Research On The Electrospun Nanofiber Covered Yarn And Its Application In Tissue Engineering

Electrospun nanofibers have been extensively studied in the field of tissue engineering scaffold materials because of their function of mimicking the structure and function of extracellular matrix(ECM).The traditional randomly arranged nanofibrous scaffolds show lower mechanical strength,and lack sufficient biological topographical guidelines,while the advantages of aligned nanofibers are highlighted.Currently,bundles/yarns are often constructed by combining nanofibrous nanostructures with various textile technologies such as weaving,knitting,and nonwoven.Scaffolds based on 3D-aligned nanofibers will be more pronounced for some applications and can be prepared through the optimization of electrospinning and post-processing,and combined with the construction of other tissue engineering scaffolding methods.In order to expand the applications of aligned nanofibers in tissue engineering scaffolds such as blood vessels,muscles,bones,and nerves,this paper proposes a new method by using nanofiber covered yarns as tissue engineering scaffold materials.A new type of electrospun device for preparation of nanofiber covered yarn was designed in this investigation.Aligned polycaprolactone(PCL)nanofibers were covered onto the medical grade polyglycolic acid(PGA)multistrand yarn to prepare aligned nanofiber covered yarns(A-PCLs).Firstly,influence of the properties of spinning solvent on the spinning process was studied.It was found that the best spinning process was as follows: PCL in chloroform/N,N-dimethylformamide(TCM/DMF,70/30),solution concentration of 10wt%,spinning voltage of 15 kV,and receiving distance of 15 cm.Secondly,the original self-made device for preparation of nanofiber covered yarn was improved,and the synchronous gear drive was introduced to make the preparation more stable.The best span of parallel aluminum sheet was confirmed at 3cm by electric field simulation and experimental observation.Finally,a covering model was constructed.Three kinds of A-PCLs scaffolds(300-PCLs,500-PCLs and 700-PCLs)were prepared under the conditions of a controlled winding speed of 30 rpm and synchronous speed at 300,500 and 700 rpm.The surface morphology was observed by electron microscopy,and the mechanical strength and porosity of the covered yarn were also tested.Results showed that diameter and pore size distribution of A-PCLs scaffolds were similar,butA-PCLs scaffolds had larger pore sizes compared with the random nanofiber covered yarns(R-PCLs).Diameter of PCL nanofibers on the surface of A-PCLs were uniformly distributed and alignment angles of nanofibers were 10°,35°,and 85° for300-PCLs,500-PCLs and 700-PCLs.PCL nanofibers could be well covered on the surface of the core yarn to form a core-shell structure.Compared with the core yarn,porosity increased from 19% to 90%,breaking strength and elongation at break were significantly increased(290 MPa to 372 MPa;19% to 28%),and the hydrophilicity increased accordingly.BALB/3T3 cells were cultured on A-PCLs to determine their in vitro biological performance,and morphological analysis and MTT assay were also performed on the growing cells.Cell culture for 3 days showed that the A-PCLs scaffolds were more beneficial to the growth of BALB/3T3 cells than the core yarn through the observation by microscopy and electron microscopy.Cell shape was spindle-shaped at three A-PCLs scaffolds(300-PCLs,500-PCLs,and 700-PCLs),and alignment angle was of 10°,35°,and 85°.However,cell shape on R-PCLs was irregularly oval.The results of MTT showed that A-PCLs scaffolds had stronger biological activity,which was significantly different from that of core yarn and R-PCLs.