NIR-triggered Composite Hydrogel Treats Periodontitis By Inhibiting Bacteria And Inducing Bone Regeneration

ObjectiveTreatment of periodontitis by near-infrared light(NIR)-triggered EGCGmodified gold-loaded composite hydrogel(E-Au@H)to explore its antimicrobial properties and the role it plays in periodontal support tissue regeneration.MethodsMaterial experiments: the prepared E-Au powder was added homogeneously to the hydrogel and sonicated to form E-Au@H.The dispersion and morphology of E-Au were observed by transmission electron microscopy,dynamic laser scattering and X-ray diffraction.The composition and in vitro release efficiency of the samples were determined by Fourier to transform infrared spectroscopy and UV-Vis spectrophotometry.The morphology of EAu@H and the distribution of E-Au in the hydrogel were observed by field emission scanning electron microscopy.Changes in the temperature of the composites were recorded by infrared thermography and near-infrared laser.Antibacterial test: Staphylococcus aureus(S.aureus)and Escherichia coli(E.coli)were selected for antibacterial performance evaluation by bacterial plate method and crystalline violet staining.Cell assay: Rat bone marrow mesenchymal stem cells(BMSCs)were extracted for in vitro osteogenesis study.The effect of the composite nanoplatforms on angiogenesis was verified by human umbilical vein endothelial cells(HUVECs).Animal experiments: Periodontitis models were constructed by ligating the maxillary first molars of rats for in vivo experimental studies.The rats were randomly divided into four groups: normal group(HL),periodontitis group (Control),E-Au@H group,and E-Au@H+NIR group.After determining the success of the periodontitis model establishment,the rats were treated with different materials.After treatment,periodontal bacteria were extracted and cultured to observe the in vivo antimicrobial properties of E-Au@H,and alveolar bone loss was detected by stereomicroscope and biological observation of periodontal tissues was performed.ResultsIn this study,EGCG was loaded into gold nanoparticle-modified hydrogels to achieve the synergistic functions of NIR photosensitization,bactericidal and periodontal tissue regeneration.The rapid temperature rises to 50.7°C within 5 minutes under NIR light exposure exerts good photothermal effects,while NIR spectra can effectively control the release of EGCG,enhance antibacterial effects,promote BMSCs aggregation and angiogenesis,and improve bone regeneration.In vitro studies showed that NIR-irradiated composites inhibited S.aureus,E.coli and S.aureus biofilms by 95%,92% and 74%,respectively,and alkaline phosphatase activity after 7 days and extracellular matrix mineralization rate after 21 days were significantly increased.A rat periodontitis model successfully demonstrated that E-Au@H inhibited dental plaque biofilm by 87% and promoted alveolar bone regeneration by 38% under NIR light irradiation.Safety studies confirmed the good biocompatibility of E-Au@H.ConclusionsThe local warming of E-Au@H under the irradiation of near-infrared light effectively inhibited the bacterial activity,promoted the migration and angiogenesis of HUVECs,and promoted the osteogenic differentiation of BMSCs,which exerted a good effect during the treatment of rat periodontitis model.