Preparation And Application Of Composite Nanofiber Biomaterials Based On Polypeptide

Biomaterials are the basis for the study of artificial organs and medical devices,and one of the important branches of contemporary materials subject.Especially with the vigorous development and major breakthroughs in biotechnology,biomaterials have become a hot spot of research and development for scientists in many countries.At the same time,biomaterials are also one of the effective tools for humans to fight against diseases.Electrospinning technology has been widely studied in various fields,nowadays,it is also a research hotspot in the field of biomedicine.The biggest advantage of using nanomaterials by electrospinning technology is that the prepared nanofiber materials can mimic the extracellular matrix well and can be used as a carrier for targeting and controlled drugs release.Polyvinylpyrrolidone（PVP）and polycaprolactone（PCL）are high molecular polymers commonly used in the preparation of biological materials by electrospinning.Rana chensinensis skin peptides（RCSPs）are hydrolyzed extracts of Rana chensinensis skin,which has the function of promoting wound healing.Corn peptide（CP）is a corn protein hydrolysate which has the function of anti-oxidation and promoting cell proliferation.In this paper,SA（sodium alginate）@Ca²⁺/RCSPs composite nanofibers with promoting wound healing and PCL/PVP@PVP-CP composite nanofibers with anti-oxidation and cell proliferation function were prepared by coaxial electrospinning technology.In this thesis,RCSPs and calcium ions were used as the core layer,PVP with good biocompatibility and SA with hemostatic function were used as shell layers,and composite nanofibers were prepared by coaxial electrospinning technology.When the nanofiber membrane comes into contact with an aqueous solution,the gelation reaction between SA and calcium ions improves the stability of the nanofibers in aqueous solution.Coaxial electrospinning technology is used to coat RCSPs and calcium ions in the nanofiber,which can not only avoid deterioration of RCSPs in contact with air,but also avoid the reaction between calcium ions and sodium alginate.The prepared nanofibers have a core-shell structure by scanning electron microscopy and transmission electron microscopy.It was verified by pore size distribution analysis that the nanofibers containing calcium ions successfully cross-linked.Thermogravimetric analysis indicated that the presence of SA increased the thermal stability of the composite nanofibers.Infrared spectroscopy analysis of functional groups shows that there is an electrostatic interaction between SA and RCSPs.The X-ray diffraction analysis indicated that the interaction between RCSPs and SA reduced the crystallization properties of the composite nanofibers.The water contact angle experiment further demonstrates the presence of a gelation reaction between SA and calcium ions.The absorption rate of SA@Ca²⁺/RCSPs composite nanofibers for simulated blood is 179.87%,and it accords with Lagergen’s quasi-first-order dynamic rate equation.When the composite nanofibers were immersed in phosphate buffered saline（PBS）for 10 seconds,the release rate of RCSPs from the nanofibers was 100%,which was consistent with the Ritger-Peppas release model.Finally,in vivo wound healing experiments,composite nanofibers not only promote wound healing in mice（the healing rate reached 97.46%on day 15）,but also improved fibroblast proliferation and collagen deposition by HE staining and Masson staining analysis.In addition,this paper also uses the corn peptide and hydrophilic polymer PVP as the core layer,the hydrophobic polymer PCL and PVP as the shell layer,and the composite nanofibers are prepared by the coaxial electrospinning technology,firstly it was found that PCL and PVP were phase-separated in a mixed solution（chloroform/N,N-dimethylformamide）,and by using this phenomenon,the same fiber with different chemical composition or properties,namely Janus fiber,is prepared by uniaxial electrospinning technology.On this basis,the corn peptide is coated in the nanofiber by the coaxial electrospinning technique.Scanning electron microscopy and transmission electron microscopy showed that the prepared nanofibers had a core-shell structure,and the composite nanofibers soaked in aqueous solution became a sheet-like"groove"type.Through the pore size distribution analysis,it is found that the composite nanofibers soaked in the aqueous solution have a smaller pore diameter than the composite nanofibers which have not been soaked in the aqueous solution.The thermogravimetric analysis indicated that the presence of CP did not alter the thermal stability of the nanofiber membrane.The mechanical properties of the nanofiber membrane（strain of 47.21%,stress of 2.5 MPa）were obtained by tensile tests.The infrared spectroscopy verified the presence of CP in the composite nanofibers.The water contact experiments verify that the presence of CP does not alter the wettability of the composite nanofiber membrane.The free radical scavenging rate of PCL/PVP@PVP-CP composite nanofiber membrane was 55.6%.When the composite nanofibers were immersed in PBS for 45 minutes,the release rate of CP from the nanofibers was 84.59%,and it accords with the first-order release model.Finally,the mice fibroblasts were cultured by the composite nanofiber membrane to find that the cells proliferated and adhered well on the nanofiber membrane,and the nanofibers was proved to have good biocompatibility.