Preparation And Study On Biological Properties Of Ag/CaP-Coated PEEK Composites

Objective:In this study,an Ag/CaP composite coating was constructed on the surface of polytheretherketone（PEEK）,and the materials were characterized,then we evaluated their biological properties through cell and bacteria experiments in vitro,aiming to modify PEEK with biological inertness to compensate for their deficiency in bioactivity and antibacterial properties.Methods:（1）The surface of PEEK was treated to form a nano topological morphology through argon low-temperature plasma,and then a polyamine（PDA）coating was formed as a secondary reaction platform on the surface of PEEK by using the polymerization reaction of dopamine（DA）.Then the[Ag（NH₃）₂]⁺in the silver ammonia solution was reduced to elemental Ag to form a nano silver coating through an oxidation-reduction reaction.Finally,the material was immersed in the mineralized solution to form a CaP coating through chemical deposition.An Ag/CaP-coated PEEK composite was obtained.（2）Using scanning electron microscopy（SEM）to observe the micro morphology of the material surface;The elemental composition and crystal structure of the material were detected and analyzed through the energy dispersive spectrometer（EDS）and the X-ray diffractometer（XRD）;The contact angle（CA）of the material surface was measured to test its hydrophilicity.（3）The materials were divided into four groups:PEEK,PDA/PEEK,Ag/PEEK and CaP/Ag/PEEK,which were co-cultured with mouse embryonic osteoblasts（MC3T3）.The morphology of cell adhesion was observed by scanning electron microscope,the cell proliferation activity and cytotoxicity of the material were detected by CCK-8 kit,and the early osteogenic activity of the material was tested by ALP activity test kit.（4）Each group of materials was co-cultured with Staphylococcus aureus and Escherichia coli,and the morphology and quantity of bacteria on the surface of the materials were observed by scanning electron microscopy.The plate bacterial count was used to test the antibacterial properties of the materials.Results:（1）Scanning electron microscope results showed that uniformly arranged nanogrooves appeared on the surface of PEEK after argon low-temperature plasma treatment,and a layer of fine particles could be observed on the surface of the material after PDA coating.Dense nano silver particles could be seen on the surface of Ag/PEEK group,while stacked white flake crystals could be seen on the CaP coating group;EDS results showed that low temperature plasma and PDA introduced N elements into the material,and Ag、Ca、P elements were successfully detected from the Ag/CaP composite coating,which the ratio of Ca to P was 1.53:1;XRD results showed that the synthesized calcium phosphate crystal was dicalcium phosphate dihydrous（DCPD）;The contact angle of the material surface gradually decreased as the coatings were synthesized in each step.The CA of CaP/Ag/PEEK group decreased to 36.32±1.35°,with a significant difference（P<0.05）.（2）SEM observation showed that the CaP/Ag/PEEK group had the strongest cell adhesion,the cells fully extended and protruded plate-like pseudopodia on the surface of the material.The CCK-8 results of MC3T3 cells cultured with each group of material extracts for 1,4,and 7 days showed that the CaP/Ag/PEEK composite had a significant tendency to promote cell proliferation,with a cell proliferation rate of 120%on the 7th day.Test results of the ALP activity of cells after 7 days of osteogenesis induction showed that the ALP activity of the CaP/Ag/PEEK group was significantly higher than that of other groups（P<0.05）,indicating that the CaP/Ag/PEEK composite had a good osteogenic ability.（3）The PDA group,Ag/PEEK group,and CaP/Ag/PEEK group all showed inhibitory effects on Staphylococcus aureus and Escherichia coli.SEM observation showed that some bacteria of these three groups had shrunk and the content flowed out.The plate colony count results showed that the antibacterial effect of the latter two groups was the most significant,with a bacteriostatic rate of over 90%.Conclusions:（1）In this experiment,a PDA secondary reaction platform was constructed on the surface of PEEK treated by argon low-temperature plasma,and an Ag/CaP composite coating was successfully prepared on the surface of PEEK.（2）The CaP/Ag/PEEK composite had biosafety,could promote cell proliferation and early osteogenic differentiation,and had good antibacterial properties.