Skin damage and insufficient healing as a result of infection at the wound site are the main causes of chronic wounds. Therefore, dressings that not only protect the wound from external harm but also heal and prevent infection are required. The aim of this study is to develop a hydrogel dressing with antibacterial and wound-healing-accelerating components for the treatment of chronic wounds. For this purpose, nanocomposite hydrogel wound dressing based on chitosan hydrogel cross-linked with oxidized tannic acid (OTA) and molecularly imprinted tin oxide (SnO2) nanoparticles with core-shell structure was eva‎luated. In this regard, first, chitosan hydrogels cross-linked with tannic acid oxide and iron chloride were synthesized with different concentrations of chitosan (3, 3.5, 4, and 4.5 wt.%) and then optimized based on its related properties. Next, SnO2 nanoparticles were synthesized by hydrothermal method and modified using 3-mercaptopropyltrimethoxysilane (MPTS) and molecularly printing method was performed on their surface. After that, nanocomposite hydrogel containing different concentrations (2, 5 and 7 wt.%) of molecularly imprinted SnO2 nanoparticles was synthesized and optimized. Various tests such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were used to characterize chitosan hydrogel, molecularly imprinted SnO2 nanoparticles, and nanocomposite hydrogels. Also, swelling capability, degradation rate, compressive mechanical properties and rheological properties of hydrogels were assesed. In addition, adhesion to natural tissue and glass, ability and duration of blood clotting and their antibacterial behavior were also eva‎luated. The amount of drug absorption at different temperatures in molecularly imprinted SnO2 nanoparticles and drug release from nanocomposite hydrogels were measured by performing ultraviolet-visible spectroscopy (UV-Vis) test. Eventually, the interaction of hydrogels with fibroblast cells was investigated. The results showed that chitosan hydrogels with OTA and Fe3+ as crosslinkers were formed through the creation of Schiff-base bonds, hydrogen bonds and metal coordination bonds. The addition of molecularly imprinted SnO2 nanoparticles by creating hydrogen interactions with the polymer chain led to a significant control of the physical, mechanical and biological properties of the hydrogel. The results showed that increasing the concentration of chitosan increases the crosslink density, reduces the swelling and increases the compressive strength from 106 to 168 kPa. Moreover, with the increase in chitosan concentration, the adhesive strength of the hydrogel increased and reached 83 kPa in the 3.5% chitosan sample. Among chitosan hydrogels, increasing the concentration up to 3.5% decreased blood clotting time (< 2 minutes). In addition, the antibacterial activity of hydrogels increased with increasing chitosan concentration. Thus, the sample containing 3.5% chitosan was selected as the optimal sample and was used in the synthesis of nanocomposite hydrogel. The results showed that the presence of molecularly imprinted SnO2 nanoparticles with different concentrations increased the stability and compressive strength and decreased the degradation rate of hydrogels. The addition of 5% of nanoparticles increased the compressive strength of the hydrogel from 124 to 256 kPa. In addition, the addition of molecularly imprinted SnO2 improved the rheological properties, stability, adhesion strength to the tissue and antibacterial properties. In this regard, the addition of 7% of molecularly imprinted SnO2 nanoparticles increased the adhesion strength to the tissue from 77 to 103 kPa. Also, the antibacterial properties of the hydrogel increased up to 2.25 times....

مهشيد خرازيهاي اصفهاني , فتح اله كريم زاده

عليرضا علافچيان , نرگس جوهري