Antibacterial And Osteogenic Properties Of Silver Nanoparticles-Antimicrobial Peptide GL13K Composite Coating On Titanium Mini-implants In Animals

Objective: Experiments in rats were performed to study the osteogenic and antibacterial properties of the coatings of silver nanoparticles-antibacterial peptide GL13 K composite on mini-implants.The result of this study will provide an important theoretical basis and new strategies for surface modification to enhance the antibacterial and osteogenic activity of the mini-implants.Methods: 1.The antimicrobial peptide GL13 K was combined with silver nanoparticles under alkaline conditions.They were coated to the titanium mini-implants,to form a composite coating containing silver nanoparticles and GL13 K.2.Scanning electron microscope(SEM),energy dispersive spectroscopy(EDS),water contact angle(WCA)were used to analyze the microscopic morphology,element distribution,hydrophilicity and hydrophobicity of the composite coating.3.A model of peri-implant infection was established at the femur of rat to evaluate the antibacterial activity of the silver nanoparticles-antibacterial peptide GL13 K composite coating.The uncoated,silver nanoparticles-coated,and GL13K-coated mini-implants were taken as controls.Colony forming unit(CFU)counting experiment and bone tissue section HE staining were used to observe the inflammation and bone destruction around each type of coated/uncoated mini-implants.4.Micro-CT and pull-out test were applied to evaluate the osteogenic property of the coated/noncoated mini-implants.Results: 1.SEM results showed that the pore alveolate structure of the composite coated mini-implant is less clear than the uncoated mini-implant,while the silver bright spots were observed.EDS results confirmed the successful coating of silver nanoparticles,GL13 K and silver nanoparticles-GL13 K.WCA results showed that the surface of the uncoated mini-implant is hydrophilic,and the silver nanoparticles coating does not significantly change the surface hydrophilicity,while the surface of the GL13 K or silver nanoparticles-GL13 K composite coating is hydrophobic.2.The results of the CFU counting experiment showed that the amount of bacteria in the composite coating group was significantly lower than that of the single coating groups and uncoating group(p<0.01),which proved that the composite coating has more excellent antibacterial properties.The results of HE staining of bone histological sections showed that the composite coating could effectively inhibit inflammation and reduce bone destruction.3.Micro-CT analysis showed the bone volume fraction of the silver nanoparticles-antibacterial peptide GL13 K composite coating was significantly higher than that of the single coating groups and uncoating group(p<0.01),while trabecular number,trabecular separation,trabecular thickness had no statistical difference(p>0.05).The results of the axial pull-out experiment showed that the maximum pull-out force of the composite coating group was greater than that of the single coating groups and uncoating group(p<0.05).These two osteogenesis experiments in vivo indicated that the silver nanoparticles-antibacterial peptide GL13 K composite coating can effectively promote osseointegration.Conclusion:The silver nanoparticles-antibacterial peptide GL13 K composite coated mini-implants showed good antibacterial and antibacterial properties in rats.