Photochemical behaviour of hydrolysed keratin.

An investigation into the influence of UV irradiation on keratin hydrolysates was carried out using UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR) and fluorescence spectroscopy. It was found that the absorption of keratin hydrolysates in solution increased during irradiation of the sample, most notably between 250-280 and 320-410 nm. The increase in absorbance in the region 320-410 was because of the new photoproducts formed during UV irradiation of keratin hydrolysates. The fluorescence of keratin hydrolysates was observed at 328 nm after excitation at 270 nm. UV irradiation caused fluorescence fading at 328 nm, and after 60 min of irradiation, a new broad weak band of fluorescence, attributable to new photoproducts, emerged in the UV wavelength region with emission maximum between 400 and 500 nm. FTIR spectroscopy results showed degradation of keratin under UV irradiation. A slight increase in oxidized sulphur species was also observed. The results obtained suggest that UV irradiation can be used as modifying agent for preparation of keratin hydrolysates for cosmetic applications.

Chemical and thermal cross-linking of collagen and elastin hydrolysates.

Chemical and thermal cross-linking of collagen soluble in acetic acid and elastin hydrolysates soluble in water have been studied. Solutions of collagen and elastin hydrolysates were treated using variable concentrations of 1-ethyl-3(3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS). Moreover, diepoxypropylether (DEPE) has been used as cross-linking agent. Films made of collagen and elastin hydrolysates were also treated with temperature at 60°C and 100°C to get additional cross-links. The effect of cross-linking has been studied using FTIR spectroscopy, thermal analysis, AFM and SEM microscopy. Mechanical and surface properties of materials have been studied after cross-linking. It was found that thermal and mechanical properties of collagen and elastin materials have been altered after thermal treatment and after the reactions with EDC/NHS and/or DEPE. Surface properties of collagen materials after chemical cross-linking have been modified. Thermal and chemical cross-linking of collagen films lead to alteration of polarity of the surface.