The photochemical stability of collagen-chitosan blends

The photochemical stability of collagen-chitosan blends in solution and film form was investigated using viscosimetry measurements, UV-Vis spectrophotometry, FTIR spectroscopy and wide angle X-ray diffraction. It was found that the relative viscosity of collagen decreased upon UV irradiation. The initial relative viscosity of collagen-chitosan blends were greater than the viscosity of collagen; upon UV irradiation the viscosity of the blends decreased rapidly. The absorption/scattering of collagen in solution increased during irradiation of the sample as shown by UV-Vis, indicating a conformational transition in the sample. FTIR showed that the amide A, B, I and 11 bands from collagen are shifted after UV irradiation to lower wave numbers; these shifts in collagen-chitosan blends are less well pronounced. Wide angle X-ray diffraction indicated that collagen and collagen-chitosan blends in film form retain much of their structural characteristics after irradiation. The viscosimetry and UV-Vis spectrophotometry results have shown that solutions of collagen-chitosan blends are less stable photochemically than a pure collagen solution. FTIR spectra have shown, that collagen-chitosan blended films are also less stable photochemically than pure collagen films. Wide angle X-ray diffraction indicates that collagen and collagen-chitosan blend samples in film form are less susceptible to conformational change than equivalent samples in solution. (C) 2004 Elsevier B.V. All rights reserved.