Study On O-Crboxymethyl Chitosan-Nano Silver/Natural Latex Composite Antibacterial Materials

With the development of science and technology and the improvement of living standard, people pay much more and more attention to health. Various medical methods were developed. Medical interventional catheter was widely used in the modern clinical medicine. However the obvious problem of catheter is that the catheter can easily lead to infection in clinic. Therefore, how to avoid the health care-associated infection caused by the material has become a prominent problem of clinical treatment.Natural latex has been widely used as the raw material to prepare the interventional catheter because of its excellent combination properties. But the catheter made from natural latex has no antibacterial property and caused infection. This has become a crucial factor which restricts the further development of the natural latex. At present, familiar scheme to solve the antibiotic property of catheter is simple coating method. However, the catheter often loses its antibacterial property because the coating flakes off easily. Chitosan has attracted many researchers in recent years because of its antibacterial property, biocompatibility, biodegradability and non-toxic. But its application is limited in many areas because it can only dissolve in several dilute acids solution. Silver, as a traditional antibacterial material, has excellent antibacterial property and non-talerance, so that it can be widely used to control infections.In this paper, chlorlacetic acid was used as etherification agent to prepare the O-carboxymethyl chitosan (O-CMCS) with better water solubility, antibacterial property from chitosan under alkalinity condition. The silver nitrate (AgNO3) solution and the O-CMCS solution were mixed uniformly, and then the sodium borohydride was added. AgNO3 was reduced by sodium borohydride in O-CMCS solution by the liquid phase reduction. Then we got the O-carboxymethyl chitosan-silver nanoparticles composite antibacterial agent (O-CMCS-nano silver). The antibacterial natural latex was prepared by mixing the composite antibacterial agent and the natural rubber latex. The influence of different factors on the process of reaction was studied. The composite antibacterial agent and the antimicrobial natural latex was detected by infrared spectroscopy (IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis and Thermogravimetry (TG). The antibacterial property of the antibacterial natural latex and the antibacterial catheter was observed by animal experiments. The results showed that:The best reaction conditions to prepare the O-CMCS had been selected:the reaction temperature was about 30℃, the mol ratio of CTS and chloroacetic acid was 1:1.5 and the chloroacetic acid was added within 0.5 h. The structure of the product with the shape of round was loose and decentralized. The crystallinity of chitosan decreased and the water solubility increased.The O-CMCS-nano silver composite antibacterial agent was prepared by the method of liquid phase reduction. The UV-Vis absorption peaks appeared around 400nm. The EDS, TEM, XRD and TG analysis results indicated that the silver nanoparticles were parpared in the composite antibacterial agent. And the size of the silver nanoparticles concentrated in 30-40 nm.The O-CMCS-nano silver composite antibacterial agent was uniformly dispersed in natural latex and combined tightly with the natural latex. The composite antibacterial agent did not appear aggregation phenomenon. The optimum proportion of the composite antibacterial mixing and natural latex was 1:1. Adding composite antibacterial agent did not only endow the latex with antibacterial property, but also improved the thermal degradation of the latex.The inhibition ring's diameters of the antibacterial latex against S. aureus was 10.5mm, while against E.coli was 9.5mm. And the inhibition ring's diameters of the antibacterial catheter against S. aureus was 11mm, while against E.coli was 8.7mm. The inhibition rings of both antibacterial latex and antibacterial catheter were larger than the standard 7mm. The inhibition ring tests indicated that the antibacterial latex and antibacterial catheter had good antibacterial property.The animal experiments showed that the antibacterial property of the two groups were different. The catheter with the antibacterial latex coating has antibacterial property.