Preparation And Performance Study Of 3D Printed NHA/PEEK Composite Scaffolds Coated With Silver Nanoparticles

The repair of bone defects caused by trauma,infection and tumor has always been a focus of medical research.Current autologous bone grafts,allogeneic or xenogeneic bone grafts exist many limitations and shortcomings,causing physical,psychological and financial burdens to patients.Hence there is a gradual rise in the use of artificial bone implants such as metals or alloys,polymer materials,inorganic non-metallic materials for repair.However,metals such as stainless steel and titanium alloys,which are traditional metal implants with high modulus of elasticity,can cause damage and resorption of the surrounding bone tissue,resulting in a stress shielding effect.Inorganic materials such as Hydroxyapatite(HA)are similar to human bone composition and have good osteoinductive properties,but HA is too brittle and has unsatisfactory mechanical properties.Polyetheretherketone(PEEK)has been widely studied and used in the field of biomaterials because of its stable physicochemical properties,its ability to circumvent stress shielding effects and its excellent toughness and radiation transmission properties.However,the biological inertness of PEEK limits its clinical application.Currently,PEEK is often modified to enhance its bioactivity and osseointegration capabilities.In this study,we propose to prepare nHA/PEEK composites by FDM 3D printing technology,and then use the metal ion complexation and redox ability of polydopamine to form silver nanoparticles(AgNPs)coating on the surface of the composites in situ to impart good antibacterial properties to the scaffold materials.The scaffolds were then evaluated for their physicochemical properties,in vitro cytocompatibility and osteogenic differentiation activity,and antibacterial properties,and their potential as artificial bone materials was initially explored.Firstly,nHA/PEEK-AgNPs composite porous scaffolds coated with silver nanoparticles were successfully prepared using FDM 3D printing,dopamine oxidation polymerization combined with silver nitrate chemical reduction.The materials were further characterized and tested for their mechanical properties and water contact angle.The results showed that the successful preparation of the silver nanoparticles coatings was demonstrated by scanning electron microscopy observation and infrared spectroscopy and X-ray diffraction spectroscopy,and the scaffolds were homogeneous in terms of pore size.The compressive strength and modulus of elasticity were(47.4±3.9)MPa and(342.0±53.1)MPa,respectively,and the mechanical strength of the composites was enhanced compared to that of the PEEK porous scaffold.The surface contact angle was approximately(33.2±3.65)°,demonstrating good hydrophilicity and providing good preconditions for cell attachment.The in vitro osteogenic differentiation performance was further evaluated by scanning electron microscopy and CCK-8 assay for cell adhesion and proliferation,alkaline phosphatase activity and expression of osteogenic differentiation-related proteins(Runx2 and Col1),and the antibacterial performance of the composite scaffolds was assessed by measuring the inhibition rate of Escherichia coli and Staphylococcus aureus.The results showed that the nHA/PEEK-AgNPs group showed good biocompatibility and significantly better cell proliferation than the PEEK group at all time points within 7 days(p<0.05).Within 14 days,the ALP activity of cells on the scaffold was significantly higher in the nHA addition group than in the PEEK group(p<0.05).And the expression levels of Runx2 gene and Col1 gene in the nHA/PEEKAgNPs group were both upregulated with time compared to PEEK(p<0.05).The inhibition rates of E.coli and S.aureus in the nHA/PEEK-AgNPs group reached(89.4±2.4)% and(85.8±4.4)%,respectively,in the inhibition assay.These results suggest that this composite scaffold facilitates cell adhesion and proliferation,significantly increases the expression of osteogenic differentiation-related genes(Runx2 and Col1),and has significant bacterial inhibition against E.coli and Staphylococcus aureus.