Preparation Of Drug@MOF Modified Sutures And Their Antibacterial And Wound Healing Properties

Surgical Site Infections（SSIs）are serious surgical complications,which can lead to difficult healing of surgical wounds,prolong hospital stay and incur high costs,increasing the risk of death and heavy economic burden for patients.Sutures are medical instruments,which can fix surgical wounds and in direct contact with the wound.Microorganisms in the external environment adjacent to the surgical area are easy to adhere to the surface of the sutures and enter the human body through the sutures,which is one of the important causes of SSIs.Especially for braided sutures,due to its braided structure,microorganisms are more likely to hide between the fiber gaps.Sutures treated with antibacterial agents can prevent microorganisms from adhering to the surface and reduce the incidence of SSIs.In recent years,some new antibacterial sutures have appeared,but there are still some problems,such as biological safety,abuse of antibiotics,single function of drug carrier,the decreased physical and handling properties and limitations in promoting healing.In view of the shortcomings of existing antibacterial sutures,Drug@MOF modified antibacterial sutures were designed in this topic.The functional Metal-Organic Frameworks（MOFs）were used as the carrier to load natural antibacterial agent Curcumin（Cur）prepared the drug-loading MOF（Cur@ZIF-8）.Using silk fibers as materials,the braided silk sutures were prepared by braided molding technology,and then the prepared Cur@ZIF-8 was modified to the surface of the silk sutures by immersion coating method to construct the silk sutures with antibacterial and healing properties.The main research contents and results are as follows:（1）Cur@ZIF-8 of the load Cur was prepared by solvent synthesis method.Physical and chemical characterization proved that the Cur was successfully loaded within the framework of ZIF-8,and the surface morphology and chemical structure of ZIF-8 would not be significantly affected after the load of the Cur.The Cur@ZIF-8drug loading capability was 8.52%,drug loading encapsulation efficiency was 70.29%.（2）Using braided molding technology,a series of silk sutures were prepared by adjusting the gear ratio.The test results showed that when the gear ratio was 82/22,there were no defects on the surface of the sutures and the structure was the most uniform and flat.The surface of silk sutures was further activated by dopamine,and a series of modified silk sutures were prepared by using different concentrations of Cur@ZIF-8 modified on the surface of the sutures by dipping coating method.By systematically characterizing the chemical structure,surface morphology,mechanical properties and drug loading of silk sutures before and after coating,the optimal Cur@ZIF-8 coating concentration was 15 mg/m L.In addition,the drug release behavior of the coated silk sutures was studied at different p H conditions.The results showed that the Cur could continuously release on the silk sutures for 7 days,and the release rate of the Cur in acidic environment was higher than that in alkaline environment on account of the p H responsiveness of ZIF-8,the sutures are expected to meet the specific needs of wound repair in different p H environments.（3）The antibacterial properties of silk sutures before and after modification were qualitatively and quantitatively characterized by agar diffusion plate method and shake flask method.The agar diffusion plate test results showed that the modified silk sutures had inhibition zones of 2.30±0.19 mm和2.09±0.44 mm against E.coli and S.aureus.Under the action of blue light,the Shake flask test results showed that the bacterial killing efficiency of modified silk sutures to E.coli and S.aureus reached 99.61%and99.96%.（4）The biocompatibility of silk sutures before and after modification was analyzed by in vitro cell and hemolysis experiment.The results showed that the modified silk sutures showed good biocompatibility.In addition,the sutures were co-cultured with macrophages,which proved that the coated silk sutures had good anti-inflammatory properties.The effect and mechanism of Cur@ZIF-8 modified silk suture on skin wound healing were studied by establishing a full-thickness skin defect model in rats.The results showed that under the synergistic effect of Zn²⁺and Cur,the Cur@ZIF-8 modified silk suture can effectively promote the healing of skin wounds.