Dextran Sulfate–STMP Crosslinked Hydrogels Incorporating Copper for Controlled 5‐Aminosalicylic Acid Delivery

ABSTRACT

In this study, dextran sulfate (DS)/sodium trimetaphosphate (STMP) hydrogel was synthesized through intermolecular side‐chain reaction of DS hydroxyl groups with STMP crosslinking agent; at 50°C under basic conditions. DS/STMP‐copper nanoparticle composite hydrogel was prepared by the reduction of Cu ²⁺ ions coordinated with hydrogel network. The structure of the obtained hydrogel was characterized using elemental analysis (C, H, and S) and Fourier Transform Infrared (FT‐IR) spectroscopy. Swelling behavior of the hydrogel was investigated in three different conditions. Surface morphologies and crystal structures of the DS/STMP hydrogel, DS/STMP/Cu ²⁺ composite hydrogel, and DS/STMP/Cu nanoparticle composite hydrogel were determined by using scanning electron microscopy (SEM) and x‐ray diffraction (XRD) analyses. Thermal stabilities of the DS/STMP hydrogel and DS/STMP/Cu ²⁺ composite hydrogel were characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analyses. Drug delivery behavior of DS/STMP/Cu nanoparticle composite hydrogel for 5‐aminosalicylic acid (5‐ASA) was investigated. Drug delivery studies were carried out using ultraviolet–visible (UV–vis) spectrophotometer. Release of 5‐ASA from the DS/STMP/Cu nanoparticle composite hydrogel in representative gastrointestinal pH condition (pH = 7.4) occurred in about 110 min. The synthesized composite hydrogel is thought to have potential applications in drug delivery within the gastrointestinal system, particularly in 5‐ASA release.