Marcin Wisniewski

Molecular interactions in collagen and chitosan blends.

Molecular interactions between collagen and chitosan (CC) have the potential to produce biocomposites with novel properties. We have characterised the molecular interactions in CC complexes by viscometry, wide angle X-ray scattering and Fourier transform infrared spectroscopy. It was found that CC are miscible at the molecular level and exhibit interactions between the components; X-ray diffraction of CC blends indicate that the collagen helix structure is lost in CC films with increasing chitosan content. Non-linear viscometic behaviour with decreasing chitosan content is interpreted as evidence of a third structural phase formed as a complex of CC. The blending of collagen with chitosan gives the possibility of producing new bespoke materials for potential biomedical applications.

Photochemical stability of collagen/poly (vinyl alcohol) blends

Abstract The photochemical stability of blends of collagen and poly(vinyl alcohol) has been studied by Fourier transform infrared spectroscopy (FTIR), UV–vis spectrophotometry, differential scanning calorimetry (DSC) and viscometry. Mechanical properties of the blends before and after UV irradiation were studied. Surface properties before and after UV irradiation were monitored using atomic force microscopy (AFM) and optical microscopy. The new materials obtained have different thermal, mechanical and photochemical stability than those of single components. They are more stable thermally and photochemically, but they have worse mechanical properties than pure collagen films.

The photochemical stability of collagen-chitosan blends

Abstract 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 II 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.

Effects of Solar Radiation on Collagen-Based Biomaterials

The effect of solar radiation on collagen and collagen/synthetic polymer blends in the form of thin films and solutions has been studied by UV-VIS and FTIR spectroscopies. Films and solutions of collagen blended with poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) were irradiated by solar light. It was found that UV-VIS spectra, which characterize collagen, collagen/PVA, and collagen/PVP blended films, were significantly altered by solar radiation. FTIR spectra of collagen, collagen/PVA, and collagen/PVP films showed that after solar irradiation, the positions of Amide A bands were shifted to lower wavenumbers. There was not any significant alteration in the position of Amide I and Amide II bands of collagen and its blends after solar radiation. The effect of solar UV radiation in comparison with artificial UV radiation has been discussed.

The influence of camphorquinone on the photochemical stability of cellulose

Abstract The photochemical stability of pure cellulose fibres and cellulose fibres with camphorquinone (CQ) has been studied by Fourier transform infrared spectroscopy (FTIR), thermogravimetry analysis (TG), derivative thermogravimetry (DTG) and differential scanning calorimetry (DSC). The initial decomposition temperature T o , temperature of the maximum rate of the process T max and specific enthalpy Δ H were higher for cellulose fibres before UV irradiation than for those UV irradiated in either N 2 or air. The weight loss was higher for the samples after UV irradiation. In the presence of CQ the initial decomposition temperature T o for cellulose fibres was the same before and after UV irradiation, but much lower than for pure non-irradiated cellulose fibres. The specific enthalpy of the process is much lower after UV irradiation. The weight loss was smaller for the samples with CQ than for pure cellulose fibres. Comparison of the shape of the derivatographic, DSC and FTIR curves before and after UV irradiation suggests that photodegradation of cellulose occurs during irradiation of this biopolymer and that this process is faster in the presence of camphorquinone (CQ). The camphorquinone is photo-excited by UV light to the reactive triplet state and causes more efficient photodegradation of the cellulose.