Photocatalytic Synergistic Oxidation System For Rapid Extraction Of Human Hair Keratin And Evaluation Of Skin Wound Repair Performance

Keratin has a wide range of sources in nature,and exists in animal hair,horns,nails,claws,and beaks etc.Keratin biomaterials have excellent biological activity and biocompatibility,It has been widely used in various biomedical fields such as hemostasis,wound repair,drug delivery,etc.Due to its excellent biological activity and biocompatibility,keratin biomaterials have been widely used in various biomedical fields such as hemostasis,wound repair,and drug delivery.Therefore,the development of an efficient and rapid keratin extraction method can not only improve the utilization efficiency of waste protein,but also effectively promote the development of keratin in the field of biomedicine.At present,the common methods for extracting keratin from human hair include chemical,physical,and enzymatic methods,but the problem of long extraction time is common.Although the extraction time of the steam flash explosion method is short,it is not easy to be widely promoted.Based on this,this paper proposes a new strategy for the rapid extraction of keratin by the photocatalytic cooperative oxidation system（TiO₂/UV/H₂O₂）.The H₂O₂ oxidation method is a commonly used keratin extraction method,and its extraction mechanism is to break the disulfide bonds with the help of superoxide free radicals;When TiO₂ particles are excited by ultraviolet light,they form a strong oxidation effect,and the free radicals produced can also catalyze the degradation of various organic substances;The synergy of photocatalysis and oxidation method can strengthen the generation and oxidation ability of free radicals,thereby improving the extraction speed and effect of keratin in human hair.This paper uses TiO₂/UV/H₂O₂ method to extract keratin from human hair.Through single factor experiment,the influence of H₂O₂ concentration,TiO₂concentration and reaction time on the extraction rate of human hair keratin was investigated,and its physical and chemical properties were characterized;Furthermore,the electrospinning method was used to prepare PCL nanofibers,and the human hair keratin/PCL composite fibers were prepared by the coating method.The hemostatic and wound performance differences of the human hair keratin obtained by different extraction methods were evaluated.The main research content and results of this article:1.Compared with H₂O₂ method,TiO₂/UV/H₂O₂ has higher extraction efficiency of human hair keratin and shorter extraction time.The H₂O₂ concentration,TiO₂concentration and reaction time were investigated by single factor analysis method,and the degradation rate and yield were used as indicators.The extraction yield of human hair keratin first increased and then decreased with the concentration of H₂O₂ and TiO₂,and the yield was highest when they were 0.5M and 0.2g/L,respectively.As the reaction time prolonged,the yield gradually increased and then stabilized.Under the optimal conditions,the yield of human hair keratin extracted by TiO₂/UV/H₂O₂was 70.31%±5.63%,and the degradation rate was 71.40%±5.29%.In addition,by optimizing the extraction conditions of the single oxidation method,the yield and degradation rate of human hair keratin extracted by H₂O₂ method were 53.24%±0.83%and 70.82%±0.63%,respectively.The extraction yield of TiO₂/UV/H₂O₂human hair keratin is significantly higher than that of H₂O₂ method,and the extraction time is only 2h,which is 1/4 of the extraction time of H₂O₂ method.2.The physical and chemical properties of human hair keratin extracted by TiO₂/UV/H₂O₂ and H₂O₂ are similar.The physicochemical properties of human hair keratin extracted by two oxidation methods were analyzed and compared.SDS-PAGE analysis found that the molecular weight distribution of keratin obtained by TiO₂/UV/H₂O₂ method is wide,and bands can be found in the theoretical molecular weight of human hair keratin,while the molecular weight of keratin extracted by H₂O₂method is small,and there is excessive oxidation.Fourier transform infrared spectroscopy（FT-IR）analysis found that the two human hair keratin extracts have similar chemical structures and have the same characteristic absorption peaks.X-ray diffraction analysis（XRD）results show that the TiO₂/UV/H₂O₂ group keratin has a more complete secondary structure and a more complete crystal form.According to the circular dichroism（CD）analysis,both keratins show anα-helix structure,but theα-helix of keratin extracted by TiO₂/UV/H₂O₂ has a higher composition.3.Keratin extracted by TiO₂/UV/H₂O₂ method has better hemostasis and wound repair effects.PCL nanofibers were prepared by electrospinning,and then coated with different types of human hair keratin to prepare composite nanofiber membranes for the investigation of its hemostatic properties and wound repair capabilities.The SD rat liver injury model was established.The results of hemostasis experiments show that the hemostatic effect of the human hair keratin/PCL composite fiber membrane is better than that of pure PCL nanofibers,and the hemostatic effect of the TiO₂/UV/H₂O₂keratin composite fiber membrane is better than that of the H₂O₂ group.The amount of wound bleeding after treatment in the TiO₂/UV/H₂O₂group was half of that in the H₂O₂treatment group.In addition,full-thickness skin defect model of SD rats was constructed to evaluate the wound repair effect of two kinds of composite keratin nanofiber membranes,and it was found that the wound repair ability of TiO₂/UV/H₂O₂ group was also better than that of the H₂O₂ group.In summary,based on the problem of long extraction time of human hair keratin,this paper proposed a photocatalytic synergism oxidation method to improve the extraction yield and speed.By discussing the effects of H₂O₂concentration,TiO₂concentration and reaction time on the extraction rate,degradation rate and the number of disulfide bonds of human hair keratin,the law of TiO₂/UV/H₂O₂ for extracting human hair keratin and the best extraction plan were obtained.The completion of this paper can provide a new option for the rapid extraction of keratin,and is of great significance to the efficient recycling of keratin waste.