Bioceramic scaffolds with two-step internal/external modification of copper-containing polydopamine enhance antibacterial and alveolar bone regeneration capability

Magnesium-doped calcium silicate(CS)bioceramic scaffolds have unique advantages in mandibular defect repair;however,they lack antibacterial properties to cope with the complex oral microbiome.Herein,for the first time,the CS scaffold was functionally modified with a novel copper-containing polydopamine(PDA(Cu^(2+)))rapid deposition method,to construct internally modified(*P),externally modified(@PDA),and dually modified(*P@PDA)scaffolds.The morphology,degradation behavior,and mechanical properties of the obtained scaffolds were evaluated in vitro.The results showed that the CS*P@PDA had a unique micro-/nano-structural surface and appreciable mechanical resistance.During the prolonged immersion stage,the release of copper ions from the CS*P@PDA scaffolds was rapid in the early stage and exhibited long-term sustained release.The in vitro evaluation revealed that the release behavior of copper ions ascribed an excellent antibacterial effect to the CS*P@PDA,while the scaffolds retained good cytocompatibility with improved osteogenesis and angiogenesis effects.Finally,the PDA(Cu^(2+))-modified scaffolds showed effective early bone regeneration in a critical-size rabbit mandibular defect model.Overall,it was indicated that considerable antibacterial property along with the enhancement of alveolar bone regeneration can be imparted to the scaffold by the two-step PDA(Cu^(2+))modification,and the convenience and wide applicability of this technique make it a promising strategy to avoid bacterial infections on implants.

Customized bioceramic scaffolds and metal meshes for challenging large-size mandibular bone defect regeneration and repair

Large-size mandible graft has huge needs in clinic caused by infection,tumor,congenital deformity,bone trauma and so on.However,the reconstruction of large-size mandible defect is challenged due to its complex anatomical structure and large-range bone injury.The design and fabrication of porous implants with large segments and specific shapes matching the native mandible remain a considerable challenge.Herein,the 6%Mg-doped calcium silicate(CSi-Mg6)andβ-andα-tricalcium phosphate(β-TCP,α-TCP)bioceramics were fabricated by digital light processing as the porous scaffolds of over 50%in porosity,while the titanium mesh was fabricated by selective laser melting.The mechanical tests showed that the initial flexible/compressive resistance of CSi-Mg6 scaffolds was markedly higher than that ofβ-TCP andα-TCP scaffolds.Cell experiments showed that these materials all had good biocompatibility,while CSi-Mg6 significantly promoted cell proliferation.In the rabbit critically sized mandible bone defects(∼13 mm in length)filled with porous bioceramic scaffolds,the titanium meshes and titanium nails were acted as fixation and load bearing.The results showed that the defects were kept during the observation period in the blank(control)group;in contrast,the osteogenic capability was significantly enhanced in the CSi-Mg6 andα-TCP groups in comparison with theβ-TCP group,and these two groups not only had significantly increased new bone formation but also had thicker trabecular and smaller trabecular spacing.Besides,the CSi-Mg6 andα-TCP groups showed appreciable material biodegradation in the later stage(from 8 to 12 weeks)in comparison with theβ-TCP scaffolds while the CSi-Mg6 group showed much outstanding mechanical capacity in vivo in the early stage compared to theβ-TCP andα-TCP groups.Totally,these findings suggest that the combination of customized strength-strong bioactive CSi-Mg6 scaffolds together with titanium meshes is a promising way for repairing the large-size load-bearing mandible defects.

Additive manufacturing of hydroxyapatite bioceramic scaffolds: Dispersion, digital light processing, sintering, mechanical properties, and biocompatibility

Hydroxyapatite(HA)bioceramic scaffolds were fabricated by using digital light processing(DLP)based additive manufacturing.Key issues on the HA bioceramic scaffolds,including dispersion,DLP fabrication,sintering,mechanical properties,and biocompatibility were discussed in detail.Firstly,the ffects of dispersant dosage,solid loading,and sintering temperature were studied.The optimal dispersant dosage,solid loading,and sintering temperature were 2wt%,50vol%,and 1250℃,respectively.Then,the mechanical properties and biocompatibility of the HA bioceramic scaffolds were investigated.The DLP-prepared porous HA bioceramic scaffold was found to exhibit excellent mechanical properties and degradation behavior.From this study,DLP technique shows good potential for manufacturing HA bioceramic scaffolds.