Study On Chitosan/natural Latex Antibacterial Composite Materials

With the development of science and technology, biomedical materials which are closely related to human health become hotspot in research. Natural latex has been applied extensively in the field of medical interventional catheter because it's excellent biocompatibility and physical properties. However, the sufferers may be infected easily because medical natural latex without antibacterial property, which means more pain and more burdens. Hence, the antibacterial natural latex has been researched for expanding its applications in the filed of biology medical area. Chitosan is the only nature alkaline polysaccharide existing in great numbers. It has excellent biocompatibility, biodegradability and non-toxic or side effects. But its application is limited in many areas because of its poor solubility.In this paper, the chitosan were modified for enhance its water-solubility used two kinds of methods. The nanometer low molecular chitosan was prepared by oxidation methodology and nanotechnology with hydrogen peroxide as the oxidant. The O-carboxymethyl chitosan was prepared in alkaline cultures of isopropyl alcohol with chloroacetic acid as modified agent. The influence of different factors on the process of reaction was studied. The structures and morphologies of two kinds of products were characterized by IR, SEM, TEM and XRD, while antibacterial effect against Escherichia coli of the two products was tested by absorbance ratio method. These results as follows:1. The preparation technological conditions of low molecular chitosan were that: the molar ratio of hydrogen peroxide to chitosan was 3:10, the drop speed of hydrogen peroxide was 5g/4h, the reaction temperature was 60℃and the time of produce was 5h. The low molecular chitosan prepared have intact structure of pyran ring. The oxidizing bond breaking occurred inβ-(1,4)-glycosidic bond. Low molecular chitosan particles are spherical with particle sizes of 0.5μm and 10nm after nanotechnology. The crystallinity of chitosan decreased obviously and the solubility increased after degradation. Low molecular chitosan had excellent and sustaining anti-bacterial performance against Escherichia coli.2. During the preparation of O-carboxymethyl chitosan, the best temperature of reaction was below 30℃, the stirring speed was 200~230r/min, after dropping of chloroacetic acid, the stirring speed was dropped to 80~120r/min. The structure of the product is loose and decentralized. Most of its particles are granular. The crystallinity of chitosan decreased and the solubility increased. O-carboxymethyl chitosan had good and sustaining antibacterial performance against Escherichia coli.Two kinds of antibacterial latex were prepared used nanometer low molecular chitosan or O-carboxymethyl chitosan as antibacterial agent and natural latex by mechanical blending method. The influence of pH value, stirring speed and temperature on the process of reaction were investigated. The structure and morphologies of unmodified and modified natural latex were characterized by IR and SEM. Antibacterial performance of modified natural latex against Escherichia coli was analyzed by inhibition ring test method.The optimum parameters of blending reaction were pH value 8.0~9.0, stirring speed 200~280r/min and temperature 18℃~25℃. Low molecular chitosan particles were combined with latex closely and evenly dispersed in latex matrix. The bonding interface did not change significantly. Slightly cracks appeared on the surface of latex after blended with O-carboxymethyl chitosan. The result of inhibition ring test indicated that the two antibacterial latexes have well antibacterial property, with the inhibition ring's diameter far more than 7mm. The experiment of compatibility in vivo was processed using low molecular chitosan antibacterial latex with better properties. The result showed the antibacterial latex had excellent compatibility and no cytotoxicity.