Wool keratin and silk fibroin are excellent biopolymers with outstanding properties that make them extremely valuable for biomedical and biotechnological applications. As proteins, fibroin and wool can be chemically modified at side chain groups of constituent amino acids, thus improving their properties according to the desired function. Among the chemical modifications techniques, graft copolymerization of vinyl monomers onto silk fibres has been considered a powerful method to substantially improve some intrinsic fibre properties. Grafted fibres represent an interesting model for studying the possible structural changes induced by grafting and the interactions between the fibre matrix and the grafted polymer chains. On the other hand, the reaction of selected chemical agents with fibres is a particularly attractive system that can be used to obtain effective and specific modifications of the fibrous substrate. Significant changes in the physical and chemical properties of the fibres can be obtained, avoiding some of the drawbacks that arise from graft-copolymerization of vinyl monomers and from the loading of the fibre with large amounts of polymer, which is often needed to obtain the desired effects. In the present study, IR and Raman spectroscopy has been used to comparatively analyse the reactivity of vinyl monomers (styrene, methacrylamide) and anhydrides (succinic and glutaric anhydrides) towards Bombyx mori and Antheraea pernyi silk fibroin, and wool. Several spectroscopic ratios were identified as markers of the extent of grafting/chemical modification, due to their rough proportionality to the fibre weight gain. Vibrational techniques have been widely recognized as valid tools for studying the secondary structure of polypeptides and proteins. The positions and relative intensities of the Amide I, II and III modes were evaluated to probe the possible occurrence of conformational rearrangements upon reaction. In wool, the Raman SS stretching region was investigated to gain insight into the conformational changes of the CC-S-S-CC system. In silk fibroin the I850/I830 Raman intensity ratio between the two Tyr bands at 850-830 cm-1 gave information on Tyr environment. Vibrational spectroscopy proved suitable for evaluating the reactivity of the analysed fibres towards the different agents; the observed differences can be explained in terms of the different composition of the fibres and accessibility of the amino acids potentially involvable in the reactions.
Vibrational study on the modifications induced by chemical and grafting agents in silk and wool fibres / P. Taddei; G. Freddi; M. Tsukada. - STAMPA. - (2010), pp. 62-62. (Intervento presentato al convegno 30th European Congress on Molecular Spectroscopy (EUCMOS) with GISR 2010 tenutosi a Florence nel 29 August - 3 September 2010).
Vibrational study on the modifications induced by chemical and grafting agents in silk and wool fibres.
TADDEI, PAOLA;
2010
Abstract
Wool keratin and silk fibroin are excellent biopolymers with outstanding properties that make them extremely valuable for biomedical and biotechnological applications. As proteins, fibroin and wool can be chemically modified at side chain groups of constituent amino acids, thus improving their properties according to the desired function. Among the chemical modifications techniques, graft copolymerization of vinyl monomers onto silk fibres has been considered a powerful method to substantially improve some intrinsic fibre properties. Grafted fibres represent an interesting model for studying the possible structural changes induced by grafting and the interactions between the fibre matrix and the grafted polymer chains. On the other hand, the reaction of selected chemical agents with fibres is a particularly attractive system that can be used to obtain effective and specific modifications of the fibrous substrate. Significant changes in the physical and chemical properties of the fibres can be obtained, avoiding some of the drawbacks that arise from graft-copolymerization of vinyl monomers and from the loading of the fibre with large amounts of polymer, which is often needed to obtain the desired effects. In the present study, IR and Raman spectroscopy has been used to comparatively analyse the reactivity of vinyl monomers (styrene, methacrylamide) and anhydrides (succinic and glutaric anhydrides) towards Bombyx mori and Antheraea pernyi silk fibroin, and wool. Several spectroscopic ratios were identified as markers of the extent of grafting/chemical modification, due to their rough proportionality to the fibre weight gain. Vibrational techniques have been widely recognized as valid tools for studying the secondary structure of polypeptides and proteins. The positions and relative intensities of the Amide I, II and III modes were evaluated to probe the possible occurrence of conformational rearrangements upon reaction. In wool, the Raman SS stretching region was investigated to gain insight into the conformational changes of the CC-S-S-CC system. In silk fibroin the I850/I830 Raman intensity ratio between the two Tyr bands at 850-830 cm-1 gave information on Tyr environment. Vibrational spectroscopy proved suitable for evaluating the reactivity of the analysed fibres towards the different agents; the observed differences can be explained in terms of the different composition of the fibres and accessibility of the amino acids potentially involvable in the reactions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
