Methods and manufacturing conditions were developed for giving ion-exchange properties to PCA fibres by graft polymerization of methacrylic acid to PCA fibres and styrene to PP fibres followed by sulfurization of the graft polystyrene. Antimicrobial surgical suture materials with fixation of antibiotics on the modified sutures by the ion-exchange mechanism were obtained. It was found that the duration and effectiveness of the antimicrobial action of the sutures are determined by the amount of antibiotic sorbed and the ionic bond strength of the latter with the ion-exchange groups in the sutures. The effect of the conditions of modification and methods of sterilization on the physicomechanical properties of the sutures was investigated. Antimicrobial surgical PCA sutures with the gentamycin Caprogent are recommended for use in general clinical practice and are being manufactured.One of the most effective methods of obtaining antimicrobial surgical suture materials is chemical modification of fibres with drugs [1]. Selection of this method predetermines a number of special requirements which must be considered in working with the initial materials and reagents.The fibres used must not only be biologically inert and sufficiently strong, but also contain active functional groups which can react with the drugs either directly or after additional modification [2]. In turn, the drugs must not be inactivated as a result of chemical addition itself or under the effect of the modification conditions. In consideration of these requirements, polycaproamide (PCA) and polypropylene (PP) fibres were used for production of antimicrobial suture materials.In view of the important losses (waste by oxidation) that take place in textile processing of fibres, chemical modification was conducted on finished textile articles. For this purpose, we made PCA and PP twisted surgical sutures with arbitrary numbers from 5/0 to 5 (metric size 1-7).To give the PCA and PP fibres antimicrobial activity, the drugs were attached to them by the ion-exchange mechanism. We developed methods for preliminary incorporation of cation-exchange groups in the fibres by grafting methacrylic acid (MAA) to the PCA fibres and styrene to PP fibres, followed by sulfonation of the graft polystyrene (PS).The reaction of grafting MAA to PCA fibre was initiated by peroxide and hydroperoxide groups obtained by mild oxidation with the Fe 3+ H 2 O 2 system. The advantages of this method are the important decrease in the probability of formation of homopolymer and preservation of the physicomechanical properties of the fibres.To incorporate peroxide and hydroperoxide groups in PCA, the fibre was successively treated with a solution of iron chloride in dilute hydrochloric acid and an aqueous solution of hydrogen peroxide. The oxidation process was monitored by the content of active oxygen in the PCA fibre.It was found that the acid medium causes swelling of PCA so that the number of peroxide and hydroperoxide groups, probably formed due to deeper penetration of the reagen...

Special technology has been developed for the production of polypropylene surgical monofilaments to meet medical needs for a suture material meeting tight specifications for physical and mechanical properties. To produce polypropylene monofilaments having improved elastic properties and strength, studies have been made on the effects of technological parameters (temperatures of liquid and of cooling bath, molding rate, thermal drawing ratios and temperatures, the thermal stabilization temperature, and temperature of additional thermal treatment of existing monofilaments with or without shrinkage) as regards the strength, elongation, the strength and elongation in knots, and bending rigidity. Conditions are given for making surgical monofilaments of various diameters with improved manipulation and strength.Polypropylene (PP) monofilaments are amongst the best nonresorbed suture materials, as they have high biocompatibility, good strength, resistance to biodegradation, lack of capillary performance, and reliable fixation of surgical knots. They have smooth surfaces and are monolithic, so they produce minimal damage on passing through tissues while providing a good cosmetic effect and reducing the painful sensations on removing the sutures. However, the characteristic rigidity means the risk of shearing of the tissues in the formation of wound swelling and difficulty in manipulation during operative intervention.The technical PP monofilaments produced by Russian industry cannot be used as surgical materials because of their low elasticity and consequently their low strength in knots, which usually does not exceed 50% of the strength of the monofilament. The strength in knots is a basic characteristic of a suture material, and it determines the reliability of the surgical procedure, so that parameter is to be found in the standardization documentation of EP and USP [1, 2].Medicine requires a material subject to tight specifications for the physicomechanical properties, so a special production technology is needed. The monofilament properties can be improved by physical modification, which is best combined with the making of the monofilaments.Monofilaments were made from isotactic polypropylene grade 21030; stabilization recipe 16 was used, which is permissible for medicine. The fluidity parameter for the liquid polymer was 2.5-4.0. The melt method was used to make the PP monofilaments, which was implemented with a continuous technological scheme on a plant made by the Italian firm of Covema.There are the following stages in making PP monofilaments: transporting and loading the polymer, melting the polymer, shaping (casting in a tank and preliminary drawing), thermal drawing, thermal stabilization, winding on a coil, and monitoring the physicomechanical properties, sorting, and packing. To improve the visualization of the filaments in a wound background, we added 0.2-0.3% of pigments permitted in medicine: phthalocyanin blue or green. In that case, the granulate before loading into the extruder bunker was treated with...

No abstract

No abstract

No abstract