Effect of sulfonation time on physicochemical, osteogenic, antibacterial properties and biocompatibility of carbon fiber reinforced polyether ether ketone.

The carbon fiber reinforced polyetheretherketone (CFR-PEEK) has been increasingly used in orthopedics dentistry due to its excellent biocompatibility and mechanical properties. However, the biological inertness and poor antibacterial activity limit its clinical applications. This paper focused on the performances of CFR-PEEK with porous morphology that were exposed to different sulfonation periods (1, 3, 5, and 10 min, corresponding to CP-S1, CP-S3, CP-S5, and CP-S10, respectively). Residual sulfuric acid was removed by acetone rinsing, NaOH immersion, and hydrothermal treatment before in vitro and in vivo studies. The results showed some significant difference in the physicochemical properties, including energy dispersive X-ray spectroscopy (EDS) map of sulfur atoms, X-ray photoelectron spectroscopy (XPS) of valences of sulfur ions, Fourier transformation infrared spectroscopy (FTIR), hydrophilicity, hardness, and elastic modulus among CP-S3, CP-S5, and CP-S10. However, CP-S5 and CP-S10 were more effective in promoting the proliferation, adhesion, and osteogenic differentiation of seeded bone mesenchymal stem cells (BMSCs) and growth inhibition of S. aureus and P. gingivalis compared with other groups. Furthermore, the CP-S5 and CP-S10 samples achieved better cranial bone repair than the non-sulfonation group in a rat model. Therefore, it can be inferred that both 5 and 10 min are viable sulfonation durations for 30% CFR-PEEK. These findings provide a theoretical basis for developing CFR-PEEK for clinical applications.

Multifunctional Mesoporous Silica Nanoparticles Reinforced Silk Fibroin Composite with Antibacterial and Osteogenic Effects for Infectious Bone Rehabilitation.

Background: Existing implant materials cannot meet the essential multifunctional requirements of repairing infected bone defects, such as antibacterial and osteogenesis abilities. A promising strategy to develop a versatile biomimicry composite of the natural bone structure may be accomplished by combining a multifunctional nanoparticle with an organic scaffold. Methods: In this study, a quaternary ammonium silane-modified mesoporous silica containing nano silver (Ag@QHMS) was successfully synthesized and further combined with silk fibroin (SF) to fabricate the multifunctional nano-reinforced scaffold (SF-Ag@QHMS) using the freeze-drying method. Furthermore, the antibacterial and osteogenic effects of this composite were evaluated in vitro and in vivo. Results: SF-Ag@QHMS inherited a three-dimensional porous structure (porosity rate: 91.90 ± 0.62%) and better mechanical characteristics (2.11 ± 0.06 kPa) than that of the SF scaffold (porosity rate: 91.62 ± 1.65%; mechanic strength: 2.02 ± 0.01 kPa). Simultaneously, the introduction of versatile nanoparticles has provided the composite with additional antibacterial ability against Porphyromonas gingivalis, which can be maintained for 15 days. Furthermore, the expression of osteogenic-associated factors was up-regulated due to the silver ions eluting from the composite scaffold. The in vivo micro-CT and histological results indicated that the new bone formation was not only localized around the border of the defect but also arose more in the center with the support of the composite. Conclusion: The multifunctional silver-loaded mesoporous silica enhanced the mechanical strength of the composite while also ensuring greater and sustained antibacterial and osteogenic properties, allowing the SF-Ag@QHMS composite to be used to repair infected bone defects.

Preliminary study of silk fibroin porous scaffold for oral soft-tissue thickening.

OBJECTIVES: This study aimed to investigate the feasibility of three different concentrations of silk-fibroin porous scaffolds applied to oral soft-tissue thickening in vivo. METHODS: Silk-fibroin scaffolds with three different concentrations (1 wt%, 3 wt%, and 5 wt%; denoted as SF1, SF3, and SF5, respectively) were prepared by freeze drying and methanol enhancement. The scaffolds were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis. Pore size, porosity, and in vitro degradation rate were also evaluated. The three groups of scaffold materials (the experimental sides) and the collagen matrix (the control side) were implanted into the oral mucosa of New Zealand white rabbits. Changed in mucosa thickness before and 3 months after operation were compared. The in vivo metabolism and regeneration effect of each group were observed by histological hematoxylin-eosin (HE) and Masson staining. RESULTS: SEM showed that the three groups of scaffolds were all cross-linked porous structures. XRD and FTIR showed that the three scaffolds were dominated by a relatively stable Silk Ⅱ structure, which degraded more slowly in vitro. Among them, SF3 had the largest pore size (133.40 µm±22.85 µm) and moderate porosity (90.05%±6.68%). In vivo results showed that the thickening effect of SF1 was similar to that of the control group because of insufficient space-maintenance property. Meanwhile, the properties of SF3 and SF5 were more stable, and the thickening effect was significantly better than those of the control group. However, unlike SF5 that induced obvious inflammation, SF3 showed better degradation, more fibrosis and angiogenesis, and less inflammatory response in vivo. CONCLUSIONS: Silk-fibroin scaffolds can be applied to effectively thicken soft tissues, among which SF3 (3 wt%) silk fibroin scaffold exhibited the best physicochemical properties, histocompatibility, and mucosal-thickening effect.

A Multifunctional Antibacterial and Osteogenic Nanomedicine: QAS-Modified Core-Shell Mesoporous Silica Containing Ag Nanoparticles.

Treatments for infectious bone defects such as periodontitis require antibacterial and osteogenic differentiation capabilities. Nanotechnology has prompted the development of multifunctional material. In this research, we aim to synthesize a nanoparticle that can eliminate periodontal pathogenic microorganisms and simultaneously stimulate new bone tissue regeneration and mineralization. QAS-modified core-shell mesoporous silica containing Ag nanoparticles (Ag@QHMS) was successfully synthesized through the classic hydrothermal method and surface quaternary ammonium salt functionalization. The Ag@QHMS in vitro antibacterial activity was explored via coculture with Staphylococcus aureus, Escherichia coli, and Porphyromonas gingivalis biofilms. Bone mesenchymal stem cells (BMSCs) were selected for observing cytotoxicity, apoptosis, and osteogenic differentiation. Ag@QHMS showed a good sustained release profile of Ag+ and a QAS-grafted mesoporous structure. Compared with the single-contact antibacterial activity of QHMS, Ag@QHMS exhibited a more efficient and stable concentration-dependent antimicrobial efficacy; the minimum inhibitory concentration was within 100 µg/ml, which was below the BMSC biocompatibility concentration (200 µg/ml). Thus, apoptosis would not occur while promoting the increased expression of osteogenic-associated factors, such as runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), osteopontin (OPN), osteocalcin (OCN), bone sialoprotein (BSP), and collagen type 1 (COL-1). A safe concentration of particles can stimulate cell alkaline phosphatase and matrix calcium salt deposition. The dual antibacterial effect from the direct contact killing of QAS and the sustained release of Ag nanoparticles, along with the Ag-promoted osteogenic differentiation, had been verified and utilized in Ag@QHMS. This system demonstrates the potential for utilizing pluripotent biomaterials to treat complex lesions.

Bimodal antibacterial system based on quaternary ammonium silane-coupled core-shell hollow mesoporous silica.

Hollow mesoporous silica (HMS) have been extensively investigated as a biomaterial for drug delivery. The present study developed quaternary ammonium silane-grafted hollow mesoporous silica (QHMS) to create a metronidazole (MDZ) sustained delivery system, MDZ@QHMS, with bimodal, contact-kill and release-kill capability. The QHMS was assembled through a self-templating method. Metronidazole was incorporated within the QHMS core using solvent evaporation. Antibacterial activities of the MDZ@QHMS were investigated using single-species biofilms of Staphylococcus aureus (ATCC25923), Escherichia coli (ATCC25922) and Porphyromonas gingivalis (ATCC33277). The MDZ@QHMS maintained a hollow mesoporous structure and demonstrated sustained drug release and bacteridal actvity against the three bacterial strains at a concentration of 100 µg/mL or above. These nanoparticles were not relatively cytotoxic to human gingival fibroblasts when employed below 100 µg/mL. Compared with HMS, the MDZ@QHMS system at the same concentration demonstrated antibiotic-elution and contact-killing bimodal antibacterial activities. The synthesized drug carrier with sustained, bimodal antibacterial function and minimal cytotoxicity possesses potential for localized antibiotic applications. STATEMENT OF SIGNIFICANCE: The present study develops quaternary ammonium silane-grafted hollow mesoporous silica (QHMS) to create a metronidazole (MDZ) sustained delivery system, MDZ@QHMS, with bimodal, contact-kill and release-kill capability. This system demonstrates sustained drug release and maintained a hollow mesoporous structure. The synthesized drug carrier with sustained, bimodal antibacterial function and excellent biocompatibility possesses potential for localized antibiotic applications.