Understanding the stimuli responsive behavior of Keratin Smart Hydrogels and their nanocomposites

VILLANUEVA, MARÍA EMILIA; PÉREZ, CLAUDIO J.; PERALTA RAMOS, MARÍA LUZ; LAZARO- MARTINEZ, JUAN; GALABURRI, GONZALO; COPELLO, GUILLERMO JAVIER

Congreso; XIV Reunión Anual de la AACr; 2018

Asociación Argentina de Cristalografía

Theinterest in the development of natural polymer-based materials isdriven by the properties typically present in these polymers. Theyare obtained from a renewable source, the are biocompatible,biodegradable and sometimes low cost, which lead to sustainability ofthe production process and high acceptability by producers, consumersregulatory authorities. Keratin-based hydrogels are also endowed withthese properties and have been studied for a long time. Nevertheless,they are typically obtained by reduction/extraction methods with lowyields and poor environmental friendliness. With the aim to overcomethese shortcomings, a greener method was developed. Thismethod leads to a material endowed with stimuli responsive behaviorthat has not been described before. It is shrunk at pH < 6 andswelled above this pH. Also, the presence of divalente cations at acertain concentration induces its contraction. Aiming to understandthis new behavior of keratin materials a thorough characterizationwas performed using several techniques, such as SS-NMR, FT-IR, Ramanor oscillatory rheology. Among them, Small angle X-ray scattering hadplayed a definitive role for the understanding of the mechanism thatis involved in the protein expansion and contraction. Whenmechanical properties or functionality are compared, natural polymerbased materials often present a lower performance than syntheticpolymers. The combination of nanotechnology with natural polymers mayclose this gap in performance, and thus, the study of nanocompositesis of great interest in the development of functional and sustainablematerials. The applicability of the keratin hydrogels was tested byobtaining several nanocomposites which can be used for adsorptionsystems or disinfection processes depending on the nanoobject. Acomprehensive study of the implication of the nanoobjects in thepH-responsive behavior and other properties of the materials havebeen carried out with the aid of SAXS and other characterizationtechniques. The influence of the nanoobjects on the material?sbehavior was found to be related to both its chemical nature and thestructural changes induced in the keratin chains.