Biofilm-inhibiting nanocomposite coatings on surgical sutures: durability and mechanistic insights

Biofilms are a critical health concern because of their ability to render tolerance and resistance against antimicrobials, which is especially challenging for surgical-site sterility and surgical wound recovery. Development of biofilm-inhibiting coatings on surgical devices could aid to limit biofilm formation at surgical site. In this context, two biofilm-inhibiting nanocomposite hydrophobic coating formulations, one with biocide and the other without biocide, were developed and deposited on various substrates such as glass, plastics, and surgical sutures, followed by biofilm inhibition evaluation. Encouraging results were obtained and reported earlier. In the present study, the biofilm-inhibiting action of coatings on surgical sutures was re-examined using a spot assay method by counting the colony-forming units. The long-term durability of the coated sutures with respect to varying temperature, humidity, inflammatory cytokines, and body fluid was studied, in order to validate their suitability for use in surgical accessories and biomedical devices. RTPCR test was carried out to look for downregulation of biofilm-forming genes. Cytotoxicity of the nanocomposite coatings was examined by carrying out an MTT assay. The downregulation of biofilm-forming genes and minimal cytotoxicity of the nanocomposite coatings further confirmed its viability for using on surgical sutures. Overall, the current study provides mechanistic insights and additional bactericidal effect of the hitherto demonstrated antibiofilm activity of the formulation. This study also establishes long-term durability of the coatings in terms of temperature, humidity, and exposure to plasma, enabling its use in surgical accessories to be commercialized in various settings.