Theoretical And Experimental Study On Feather Regeneration Keratin Dissolved In Deep Eutectic Solvent

The content of keratin in feather is as high as 90%,and has excellent biocompatibility and biodegradability.It has broad development prospects in the field of protein.Keratin contains a large number of hydrogen bonds and disulfide bonds,which makes keratin have good mechanical properties,which also leads to the problems that feathers are difficult to dissolve in ordinary solvents and keratin extraction is difficult.Therefore,it is of great significance to find a solvent that can efficiently dissolve feathers and extract keratin.As a green solvent,deep eutectic solvent（DES）has the function of dissolving biological macromolecules.In recent years,des has been widely used in the fields of biomass resource pretreatment and dissolution.According to the designability of DES,a series of DES were prepared for dissolving feather regeneration keratin.The mechanism of DES dissolving feather was studied by quantum chemical calculation method,and the extraction of keratin by DES was experimentally studied.The specific work contents are as follows:（1）Using cystine as the model compound of hydrogen bond and disulfide bond in keratin,the structure optimization and frequency calculation of DES and the reaction system with cystine were carried out based on density functional theory,so as to obtain the most stable configuration of each substance.The calculation results of the interaction energy of the reaction system show that DES can effectively reduce the interaction energy of the reaction system and promote the dissolution of feathers in DES.The hydrogen bond energy and hydrogen bond position of DES and cystine were calculated by atom in molecule（AIM）analysis and reduced density gradient function（RDG）analysis.The results showed that P=O,P-O and Cl^-in DES could form hydrogen bond scissors and break the hydrogen bond in keratin.The results of molecular dynamics calculation of radial distribution function（RDF）show that DES can effectively reduce the distribution probability of H around o,that is,the hydrogen bond interaction is weakened,which verifies the accuracy of quantum chemical calculation.（2）Six DESs with different proportions were prepared and characterized by FT-IR and TGA.They were used as solvents and catalysts in the reaction of dissolving feather regeneration keratin.The structure,stability and functional groups of the regenerated protein were characterized by FT-IR,XRD,TGA,elemental analysis and XPS.The effects of different des on the yield of keratin under the same conditions were studied,and the effects of reaction temperature,reaction time,amount of water and amount of DES on the yield of keratin were investigated.The results showed that the extraction effect of[CHCl][P]1:5keratin was the best.The reaction temperature was 110℃and the reaction time was 15 min.the highest yield of keratin was 83.2%.（3）In order to further improve the yield of keratin,in order to enhance the hydrogen bond shear ability of DES,ternary DES was designed and used as solvent and catalyst to dissolve feather regenerated keratin.Through the optimization of experimental conditions,the extraction effect of[CHCl][P][Zn Cl₂]1:5:2 keratin was the best.When the reaction temperature was 110℃and the reaction time was 10 min,the yield of keratin was the highest,87.9%.After[CHCl][P][Zn Cl₂]1:5:2 was recycled for 4 times,the catalytic activity remained basically unchanged and showed excellent catalytic performance.