated by cyclic voltammetry (CV). In addition, CS-PVP was successfully loaded on a low background fluorescent test paper to achieve real-time visual intelligent determination of 4-NP in real samples with the help of a color scanning APP of a smartphone.