Study On The Preparation Of Pcl Tissue Engineering Scaffold By SCCO₂ Foaming

As one of the basic elements of tissue engineering,the development of its preparation process is a research hotspot in the field of tissue engineering.The use of supercritical fluid technology to prepare biodegradable porous scaffolds can effectively avoid the use of organic solvents and high-temperature operating conditions in traditional preparation methods,and has broad application prospects in the fields of tissue engineering and medical materials.This article takes polycaprolactone?PCL?,poly?lactic acid-glycolic acid?copolymer?PLGA?and ibuprofen as the research objects,using supercritical carbon dioxide?SCCO₂?foaming method and assisting with supercritical carbon dioxide impregnation technology?SSI?,PCL single-layer scaffolds with excellent connectivity,PCL/PLGA double-layer scaffolds and PCL scaffolds loaded with ibuprofen drugs were prepared,and the properties of the scaffolds were characterized.In present study,the PCL single-layer scaffold was studied firstly,a solvent-free foaming method aided by supercritical carbon dioxide?SCCO₂?is developed to prepare porous polycaprolactone?PCL?scaffolds for tissue engineering.The effects of molecular weight,the foaming pressure,temperature and depressurization rate on the scaffold structure were investigated in detail.The results showed that the pore size decreased and the pore size distribution narrowed while increasing molecular weight of PCL;higher pressure led to higher cell density and smaller pores;pore coalescence occurred at low depressurizing rates.When the polymer was in a high elastic state,the pore size increased while increasing the temperature;however,further increasing the temperature led to the slightly smaller pore sizes.In addition,the mechanical strength of the scaffold was also studied,and it was found that it belonged to the application category of tissue engineering scaffold material.Supercritical carbon dioxide foaming method makes it possible to fabricate PCL porous scaffold materials with controlled pore diameters in the range of 132⁴50?m.Through mechanical tests these scaffolds exhibited a elastic modulus of 10 MPa,meeting the mechanical requirements of tissue engineering scaffold material.On the basis of PCL single layer foaming,PLGA layer is introduced.In present study,an efficient solvent-free foaming method aided by supercritical carbon dioxide?SCCO₂?is developed to prepare porous PCL/PLGA bilayer membranes for potential guided tissue regeneration?GTR?applications.First rheological properties and foaming behaviors of PLGA and PCL were studied in detail.Compared with PLGA,PCL had lower viscosity with loss tangent tan?over 1 thus got bigger and highly interconnected pores after foaming.Based on this,membranes with distinct porous PCL and PLGA bilayer were prepared via a one-step foaming.SEM showed the pore size of the PCL layer was 300⁶00?m,and that of the PLGA layer was less than 20?m.Through tensile tests these membranes exhibited a tensile strength of3.98 MPa and a elongation at break of 58.1%,meeting the mechanical requirements of GTR.Further cell tests demonstrated that the PCL layer suited for the proliferation of osteoblasts and the PLGA layer inhibited the ingrowth of fibroblasts.The porous PCL/PLGA bilayer membranes fabricated using this one-step foaming meet the requirements of GTR and possess great commercial potential.Finally,using supercritical carbon dioxide?SCCO₂?foaming and assisted by supercritical carbon dioxide impregnation technology?SSI?to prepare bioactive porous PCL stents with drug release effect.It mainly includes the following research contents:taking ibuprofen as the research object,coupling SCCO₂ with SSI technology,completing the PCL foaming process while the drug is loaded,and then measuring the drug loading of the stent and the release process of the study drug.