Design and Selection of Anti-bacterial Polymeric Surgical Sutures

Abstract

In this work, a formulation was designed to produce multifunctional polymer surgical sutures based on polypropylene (PP) to utilize its mechanical properties. The resulting sutures are characterized by their antibacterial properties, therapeutic release capacity, and biodegradability. A specialized extruder was designed for the production of these sutures, consisting of an extrusion chamber, a piston, and a water bath for cooling the resulting sutures. Initially, mixtures of polypropylene and polylactic acid were prepared in three ratios. The results showed that the 1:1 mixture was the best due to its superior mechanical properties and wetting ability. However, due to the incompatibility of the two polymers, a compatibility factor was added in three ratios, and the optimal ratio, 2%, was selected. To accelerate wound healing and improve compatibility, collagen was added in three ratios, and the ratio 5% provided the best balance between mechanical properties, compatibility, and wetting ability. Chitosan was added in three proportions to help stop bleeding and impart antibacterial properties. Polyethylene glycol (PEG) was chosen as the superior of the three proportions because it gave the surgical suture sufficient elongation and ductility for suturing. To enhance the antimicrobial activity, ZnO nanopartilce was added. Amoxicillin as an antibiotic drug with a broad antibacterial spectrum was loaded. Results proved that drug-loaded suture exhibits superior antibacterial efficiency, highlighting its potential for use in antimicrobial surgical sutures to reduce postoperative infections. Gram-negative bacteria (E. coli) exhibit relatively higher resistance than Gram-positive bacteria (S. aureus) due to the presence of an outer membrane barrier in their cells. MTT assay results showed that the cytotoxic effect of the coated suture against the human breast cancer cell line (MCF-7) clear signs of cytotoxic damage including cell shrinkage, reduced cell density, membrane irregularities, and partial detachment from the culture surface. The biocompatibility was evaluated on the normal epithelial cell line (MCF-10). Results demonstrated that the treated cells maintained high viability after exposure to coated suture, indicating that current suture formula exhibited no significant cytotoxic effect on MCF-10 cells. The photocatalytic activity of the drug-loaded sutures was evaluated through the degradation of methylene blue (MB) under irradiation. After 180 min of irradiation, the degradation efficiency of drug-loaded suture was about 77%, meaning that the loaded suture is quite photo catalytic.