The Preliminary Study On Antibacterial And Biocompatibility Of Silver-coated PEEK Composites

Objective:This experiment intended to prepare silver-coated PEEK composites by depositing silver nanoparticles on the PEEK surface through the technique of dopamine oxidative self-polymerization.The anti-bacterial properties and cytobiocompatibility of composites were tested in vitro,while the effect of soft tissue healing was observed in vivo.It provides experimental data for the study of silver-coated PEEK composites in implantation.Methods:Preparation of the silver-coated PEEK composites:The PEEK rod with a diameter of 5 mm was cut into a wafer with a diameter of 5mm and a thickness of 1mm.Then wafers were polished with sandpaper step by step,followed by cleaning and disinfection for later use.The prepared PEEK were immersed in 2 g/L dopamine solution and stirred at room temperature for 24hours to obtain polydopamine-coated PEEK?PEEK-PDA?.PEEK-PDA was placed in 0.05mol/L AgN0₃ solution and subjected to an oscillating reaction under dark conditions for 4 hours to obtain silver-coated PEEK?PEEK-PDA-Ag?.The specimens were divided into three groups according to the coating on the surface:group A?PEEK?,group B?PEEK-PDA?,and group C?PEEK-PDA-Ag?.Scanning electron microscope was used to observe the surface morphology of the specimen,energy disperse spectroscopy was used to analyze the element composition and content,and contact angle tester was used to detect the hydrophilicity.The study on the effects of silver-coated PEEK to porphyromonas gingivalis:Porphyromonas gingivalis was used as the experimental strain.After the materials co-cultured with porphyromonas gingivalis solution,the number of bacterial adhesion on the surface of the specimens was detected by scanning electron microscopy and CCK-8 assay?1 hour,2 hours,4 hours?,and the antibacterial rate and bacterial adhesion rate were detected by streak plate technique.The study on the effects of silver-coated PEEK to human gingival fibroblasts:Human gingival fibroblasts were used as experimental cells.The adhesion morphology of the cells on the surfaces of the specimens was observed by scanning electron microscopy,and the cell separation rate was measured.The cell proliferation was detected by CCK-8 assay,and collagen deposition on materials surface was detected by Sirius red staining.The study on the effects of silver-coated PEEK in healing of soft tissues:The PEEK was processed into an implant with a diameter of 3mm and a length of 6mm.The implant surface treatment method was as described above.Healthy female New Zealand rabbits were selected as the experimental objects.The implant was implanted into the right mandibular incisor tooth extraction nest of the experimental animal.Animals were killed and specimens were collected at 14 days and 28 days after surgery.Then HE staining was used to observe the healing of soft tissues around the implant.Results:Preparation of the silver-coated PEEK composites:?1?The SEM observation showed that the material surface with PDA coating was rougher than the pure PEEK.The silver nanoparticles were round and evenly distributed on the material surface,with a diameter of about 65nm.?2?Energy disperse spectroscopy results showed that the elements on the pure PEEK surface were composed of C and O.After the treatment with DA solution,the elements on the material surface were composed of C,O and N.After the treatment with AgNO₃ solution,the elements on the material surface were composed of C,O,N and Ag.?3?Contact angle test results showed that the PEEK surface contact angle was 108.4^°±1.4^°,PEEK-PDA surface contact angle was 71.8^°±1.0^°and PEEK-PDA-Ag surface contact angle was 53.4^°±1.5^°.The study on the effects of silver-coated PEEK to porphyromonas gingivalis:?1?The SEM observation showed that the number of bacterial adhesion in group A was the highest,followed by group B,and group C was the lowest.?2?The results of CCK-8 assay showed that at 1 hour the bacteria number in group A was the highest,and the difference was statistically significant?P<0.05?.With the extension of time,the number of bacteria adhesion in each group increased gradually.At 2 and 4 hours,the number of bacteria adhesion in group A was still the highest,the number in group C was the lowest,and the number in group B was between group A and group C.But the difference between the three groups was not statistically significant?P>0.05?.?3?The plate streaking test showed that the number of bacteria colonies in group A was the highest,the number in group C was the lowest,and the number in group B was between group A and group C.The antibacterial rate of group B was 66.57%,and that of group C was 96.66%.The adhesion rate was 33.43%in group B and 3.34%in group C.The difference of antibacterial rate and the adhesion rate between three groups was statistically significant?P<0.05?.The study on the effects of silver-coated PEEK to human gingival fibroblasts:?1?The SEM observation showed that the gingival fibroblasts adhered on the surface in group A were hemispherical and protruded on the surface of the specimen,with less pseudopod extension and smaller cell extension area.In group B,gingival fibroblasts were spread on the surface of the specimen,with more plate-like pseudopod protruding,less filamentous pseudopod protruding,and larger cell extension area than group A.Gingival fibroblasts in group C were also hemispherical and protruded on the surface of the specimen like group A.And there were fewer plate-like pseudopods protruding and more filamentous pseudopods protruding than group B.The cell extension area was larger than group A.?2?The cell separation rate in group A was the highest?68.78%±3.32%?,in group B was 54.92%±4.96%,and in group C was 56.98%±4.00%.The difference between group A,group B and group A,group C was statistically significant?P<0.05?.But the difference between group Band group C was not statistically significant?P>0.05?.?3?The CCK-8assay showed that the number of fibroblasts in each group showed a proliferation trend over time.At 1 day,the cell number in group A was the highest,followed by group C,and the number in group B was the lowest.The difference between group A and group B,group A and group C was statistically significant?P<0.05?.At 3 days and 5 days,the cell number in group A and group B was higher than that in group C,and the difference was statistically significant?P<0.05?.At 7 days,the cell number in group B was the highest,followed by group A,and that in group C was the lowest.The difference between the three groups showed statistical significance?P<0.05?.?4?At 3days and 7 days,the OD values of Sirius red staining in group B was the highest,and the difference was statistically significant?P<0.05?.At 14 days,the OD values in group B and group C was higher than that in group A,and the difference was statistically significant?P<0.05?.The study on the effects of silver-coated PEEK in healing of soft tissues:The results of HE staining showed that at 14 days after surgery,the soft tissues around implants in three groups healed well,and the epidermis was visible on the interface between the implant and soft tissue without nailing process.And the growth was in the direction of the long axis of the implant toward the root side.Epithelial cells in group A and group B grew faster than that in group C.At 28 days after surgery,epithelial adhesion was basically formed around the implants,and the epithelial bands were significantly thicker than that at 14 days.The combined epithelial length was shorter than that of natural teeth,but the epithelial was thicker.The general histological morphology of epithelial adhesion was close to that of natural teeth.Conclusion:In this experiment,through the examination of antibacterial properties and biological properties on silver-coated PEEK,we can draw the following conclusions:1.In this study,silver nanoparticles were deposited on PEEK surface and PEEK-PDA-Ag was successfully prepared.2.The hydrophilicity of PEEK-PDA-Ag was superior to PEEK and PEEK-PDA.3.PEEK-PDA-Ag could reduce the adhesion and inhibit the proliferation of porphyromonas gingivalis.4.Human gingival fibroblasts had a large extension area on the surface of PEEK-PDA-Ag material and had a good adhesion effect.5.PEEK-PDA-Ag had barely toxic effect on the proliferation of human gingival fibroblasts.6.PEEK-PDA-Ag could promote the secretion of collagen fibers in human gingival fibroblasts.7.The soft tissue around the PEEK-PDA-Ag implant healed well,and the epithelium morphology was similar to that of natural teeth.