AFM Study On Properties Of Chitosan, Collagen And Their Blends

Atomic force microscopy was invented in 1990s'. As a useful tool in surface analysis, it has been used in biology, medical science, material science, and many other fields. Nowadays it is been finding more and more apply in some new field.type I collagen from bovine skin radiated under UV-B were imaged by Atomic force microscope(AFM). It was found an obvious increase in the degree of collegen crosslinking after UV-B radiating. The degree of crosslinking didn't have further change after 3 hours exposure . The crossinking behavior of collgen fibril under UV-B exposure can be clearly observed by means of AFM. Over radiating made the fibril of collagen breaked in some points. It means some functions will be lost if it was in vivo. IR spectra indicated there was no new chemical bonds were formed. It is proved that AFM is an excellent technique for the study of collagen fibril.The interaction of collagen and glutaraldehyde, a sort of crosslinking solvent, was invested by IR. IR spectra indicate the position and strength of amide bonds I and amide bonds II was changed. The result displays the inter-molecular hydrogen bonds of collagen stronger and hydrogen bonds in molecular weaker. This was comformed by the result of AFM investment. The morphology of collagen before and after crosslinking changed obviously and the network structure of collagen disappeared. It means the basic structure of collagen was distrusted.Mixtures of collagen and chitosan were prepared and then cast to get blending films. For the first time the films were observed by AFM. The results suggest that an interpenetrating polymeric network was formed in collagen and chitosan blending films, differing to the tight network of collagen fiber (100-400nm) in pure collagen film, or the linear structure in pure chitosan film . As the ratio of chitosan increased, The bunch of collagen fiber was loosened and the holes were filled by particles of chitosan. The interaction of the two components can adjust the surface adsorbing force that helps the growth and moving of cells. Such a structure in blending films have the potential to produce biocomposites with unique functions.The influence of chitosan, collagen, and chitoson-collagen blending film on red blood cells was invested by AFM. Red blood cells coagultated obviously on chitosan film with positive charges, but didn't coagulate on collagen film with negative charges. the situation on chitoson-collagen film was a little different , because more anion or more cation may exist in micro-area on blending film, though the total film was negative, red cell adsorbed on blend film slightly and the shape of it changed a little also.