Synthesis,Functional Modification And Medical Application Of Bio-based And Degradable Polyurethane

Degradable PU is characterized by strong molecular designability and environmental friendliness,which can realize the control of material properties,degradation mode and degradation rate.It is currently a research hotspot in the development of new biomedical materials.However,the existing synthetic degradable PU generally have poor cell adhesion performance,lack of biological activity and function,and the research on their degradation performance,degradation mechanism and biocompatibility of degradation products need to be further consummate.Therefore,the molecular design,synthesis and functional modification of degradable PU are of great significance for promoting their application in biomedical field.In this paper,two kinds of biodegradable PU were designed and synthesized from biodegradable polyester diol,amino acid,bio-based polyether polyol and polyethylene glycol,and their processability,mechanical properties and biocompatibility were systematically studied.On this basis,microbial derived polysaccharides,animal derived polysaccharides,plant protein and animal protein were introduced into the synthetic PU to improve their biocompatibility,mechanical properties and degradation properties.The modified PU materials were applied to 3D bioprinting,drug release and cartilage tissue regeneration,laying the foundation for the clinical application of degradable PU materials in the biomedical field.A series of amino acid modified anioic waterborne polyurethane(WBPU)were synthesized,and the effect of hydrophilic chain extender content on the structure and performance of WBPU was also studied.Comparative studies on the degradation performance of PLA and WBPU confirmed that the degradation products of WBPU are non-cytotoxic and will not cause the accumulation of local acidic products.The WBPU tissue engineering scaffolds with complex structure were successfully printed at 50?60? by the fused deposition molding technology.The effect processing parameters such as neddle size,extrution speed and microfilament spacing were studied,and the cell compatibility,blood compatibility and histocompatibility of WBPU were also evaluated.The results showed that rabbit chondrocyte and L929s can adhere and proliferate on the printed scaffolds,and the WBPU will not cause hemolysis and acute immune rejection,indicating that it has decent biocompatibility.CS,BCN,SF and SP were used to functionally modify PU to prepare composite nanohydrogels.The comparison of mechanical properties,degradation performance,water absorption,hydrophilicity and biocompatibility of different biomass modified hydrogles shows that the comprehensive performance of PU/BCN and PU/CS nanocomposites were significantly improved compared with pure PU,and PU/BCN was more suitable for printing tissue engineering scaffolds by low temperature deposition technology.The printed PU/BCN scaffolds were used to repair the defects of elastic cartilage of bama miniature pig.The results showed that the generation of new cartilage tissue was formed in defect site and the scaffolds were completely degraded and absorbed after 8 months of implantation.A series of WPU/CS composite membranes were prepared by the supramolecular electrostatic interaction between degradable WPU and CS.The chemical structure,microstructurc,hydrophilicity,thermal performance,degradation performance,blood compatibility and cell compatibility of the composite membranes were also studied.In this base,an implantable sustained-release system based on antitumor drug doxorubicin(DOX)was designed,and the loading efficiency of DOX and release behavior under ultrasonic control were also investigated.In vitro release behavior and cell experiment reflect the DOX loading efficiency of the DOX-loadded membrane was more than 95%.Among them,WPU/CS-KH550-DOX possessed the best sustained-release effect.The relase rate of WPU/CS-KH550-DOX was stable and controllable,and the antitumor efficiency has a significant dose-response relationship with DOX loading.A series of injectable PU/SP composite porous scaffolds(PUSF)were synthesized with caster oil polyoxyethylene ether(EL20),IPDI,PEG and SP.The effects of catalyst ratio,foaming agent ratio and foaming stabilizer content on the structure and properties of the scaffold were also studied.Rabit chondrocytes were cultured on PUSF scaffolds to observe the morphology of the cells and verifiy the expression of cartilage characteristic protein on the scaffolds.On this basis,the optimized PUSF was loaded with stromal cell-derived factor(SDF-1)to test the recruitment effect of SDF-1 on BMSCs.The in vitro results show that the PUSF@SDF-1 can effectively induce the migration of BMSCs and the induction ability was positively correlated with the loading concentration of SDF-1.The in vivo result shows that the PUSF@SDF-1 possessed mild inflammation and was safe to implantation in the body as a cell-free tissue engineering scaffold.