Preparation And Characterization Of 3D Printed Biomimetic Cartilage Scaffolds

Objective: The aim of this study is to fabricate a 3D printed biomimetic cartilage repair scaffold that mimics the natural cartilage in terms of gradient,stiffness and multilayer structure.By evaluating its physicochemical characteristics,mechanical properties,internal morphology,and cell compatibility,we seek to investigate the feasibility of this biomimetic scaffold as a cartilage repair material.Methods: The scaffold’s upper and middle layers were constructed through a compound of Polycaprolactone(PCL)and Poly(ethylene glycol)diacrylate(PEGDA),while the lower layer was built with a compound of PCL and Nano-Hydroxyapatite(HA).Through the adjustment and selection of the optimal proportions of each component for cartilage repair,we printed a three-layer gradient scaffold,the properties of which were tested to evaluate its feasibility as a cartilage repair scaffold.(1)We prepared PCL-HA and PCL-PEGDA composite materials in different mass ratios.The successful preparation of these two composite materials was confirmed through Fourier Transform Infrared Spectroscopy(FTIR),X-ray Diffraction(XRD),and Thermogravimetric Analysis(TGA).We analyzed the internal structure,surface morphology,mechanical properties,hydrophilicity,swelling performance,and porosity of the two types of composite materials at different mass ratios.We then selected the optimal material combination for scaffold printing,and characterized the interlayer structure of the printed scaffold samples through Scanning Electron Microscopy(SEM)and elemental analysis.(2)We used a universal testing machine to perform tensile tests on the scaffold material,evaluating its interlayer bonding strength.(3)Through tribological tests,we assessed the tribological behavior of the scaffold’s upper layer material under different loads.(4)We assessed the controlled release capability of Kartogenin(KGN)by the printed scaffold through drug release experiments.(5)We evaluated the degradation performance of the printed scaffold through in vitro degradation experiments.(6)Using the MTT method and Live/Dead cell staining method,we evaluated the cell compatibility of the printed scaffold.Results:(1)We successfully synthesized PCL-HA and PCL-PEGDA composite materials in different mass ratios.FTIR,XRD,and TGA confirmed the successful combination of materials.The internal part of both composite materials contained numerous pores,and different ratios had different surface roughness.Out of all the composite materials,samples from the groups PP1-1(PCL:PEGDA mass ratio 1:1),PP2-0.5(PCL:PEGDA mass ratio 2:0.5),and PH2-5(PCL:HA mass ratio 2:5)exhibited Young’s modulus similar to natural cartilage.At the same time,these three groups of materials had good swelling performance and high porosity,and were therefore selected as the printing materials for the biomimetic multilayer cartilage repair scaffold.SEM showed that the printed scaffold structure was stable with tight interlayer bonding.(2)Tensile testing showed that the interfacial bonding strength between different scaffold materials was greater than the internal bonding strength of the fracturing side material.(3)Tribological testing demonstrated that the surface-treated upper layer scaffold material had a lower friction coefficient under different loads.(4)The printed scaffold had excellent controlled release capability for the KGN drug,releasing 81.9% of the total amount of the drug by day 30.(5)The printed scaffold had better degradation performance compared to the regular PCL scaffold.(6)The MTT detection results showed that the multilayer printed scaffold had good cell compatibility,which was also confirmed by the Live/Dead cell staining results.Conclusions:This study successfully synthesized PCL-HA and PCL-PEGDA materials capable of mimicking the gradient and stiffness of natural cartilage.These two materials have a large number of interconnected internal pores and have excellent water swelling performance,with only relatively small volume changes occurring during swelling.The multilayer biomimetic cartilage repair scaffold fabricated through 3D printing using these two materials has a stable structure,tight interlayer bonding,excellent drug release capability,degradation performance,and cell compatibility.It shows potential for clinical applications as a cartilage repair material.