Preparation And Experimental Research Of High-Performance Biological Scaffold Based On Electric-Field-Driven Jet Deposition Micro-Nano 3D Pringting

With the rapid development of tissue engineering,biological scaffold implanting has shown great application prospects as the one of the most effective treatment method in biomedicine.Serving as cell carriers,biological scaffolds are necessary to have the capacity to mimic the extracellular matrix environment of cell survival which could be achieved by meeting the requirements of comparable cell characteristic size(small period/small pore size,highly ordered,multi-layer)etc.However,the existing technologies still face insurmountable problems manufacturing high-performance biological scaffolds.To break through the dilemma,this paper proposes a new method that combines electric-field-driven(EFD)technique and symmetric printing strategies to achieve high-performance(small cycle,highly ordered,multilayer)bio-scaffold preparation.Both experiment and simulation studies reveal influence laws of main process parameters(printing speed,printing voltage,printing layer thickness and printing cycle,etc.)on the preparation of high-performance biological scaffolds,and a optimal printing process window for polylactic acid(PLA)has been obtained.Finally,as-printed highperformance biological scaffolds are used for cardiomyocytes derived from human embryonic stem cell and nerve cell culture.The detailed research contents are as follows:(1)The novel method of manufacturing high-performance biological scaffolds based on electric-field-driven(EFD)technique is introduced.It takes the advantage of single-potential electrostatic induction to generate the needed electric field with a fixed distance between a printing nozzle and the opposite substrate,which could significantly reduce residual charges and improve the electric field stability during multilayer printing.The results show that: 1)With the increasing of the printing height from 0.1mm to 3mm,the intensity of generated electric field in EFD reduces by 10.5%,which is significantly smaller than that in the existing melt electrospinning writing(MEW)and other technologies.2)Combined with the proposed symmetric printing strategy,printed fibers deposite in the middle of the printed structure,which can balance the electric field force and reduce the stent aperture(printing cycle).The result proves that the proposed method is feasible to prepare small-period,highly ordered,highperformance biological scaffolds.(2)Through systematic experiments,the influence laws of main process parameters on high-performance(small cycle,highly ordered,multi-layer)bio-scaffold printing are studied.Specifically,the paper mainly investigates the influence of printing voltage,printing height,fiber diameter,substrate material and other parameters on the deposition accuracy of singlelayer fiber.No charge repulsion phenomenon was found during entire printing process by using our method,which makes it different from the existing MEW technique.It can achieve precise deposition of printed fibers with a diameter of 20 ?m and a period of 80 ?m.It's well known that the stability of the electric field strength plays a critical role in preparation of the multilayer biological scaffold,and the field strength is mainly determined by the thickness of single printing layer and the applied voltage.Further study was carried out to reveal the effects of three matching relationships(voltage and height remain constant,voltage is constant,printing layer thickness increases,voltage rises,and printing layer thickness increases)on the surface morphology of the biological scaffold.The experimental results prove that high-performance biological scaffolds with good surface morphology can be prepared by controlling the working distance in our method,which paves a new way to achieve controllable preparation of highperformance biological scaffolds.(3)Using optimized process parameters and the symmetric printing strategy,the polycaprolactone(PCL)bio-scaffold with fiber diameter of 5 ?m,period of 50 ?m,and pore size of 40 ?m,and the PLA bio-scaffolds with fiber diameter of 20 ?m,period of 60-100 ?m and pore size of 40-80 ?m were prepared.And the PLA bio-scaffolds are partially used to culture Human embryonic stem cell and nerve cell.Experimental results show that the prepared high-performance bio-scaffolds are suitable for the growth of cardiomyocytes derived from human embryonic stem cell and neurons.The feasibility of EFD technology to prepare highperformance biological scaffolds was verified.(4)In order to improve the performance of biological scaffolds and expand the application of biological scaffolds,the feasibility of printing conductive biological scaffolds have been explored by using EFD technology to achieve the printing of PLA/carbon nanotubes(MWCNTs)composite materials.The relationship between the content of MWCNTs and temperature on the viscosity of the composite was studied,and the influence of printing speed,printing voltage and screw speed on line width and morphology was discussed.The single-layer scaffolds with the MWCNT loading of 1 wt.% and the line width of 30 ?m,the MWCNTs loading of 2 wt.% and the line width of 60 ?m and the six layers scaffolds with 5 wt.% MWCNT and the line width of100 ?m were prepared,which their electrical performance were tested.