Study Of Braided Silk Surgical Suture With Antibacterial Property

Braided silk surgical suture has become one of excellent and widely used sutures in the world for good performances of silk and its stable, easy-handle braided structure. But bacteria prefer to adhere to the silk material and get into the crack of braided sutures, increasing the risk of Surgical Site Infections (SSIs). SSIS not only make the patient much more painful for the delay of wound healing, and increase their, even the society’s, economy burdens. If suture is antimicrobial and can prevent bacteria attaching and growing onto, it could reduce the probability of SSIs.For these reasons, the study of braided silk surgical suture with antimicrobial property has a great important value on clinical application.In the paper, ZL was chosen as the antimicrobial agent. Firstly, braided silk suture were dipped in antimicrobial agent ZL. Then sutures before and after treatment were tested for in vitro efficacy against Staphylococcus aureus and Escherichia coli by a zone of inhibition assay to determine whether the agent ZL was useful.Secondly, sutures were evaluated for sustained antimicrobial efficacy, compared with commercial antimicrobial sutures, and for stability after24-h aqueous immersion and ethylene oxide sterilization. Thirdly, sutures were coated with three kind of antimicrobial treatment agents ZLS, ZLC and ZLP respectively which were made from sustained-release materials fibroin, chitosan and Polycaprolactone. Finally, the best sustained-release material and the better antibacterial coating process was screen out by analyzing the effects of different parameters on coating, SEM analysis, agent release assay, and evaluating the physical and mechanical properties.The results of the study show that:Sutures with ZL exhibited distinct zones of inhibition against Staphylococcus aureus and Escherichia coli. But the antibacterial duration was shorter, the longest for threedays, while Coated Vicryl(?)Plus Antibacterial Suture for7days.The antimicrobial performance of Suture with ZL was unstable to water for the zone of suture after water immersion greatly reduced.The zones of Suture with ZL after ethylene oxide sterilization against staphylococcus aureus, Escherichia coli was reduced by18.36% and3.39%apartly, but antibacterial continuous days were changeless, which showed that ethylene oxide sterilization had less effect on the antimicrobial performance of suture with ZL.The antimicrobial property of sutures with ZLS and ZLC didn’t make an improvement, while suture with ZLP demonstrated good sustained antimicrobial efficacy for its zone maintaining for7days as same as commercial antibacterial.The surface of suture with ZLP was smooth comparing with untreated suture and no bacteria adhere on after being inoculated on Staphylococcus aureus by observing in the SEM.The results of agent release assay were same as antibacterial durability test. ZLP can control ZL releasing slowly from suture and can make suture maintain a long antimicrobial effect. The concentration of ZL released from suture was less than the blood medicine peak concentration, in a safe range.After coating sutures with rollers, the coating was thin and uniform with antibacterial duration decreasing. But it can be improved through increasing the times of coating, the molecular weight of PCL and PCL concentration. Comprehensive consideration of the antibacterial durability, quality and diameter changes after coating, the optimal process was determined and was18/7.5(5), namely PCL molecular weight was180000, PCL concentration was7.5%and the coating times were5.Suture coated with ZLP was even and had no hairiness on the surface. The gaps of braided structure reduced and got closer. After coating, suture diameter increased a little and the tensile strength of suture declined, but still met requirement; The Initial modulus increased but was still less than commercial suture’s, maintained the silk material pliable advantage and has no effect on the operation using.In conclusion, antibacterial ZL demonstrated the excellent antibacterial properties when applied on sutures. After adding slow-release material PCL, its antibacterial duration was longer and produced similar sustained antimicrobial efficacy against S.aureus as Coated Vicryl (?) Plus Antibacterial Suture. Antibacterial agent released slowly with low concentration and was non-toxic. After coating, suture had smoother surface and the changes of its gauge, tensile strength, and flexibility were acceptable and conformed the suture using standard.