Atomic Force Microscopy Studies Of Polysaccharide Nano-film

Organic nanofilm is a kind of nanofilm refers to the unit composed of thin-film or single or multi-layerfilm are organic molecules or nanoscale particles whose size is in nanometer scale. It has uniquemechanical, optical, and electromagnetic characteristics, and thus demonstrated in the field of heavyindustry, optical industry, military petrochemical and other broad application prospects. After decadesof development, nanofilms also demonstrate its potential applications in biology, medicine, optical andother fields. In addition, the research of nano-scale organic thin-film, involving the exploration ofmolecular self-assembly, the study of weak interactions between molecules, aggregation or assembly of thecomplex of biological macro molecules and super molecular systems dynamics, structure and function ofthe relationship between research and so on. The successfully resolving of the issues will provide approachto address the nature of law in the field of life sciences, and become a major topic.Polysaccharide nanofilm，as a organic nanofilm, has been focused because of the huge potentialapplication in biomedical field. The preparation and application of organic nano-thin film are urgently to beexplored. Nanomaterials have the unique properties in contrast to conventional materials. For example, theproperties of nano-film, including thickness, roughness, elastic strength, hardness and surface friction,cannot be achieved by conventional techniques. And the atomic-level flatness and nano-scale thickness,making the characterization of its nature to become a hot and difficult issue. A number of high-precisiontechnologies and equipments have been used in the measuremnt, such as small angle scattering, X-raydiffraction, atomic force microscopy, scanning electron microscopy and other means. Among manyadvanced instruments, atomic force microscope are accepted due to its unique performance in themeasurement of thin films.Chitosan and xanthan gum are two polysaccharides, the application not only refer to medicine, food,chemicals, cosmetics, water treatment, but also in biology, medicine and other fields. They have attractedwidespread concerns because of the excellent performance in life scicence, such as have goodbio-functional and compatibility, blood compatibility, security, microbial degradation. Chitosan has beenused as the carrier of DNA, genes, and heart disease drugs, and xanthan gum is a good food additive. Today, the complex of chitosan and xanthan gum is considered to be a good drug delivery system to make up forthe defects of the chitosan, and it has broad application prospects.In our experiments, we use different methods of preparation of two polysaccharidenano-film materialsand composite nanofilm material (chitosan and xanthan gum). And we explored the mechanical properties.The contents are listed as follows:1. The preparation xanthan gum and chitosan film material by molecular self-assembly method, thecharacterization of film by using AFM, studying the self-assembly properties. In the trial, theporous film and dense film of chitosan and xanthan gum were obtained.2. The preparation of ultrathin chitosan biofilms prepared by the combination of spin-coatingmethod and the AFM technology. The method not only to ensure the thickness of2nm, but alsosave the time of the preparation, As well the changes of film can be observed in real time.3. The preparation of the composite films of chitosan and xanthan gum, and the exploration of themechanism. The results show that, with the positively charged chitosan molecules unwindsnegatively charged xanthan gum fiber into helices, and finally the two polysaccharides form ofnew chitosan-xanthan composite.4. The characterization of xanthan scaffold structure by using Pico-Newton level of single moleculeforce spectroscopy(SMFS). It was found that the force spectrum of xanthan scaffold structure is acomplex mechanical fingerprint, and its mechanical properties different from the single fiber.Through in-depth analysis we found that the complex force spectrum consists of three basic forcespectrums randomly.