Development And Characterization Of Antimicroblal Coating On Braided Silk Suturess

The development of a medical silk suture with slow released antimicrobial properties which can match the process of wound healing has important clinical value and it reduces the risk of Surgical Site Infections (SSIs). The purpose of this research was to explore the study of antimicrobial silk braided sutures coated with a combination of biodegradable drug carrier coating polymer and a suitable antimicrobial agent. A dip coating method was used to coat braided silk sutures using a combination of Poly Epsilon-Caprolactone (PCL) and Compound Sulphamethoxazole (SMZ) to investigate their antimicrobial performance at different coating paremeters. PCL is a biodegradable polymer used in devices approved by the Food and Drug Administration and SMZ is a sinergic drug which acts as an antibacterial agent. An in vitro performance evaluation on antimicrobial properties of suture was then carried out to find out the best coating method for the silk suture. This included the zone of inhibition assay, Sustained efficacy assay, SEM tests, and then mechanical evaluation whereby the suture without coating acted as the control. The antimicrobial activity of PCL+SMZ coated braided silk suture was done against Escherichia coli (E. coli) and Staphylococcus Aureus (S.Aureus) and was evaluated using the agar diffusion method. The Universal Testing System was used to measure the tenacity and/flexibility, knot strength, elongation at break and the work of rapture of the silk sutures. Using the Scanning Electron Microscopy the surface characteristics of the suture before and after coating where studied.Antimicrobial test results showed that the Compound SMZ and PCL treated silk sutures exhibits greater antimicrobial efficacy against gram negative (Escherichia coli) and gram positive bacteria (Staphylococcus aureus) at higher concentrations of PCL. A slight decrease in the suture tenacity and knot strength was observed for low concentrations of PCL but as the concentrations where increased a relative increase was observed. The drug release results from the treated silk sutures showed that the increase in the concentration of PCL has a positive effect on the drug released from the sutures as significant traits of antibacterial agent (SMZ) were observed for up to4days on10%PCL coated silk sutures. A lawn of bacteria was observed on the surface of the untreated silk sutures through the scanning electron microscope, whereas treated sutures showed a smoother surface with no bacteria on the surface.Through these results it can be concluded that Compound SMZ mixed with a higher concentration of PCL can be a suitable antibacterial coating agent for braided silk sutures. However further optimization of the coating process parameters still need to be done for sutures to meet the full requirements of antimicrobial sutures.