Ceramic Nanofiber Materials for Wound Healing and Bone Regeneration: A Brief Review

Ceramic nanofibers have been shown to be a new horizon of research in the biomedical area, due to their differentiated morphology, nanoroughness, nanotopography, wettability, bioactivity, and chemical functionalization properties. Therefore, considering the impact caused by the use of these nanofibers, and the fact that there are still limited data available in the literature addressing the ceramic nanofiber application in regenerative medicine, this review article aims to gather the state-of-the-art research concerning these materials, for potential use as a biomaterial for wound healing and bone regeneration, and to analyze their characteristics when considering their application.

Antimicrobial Peptide-Loaded Pectolite Nanorods for Enhancing Wound-Healing and Biocidal Activity of Titanium

Titanium is widely utilized for manufacturing medical implants due to its inherent mechanical strength and biocompatibility. Recent studies have focused on developing coatings to impart unique properties to Ti implants, such as antimicrobial behavior, enhanced cell adhesion, and osteointegration. Ca- and Si-based ceramic (CS) coatings can enhance bone integration through the release of Ca and Si ions. However, high degradation rates of CS ceramics create a basic environment that reduces cell viability. Polymeric or protein-based coatings may be employed to modulate CS degradation. However, it is challenging to ensure coating stability over extended periods of time without compromising biocompatibility. In this study, we employed a fluorous-cured collagen shell as a drug-loadable scaffold around CS nanorod coatings on Ti implants. Fluorous-cured collagen coatings have enhanced mechanical and enzymatic stability and are able to regulate the release of Ca and Si ions. Furthermore, the collagen scaffold was loaded with antimicrobial peptides to impart antimicrobial activity while promoting cell adhesion. These multifunctional collagen coatings simultaneously regulate the degradation of CS ceramics and enhance antimicrobial activity, while maintaining biocompatibility.

Integrating silicon/zinc dual elements with PLGA microspheres in calcium phosphate cement scaffolds synergistically enhances bone regeneration

Integrating multiple pro-osteogenic factors into bone graft substitutes is a practical and effective approach to improve bone repair efficacy. Here, Si-Zn dual elements and PLGA microspheres were incorporated into calcium phosphate cement (CPC) scaffolds (PLGA/CPC-Si/Zn) as a novel strategy to synergistically enhance bone regeneration. The incorporation of PLGA microspheres and Si/Zn dual elements within CPC scaffolds improved the setting time, injectability and compressive strength. The PLGA/CPC-Si/Zn scaffolds displayed controlled sequential release of Si and Zn ions. In vitro, RAW 264.7 cells displayed the M2 phenotype with a high level of anti-inflammatory cytokines in response to PLGA/CPC-Si/Zn. The conditioned medium of RAW 264.7 cells cultured on the PLGA/CPC-Si/Zn scaffolds significantly enhanced the osteogenic differentiation of rat BMSCs. In a rat femur defect model, the implanted PLGA/CPC-Si/Zn scaffolds led to obvious new bone formation after 4 weeks, apparent bone ingrowth into the PLGA microspheres after 12 weeks, and was almost completely filled with mature new bone upon degradation of the PLGA microspheres at 24 weeks. These findings demonstrate that the PLGA/CPC-Si/Zn scaffolds promote osteogenesis by synergistically improving the immune microenvironment and biodegradability. Hence, integrating multiple trace elements together with degradable components within bone graft biomaterials can be an effective strategy for promoting bone regeneration.

Novel Reduced Graphene Oxide/Zinc Silicate/Calcium Silicate Electroconductive Biocomposite for Stimulating Osteoporotic Bone Regeneration

In the absence of external assistance, autogenous healing of bone fracture is difficult due to impaired regeneration ability under osteoporosis pathological conditions. In this study, a reduced graphene oxide/zinc silicate/calcium silicate (RGO/ZS/CS) conductive biocomposite with an optimal surface electroconductivity of 5625 S/m was prepared by a two-step spin-coating method. The presence of lamellar apatite nanocrystals on the surfaces of the biocomposite suggests that it has good in vitro biomineralization ability. The silicon and zinc released from the biocomposite induced a significant increase in the osteogenesis of mouse bone mesenchymal stem cells (mBMSCs). Furthermore, alkaline phosphatase activities were further promoted when 3 μA direct current was applied to stimulate the mBMSCs that were cultured on the RGO/ZS/CS surface. However, electrical stimulation failed to further upregulate the osteogenesis-related gene expression. Moreover, RGO/ZS/CS extracts were found to suppress the receptor activator of nuclear factor-κB ligand-induced osteoclastic differentiation of mouse leukemic monocyte macrophages (RAW264.7 cells). Although the zinc ions in the RGO/ZS/CS extracts showed an inhibitory role in human umbilical vein endothelial cell (HUVEC) proliferation, dilutions of the RGO/ZS/CS extracts (1/16, 1/32, and 1/64) promoted HUVEC proliferation, and their angiogenesis-related gene expression was also upregulated. On the basis of the results of the in vitro angiogenesis model, more interconnected tubes formed when the above dilutions of RGO/ZS/CS extracts were added to ECMatrix. The new RGO/ZS/CS electroconductive biocomposite has potential to be used for stimulating osteoporotic bone regeneration.

Mechanically Stiff, Zinc Cross-Linked Nanocomposite Scaffolds with Improved Osteostimulation and Antibacterial Properties

Nanocomposite scaffolds are studied widely due to their resemblance with the natural extracellular matrix of bone; but their use as a bone tissue engineered scaffold is clinically hampered due to low mechanical stiffness, inadequate osteoconduction, and graft associated infections. The purpose of the current study was the development of a mechanically stiff nanocomposite scaffold using biodegradable gellan and xanthan polymers reinforced with bioglass nanoparticles (nB) (Size: 20-120 nm). These nanocomposite scaffolds were cross-linked with zinc sulfate ions to improve their osteoconduction and antibacterial properties for the regeneration of a functional bone. The compressive strength and modulus of the optimized nanocomposite scaffold (1% w/v polymer reinforced with 4%w/v nB nanoparticles, cross-linked with 1.5 mM zinc sulfate) was 1.91 ± 0.31 MPa and 20.36 ± 1.08 MPa, respectively, which was comparable to the trabecular bone and very high compared to nanocomposite scaffolds reported in earlier studies. Further, in vitro simulated body fluid (SBF) study suggested deposition of biomimetic apatite on the surface of zinc cross-linked nanocomposite scaffolds confirming their bioactivity. MG 63 osteoblast-like cells cultured with the nanocomposite scaffolds responded to matrix stiffness with better adhesion, spreading and cellular interconnections compared to the polymeric gellan and xanthan scaffolds. Incorporation of bioglass nanoparticles and zinc cross-linker in nanocomposite scaffolds demonstrated 62% increment in expression of alkaline phosphatase activity (ALP) and 150% increment in calcium deposition of MG 63 osteoblast-like cells compared to just gellan and xanthan polymeric scaffolds. Furthermore, zinc cross-linked nanocomposite scaffolds significantly inhibited the growth of Gram-positive Bacillus subtilis (70% reduction) and Gram-negative Escherichia coli (81% reduction) bacteria. This study demonstrated a facile approach to tune the mechanical stiffness, bioactivity, osteoconduction potential and bacteriostatic properties of scaffolds, which marked it as a potential bone tissue engineered scaffold.

Design and evaluation of multifunctional antibacterial ion-doped β-dicalcium silicate cements favorable for root canal sealing

Cu or Zn-doping dicalcium silicate-based cements exhibit multifunctional physiochemical and biological performances and meet some challenging criteria in root canal treatment.

High mechanical strength bioactive wollastonite bioceramics sintered from nanofibers

The high mechanical strength bioactive wollastonite bioceramics were successfully fabricated via pressureless sintering using nanofibers as raw materials.