Preparation Of High-Strength Porous Polyetheretherketone For The Application Of Osteogenesis And Antibacterial

Polyetheretherketone(PEEK)is a semi-crystalline non-degradable thermoplastic polymer material,which is widely used in the field of bone repair due to its good biocompatibility,excellent mechanical properties,corrosion resistance,etc.However,the biological inertness of PEEK and implant-associated infections caused by bacteria can lead to substantial harm to patients and even surgical failure.Therefore,improving the osseointegration ability and antibacterial properties of PEEK has become a hot topic.Studies have indicated that bone grafting materials with high porosity and good pore connectivity are conducive to cell adhesion,nutrient exchange,and bone healing.Currently,the research on porous PEEK is less explored and it is difficult to meet the requirements of porosity,pore connectivity,and mechanical properties at the same time.In this study,a high-strength porous PEEK was prepared and its interconnected porous structure was used for functional design to improve the osseointegration ability and antibacterial ability,and drug sustained-release ability,detailed below.Firstly,a porous polyetheretherketone(PO-PEEK)with different densities has been successfully synthesized by stepwise polymerization and thermally induced phase separation technology.PO-PEEK possessed an interconnected porous structure,and the molecular weight,porosity and mechanical properties can be adjusted by changing the density.The porosity of PO-PEEK is between 30 % and 90 %,and the pore size exhibits different distributions as the density changes.The solvent resistance of PO-PEEK was not reduced due to its porous structure.The mechanical properties of PO-PEEK are increased with increasing density,but a higher density is not conducive to the increase in molecular weight.The maximum compressive strength and compression modulus of the PO-PEEK reach 50 MPa and 0.92 GPa,respectively,which meet the requirements for the mechanical properties of bone grafting materials.To further improve the osseointegration ability of PO-PEEK,a high-strength porous polyetheretherketone loaded with hydroxyapatite(PO-PEEK/HA)was prepared by hydrothermal synthesis.The osteoblast differentiation experiments in vitro showed that PO-PEEK/HA can effectively increase the content of intracellular alkaline phosphatase and calcium nodules while promoting the expression of intracellular osteogenic differentiation genes.The treatment of critical calvaria defects in rats shows that PO-PEEK/HA can contribute to bone formation and show the best osseointegration ability.Compared with non-porous IM-PEEK,the porous structure of PO-PEEK can improve the osseointegration induction ability to a certain extent.This work not only provides an effective treatment for critical-sized bone defects but also brings a new method for improving the biological activity of PEEK.In light of implant-associated infections caused by bacteria,a high-strength porous polyetheretherketone loaded with nano-silver(PO-PEEK/n Ag)was prepared by vacuum impregnation and hydrothermal synthesis method.Compared with nano-silver coated PEEK(Coat-PEEK/n Ag),the nano-silver on the surface of PO-PEEK/n Ag will not disappear after friction,which overcomes the shortcomings of weak binding force between coating and substrate.In vitro antibacterial experiments show that the antibacterial rates of PO-PEEK/n Ag against Staphylococcus aureus and Escherichia coli were 96.8 % and 94.4 %,respectively.Subcutaneous infection tests in rats exhibited that PO-PEEK/n Ag can effectively reduce the number of inflammatory cells caused by bacteria.This work provides an effective method for the development of antibacterial PEEK.Although PO-PEEK/n Ag exhibits good antibacterial ability,in the early stage of antibacterial,due to the hydrophobicity of PEEK,the antibacterial ability of POPEEK/n Ag is insufficient.In this chapter,the thermosensitive hydrogel(PLGA-PEGPLGA)was used as a drug sustained-release carrier to increase the antibacterial efficiency,and a high-strength porous polyetheretherketone loaded vancomycin-loaded hydrogel(PO-PEEK/VGel)was prepared by the good fluidity of PLGA-PEG-PLGA at low temperature.This approach achieved the goal of combining drug sustained-release and bone repair materials successfully.In the initial drug release phase of POPEEK/VGel,there is an obvious burst release,and the amount of drug released reaches70 % within 10 days.The antibacterial rate of PO-PEEK/VGel against methicillinresistant Staphylococcus aureus(MRSA)reaches 99.7 % and possesses effective therapeutic benefits against postoperative suppurative infection caused by MRSA in rats.This strategy provides an effective method for the functional application of polyetheretherketone.In summary,a high-strength porous PEEK was prepared,and its porous structure was used for functional design to improve the osteogenic differentiation ability,antibacterial ability,and drug sustained-release ability of PEEK,which provides an experimental basis and new strategy for the application of PEEK.