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Calcium silicate (CS) is envisioned as a good substrate for bone tissue engineering applications because it can provide bioactive ions like Ca 2+ and Si 4+ to promote bone regeneration. Calcination temperature is a critical factor in determining the crystallinity of CS ceramic, which subsequently influences its degradation and ion release behaviors. To investigate the effect of calcination temperature on the capacity of CS in inducing bone regeneration, CS nanofibers were fabricated via electrospinning of precursor sol-gel and subsequent sintering at 800 °C, 1000 °C or 1200 °C. As the calcination temperature was increased, the obtained CS nanofibers displayed higher crystallinity and slower degradation rate. The CS nanofibers calcined at 800 °C (800 m) would like to cause high pH (>9) in cell culture medium due to its rapid ion release rate, displaying adverse effect on cell viability. Among all the preparations, it was found the CS nanofibers calcined at 1000 °C (1000 m) demonstrated the strongest promotion effect on the osteogenic differentiation of bone marrow mesenchymal stromal cells. To facilitate in vivo implantation, the CS nanofibers were shaped into three-dimensional macroporous scaffolds and coated with gelatin to improve their mechanical stability. By implanting the scaffolds into rat calvarial defects, it was confirmed the scaffold made of CS nanofibers calcined at 1000 °C was able to enhance new bone formation more efficiently than the scaffolds made of CS nanofibers calcined at 800 °C or 1200 °C. To summarize, calcination temperature could be an effective and useful tool applied to produce CS bioceramic substrates with improved potential in enhancing osteogenesis by regulating their degradation and bioactive ion release behaviors., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Electrospinning is a common and effective technology used for the fabrication of biomimetic nanofibers targeting tissue regeneration applications. As for cartilage regeneration, nanofibers containing natural components derived from cartilage extracellular matrix (ECM) are preferred. However, it is not easy an task to electrospin glycosaminoglycan (GAG) like hyaluronic acid (HA) and chondroitin sulfate (CS) by themselves. In this study, HA and/or CS were co-electrospun with poly(L-lactide) (PLLA) or PLLA/gelatin (1:1 in weight ratio) to obtain GAG-containing composite nanofibers. All the prepared composite nanofibers were non-cytotoxic, able to support cell attachment, spread and proliferation. In the differentiation studies, the PLLA/GAG and the PLLA/gelatin/GAG nanofibers demonstrated stronger capacities in promoting the chondrogenic differentiation of both the bone marrow mesenchymal stromal cells (BMSCs) and chondrocytes than the respective PLLA and PLLA/gelatin nanofibers, even in the proliferation medium without extra inductive factors. The incorporation of gelatin greatly improved the hydrophilicity of the fibrous meshes. At the meantime, the PLLA/gelatin/GAG nanofibers were more efficient than the PLLA/GAG nanofibers in enhancing the chondrogenic differentiation. It was found that the PLLA/gelatin/HA/CS (HA and CS in 1:1 weight ratio) nanofibers demonstrated a stronger synergetic effect on up-regulating chondrogenesis than both the PLLA/gelatin/HA and the PLLA/gelatin/CS nanofibers, when the GAG amounts in all the preparations were controlled as 3 wt.%. Herein, GAG-containing composite nanofibers were successfully electrospun and their potentials for cartilage repair were proved.

Type I collagen, used as a raw material, plays a pivotal role in the development of medical devices and tissue engineering. Due to the risk of zoonotic transmission and religious constraints for mammalian collagen, fish collagen gains increased attention and is widely seen as an alternative. In this study, two collagen micro/nanofiber materials, self-assembled collagen nanofiber and electrospun collagen nanofiber, were prepared by tilapia skin collagen and their biocompatibility and immunogenicity was thoroughly investigated. The result revealed that the state of tilapia skin collagen in self-assembled collagen nanofiber and electrospun collagen nanofiber was different. The circular dichroism spectrum indicated that collagen in self-assembled collagen nanofiber retained the triple helical structure of the native collagen, while collagen in electrospun collagen nanofiber was denatured into gelatin. Nevertheless, the evaluation according to ISO10993, including tests of cytotoxicity, hemolysis, skin sensitization, acute systemic toxicity, mouse immunization and lymphocyte proliferation, demonstrated good biocompatibility and low immunogenicity for both self-assembled and electrospun collagen nanofiber materials. Overall, the present study highlighted that type I collagen from tilapia skin would be a promising biomaterial for the development of regenerate medical products.

The strategy of using multipotential stem cells like bone mesenchymal stromal cells (BMSCs) for nerve tissue engineering is proven feasible. The promotion effects on neural transdifferentiation of BMSCs from factors including nerve growth factor (NGF), laminin and electrical stimulation (ES) have been reported, while it is not known if these factors can achieve a strong synergetic impact when the cells are cultured on conductive substrates. In this study, it was identified that any single factor (NGF, laminin, or conductive substrate) combined with ES demonstrated the capacity to induce BMSCs transdifferentiating into neural cells, while the efficiency was found in the order of NGF > laminin > conductive substrate. The combination of any two of the factors would be more efficient in inducing the neural transdifferentiation than individual factor. As expected, the strongest promotion in inducing BMSCs to transdifferentiate into neural cells was identified when BMSCs were cultured on laminin-treated conductive nanofibrous mesh in the presence of NGF and under proper ES simultaneously, showing significant synergetic efficiency from these multiple factors. Studies on the Notch-1 signaling pathway, a main negative regulator of neurogenesis, revealed these factors sharing a similar molecular mechanism in regulating the neural transdifferentiation of BMSCs. The results suggested that satisfactory nerve regeneration might be achievable if these synergetic multiple factors could be involved in nerve guidance conduit design, especially, when BMSCs were applied as co-implanted cells., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Bone tissue engineering using bone mesenchymal stromal cells (BMSCs) is a multidisciplinary strategy that requires biodegradable scaffold, cell, various promoting cues to work simultaneously. Electrical stimulation (ES) is known able to promote osteogenic differentiation of BMSCs, but it is interesting to know how can it play the strongest promotion effect. To strengthen local ES on BMSCs, parallel-aligned conductive nanofibers were electrospun from the mixtures of poly(L-lactide) (PLLA) and multi-walled carbon nanotubes (MWCNTs), and used for cell culture. Osteogenic differentiation of BMSCs was conducted by applying ES (direct current, 1.5 V, 1.5 h/day) perpendicular to the fiber direction during the day 1-7, day 8-14, or day 15-21 period of the osteoinductive culture. In comparison with ES-free groups, bone-related markers and genes were found significantly up-regulated when ES was applied on BMSCs growing on nanofibers having higher conductivity. When the ES was applied at the earlier stage of osteoinductive culture, the promotion effect on osteogenic differentiation would be stronger. In the presence of a BMP blocker, the down-regulated expressions of bone-related genes were able to be slightly recovered by ES, especially when the ES was applied at the beginning of osteoinductive culture (i.e. day 1-7). The promotion effect generated by ES in the early stage was found sustainable to later stages of differentiation, while those ES applied at later stages of differentiation should have missed the optimal point. In other words, later ES was not so necessary in inducing the osteogenic differentiation of BMSCs. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3369-3383, 2017., (© 2017 Wiley Periodicals, Inc.)

In addition to providing maneuverability, electrospun nanofibrous meshes can make excellent supports for constructing flexible cell sheets to regulate cell behavior by nanofiber features. With the target of bone regeneration, herein composite nanofibers with two different fiber arrangements (nestlike, random) were electrospun from a blend solution containing poly(l-lactide) (PLLA) and gelatin (1:1 in weight ratio). Unlike the non-woven morphology in a random nanofibrous mesh, PLLA/gelatin composite nanofibers in the nestlike nanofibrous mesh displayed both non-woven and parallel morphologies. Both kinds of nanofibrous mesh were ∼50 μm thick as-prepared, and shrank to ∼30 μm after seeding with bone mesenchymal stromal cells (BMSCs). After 7 days of in vitro culture, cell sheets could form on both meshes (CSM) and on the culture plate. It was found that application of nanofibrous mesh promoted the osteogenic differentiation of BMSC sheets compared with the control. The nestlike mesh displayed slight superiority over the random mesh in enhancing osteogenic differentiation, but their different fiber arrangements did not cause much difference in cell proliferation. Three-dimensional multi-layered CSM constructs were built by stacking four mono-layered CSMs together. The CSM constructs (based on a nestlike or random nanofibrous mesh) were incubated in vitro for 3 days before being implanted into rat cranial defects. In comparison with the control group, there was significant formation of new calcified bone in both CSM construct-filled groups at 12 weeks' post-operation. The nestlike group showed slightly better bone healing (based on both qualitative and quantitative analysis) than the random group, while showing insignificant differences. We showed that the concept of using a three-dimensional multi-layered CSM construct in enhancing bone regeneration was feasible. Future studies should take more nanofiber features (e.g. bioactive components) into account to further enhance osteogenesis.

Mimicking the natural bone extracellular matrix, biomineralized nanofibers are envisioned as good choices for bone regeneration. Herein, composite nanofibers composed of poly(L-lactide) (PLLA) and gelatin (50/50, w/w) were electrospun and soaked in a modified five times simulated body fluid (SBF) for 6-24 h. Along with the soaking time, the amounts of deposited minerals increased, and the minerals transformed from dicalcium phosphate dehydrate (DCPD) to hydroxyapatite (HA). Mineral dissolution and Ca(2+) ion release of these biomineralized nanofibers were investigated by putting them in deionized water or Hank's balanced salt solution. MC3T3-E1 osteoblasts were cultured in transwell chambers without contacting the materials or on the biomineralized nanofibers directly. In the noncontact culture, the released ions were found able to enhance osteogenic differentiation more significantly in comparison with cell proliferation. In the contact culture, all biomineralized nanofibers demonstrated strong ability in promoting both cell proliferation and osteogenic differentiation. Due to the fast dissolution of DCPD, the biomineralized nanofibers obtained from short SBF soaking was found to be inferior in enhancing osteogenic differentiation. Whereas the cells displayed high levels of alkaline phosphatase activity and collagen I synthesis when the material had abundant deposition of apatite. The results revealed that cell biological behaviors were synergistically influenced by the ionic dissolution products, the composition, and the morphology of biomineralized nanofibers, which could be regulated by timed biomineralization. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1968-1980, 2016., (© 2016 Wiley Periodicals, Inc.)

The direct fabrication of hybrid nanofibres composed of poly(methyl methacrylate)-grafted SiO2 (SiO2-PMMA) nanospheres via electrospinning was investigated in detail. SiO2-PMMA nanospheres were successfully prepared, with the SiO2 nanospheres synthesized via the Stober method, followed by in situ surface-initiated atom transfer radical polymerization of methyl methacrylate (MMA). Electrospinning was carried out with N,N-dimethylformamide (DMF) as the solvent to disperse SiO2-PMMA nanospheres. The size of the SiO2 core, the molecular weight of the PMMA shell and the concentration of the SiO2-PMMA/DMF solution all had substantial effects on the morphology and structure of electrospun nanofibres composed of SiO2-PMMA nanospheres. When these determining factors were well-tailored, it was found that one-dimensional necklace-like nanofibres were obtained, with SiO2-PMMA nanospheres aligned one by one along the fibre. The successful fabrication of nanofibres by directly electrospinning the SiO2-PMMA/DMF solution verified that polymer-grafted particles possess polymer-like characteristics, which endowed them with the ability to be processed into desirable shapes and structures., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Hybridized carbon nanofibers containing calcium phosphate nanoparticles (CNF/CaP) were investigated as osteocompatible nanofillers for epoxy resin. The CNF/CaP was produced by electrospinning mixture solution of polyacrylonitrile and CaP precursor sol-gel, followed by preoxidation and carbonization. The continuous and long CNF/CaP was ultrasonically chopped, mixed into epoxy resin and thermo-cured. Compared to pure CNFs with similar ultrasonication treatment, the shortened CNF/CaP reinforced composites demonstrated significant enhancement in flexural properties of epoxy composites, benefiting from the improved interfacial adhesion between CNF/CaP and resin matrix. The resulting composites also displayed good biocompatibility and sustained calcium ion release, which categorized them as promising materials for bone repairing., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The major objective of this study was to explore the effects of silicon dioxide (SiO2) nanofibers on the performance of 2, 2-bis-[4-(methacryloxypropoxy)-phenyl]-propane (Bis-GMA)/tri-(ethyleneglycol) dimethacrylate (TEGDMA) dental composites. At first, the mechanical properties of Bis-GMA/TEGDMA (50/50, w/w) resins containing different contents of SiO2 nanofibers were evaluated to identify the appropriate composition to achieve the significant reinforcing effect. Secondly, optimized contents (5 or 10wt.%) of SiO2 nanofibers were mixed into resins together with SiO2 microparticles, which was 60wt.% of the resin. Controls for comparison were Bis-GMA/TEGDMA resins containing only SiO2 microparticles (60wt.%) or with additional SiO2 nanoparticles (5 or 10wt.%). Properties including abrasion, polymerization shrinkage and mechanical properties were evaluated to determine the contribution of SiO2 nanofibers. In comparison with SiO2 nanoparticles, SiO2 nanofibers improved the overall performance of Bis-GMA/TEGDMA composite resins, especially in improving abrasion resistance and decreasing polymerization shrinkage. The explanations were that one-dimensional SiO2 nanofibers were able to shield particular fillers from being abraded off, and able to form a kind of overlapped fibrous network to resist polymerization shrinkage. With these approaches, SiO2 nanofiber-containing Bis-GMA composite resins were envisioned a promising choice to achieve long-term durable restorations in clinical therapies., (Copyright © 2015. Published by Elsevier B.V.)

Bioactive glass (BG)-containing carbon nanofibers (CNFs) are promising orthopaedic biomaterials. Herein, CNF composites were produced from electrospinning of polyacrylonitrile (PAN)/BG sol-gel precursor solution, followed by carbonization. Choosing 58S-type BG (mol%: 58.0% SiO2-26.3% CaO-15.7% P2O5) as the model, micro-structural evolution of CNF/BG composites was systematically evaluated in relating to aging times of BG precursor solution. With aging time prolonging, BG precursors underwent morphological changes from small sol clusters with loosely and randomly branched structure to highly crosslinked Si-network structure, showing continuous increase in solution viscosity. BG precursor solution with low viscosity could mix well with PAN solution, resulting in CNF composite with homogeneously distributed BG component. Whereas, BG precursor gel with densely crosslinked Si-network structure led to uneven distribution of BG component along final CNFs due to its significant phase separation from PAN component. Meanwhile, BG nanoparticles in CNFs demonstrated micro-structural evolution that they transited from weak to strong crystal state along with longer aging time. Biomineralization in simulated body fluid and in vitro osteoblasts proliferation were then applied to determine the bioactivity of CNF/BG composites. CNF/BG composites prepared from shorter aging time could induce both faster apatite deposition and cell proliferation rate. It was suggested weakly crystallized BG nanoparticles along CNFs dissolved fast and was able to provide numerous nucleation sites for apatite deposition, which also favored the proliferation of osteoblasts cells. Aging time could thus be a useful tool to regulate the biological features of CNF/BG composites., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Proliferation and differentiation of bone-related cells are modulated by many factors such as scaffold design, growth factor, dynamic culture system, and physical simulation. Nanofibrous structure and moderate-intensity (1 mT-1 T) static magnetic field (SMF) have been identified as capable of stimulating proliferation and differentiation of osteoblasts. Herein, magnetic nanofibers were prepared by electrospinning mixture solutions of poly(L-lactide) (PLLA) and ferromagnetic Fe3O4 nanoparticles (NPs). The PLLA/Fe3O4 composite nanofibers demonstrated homogeneous dispersion of Fe3O4 NPs, and their magnetism depended on the contents of Fe3O4 NPs. SMF of 100 mT was applied in the culture of MC3T3-E1 osteoblasts on pure PLLA and PLLA/Fe3O4 composite nanofibers for the purpose of studying the effect of SMF on osteogenic differentiation of osteoblastic cells on magnetic nanofibrous scaffolds. On non-magnetic PLLA nanofibers, the application of external SMF could enhance the proliferation and osteogenic differentiation of MC3T3-E1 cells. In comparison with pure PLLA nanofibers, the incorporation of Fe3O4 NPs could also promote the proliferation and osteogenic differentiation of MC3T3-E1 cells in the absence or presence of external SMF. The marriage of magnetic nanofibers and external SMF was found most effective in accelerating every aspect of biological behaviors of MC3T3-E1 osteoblasts. The findings demonstrated that the magnetic feature of substrate and microenvironment were applicable ways in regulating osteogenesis in bone tissue engineering., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Carbon nanomaterials (CNMs), such as carbon nanotube (CNT) and graphene, are highlighted in bone regeneration because of their osteoinductive properties. Their combinations with nanofibrous polymeric scaffolds, which mimic the morphology of natural extracellular matrix of bone, arouse keen interest in bone tissue engineering. To this end, CNM were incorporated into nanofibrous poly(L-lactic acid) scaffolds by thermal-induced phase separation. The CNM-containing composite nanofibrous scaffolds were biologically evaluated by both in vitro co-culture of bone mesenchymal stem cells (BMSCs) and in vivo implantation. The nanofibrous structure itself demonstrated significant enhancement in cell adhesion, proliferation and oseogenic differentiation of BMSCs, and with the incorporation of CNM, the composite nanofibrous scaffolds further promoted osteogenic differentiation of BMSCs significantly. Between the two CNMs, graphene showed stronger effect in promoting osteogenic differentiation of BMSCs than CNT. The results of in vivo experiments revealed that the composite nanofibrous scaffolds had both good biocompatibility and strong ability in inducing osteogenesis. CNMs could remarkably enhance the expression of osteogenesis-related proteins as well as the formation of type I collagen. Similarly, the graphene-containing composite nanofibrous scaffolds demonstrated the strongest effect on inducing osteogenesis in vivo. These findings demonstrated that CNM-containing composite nanofibrous scaffolds were obviously more efficient in promoting osteogenesis than pure polymeric scaffolds., (© 2014 Wiley Periodicals, Inc.)

Biodegradable polyphosphazenes were categorized as osteoinductive materials because of their phosphorus-containing feature; however, they were less supportive in cell attachment and proliferation at earlier points in comparison with biodegradable aliphatic polyesters. Therefore, mussel-inspired surface modification of poly(alanine ethyl ester-co-glycine ethyl ester)phosphazene (PAGP) was studied, intending to circumvent the above-mentioned disadvantage of polyphosphazene. To this end, PAGP and poly(L-lactide) (PLLA) were electrospun into nanofibrous substrates and surface treated with dopamine aqueous solution. With the analysis of scanning electron microscope, transmission electron microscope, X-ray photoelectron spectroscope, and Fourier transform infrared spectroscope, the successful poly(dopamine) coating was identified on both PAGP and PLLA nanofibers. MC3T3-E1 osteoblasts were found attaching and proliferating much well on poly(dopamine)-modified nanofibrous substrates in comparison with the pristine ones. In addition, the poly(dopamine) coating demonstrated high activity in promoting osteogenous differentiation. Because the phosphorus content on nanofiber surface was decreased with the poly(dopamine) coating, the poly(dopamine)-coated PAGP nanofibrous substrate was slightly inferior to pure PAGP nanofibrous substrate in osteogenous differentiation. In a summary, the results confirmed that poly(dopamine)-modified polyphosphazenes were promising scaffold materials with both high cell affinity and high osteocompatibility for bone regeneration., (© 2013 Wiley Periodicals, Inc.)

Composite nanofibers composed of polyacrylonitrile (PAN)-based carbon nanofibers and bioactive glass (BG) nanoparticles have been prepared by electrospinning and in situ sintering. Morphology observation showed that the BG nanoparticles of size 20-50 nm were uniformly distributed on the surface of composite nanofibers with 350 nm average diameter after carbonization. Biological mineralization indicated the formation of apatite-like layer on the surface of composite nanofibers, in which the composition of carbonate hydroxyapatite was proved by FTIR and XRD analysis. Cell growth dynamics according to cellular morphology, CCK-8 assay, and alkaline phosphatase activity assay exhibited better cell adhesion, proliferation, and osteogenic induction of bone marrow-derived mesenchymal stem cells cultured on the composite nanofibers, which suggested the higher bioactivity of composite nanofibers compared to pure PAN-based carbon nanofibers.

Nanotopographic cues from biomaterials exert powerful effects on the osteogenic differentiation of mesenchymal stem cells because of their niche-mimicking features. However, the biological mechanisms underlying cell lineage determination by surface nanotopography have not been clearly elucidated. Here, we explored the osteogenic behavior of human bone marrow mesenchymal stem cells (hBMSCs) on poly-l-lactide nanofibers with different orientations and monitored the dynamic changes in global gene expression triggered by topographical cues. RT-PCR analysis of osteogenic marker genes and ALP activity assays demonstrated that hBMSCs cultured on random nanofibers showed enhanced osteogenic-specific fate compared with those on aligned nanofibers. Microarray analysis demonstrated a similar temporal change in gene expression patterns between hBMSCs cultured on random nanofibers and those induced with an osteogenic supplement (OS). However, the extent of osteogenic differentiation on the fibrous scaffold was much lower than that driven by chemical OS. In-depth pathway analysis revealed that focal adhesion kinase, TGF-β, Wnt, and MAPK pathways were involved in the activation of osteogenic differentiation in hBMSCs on random nanofibers. These findings suggested that a lower extent but similar rhythm of dynamic cellular behavior was induced on random nanofibers when compared with the OS condition and that mechanotransduction could trigger nonspecific and multilevel responses in hBMSCs. This study provides insight into the regulation of osteogenesis directed by substratum surfaces.

Magnetic poly(L-lactide) (PLLA)/Fe3O4 composite nanofibers were prepared with the purpose to develop a substrate for bone regeneration. To increase the dispersibility of Fe3O4 nanoparticles (NPs) in the PLLA matrix, a modified chemical co-precipitation method was applied to synthesize Fe3O4 NPs in the presence of PLLA. Trifluoroethanol (TFE) was used as the co-solvent for all the reagents, including Fe(II) and Fe(III) salts, sodium hydroxide, and PLLA. The co-precipitated Fe3O4 NPs were surface-coated with PLLA and demonstrated good dispersibility in a PLLA/TFE solution. The composite nanofiber electrospun from the solution displayed a homogeneous distribution of Fe3O4 NPs along the fibers using various contents of Fe3O4 NPs. X-ray diffractometer (XRD) and vibration sample magnetization (VSM) analysis confirmed that the co-precipitation process had minor adverse effects on the crystal structure and saturation magnetization (Ms) of Fe3O4 NPs. The resulting PLLA/Fe3O4 composite nanofibers showed paramagnetic properties with Ms directly related to the Fe3O4 NP concentration. The cytotoxicity of the magnetic composite nanofibers was determined using in vitro culture of osteoblasts (MC3T3-E1) in extracts and co-culture on nanofibrous matrixes. The PLLA/Fe3O4 composite nanofibers did not show significant cytotoxicity in comparison with pure PLLA nanofibers. On the contrary, they demonstrated enhanced effects on cell attachment and proliferation with Fe3O4 NP incorporation. The results suggested that this modified chemical co-precipitation method might be a universal way to produce magnetic biodegradable polyester substrates containing well-dispersed Fe3O4 NPs. This new strategy opens an opportunity to fabricate various kinds of magnetic polymeric substrates for bone tissue regeneration., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Poly(lactide-co-glycolide) (PLGA) copolymers are the most prevalent materials for tissue engineering applications. To mimic the real microenvironment of extracellular matrix (ECM) for cell growth, nanofibrous PLGA scaffolds are preferred. PLGA5050 (in which the molar ratio of lactidyl to glycolidyl units is 50:50), which is an utterly amorphous polymer, was first reported to be made into nanofibrous networks (fiber diameter around 500 nm) using phase separation from PLGA5050/THF solutions in this study. The concentration of polymeric solution had significant effects on fiber diameter and unit length. Nonsolvent (e.g. H2O) was unnecessary to form the PLGA5050 gel, which was critical to nanofibrosis, as if the environmental temperature for gelation occurrence was low enough (-70 °C). The physical crosslinks to stabilize the PLGA5050/THF gel were believed to be GA segments along the backbone owing to their inferior solubility in THF. The addition of H2O would cause adverse effects of liquid-liquid phase separation and nanofibrosis failure owing to the hydrophilicity of glycolidyl units. Associating with the phase separation method, particle-leaching technique was applied to fabricate three-dimensional scaffolds with macroporous and nanofibrous structures. To ensure the occurrence of nanofibrosis on macropore walls, the temperature of salt particles should be best lowed to -70 °C beforehand. Accordingly, scaffolds prepared under varied parameters exhibited different nanofiber and pore morphologies, which affected the pore size, porosity, specific surface area, water contact angle and protein adsorption ability etc. The preliminary cell (MC3T3-E1) culture confirmed the cell ingrowth into the macroporous and nanofibrous PLGA5050 scaffolds in comparison with the solely nanofibrous matrixes. This kind of bi-scaled three dimensional matrixes can be superior candidate scaffolds for tissue engineering applications., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Electrospun tetracycline (Tet)-loaded poly(D,L-lactide-co-glycolide) (PLGA) nanofibers are considered to have great potential as local drug-delivery systems. This study was designed to explore the effects of the lactidyl/glycolidyl (LA/GA) unit ratio and molecular weight of PLGA on Tet entrapment efficiency and in vitro release kinetics. Three kinds of PLGA (PLGA75/25, M w = 100 000 or 50 000; PLGA50/50, M w = 50 000) were examined in this study. Electrospun nanofibers were fabricated containing 3, 5, 10 wt% Tet. The results showed that PLGA50/50 entrapped more Tet than both PLGA75/25 co-polymers, and the PLGA75/25 of M w = 100 000 entrapped the least amount of Tet, suggesting that the lower the molecular weight of PLGA was, the higher the GA content in PLGA was and the higher the resulting Tet entrapment. Tet loading played an important role in Tet release. Nanofibers with 3 and 5 wt% Tet loading exhibited a sustained release for more than 28 days, whereas 10 wt% Tet only lasted 14 days. Loading of 3 wt% Tet resulted in approx. 35% release in the initial 12 h, 5 wt% Tet released approx. 70% and 10 wt% Tet resulted in approx. 85% release. The integrity of Tet incorporated into electrospun PLGA nanofibers was identified by FT-IR spectrum examination and the bacterial inhibition test. The modified Kirby-Bauer test showed dose-dependent inhibition of Staphylococcus aureus growth by Tet, confirming Tet structural stability throughout the electrospinning procedure. MG-63 cells demonstrated good adhesion and proliferation on all PLGA/Tet fibrous membranes. These results indicate that Tet entrapment and release kinetics of PLGA/Tet composite fibrous scaffolds can be tailored by the LA/GA ratios, molecular weights and drug loadings. Tet-loaded fibrous scaffolds show great potential for local drug delivery and bone defect repair.

In this study, poly (L-lactic acid) (PLLA)/trifluoroethanol (TFE) solution was electrospun to fabricate fibrous scaffolds with different fiber orientations. Random and parallel PLLA nanofiber alignments were achieved by using a metal plate and a rolling rod as the receiver, respectively. The parallel PLLA fibrous scaffolds were further hot-stretched to obtain hyperparallel PLLA fibrous scaffolds. The PLLA fibrous scaffolds were characterized by fiber diameter, interfiber distance, fiber array angle, water contact angle, morphology and mechanical strength. The tensile strength of hyperparallel nano-fibers was approximately 5- and 14-times the parallel and random fibers, respectively. Osteoblast-like MG63 cells were cultured on the PLLA scaffolds to study the effects of fiber orientation on cell morphology, proliferation and differentiation. The cells on the randomly-oriented scaffolds showed irregular forms, while the cells exhibited shuttle-like shapes on the parallel scaffolds and had larger aspect ratios along the fiber direction of the hyperparallel scaffolds. Alkaline phosphatase (ALP) activity and collagen I (placeStateCol I) and osteocalcin (OC) deposition exhibited fiber orientation dependence. With an increase in parallelism of the fibers, there was a decrease in ALP activity and placeStateCol I and OC production. These results suggest that exploitation of PLLA fiber orientation may be used to control osteoblast-like cell responses., (Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.)

Objectives: The polyacrylonitrile (PAN)-poly(methyl methacrylate) (PMMA) core-shell nanofiber reinforced dental composites have been investigated for their excellent interface adhesive, and this kind of novel dental composite has the potential for clinical uses such as denture base resin and crown-bridge material. The first objective of this work was to determine the improving effect of tensile properties by post-drawing PAN-PMMA nanofibers membrane. The second objective was to examine the flexural strength (Fs), flexural modulus (Ey) and work of fracture (WOF) of Bis-GMA/TEGDMA composites reinforced with PAN-PMMA nanofibers., Methods: PAN(core)-PMMA(shell) nanofiber was made by an electrospinning setup with a high-speed rotating rod-like collector. The post-draw process was carried out at 120 degrees C for 5 min, and all the nanofiber membranes were elongated to the desired elongation ratio (30%, 60% or 100%). Tensile properties and flexural properties of both nanofiber membranes and nanofiber reinforced Bis-GMA/TEGDMA composites were investigated. A scanning electron microscope (SEM) was used to observe the fiber morphology and the fracture surface of the composite. A dynamic mechanical thermal analyzer (DMTA) was employed to determine the dynamic mechanical properties such as tandelta and E'., Results: The post-drawing treatment significantly improved the tensile properties and fiber parallelism of nanofiber membranes. The addition of PAN-PMMA nanofibers into Bis-GMA/TEGDMA clearly showed the reinforcement effect; the flexural strength (Fs), flexural modulus (Ey) and work of fracture (WOF) kept rising with the nanofiber mass fraction changing from 0%, 0.6%, 0.8%, 1.0% to 1.2%. The flexural properties of composites reinforced with post-drawn nanofiber were further increased in comparison with those of untreated nanofiber reinforced ones. Also, the SEM observations of the fracture surface of the composites demonstrated good interfacial adhesion between fibers and resin., Significance: The post-drawing treatment was confirmed as a useful method for significantly increasing the tensile strength (673.4%) and tensile modulus (875.3%) of nanofiber membranes. In addition, the composites reinforced with post-drawn PAN-PMMA nanofibers exhibited higher Fs (13.6%), Ey (5.3%) and WOF (30.4%) than those reinforced with as-electrospun PAN-PMMA nanofibers. When 1.2% mass fraction of post-drawn nanofibers were added to Bis-GMA/TEGDMA resin, the Fs, Ey and WOF increased by 51.6%, 64.3% and 152.0%, respectively, compared with neat resin., (Copyright 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.)

Electrospun tetracycline (Tet)-loaded poly(D,L-lactide-co-glycolide) (PLGA) nanofibers are considered to have great potential as local drug-delivery systems. This study was designed to explore the effects of the lactidyl/glycolidyl (LA/GA) unit ratio and molecular weight of PLGA on Tet entrapment efficiency and in vitro release kinetics. Three kinds of PLGA (PLGA75/25, Mw = 100 000 or 50 000; PLGA50/50, Mw = 50 000) were examined in this study. Electrospun nanofibers were fabricated containing 3, 5, 10 wt% Tet. The results showed that PLGA50/50 entrapped more Tet than both PLGA75/25 co-polymers, and the PLGA75/25 of Mw = 100 000 entrapped the least amount of Tet, suggesting that the lower the molecular weight of PLGA was, the higher the GA content in PLGA was and the higher the resulting Tet entrapment. Tet loading played an important role in Tet release. Nanofibers with 3 and 5 wt% Tet loading exhibited a sustained release for more than 28 days, whereas 10 wt% Tet only lasted 14 days. Loading of 3 wt% Tet resulted in approx. 35% release in the initial 12 h, 5 wt% Tet released approx. 70% and 10 wt% Tet resulted in approx. 85% release. The integrity of Tet incorporated into electrospun PLGA nanofibers was identified by FT-IR spectrum examination and the bacterial inhibition test. The modified Kirby-Bauer test showed dose-dependent inhibition of Staphylococcus aureus growth by Tet, confirming Tet structural stability throughout the electrospinning procedure. MG-63 cells demonstrated good adhesion and proliferation on all PLGA/Tet fibrous membranes. These results indicate that Tet entrapment and release kinetics of PLGA/Tet composite fibrous scaffolds can be tailored by the LA/GA ratios, molecular weights and drug loadings. Tet-loaded fibrous scaffolds show great potential for local drug delivery and bone defect repair. [ABSTRACT FROM AUTHOR]

Abstract: Polyacrylonitrile-based carbon fibers, embedded with single-walled carbon nanotubes have been prepared by the electrospinning technique. The as-spun nanofibers were hot-stretched in an oven to enhance the orientation and crystallinity which has been confirmed by X-ray diffraction and DSC etc. With the hot-stretched process and the introduction of SWNTs, the mechanical properties of PAN nanofibers such as the modulus and tensile strength will be enhanced correspondingly. In addition, the electrical conductivities of the PAN/SWNTs nanofiber composites were also enhanced. It was concluded that the hot-stretched nanofibers and the PAN/SWNTs nanofiber composites can be used as a potential precursor to produce high-performance carbon nanocomposites. [Copyright &y& Elsevier]

[Display omitted] The active cyano-group in polyacrylonitrile has severe passivation of lithium anode under larger current density, which restricts the wide application of polyacrylonitrile(PAN) in lithium metal batteries. Herein, in order to address the excessive passivation of lithium metal by PAN, inspired by the pre-oxidation of carbon fibers, PAN was pre-oxidized at 230 °C, which transformed part of the cyano group into a more chemically stable cyclized structure. The electrochemical and mechanical properties of the composite solid electrolyte were effectively improved by introducing the fast ionic conductor Li 6.25 La 3 Zr 2 Al 0.25 O 12 into PAN by electrospinning. The oxidized PAN-based composite solid electrolyte presents high ionic conductivity (3.05 × 10−3 S·cm−1) and high lithium transference number of 0.79 at 25 °C, further contributing to a high electrochemical window (5.3 V). The solid-state batteries assembled by Li||10 wt%-LLZAO@230-oxy-PAN||NCM523 behave superb electrochemical performance, delivering a high initial discharge capacity of 157 mAh g−1 at 0.2 C. After 100 cycles, the capacity retention was 93.3 %, indicating the electrolyte displays great electrochemical stability. This work provides new insights into the structural design of polymer-based high-voltage batteries. [ABSTRACT FROM AUTHOR]

The piezoelectric nature of natural bone tissue makes the use of piezoelectric biomaterials in promoting bone regeneration to be a feasible and attractive strategy. Barium titanate (BaTiO 3) is well-known for its high piezoelectricity and widely studied as bone repairing bioceramic, but its lacking of bioactive ions may compromise its contribution to osteogenesis. Calcium is the richest metallic element in bone mineral, and manganese is an important doping element for hydroxyapatite, therein, Ca2+ and Mn4+ were individually or co-doped into BaTiO 3 nanofibers via sol-gel/electrospinning/calcination technique in this study. Compared to pure BaTiO 3 nanofibers, though the piezoelectric coefficient (d 33) of Ca2+ and/or Mn4+-doped BaTiO 3 nanofibers decreased with increase in ion doping amount, it could maintain approx. 0.9–3.7 pC/N and comparable to that of native bone (0.7–2.3 pC/N) at an optimized content. Under the synergistic effect of the released bioactive ions and the material piezoelectricity, the BaTiO 3 nanofibers co-doped with Mn4+ (2 mol%) and Ca2+ (10 mol%) (i.e., the sample 2Mn10Ca-BT) achieved the strongest capacity in enhancing the osteogenic differentiation of bone marrow mesenchymal stromal cells (BMSCs), while showing no cytotoxicity. In summary, bioactive ions-doped BaTiO 3 nanofibers are promising scaffolds for bone tissue engineering, thanks to their acceptable biocompatibility, appropriate piezoelectricity, and improved osteogenic activity. [Display omitted] • Bioactive Ca2+ and Mn4+ are individually or co-doped into BaTiO 3 nanofibers. • The ion-doped BaTiO 3 nanofibers remain comparable piezoelectricity to natural bone. • The optimized Ca2+/Mn4+ co-doped BaTiO 3 nanofibers achieve significantly improved osteogenic activity. [ABSTRACT FROM AUTHOR]

Bioceramic materials currently applied in bone repairing mainly base on calcium phosphate compounds like hydroxyapatite (HA), however, issues including slow degradation rate and insufficient bioactivity limit their efficiency in promoting bone regeneration. Calcium silicate (CS) is a promising alternative for the purpose thanks to its degradability and bioactive Si4+ release ability, while its fast degradation rate will cause pH problem and does not match the rhythm of osteogenesis. Herein, 3D composite bioceramic scaffolds were fabricated by blending different weight fractions (1:0, 3:1, 1:1, 1:3 or 0:1) of CS nanofibers (CSNFs) and HA nanowires (HANWs) via steps of fiber-dispersing, freeze-drying and sintering. With subsequent polymer coating, the porous structure and mechanical properties of the CSNF/HANW scaffolds were improved and scaffold performances were further regulated in dependence on the hydrophobicity/hydrophilicity and degradation rates of the polymers. Poly(l -lactide) (PLLA), poly(lactide-co-caprolactone) (PLCL) and gelatin were applied as the polymer coating. It was found that PLLA- and PLCL-coating would slow down the scaffold degradation and ion release rate compared to the gelatin-coating, while the increasing fraction of CSNFs would accelerate these events to increase medium pH due to the alkalinity of the bioceramic material. Finally, proliferation and osteogenic differentiation of bone marrow mesenchymal stromal cells (BMSCs) achieved desirable outcomes on gelatin-coated CSNF/HANW scaffolds with their fractions of 1:1 and 1:3, strongly suggesting the potential of these scaffolds for bone regeneration. [Display omitted] • Calcium silicate nanofibers (CSNFs) and hydroxyapatite nanowires (HANWs) are fabricated. • Bioceramic fibrous scaffolds are fabricated with different fractions of CSNF/HANW. • The scaffolds are coated with hydrophobic or hydrophilic polymers with different degradation rates. • The developed composite scaffolds demonstrate controllable regulation capacity for bone regeneration. [ABSTRACT FROM AUTHOR]

A biodegradable and multifunctional air filtration membrane was prepared by electrospinning of soy protein isolate (SPI)/polyvinyl alcohol (PVA) system in this paper. The optimized SPI/PVA proportion in the spinning solution was determined according to the analyses of microstructure, surface chemical characteristic and mechanical property of the hybrid nanofiber membranes. Under the preferred preparation condition, two kinds of polymer materials displayed a good compatibility in the hybrid nanofibers, and a large number of polar groups existed in the membrane surface. The loading filtration efficiency of the nanofiber membrane with optimal material ratio and areal density can reach 99.99% after test of 30 min for fine particles smaller than 2.5 μm in the case of small pressure drop. Besides, this kind of filtration membrane showed an antimicrobial activity to Escherichia coli in the study. The SPI/PVA hybrid nanofiber membrane with proper material composition and microstructure can be used as a new type of high performance eco-friendly filtration materials. [ABSTRACT FROM AUTHOR]

The polymer nanofiber membranes with core (polyacrylonitrile, PAN)–shell (polyethylene oxide, PEO) structure were prepared by using coaxial electrospinning under different concentration of spinning solution. The polyporous nanofiber membranes were activated in liquid electrolytes and transformed into gel polymer electrolytes (GPEs). The microstructure, crystallization behavior and mechanical properties of nanofiber membranes were studied. Based on the proper collocation of polymer materials, desirable microstructure, appropriate crystallinity and moderate radiation-crosslinking, the high saturated electrolyte uptake, conservation rate and mechanical properties of polymer membranes were obtained. The electrochemical testing of the resulting GPEs revealed high ionic conductivities, good electrochemical stability and appropriate lithium-ion transference numbers, which are realized through choosing an optimal concentration of core/shell spinning solution. Moreover, the Li/GPE/LiCoO 2 cells with GPEs based on the radiation-crosslinked nanofiber membranes with optimized core–shell structure showed excellent initial discharge capacities as well as remarkable cycle performance. Through the implementation of the proper collocation of two ordinary polymer materials and facile preparation techniques, comprehensive performance of the resulting GPEs was more superior to that of GPEs involved with pure PAN and commercial Celgard ® 2500. The radiation-crosslinked nanofiber membranes with well-designed core–shell structure can be used as an ideal skeleton material in GPEs for lithium-ion batteries with high performance. [ABSTRACT FROM AUTHOR]

From physiological point of view, organic–inorganic composite nanofibers are envisioned promising substrates for bone tissue engineering. Biomineralization on polymeric nanofibers using simulated body fluid (SBF) is a common technique to obtain the composite nanofibers. Many factors, however, will affect the nucleation and crystal growth of deposited apatite, such as the additives like amino acids in SBF. In this study, electrospun composite nanofibers consisting of poly( l -lactide) (PLLA, 50 wt%) and gelatin (50 wt%) were soaked in 2.5 times SBF (2.5SBF) for different time periods (1, 2, 3, 5 and 7 days) to perform the biomineralization. Three amino acids (glycine, aspartic acid, or arginine) of different charge characteristics were introduced into the SBF, and their effects on nucleation and transformation of calcium phosphate depositions were systematically investigated. The results revealed that amino acids could take part in the early stage formation of pre-nucleation clusters, leading to different assemblies dependent closely on the feature of amino acid. In comparison with normal 2.5SBF, the presence of amino acid was able to enhance the preferred orientation of hydroxyapatite (HA) crystal along c axis and the transformation from amorphous calcium phosphate to hierarchical HA. The incorporation of glycine had promoted the formation of the well-evolved needle-like HA crystals in comparison with aspartic acid or arginine. It was suggested that the addition of amino acids into SBF might be a useful tool to regulate the biomineralizaiton for preparing organic–inorganic composite nanofibers. [ABSTRACT FROM AUTHOR]

Abstract: Scaffolds with both macro- and nanoscale structures have shown promise in tissue engineering; however, their mechanical properties are not satisfactory for load-bearing bone regeneration. In this study, calcium phosphate-coated multiwalled carbon nanotubes (MWCNTs-CaP) were developed to reinforce macroporous poly(L-lactide) (PLLA) scaffolds with nanofibrous pore walls. The scaffolds were prepared using a phase separation/particle-leaching method. One-dimensional MWCNTs-CaP were prepared via phosphorylation and mineralization. The addition of the MWCNTs-CaP did not affect the nanofibrous pore walls of the resulting PLLA scaffolds. In comparison with pure PLLA scaffolds, the compressive properties of PLLA/MWCNTs-CaP composite scaffolds were significantly improved, indicating their potential in bone regeneration applications. [Copyright &y& Elsevier]

Abstract: A kind of core–shell nanofibers containing sodium fluoride (NaF) was produced and used as reinforcing materials for dimethacrylate-based dental restorative resins in this study. The core–shell nanofibers were prepared by coaxial-electrospinning with polyacrylonitrile (PAN) and poly(methyl methacrylate) (PMMA) solutions as core and shell fluids, respectively. The produced PAN–PMMA nanofibers varied in fiber diameter and the thickness of PMMA shell depending on electrospinning parameters. NaF-loaded nanofibers were obtained by incorporating NaF nanocrystals into the core fluid at two loadings (0.8 or 1.0wt.%). Embedment of NaF nanocrystals into the PAN core did not damage the core–shell structure. The addition of PAN–PMMA nanofibers into Bis-GMA/TEGDMA clearly showed the reinforcement due to the good interfacial adhesion between fibers and resin. The flexural strength (Fs) and flexural modulus (Ey) of the composites decreased slightly as the thickness of PMMA shell increasing. Sustained fluoride releases with minor initial burst release were achieved from NaF-loaded core–shell nanofibers and the corresponding composites, which was quite different from the case of embedding NaF nanocrystals into the dental resin directly. The study demonstrated that NaF-loaded PAN–PMMA core–shell nanofibers were not only able to improve the mechanical properties of restorative resin, but also able to provide sustained fluoride release to help in preventing secondary caries. [Copyright &y& Elsevier]

The reconstruction of the local electrical microenvironment at the defect site has been considered as an effective strategy in stimulating bone regeneration. To mimic the electrophysiological nature of native bone tissue, piezoelectric ceramics and polymers are widely used as scaffolding materials. Herein, novel piezoelectric Ca/Mn co-doped BaTiO 3 (CMBT) nanofibers were composited with poly(l -lactide) (PLLA), to obtain a kind of substrates with strengthened piezoelectricity after polarization. Compared to pure BaTiO 3 nanofibers, the CMBT nanofibers exhibited extra osteogenic activity with the incorporation of bioactive Ca/Mn elements in addition to their piezoelectric property. Compared to non-degradable piezoelectric polymers like poly(vinylidene fluoride) (PVDF), polarized PLLA is not only biodegradable, but also piezoelectric. Therefore, as the CMBT nanofibers forming a network within the PLLA matrix, the PLLA/CMBT composites could significantly improve osteogenic activity both in vitro and in vivo. Using non-piezoelectric polycaprolactone (PCL) and polarized PLLA as controls, the strong antibacterial and anti-inflammatory activities of piezoelectric PLLA/CMBT composites were also identified, providing additional benefits for bone repairing. In summary, the polarized PLLA/CMBT composites are promising candidates for bone regeneration and function reconstruction, due to their multi-functionality in terms of electroactivity, biodegradability, antibacterial and anti-inflammatory activities, to meet the challenged requirements in inducing osteogenesis. [Display omitted] • Polarized poly(l -lactide) (PLLA) demonstrates piezoelectric activity. • Piezoelectric composites are fabricated by blending Ca2+/Mn4+ co-doped BaTiO 3 nanofibers into the PLLA matrix. • The composites with optimized piezoelectricity achieve significantly improved osteogenic activity. • The antibacterial and anti-inflammatory activity of the composites further contribute to osteogenesis. [ABSTRACT FROM AUTHOR]

Abstract: Magnetic poly(l-lactide) (PLLA)/Fe3O4 composite nanofibers were prepared with the purpose to develop a substrate for bone regeneration. To increase the dispersibility of Fe3O4 nanoparticles (NPs) in the PLLA matrix, a modified chemical co-precipitation method was applied to synthesize Fe3O4 NPs in the presence of PLLA. Trifluoroethanol (TFE) was used as the co-solvent for all the reagents, including Fe(II) and Fe(III) salts, sodium hydroxide, and PLLA. The co-precipitated Fe3O4 NPs were surface-coated with PLLA and demonstrated good dispersibility in a PLLA/TFE solution. The composite nanofiber electrospun from the solution displayed a homogeneous distribution of Fe3O4 NPs along the fibers using various contents of Fe3O4 NPs. X-ray diffractometer (XRD) and vibration sample magnetization (VSM) analysis confirmed that the co-precipitation process had minor adverse effects on the crystal structure and saturation magnetization (Ms) of Fe3O4 NPs. The resulting PLLA/Fe3O4 composite nanofibers showed paramagnetic properties with Ms directly related to the Fe3O4 NP concentration. The cytotoxicity of the magnetic composite nanofibers was determined using in vitro culture of osteoblasts (MC3T3-E1) in extracts and co-culture on nanofibrous matrixes. The PLLA/Fe3O4 composite nanofibers did not show significant cytotoxicity in comparison with pure PLLA nanofibers. On the contrary, they demonstrated enhanced effects on cell attachment and proliferation with Fe3O4 NP incorporation. The results suggested that this modified chemical co-precipitation method might be a universal way to produce magnetic biodegradable polyester substrates containing well-dispersed Fe3O4 NPs. This new strategy opens an opportunity to fabricate various kinds of magnetic polymeric substrates for bone tissue regeneration. [Copyright &y& Elsevier]

Abstract: MWNTs-EP were successfully prepared by functionalization of MWNTs with epoxy-based groups, and MWNTs-EP/polysulfone (PSF) hybrid nanofibers were fabricated to obtain ex-situ dispersion and alignment of MWNTs-EP by electrospinning. The prescribed morphology and interface correlation of hybrid nanofibers reinforced and toughened epoxy matrix (RTEP) were investigated. The alignment degree of hybrid nanofibers was enhanced with increasing MWNTs-EP loadings, and MWNTs-EP were found to be well dispersed and aligned along the nanofiber axis. The dispersion and alignment states of MWNTs-EP during inhomogeneous phase separation of RTEP were proposed and verified. MWNTs-EP dispersed and aligned along the orginal nanofiber axis were enveloped, bridged or pinned by PSF spheres arranged in the nanofiber direction. The interface chemical correlation between MWNTs-EP and resin matrix was generated due to the further reaction of epoxide rings on the surface of MWNTs-EP, which resulted in simultaneous improvement of mechanical and thermal properties of RTEP. [Copyright &y& Elsevier]

Abstract: Gelatin/β-TCP composite nanofibers were fabricated by incorporated different content of β-TCP nanoparticles (0, 5, 10, and 20wt.%) into electrospun gelatin nanofibers. The morphology and chemical structure of the composite nanofibers were characterized by SEM, TEM, XRD, and TGA techniques. Especially, calcium ion release behaviors from the composite nanofibers were investigated in the cell culture medium and correlated to the osteoblastic behavior of MG-63 cells. The results demonstrated that the adhesion, spreading, proliferation and the early osteogenic differentiation of osteoblast-like MG-63 cells on the composite nanofibers depended positively on the content of incorporated β-TCP nanoparticles and their dissolution behavior in the medium thereof. [Copyright &y& Elsevier]

Abstract: Nanosized anatase titanium dioxide loaded porous carbon nanofibers (TiO2/PCNFs) were prepared from electrospun TiO(OAc)2/PAN/PMMA composite precursor fibers with different amount of PMMA porogen, which were sequentially heat-treated in different environments. Electrochemical measurement results show that these as-prepared TiO2/PCNFs present higher cyclic reversible capacity than the TiO2/CNFs counterpart (without PMMA porogen in its precursor fibers). Among the as-prepared TiO2/PCNFs samples, the representative TiO2/PCNFs (the mass ratio of PAN to PMMA is 3:1) exhibits the best high-rate performance with a high stable capacity retention about 200mAhg−1 at a current density as high as 800mAg−1. This novel TiO2/PCNFs composite material opens up a promising application in high-power lithium-ion batteries. [Copyright &y& Elsevier]

Abstract: Reticular tin nanoparticle-dispersed carbon (Sn/C) nanofibers were fabricated by stabilization of electrospun SnCl4/PAN composite fibers and subsequent carbonization at different temperatures. These Sn/C composite nanofibers used as anode materials for rechargeable lithium-ion batteries (LIBs) show that the Sn/C nanofibers at 700 and 850°C present much higher charge (785.8 and 811mA h g− 1) and discharge (1211.7 and 993mA h g− 1) capacities than those at 550 and 1000°C and the as-received CNFs at 850°C, corresponding to coulombic efficiencies of 64.9% and 81.7%, respectively. The superior electrochemical properties of the intriguing Sn/C nanofibers indicate a promising application in high performance Li-ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: Carbon nanofibers decorated with β-tricalcium phosphate (β-TCP) nanoparticles (β-TCP/CNFs) have been prepared by sintering electrospun polyacrylonitrile fibers with calcium nitrate tetrahydrate as the calcium source and triethyl phosphate as the phosphorus source. Microstructure and phase composition analysis indicate that the resulting materials are composed of β-TCP nanoparticles and CNFs. And the long β-TCP/CNFs can be cut into organism-eliminable short CNFs gradually in hydrochloric acid solution due to the solubilization of β-TCP nanoparticles. The materials exhibit good biocompatibility, and have comparable effect on cell growth with pure CNFs, with their tuning ability in degradation. [Copyright &y& Elsevier]

Abstract: Curing kinetics and mechanisms of polysulfone nanofibrous membranes toughened TGDDM/DDS were investigated by using isothermal DSC and NIR, and compared to those of TGDDM/DDS and PSF films toughened TGDDM/DDS. At early curing stage, the curing rate of nanofibrous membranes toughened system was faster than those of other two systems, whereas the final conversion of toughened systems was lower than that of resin matrix. Most of the primary amine was consumed by gelation and the concentration of secondary amine reached the maximum around gelation. The faster consuming rates of primary and secondary amines in nanofibrous membranes toughened system resulted in higher concentration of hydroxyl groups and tertiary amines at gelation, which led to larger amounts of branching and crosslinking compared to resin matrix. The comparison of the results obtained from two methods showed that the epoxide conversion exhibited identical variations as a function of time, as well as the curing rate. [Copyright &y& Elsevier]

Abstract: The phase separation process and morphology evolution of 5wt% polysulfone (PSF) nanofibrous membranes toughened epoxy resin at different temperatures were investigated by synchrotron radiation small angel X-ray scattering (SR-SAXS), phase contrast microscopy (PCM) and scanning electron microscopy (SEM). The onset time of phase separation obtained by different methods was basically identical. As the curing proceeded at constant temperature, the scattering peak corresponding to the maximum scattering intensity shifted to a smaller scattering vector (q m ), and the average diameters of PSF spheres increased, which showed a phase separation pattern of nucleation and growth mechanism. PSF spheres exhibited random alignment in “sea-island” morphology, which was attributed to the in situ phase separation of PSF nanofibers. Also, the effects of phase separation kinetics on the phase morphology and fracture toughness of nanofibrous membranes toughened epoxy resin were investigated. Results showed that the phase separation process was faster than the curing reaction process, which implied that the diffusion coefficient of PSF in epoxy resin increased with increasing the curing temperature, resulting in the increase of PSF sphere size that in turn improved the fracture toughness at higher temperature. [Copyright &y& Elsevier]

Abstract: A novel TiO2− x N x /CNFs heterostructured photocatalyst was facilely fabricated by stabilization, NH4OH pretreatment and carbonization of electrospun TiO(OAc)2/PAN hybrid nanofibers. The uniformly aligned CNFs were interspersed with 25wt% of anatase TiO2− x N x nanoparticles, in which the x value or doped N atomic ratio was ∼0.52%. The TiO2− x N x /CNFs had a considerable surface area of 130m2/g and extraordinary mesoporous morphology. Owing to the synergistic effect between high adsorption capacity of CNFs and excellent vis-photocatalytic activity of TiO2− x N x nanoparticles, the TiO2− x N x /CNFs showed higher photocatalytic efficiency than referenced TiO2/CNFs and TiO2− x N x powders. [Copyright &y& Elsevier]

Abstract: PAN core–PMMA shell nanofiber fabric was prepared by electrospinning of polymer blends to reinforce 2,2-bis-[4-(methacryloxypropoxy)-phenyl]-propane (Bis-GMA) a dental resin system. The core–shell structure of the PAN–PMMA nanofiber was confirmed by scanning electron microscopy (SEM) and transmission electron microscope/energy dispersive spectroscopy (TEM/EDS) observation. The flexural properties and dynamic mechanical properties of the PAN–PMMA nanofiber reinforced Bis-GMA composites were studied. Results showed that PMMA shell was partly dissolved with the Bis-GMA resin. After photopolymerization, liner PMMA chains interpenetrated and entangled with the dental resin network, which resulted in an in situ nano-interface in the shell structure. Improvement of the mechanical properties of the PAN–PMMA nanofiber reinforced Bis-GMA composites has been achieved through this nano-interface formation. [Copyright &y& Elsevier]

Abstract: Novel carbon fiber/epoxy composite toughened by electrospun polysulfone (PSF) nanofibers was prepared to enhance fracture toughness of the composite, and compared the morphology and toughness to those of composite toughened by PSF films prepared by solvent method. Polysulfone nanofibers with the average diameter of 230 nm were directly electrospun onto carbon fiber/epoxy prepregs to toughen the composite. SEM observations of the polysulfone nanofibers toughened composite revealed that polysulfone spheres with uneven sizes presented uniform dispersion through interleaves of the composite, which was different from those of composite toughened by PSF films. Mode I fracture toughness (G IC) of the nanofibers toughened composite was 0.869 kJ/m2 for 5.0 wt.% polysulfone nanofibers content, which was 140% and 280% higher than those of PSF films toughened and untoughened composite due to the uniform distribution of polysulfone spheres. [Copyright &y& Elsevier]

The development of high-energy lithium-ion and sodium-ion capacitors (LICs and SICs) is still a challenge due to the kinetics mismatch between the insertion/deinsertion anode and adsorption/desorption cathode. Here, high-level N/P-doped Sn-carbon nanofibers (Sn-NP-CNFs) were fabricated via an electrospinning technique followed by pre-oxidization and carbonization. The N/P-doping increased the defects and carbon interlayer distance to inhibit the precipitation and volume expansion of the Sn and improve the Li/Na-adsorption, resulting in an ultrahigh pseudocapacitance and rate capability of the Sn-NP-CNF. An advanced LIC and SIC were composed of an activated carbon cathode and a Sn-NP-CNF anode. The LIC and SIC displayed ultrahigh energy densities (186.0 Wh kg−1 and 134.6 Wh kg−1) and power densities (20.0 kW kg−1 achieved at 22.2 Wh kg−1) with superior energy retentions (83.7% and 79.8% after 10,000 cycles at 5.0 A g−1). [ABSTRACT FROM AUTHOR]