Chitosan Complexed Films Investigated By Atomic Force Microscopy (AFM)

Chitosan is a biodegradable, biocompatible, naturally occurring polymer. It is one of the major components used in vascular surgery, tissue culture, and tissue regeneration. It is key challenge to improve the fragile nature of films and membrane permeability chitosan as a biomaterial. And to implant the films in the body or used as cell culture biomaterials, it is vital important to study the morphology properties. Atomic force microscopy (AFM) was employed to characterize the topography and roughness of the films, which will provide theoretic base to use the chitosan films.The blend films of chitosan/poly(ethylene glycol)(PEG) were prepared. In order to investigate the morphology changes of blend films under different processing conditions, the chitosan/PEG blend films were imaged by AFM and with thermodynamic analysis. When the ratio is 1/9 (v/v), the morphology of the film is the same as those of the pure chitosan with hole network, this will enhance the mechanic hydrophilic and permeability. Under 50℃ dried, the hole on the surface network is benefit for protein absorption and cell growth, and in a biological environment, such as water, the network structure on the surface of the film(1/9,v/v) changed to granular; the granular on the surface of the film dried under ambient ambitions changed even smaller.The complexed films were prepared by sol-gel process with different degree of deacetylation chitosan and titanium dioxide nanoparticles. The molecular interactions in chitosan and TiO₂ were studied by FTIR. The microstructure of the films and distribution of nano-particles were investigated by AFM. The results concluded there are four factors influence the nanoparticles distribution: (1) distributions of surface charges; (2) effects of space protects; (3) interactions of chemical bonds; (4) ultrasonic distribution. The morphology and ultrastructure of the Escherichia coli were observed by AFM. There were two obvious characters: (1) Cell contents began to leak; (2) many blebs were formed on the cell surface.Applied two different methods to prepare chitosan and fibronectin(Fn) films, the surface properties of the films were studied using AFM. Comparing with two different films, it was found the surface of chitosan and fibronectin blend film is smoother and ordered comparing to the lay-by-lay self-assembly one. The results indicated it is more benefit for construct...