Preparation And Properties Of Silk Fibroin Nanofiber Reinforced Homogenous Composite Bioscaffolds

Due to congenital developmental abnormalities,diseases or accidents causing trauma and infection,causing tissue and organ damage or dysfunction,there are still huge challenges in clinical treatment.The application of tissue engineering scaffold materials provides a fundamental solution to this challenge.Especially,the micro-nano composite structure scaffold that can mimic the extracellular matrix,is the current research hotspot.Silk fibroin is a natural biological macromolecular protein with a wide range of sources,and it has good biocompatibility,biodegradability,low immunogenicity,etc.,To construct silk fibroin-based composite three-dimensional fibers reinforced by silk fibroin nanofibers which the bio-scaffold with aggregate mesh structure can provide new ideas and theoretical basis for its application in tissue engineering.In this paper,silk fibroin is extracted from silkworm cocoons with an inorganic salt dissolving system.The short silk fibroin nanofibers(SFNF)are prepared by a combination of electrospinning and ultrasonic pulverization.A kind of silk fibroin nanofiber/silk fibroin biological composite scaffold(SFNF/SF and SFNF/SF_YN)with three-dimensional fiber assembly structure was constructed by vacuum freeze-drying at-20?and-196?.On the basis of the above-mentioned scaffold material,polypyrrole is coated on the scaffold by a chemical in-situ polymerization method to obtain a conductive composite scaffold material with three-dimensional fiber aggregate structure characteristics combined with silk fibroin and polypyrrole.The properties of silk fibroin homogenous composite scaffold material and conductive composite scaffold material were studied.In this paper,the morphology observation,chemical structure characterization and porosity test of SFNF/SF scaffolds and SFNF/SF_YN scaffolds with different ratios are performed.The results showed that,especially the SFNF/SF_YN scaffold,generally presents a three-dimensional fiber assembly network structure with a more uniform appearance.75%ethanol treatment promoted the formation of silk fibroin?-sheet structure and improved its stability.The SFNF/SF scaffold has a larger porosity than the SFNF/SFYN scaffold,but the average porosity of the SFNF/SFYN scaffold is also above 80%,which can meet the requirements of biological scaffolds.The addition of nanofibers can adjust the macro morphology of the scaffold,increase the porosity,and has no effect on the molecular structure.The biocompatibility of the scaffold materials was investigated,and the results showed that cells have good biocompatibility on the two scaffold materials,and the addition of short nanofibers can provide cell recognition sites and promote cell adhesion and proliferation.In addition,by changing the concentration of the oxidant FeCl3,the microscopic morphology,chemical structure,and electrical conductivity changes of the conductive composite scaffold were discussed,and its biocompatibility was tested and characterized.At the same time,the effects of different electrical stimulations on cell growth were explored.The results showed that the surface roughness of the stent was increased after coating with polypyrrole,and the stent had good conductivity.When p-toluenesulfonic acid was used as the dopant and the oxidant concentration was0.7mol/L,the maximum conductivity of the stent was 1S/cm.The biocompatibility test showed that the cell growth was not significantly inhibited after polypyrrole was added,and the growth,proliferation and migration conditions were satisfactory.The results of electrical stimulation showed that the cell proliferation and growth morphology was the best when the current was constant at 15 min/day and the current was 50?A;when the current was constant at 50?A,the cell morphology and proliferation were good when the current was 5 min/day.