Preparation, Antibacterial Activity And Toxicology Of Hollow Fiber Loaded With Silver Particles

Silver has been used for centuries to prevent and treat a variety of diseases, mostly notably infections. Previous work has shown that silver ions have strong inhibitory and bacterial effects as well as broad spectrum of activity, and concomitant low toxicity to mammalian cells. The inhibitory effect of silver ions was believed to be due to its sorption to the negatively charged bacterial cell wall, deactivating cellular enzymes, disrupting membrane permeability, and ultimately leading to cell lysis and death. Nowadays the introduction of new silver-based antibacterial polymers represented a great challenge for both academic world and industry. The silver-based thermoplastic polymer composites combined the excellent process properties of the thermoplastics with the inherent antibacterial ability of the silver. The products loaded with silver had disadvantages more or less, as lasting, staining, uncontrolled release, and et al.Hollow fiber loaded with silver particles (silver fiber) was prepared in the study through the different press effect and the silver mirror reaction, and the silver was displaced and adhered on the fiber inner wall. The size of silver particles was approximately 0.1～0.5μm, which was measured by SEM test. X-ray of PET hollow fiber was compared to the silver fiber. The most important peaks are denoted clearly. The curve exhibited the obvious peaks at 2θ=38.2°, 44.3°, and 64.5°, which are due to the face-centered cubic crystalline silver, corresponding to the crystal faces of (111), (200), and (220) of silver, respectively. And the peaks at 2θ=77.4°and 81.5°, which are due to the crystal faces of (311) and (222) of silver, had not appeared. Therefore, it was very clear that the silver fiber was consisted of silver particles and the size of silver particles was small, which was consistent with SEM results.When the silver fiber was entered in a water environment, the silver ions would be released form the two ends of the fiber. And the silver ions were the principle factor on the antibacterial efficiency. So the release of silver ions was investigated by release experiments and qualitative analysis. It was found that the concentration of silver ions released from the silver fiber was affected by many factors, such as release hours, fiber length, concentration of silver particles and fiber type. With the increase of release hours, the concentration of silver ions released from the silver fiber increased, and would be invariable after 3 days. And when there was the same weight of silver fiber, with the increase of the length of silver fiber, there were fewer points to release silver ions. And the silver ions released increased as well as the increase of concentration of silver particles. The study also indicated that the hollow fiber which had good moisture absorption released more concentration of silver ions.In this paper, a silver ion-bacterium model was established to determine the threshold concentration of silver ions. The silver ion-bacterium model was similar to predator-prey model also known as the Lotka-Volterra model which described the dynamics of biology system in which two species interacted, one a predator and one its prey. Silver ions were antibacterial and treated as predators; bacteria were killed by silver ions and treated as preys. The concentration of silver ions was a critical parameter in medicine applications. When it was too high, it was lethal to the human organism, this was Argyria; while it was too low, the inhibitory efficiency was seriously affected. It was important to determine the threshold concentration of silver ions, , where a varied with different bacteria, andα=0.82 for S. aureus;λvaried with different hollow fibers and number of silver particles on the inner surface. They were easy to be got by experimental results.The antibacterial test showed that the silver fiber had great board-spectrum antibacterial activity, and had inhibitory effect on drug resistant bacteria. The antibacterial efficiency was dependent on the wateriness of the fibers, because the watery silver fiber released silver ions more than that of waterless. The antibacterial concentration of 38mm silver fiber was 37.5μg/ml. At that concentration, the inhibitory ratio reached up to 90%. From the SEM images of bacteria treated by silver fiber, it was found that the bacteria was expanded and cracked, and the different effect on Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) may be due to the different configuration of cell walls of these two bacteria.Four clay cell types were chosen to determine the cytotoxicity of the silver fiber, which were Vero, Hela, WI-38 and fibroblasts developed from primary culture of discarded surgical tissue, foreskins. And the experimental results showed that the cell proliferation was not affected by the concentration of silver fiber for antibacterial activity. And when treated by 4mg/ml silver fiber, the cell became less polyhedral, more fusiform, shrunken and rounded. It showed that cell proliferation and morphology of all cells was normal in the presence of the silver fiber down to a concentration of 4mg/ml, including 37.5μg/ml. However, abnormal size, shrinkage and rounded appearance of cells at higher dose (4mg/ml) suggested toxicity of the silver fiber.During the process of the study, toxicity test on Guinea pig was conducted from the perspective of immunology and hygienic toxicology, in which two different contamination methods were used, including skin smearing and embedding. The effect of the silver fiber on immunity level, including humoral, cellular and non-special immunity, and germ plasm of Guinea pig were detected. Furthermore, pathological analysis was carried out on some primary organs, such as stomach, liver and kidney. Based on the elementary research on the effect of the silver fiber on immune function and germ plasm of the tested animals, it was found that in the presence of the silver fiber down to 0.03g, the silver fiber would not cause harm to the immune function, germ plasm and organs. But when in high dose, as 0.03g, hemolytie plaque-forming cell, immune complexes and red cell osmotic fragility was abnormal, and the pathological analysis further testified that the liver and kidney were really injured by 0.03g silver fiber. Therefore, the reasonable quantity control of the silver fiber during its application process is necessary, which requires that series of large-scale experiments need to be undertaken in further research process so as to acquire the dose-effect relation of silver fiber and provide reliable evidence for its extensive application.The study prepared the hollow fiber loaded with silver particles and investigated its release property, antibacterial activity, cytotoxicity and toxicology. The conclusions in this paper provided an experimental and theorical foundation for its practical application. However, the fiber was failed to produce into fabric such as hydroentangle nonwovens due to the limitation of our experimental equipment, and thus the manufabrication and properties of fabrics need to be further studied in future.