A Novel Coated Suture Displays Antimicrobial Activity without Compromising Structural Properties

Background Treated or coated sutures promise to prevent contamination of wounds. Purpose Purpose of the study was to coat surgical sutures with a new quaternary ammonium silane (QAS) antimicrobial compound at two different application temperatures and then to evaluate resulting structural, physical, mechanical, and biological properties. Study Design, Setting and Sample In-vitro and in-vivo studies were conducted using male albino Wistar rats approved by Joint Ethical Committee of IMU and Postgraduate Medical Institute, Lahore. Only suture samples, coated uniformly with verified presence of the compound and of adequate length were used. Samples which were not coated uniformly and with inadequate length or damaged were excluded. Predictor Variables Predictor variables were sutures with and without QAS coatings and different temperatures. Sutures were coated with QAS at 0.5% and 1.0% wt/vol using dip coating technique and sutures with and without QAS coating were tested at 25oC and 40oC temperatures. Main Outcome Variable Outcome variables of structural and physico-mechanical, properties of QAS coated and non-coated sutures were measured using Fourier transform infrared spectroscopy (FTIR) (for structural changes), confocal laser and scanning electron (for diameter changes), and tensile strength/modulus (for mechanical testing). Biologic outcome variables were tested (bacterial viability); macrophage cultures from Wistar rats were tested (M1/M2 polarization detecting IL-6 and IL-10). Macrophage cells were analyzed with CD80+ (M1) and CD163+ (M2). Chemotaxis Index was calculated as a ratio of quantitative fluorescence of cells. Covariates Not applicable. Analysis Ordinal data among groups were compared using Wilcoxon Mann-Whitney U test along with comparison of histological analysis using Wilcoxon Sign-rank test (p < 0.05). Results FTIR peak at 1490 cm-1 confirmed presence of QAS on suture’s surfaces with significant increase (p<0.05) in diameter (0.99±0.5-mm) and weight (0.77±0.02-mg) observed for 1% QAS-groups treated at 40°C. Non-coated samples heated at 25°C had significantly (p<0.05) less diameters (0.22±0.03-mm) and weights (0.26±0.06-mg). Highest tensile strength/modulus was observed for 0.5% QAS-coated samples which also had significantly high antibacterial characteristics than other sutures (p<0.05). QAS-coated sutures significantly increased M1 and M2 markers. Conclusions and Relevance QAS coating conferred antibacterial action properties without compromising physical and mechanical properties of the suture.