| The tissue engineering blood vessel(TEBV)scaffold played an important role during the process of vascular reconstruction.The ideal TEBV scaffold should have the good cell compatibility,appropriate pore structure and mechanical properties,which offered the artificial extracellular matrix(ECM)situation for the vascular endothelialization and tissue regeneration.The material of the scaffold should have good biocompatibility,the pore structure need to meet the requirements of the nutrition and information exchanges during the cell proliferation,the mechanical properties of the scaffold can provide the necessarily structure supports.In this paper,the TEBV scaffold,which mimic the function and structure of the native vessels,were fabricated by electrospun,and explored the biocompatibility,nonlinear mechanical property and aligned fibrous structure.The main research work of this paper is as follows:In Chapter 2,the nanofibers TEBV scaffold were fabricated using the biodegradable polylactic acid(PLA)by electrospinning,molecular structures of PLA lacking of hydrophilic groups and need to conduct surface modification to promote the biocompatibility of the scaffold.The scaffold were modified with oxygen plasma treatment,exploring the influence of process parameters to the surface chemical properties.The results suggested that the water contact angle(WCA)of the scaffold were dropped down to 26.8° from 115.6° after 3 min oxygen plasma treatment,hydrophilicity of the scaffold were highly increased and promoting the cell proliferation.The WCA of the scaffold could change under the oxygen in the room condition and then turn to be stable after 3 days.However,the plasma treatment damaged the fiber structure,resulting the decrease of the mechanical property of the scaffold.After the treatment of the nonsolvent-solvent,the scaffold were not only easy to demold but increased the mechanical properties because of the increase of the physical crosslinking points between fibers.In Chapter 3,the scaffold have the nonlinear elasticity by the method of pre-stretch in order to promote the compliance.Four kinds polymer scaffold were conducted by pre-stretch,the results demonstrated that the polymer of PLA and PCL showed large irreversible plastic deformation while TPU and PLCL had nonlinear properties because of stress softening effect(Mullins effect)after the pre-stretch treatment,the stress and strain curve turned to nonlinear from linearity.The Mullins effect of the PLCL/PCL blend fibrous scaffold were measured,the result revealed that the first load-unload behavior had the greatest impact on the scaffold's property.The reversibility of Mullins effect and degradation of PLCL scaffold were tested,the results suggested that PLCL scaffold with pre-stretched were still had the good nonlinear elasticity after soaking in absolute ethanol for 7 days,or annealing at 50? for 24 hours,or putting in the room condition of 58 days.After in vitro degradation for 4 weeks,the mechanical properties of the PLCL scaffold were decreased,but they still can meet the clinical requirement.In Chapter 4,the 3D small diameter TEBV scaffold with high fiber orientation and nonlinear elasticity were innovatively fabricated in order to mimic the structure and function of the human native vessels.The FFT results suggested that the alignments of circumferential and axial orientation scaffolds were 0.23 and 0.28 respectively.The stress-strain curve of the scaffold with pre-stretched was matched with the human native vessel.The tensile strength of the scaffolds were as three times high as porcine abdominal aorta,the compliance and burst pressure of the scaffolds were matched with the human native vessels that reported in literatures.The cell proliferation results demonstrated that the endothelial cells grow well on scaffold,the scaffold with the aligned fibers have great influence on cell behavior and inducing the cell morphology.Therefore,the aligned tubular scaffold might have potential application in vascular tissue engineering. |
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