Design And Fabrication Of Polycaprolactone/Hydroxyapatite Composites Biomaterails For Bone Tissue Scaffolds

In the current clinical medicine,bone tissue engineering has being applied to regenerative medicine as an important treatment of bone repair.The key to prepareing tissue-matched implant scaffolds is find a suitble biomaterials with a great mechanical and biological properties.Polycaprolactone(PCL)is a biodegradable material which is widely studied and applied at present.It has good biocompatibility,controllable degradation and other biological properties.Hydroxyapatite(HA)is a major component of bone.Making use of hydroxyapatite(HA)to form a composite with PCL can effectively improve the meterial's degradability,cell adhesion and mechanical strength of PCL.On the other hand,the composite could get a better processing performance.The scaffold made by this composite materials will have a more excellent biological and mechanical properties.The interface combination of PCL/HA composite is weak.To solve this problem HA/PCL composites were prepared in two ways which effectively improved the composite strength in this paper.The details are as follows :(1)The use of nano-hydroxyapatite as an initiato to induce a ring-opening reaction of ?-cl to form PCL on the HA surface.The interfacial adhesion and dispersibility of the material are enhanced by establishing a chemical bond between HA and PCL.Comparisons between conventional PCL and PCL/HA blends with similar molecular weight were made.Compression tests and bending tests showed that the introduction of HA significantly increased the compressive modulus and flexural modulus of the composites and increased the elongation at break.At the same time,HA reduced the crystallinity of PCL and increased the toughness of the composites.Compared with PCL / HA blends,the dispersion of HA was better and the agglomeration of HA decreased obviously.All of these show that HA-induced composites have better interfacial adhesion and dispersibility.(2)Modified PCL and HA surface were modified with UPy,and PCL/HA composites with hydrogen bonds were prepared.Because hydrogen bonding is a strong intermolecular force,the formation of hydrogen bonding structure can enhance the intermolecular chain strength of PCL and reduce the crystallinity,so as to enhance the mechanical properties.On the other hand,hydrogen bonding with HA Can effectively enhance the bonding strength of the two materials.After preparing the characterizing of PCL and PCL-UPy,we found that PCL-UPy significantly increased the biological and mechanical properties of PCL.DSC and polarizing microscope tests show that the crystallinity of the material is significantly reduced.Comparing the PCL-UPy / HA-UPy composites with PCL-UPy without hydrogen bond,the compressive modulus and flexural modulus of PCL-UPy / HA-UPy composites are further increased,and the crystallinity of PCL is obviously affected.Scanning electron microscopy found that HA agglomeration in the PCL decreased,and the combination of the PCL interface more closely.It is shown that the references of quadruple hydrogen bonds successfully improve the mechanical properties and the interfacial compatibility of HA/PCL composite materials.