Fluorescent Properties of Mesalazine-Loaded Hydrogel Nanocomposites for the Treatment of Ulcerative Colitis

This study synthesizes a novel three-dimensional (3D) porous coordination polymer (CP), {[Co(L)₀.₅(H₂O)]·NMP·H₂O}_n (1), via a solvothermal method in a mixed solvent of water and NMP (1-methyl-2-pyrrolidinone), reacting Co(II) ions with H₄L (1,4-bis(5,6-carboxybenzimidazolylmethyl)benzene). The CP exhibits unique fluorescence properties, emitting at 420 nm under UV light excitation at 350 nm, and serves as a carrier for Mesalazine (MSZ) in therapeutic applications. To enhance biocompatibility, MSZ-loaded fluorescent metal particles were encapsulated with chitosan (CMCS) and hyaluronic acid (HA), forming a bio-friendly drug delivery system, HA/CMCS-CP1@MSZ. The system was extensively characterized, confirming its stability and fluorescence properties, which facilitate drug tracking and controlled release. In vitro tests in ulcerative colitis (UC) models demonstrated that the HA/CMCS-CP1@MSZ system significantly reduced LPS-induced TNF-α and IL-6 levels, indicating its potential to effectively downregulate UC-associated inflammatory factors and be developed as a clinical treatment for UC. Furthermore, the fluorescence sensitivity of the system was explored, revealing its broad application potential beyond Fe³⁺ sensing, including drug release monitoring and tracking biological processes. This feature not only supports UC treatment but also presents new possibilities for iron ion monitoring in various iron metabolism-related diseases, such as anemia and cancer. Molecular docking simulations suggest that the carboxyl functional groups on the cobalt metal complex play a crucial role in the bioactivity, while the benzimidazole groups, serving as ligands, have a minimal direct impact on the bioactivity.