Preparation And Properties Of Xanthan-silver And Gold Nanomaterials

Metal nanomaterials are widely applied in the field of catalysis, electronics, aerospace, and biomedicine because of their fascinating properties such as mechanics, thermotics, optics and electronics. The size, shape and composition of metal nanomaterials determined their physical and chemical properties, so it is great meaningful to study the morphology of metal nanomaterials. In this paper, we use solution-phase reduction method with sodium citrate as protective agent, and sodium borohydride as reducing agent to prepare gold colloidal under ice immersion. The gold dendritic nanostructures were prepared by self-assembly method. After studying the effect of reducing agent, substrate and temperature, the results showed that the amount of reducing agent, the hydrophobicity of substrate, and temperature of self-assembly could all have impacts on gold dendritic structure. By using Rhodamine 6G as the probing molecules, we detected the different morphologies of gold dendritic structure as SERS substrate activity.Nanosilver material as an antibacterial agent with a widely applicable antimicrobial property, high bactericidal rate, uneasy to produce drug-resistance and safety property, has been widely used in the field of antibacterial materials, medicine, cosmetics, and ecological environment. At present, there are many methods developed for the preparation of nanosilver particles, but most of them are prepared by colloidal chemical method which will not only introduce impurity, but also are difficult to control the particle size. Moreover, the preparation technology of microwave method, template method, and irradiation method are complex. In this paper, silver colloid is prepared by the method of gold seed-mediated, and the different size of silver colloid is prepared by changing the proportion of Au-seed and silver nitrate. After that, the absorption of three prepared silver colloid is deteced by UV-visible spectroscopy. The results showed that the absorption peak of three kinds of colloidal silver nanoparticles are all within the range of characterized absorption peak; the absorption peak could lead to red shift with the increasing concentration of silver nitrate; AFM characterization revealed that three kinds of silver nanoparticles are in spherical shape, and the distribution of particle sizes are uniform. The size of silver nanoparticles increases gradually with the increasing concentration of silver nitrate.Polysaccharide of xanthan gum is composed of a plurality of monosaccharides with glycosidic linkages, and it is a renewable energy source which has been widely in animals, plants, microbes and fungus. Xanthan is also a biopolymer hetero polysaccharide, and has been widely used in the fields of cosmetics, food and medicine for its good biocompatibility, water-soluble and PH stability. Since xanthan gum contains many functional groups, its conformation is diverse under different conditions, and a certain concentration of xanthan gum solution by molecular self-assembly can form a network topology. In this article, different mesh size of the net-like structures are prepared by changing the concentration of xanthan gum using self-assembly method, the results showed that xanthan gum mesh structure has no antibacterial activity by MTT method. The antibacterial properties of different size of silver nano particles and the minimum inhibitory concentration of the minimum diameter of the silver nanoparticles are studied by the method of MTT. The results showed that with the increasing of silver nanoparticles size, the antimicrobial properties of the particle gradually reduced, the minimum inhibitory concentration of 8nm silver particles is 0.331Ug/mL. Xanthan-silver nanocomposites are prepared by mixing different volume ratio of xanthan gum and silver colloid. The morphology of composites was detect by AFM, the results showed that silver nanoparticles are very uniformly separated on the network structure of xanthan, and there are no silver nanoparticles in the holes of xanthan mesh network. This result can be used to address the problem of easy to reunite of silver nanoparticles. The antibacterial properties of xanthan-silver nanocomposites were studied by the method of MTT, the results showed that the antibacterial properties of xanthan-silver nanocomposites is stronger than single silver nanocomposites. The findings indicated that xanthan-silver nanocomposites have a broad application prospects in the field of biomedicine, antibacterial materials.