The Design And Research Of Polyurethane Material For Cartilage Repair

Tissue engineering utilizes biology,engineering and other technical methods in vitro or in vivo to build human tissues and organs.The development of it brings new hope for the repair and replacement of human lesions.Tissue engineering scaffolds are in direct contact with cells/tissues,and their selection or design needs to be further optimized for their molecular structure to meet the appropriate degradation rate.The scaffold material can provide adherent cells with environmental conditions similar to extracellular matrix and will promote the effect of cell regeneration and quickly repairs of damaged tissue.The active functional groups introduced by the surface modification in the biodegradable tissue engineering scaffold material will rapidly disappear with the degradation of the material,which is not conducive to the role of the material inducing tissue growth for a long time.For the regeneration of tissues and organs with relatively long regeneration period,the active functional structure is introduced into the body structure of the material,and its biological activity can maintain till the material is completely degraded,which will make it more prominent in tissue engineering application.A key issue in the regeneration of articular cartilage is to avoid the early regenerative hyaline articular cartilage degenerated into fibrous articular cartilage in the long term.TGF-?1 is an important growth factor to maintain the hyaline articular cartilage's phenotype.Being compounded onto the scaffold and ensures its long-term effect,TGF-?1 with the scaffold will greatly reduce the probability of regenerative articular cartilage's long-term degeneration and thus solve the problems mentioned above.To solve these problems,this paper designs and realizes the molecular structure of the elastic polyurethane materials,and then introduce the short peptide HSNGLPL,which can bind TGF-?1 by affinity,into the material structure.By binding and enriching the TGF-?1 molecule,the material can achieve the purpose of maintaining the regenerated cartilage phenotype.In this paper,we will focus on the molecular structure design and implementation of related materials,and verify the performance of binding TGF-?1.The PCL or PTMG polymer diol was used as the soft segment,and HDI together with the small molecular diol DPPD are used as the hard segment of the polyurethane.The active HSNGLPL peptide was introduced on the DPPD pendant.Through the exploration of the related technology,the control of the content of alkynyl on the polyurethane material was realized.Polyurethane with alkynyl content ranging from 0.18 to 1.02mmol/g were obtained.Before the chemical modification of these materials with HSNGLPL,the catalytic system of the CuAAC reaction was explored.The reaction efficiency of azido-heptapeptide and alkynyl-containing compounds in five groups of catalytic systems was explored.The most suitable catalytic system for azido-heptapeptide reaction is CuSO4·5H2O/Naasc system.Then,it was studied that the azido-peptide was modified to the alkynyl-containing polyurethane by the CuAAC reaction.The results showed that when the reaction temperature was about 25 ? and the molar ratio of raw materials was 1:0.8 ~ 1,the peptide grafting efficiency is higher.It indicates that the product has the correct molecular structure,and the maximum grafting rate can be more than 90%.Finally,the adsorption and desorption experiments of growth factor-?1 were carried out.The results showed that the heptapeptide on PU-P could achieve the adsorption of TGF-?1 by affinity.The TGF-?1 adsorption capacity of PU-P is 409.4 ng/cm2.TGF-?1 can still adsorb on the surface after it's coated with BSA,and the total adsorption capacity of BSA and TGF-?1 was 648.9 ng/cm2.The desorption rate was lower than that of TGF-?1adsorption alone.The adsorption film formed on the PU-P surface has higher viscoelasticity,and its molecular structure is more stretch on the surface of the material,which is beneficial to the maintenance of its spatial structure.The results show that the material can achieve the target of binding to TGF-?1,and its spatial conformation is more stretched,which is conducive to the combination of molecules and cell membrane surface receptors.Therefore,it can be used as materials to regenerate or repair articular cartilage in tissue engineering.