Electrospinning of in situ synthesized silica-based and calcium phosphate bioceramics for applications in bone tissue engineering: A review

The field of bone tissue engineering (BTE) focuses on the repair of bone defects that are too large to be restored by the natural healing process. To that purpose, synthetic materials mimicking the natural bone extracellular matrix (ECM) are widely studied and many combinations of compositions and architectures are possible. In particular, the electrospinning process can reproduce the fibrillar structure of bone ECM by stretching a viscoelastic solution under an electrical field. With this method, nano/micrometer-sized fibres can be produced, with an adjustable chemical composition. Therefore, by shaping bioactive ceramics such as silica, bioactive glasses and calcium phosphates through electrospinning, promising properties for their use in BTE can be obtained. This review focuses on the in situ synthesis and simultaneous electrospinning of bioceramic-based fibres while the reasons for using each material are correlated with its bioactivity. Theoretical and practical considerations for the synthesis and electrospinning of these materials are developed. Finally, investigations into the in vitro and in vivo bioactivity of different systems using such inorganic fibres are exposed.

Mimicking the electrophysiological microenvironment of bone tissue using electroactive materials to promote its regeneration

The process of bone tissue repair and regeneration is complex and requires a variety of physiological signals, including biochemical, electrical and mechanical signals, which collaborate to ensure functional recovery. The inherent piezoelectric properties of bone tissues can convert mechanical stimulation into electrical effects, which play significant roles in bone maturation, remodeling and reconstruction. Electroactive materials, including conductive materials, piezoelectric materials and electret materials, can simulate the physiological and electrical microenvironment of bone tissue, thereby promoting bone regeneration and reconstruction. In this paper, the structures and performances of different types of electroactive materials and their applications in the field of bone repair and regeneration are reviewed, particularly by providing the results from in vivo evaluations using various animal models. Their advantages and disadvantages as bone repair materials are discussed, and the methods for tuning their performances are also described, with the aim of providing an up-to-date account of the proposed topics.

Preparation and properties of a biodegradable poly(lactide-co-glycolide)/poly(trimethylene carbonate) porous composite scaffold for bone tissue engineering

New biodegradable PLGA/PTMC composite porous scaffold with high porosity, mechanical properties, significant homogeneous, interconnected pore network and good biocompatibility.

The effect of ethenyltrimethoxysilane modification of nano bioactive glass on the physiochemical and mechanical properties and in vitro bioactivity of poly(lactide-co-glycolide)/poly(trimethylene carbonate) composite

The new biodegradable PLGA/PTMC/YDH-NBG composite with excellent mechanical properties and good in vitro bioactivity.

Promoting osteoblasts responses in vitro and improving osteointegration in vivo through bioactive coating of nanosilicon nitride on polyetheretherketone

Objective

To enhance the bioactivity of polyetheretherketone (PEEK) while maintain its mechanical strengths.

Methods

Suspension coating and melt bonding.

Results

Silicon nitride (Si₃N₄, SN) coating lead to higher surface roughness, hydrophilicity and protein absorption; SN coating could slowly release Si ion into simulated body fluid (SBF), which caused weak alkaline of micro-environment owing to the slight dissolution of SN; SN coating resulted in the improvements of adhesion, proliferation, differentiation and gene expressions of MC3T3-E1 cells in vitro; SN coating of PEEK with bioactive SN coating (CSNPK) obviously promoted bone regeneration and osseointegration in vivo.

Conclusions

CSNPK with SN coating as bone implant might be a promising candidate for orthopedic implants.

The Translational Potential of this Article

The silicon nitride-coated polyetheretherketone (CSNPK) prepared in this article could induce MC3T3-E1 cells adhesion, proliferation and differentiation in vitro; it could also induce bone regeneration in bone defect in vivo, which indicate its good cytocompatibility and biocompatibility. If the raw materials are medical grade, and preparation process as well as production process of this article are further improved, it will have great translational potential.

Optimized synthesis of carbon-doped nano-MgO and its performance study in catalyzed ozonation of humic acid in aqueous solutions: Modeling based on response surface methodology

This research study focused on the optimization of the synthesis of carbon-doped nano-MgO (C-MgO) and the investigation of its catalytic capacity in a catalytic ozonation process (COP) for the removal of humic acid (HA). Characterization analyses, including SEM, EDX, XRD, BET, and photoluminescence test showed that the C-MgO was successfully synthesized. L8 orthogonal arrays according to the Taguchi methodology optimized the synthesis of the C-MgO as follows: sucrose to MgO ratio = 0.5, sonication time = 15 min, calcination temperature = 400 °C and pH = 10.5. A central composite design based on response surface methodology was employed to optimize and model the COP in the removal of HA. A quadratic polynomial model with p-value < 0.0001 and R² = 0.9988 showed a better fit to experimental responses. The optimum levels of the studied parameters in the COP based on the predictive model were obtained as follows: pH = 9.5, reaction time = 12 min, catalyst dose = 1 g/L, and HA concentration = 5 mg/L. The HA mineralization was determined to be 86.8% at the 100 min reaction time. Additionally, the COP exhibited 34% synergistic effect and the kinetic rate constant of 0.1898 min^-1 in the HA removal. The presence of tert-butanol, methanol, salicylic acid, and some anions did not significantly affect the removal of the HA in the COP. From a practical view, this report indicated that the C-MgO catalyst could be potentially applied in the COP for the treatment of the water having high concentrations of HA substances.

Electrically conductive nanomaterials for cardiac tissue engineering

Patient deaths resulting from cardiovascular diseases are increasing across the globe, posing the greatest risk to patients in developed countries. Myocardial infarction, as a result of inadequate blood flow to the myocardium, results in irreversible loss of cardiomyocytes which can lead to heart failure. A sequela of myocardial infarction is scar formation that can alter the normal myocardial architecture and result in arrhythmias. Over the past decade, a myriad of tissue engineering approaches has been developed to fabricate engineered scaffolds for repairing cardiac tissue. This paper highlights the recent application of electrically conductive nanomaterials (carbon and gold-based nanomaterials, and electroactive polymers) to the development of scaffolds for cardiac tissue engineering. Moreover, this work summarizes the effects of these nanomaterials on cardiac cell behavior such as proliferation and migration, as well as cardiomyogenic differentiation in stem cells.

Microporous Coatings of PEKK/SN Composites Integration with PEKK Exhibiting Antibacterial and Osteogenic Activity, and Promotion of Osseointegration for Bone Substitutes

To improve the antibacterial and osteogenic activities of poly(etherketoneketone) (PEKK), concentrated sulfuric acid (H₂SO₄) suspension with silicon nitride (SN) microparticle was utilized to modify PEKK surface. Through sulfonation reaction, microporous coatings of PEKK/SN composites were created on PEKK surface, which were integrated with PEKK substrate. The results showed that the content of SN in the microporous coatings increased with the increase of SN content in H₂SO₄ suspension (PKS without SN, PKSC5 and PKSC10 with 5 and 10 wt % SN content in H₂SO₄) and that the surface roughness and hydrophilicity of microporous coatings on PEKK were significantly improved with the SN content increasing. In addition, the microporous coating of PKSC10 with high SN content exhibited excellent antibacterial activity due to the synergistic action of the presence of amino (-NH₂) and sulfonic acid (-SO₃H) groups as well as the improvement of protein absorption. Moreover, the microporous coating of PKSC10 obviously stimulated adhesion, proliferation, and osteogenic differentiation of rat bone mesenchymal stem cells. Furthermore, histological and push-out load evaluation indicated that the microporous coating of PKSC10 significantly promoted osteogenesis and osseointegration in vivo. The results suggested that the microporous coating of PKSC10 with high SN content display good biocompatibility, antibacterial and osteogenic activities, and osseointegration ability, which would have great potential for bone substitutes.

LAPONITE® nanorods regulating degradability, acidic-alkaline microenvironment, apatite mineralization and MC3T3-E1 cells responses to poly(butylene succinate) based bio-nanocomposite scaffolds

Novel bio-nanocomposite scaffolds for bone tissue engineering were prepared by incorporation of LAPONITE® (LAP) nanorods into poly(butylene succinate) (PBSu). The results showed that the scaffolds had well interconnected macroporous structures with macropore size in the range of 200–400 μm and porosity of around 70%. In addition, the water absorption, degradability and apatite mineralization ability of the scaffolds were clearly enhanced with the increase of LAP content. Moreover, the degradation of LAP produced alkaline products, which neutralized the acidic degradable products of PBSu, and formed a weak alkaline microenvironment similar to a biological environment. Furthermore, the adhesion, proliferation and differentiation of MC3T3-E1 cells onto the scaffolds were significantly promoted with the increase of LAP content, in which the scaffold with 30 wt% LAP (sPL30) exhibited the best stimulation effect on the cells responses. The results suggested that the promotion of cells responses could be ascribed to the improvements of surface characteristics (including roughness, hydrophilicity, ions release and apatite formation, etc.) of the scaffolds. The sPL30 scaffold with excellent biocompatibility, bioactivity and degradability had great potential for applications in bone tissue engineering.

PBSu/LAP bio-nanocomposite scaffolds were prepared, and the sPL30 scaffolds significantly stimulated cell adhesion and proliferation.

Zein regulating apatite mineralization, degradability, in vitro cells responses and in vivo osteogenesis of 3D-printed scaffold of n-MS/ZN/PCL ternary composite

Bioactive and degradable scaffolds of nano magnesium silicate (n-MS)/zein (ZN)/poly(caprolactone) (PCL) ternary composites were prepared by 3D-printing method. The results showed that the 3D-printed scaffolds possessed controllable pore structure, and pore morphology, pore size, porosity and pore interconnectivity of the scaffolds can be efficiently adjusted. In addition, the apatite-mineralization ability of the scaffolds in simulated body fluids was obviously improved with the increase of ZN content, in which the scaffold with 20 w% ZN (C20) possessed excellent apatite-mineralization ability. Moreover, the degradability of the scaffolds was significantly enhanced with the increase of ZN content in the scaffolds. The degradation of ZN produced acidic products that could neutralize the alkaline products from the degradation of n-MS, which avoid the increase of pH value in degradable solution. Furthermore, the MC3T3-E1 cells responses (e.g. proliferation and differentiation, etc.) to the scaffolds were significantly promoted with the increase of ZN content. The in vivo osteogenesis of the scaffolds implanted the femur defects of rabbits was investigated by micro-CT and histological analysis. The results demonstrated that the new bone formation was significantly enhanced with the increase of ZN content, in which the C20 scaffold induced the highest new bone tissues, indicating excellent osteogenesis. The results suggested that the ZN in the ternary composite scaffolds played key roles in assisting bone regeneration in vivo.

Zein regulating apatite mineralization, degradability, cells responses and osteogenesis of 3D-printed scaffold of n-MS/ZN/PCL ternary composite.

Enhancing the biological properties of carbon nanofibers by controlling the crystallization of incorporated bioactive glass via silicon content

Mechanism and model of biomineralization behavior of CNF and CNF/BG hybrids containing BG with different silicon contents.

Regulating micro-structure and biomineralization of electrospun PVP-based hybridized carbon nanofibers containing bioglass nanoparticles via aging time

Morphological and micro-structural evolution of BG components in PVP-based CNF/BG composite with aging time.

Thermal-based regulation on biomineralization and biological properties of bioglass nanoparticles decorated PAN-based carbon nanofibers

The mechanism and model for biomineralization behavior and cell culture of CNF/BG sintered at various temperatures.