RESUMO
Bone defects caused by tumors are difficult to repair clinically because of their poor morphology and residual tumor cell-induced recurrence. Scaffolds with the dual function of bone repair and bone tumor treatment are urgently needed to resolve this problem. In this study, a poly(L-lactic acid) (PLLA)/nanoscale hydroxyapatite (nHA)/metformin (MET) nanocomposite scaffold was constructed via selective laser sintering. The scaffolds were expected to combine the excellent mechanical strength and biodegradability of PLLA, the good bioactivity of nHA, and the water solubility and antitumor properties of MET. The PLLA/nHA/MET scaffolds showed improved cell adhesion, appropriate porosity, good biocompatibility and osteogenic-induced ability in vitro because metformin improves water solubility and promotes the osteogenic differentiation of cells within the scaffold. The PLLA/nHA/MET scaffold had an extended drug release time because the MET particles were wrapped in the biodegradable polymer PLLA and the wrapped MET particles were slowly released into body fluids as the PLLA was degraded. Moreover, the scaffold induced osteosarcoma (OS) cell apoptosis by upregulating apoptosis-related gene expression and showed excellent tumor inhibition characteristics in vitro. In addition, the scaffold induced osteogenic differentiation of bone marrow mesenchymal cells (BMSCs) by promoting osteogenic gene expression. The results suggest that the PLLA/nHA/MET composite scaffold has the dual function of tumor inhibition and bone repair and therefore it provides a promising new approach for the treatment of tumor-induced bone defects.
Assuntos
Neoplasias Ósseas , Metformina , Neoplasias Ósseas/tratamento farmacológico , Durapatita , Humanos , Ácido Láctico , Metformina/farmacologia , Osteogênese , Poliésteres , Engenharia Tecidual , Alicerces TeciduaisRESUMO
Hydroxyapatite (HAP) can endow a biopolymer scaffold with good bioactivity and osteoconductive ability, while the interfacial bonding is fairly weak between HAP and biopolymers. In this study, HAP was in situ generated on poly(l-lactic acid) (PLLA) particles, and then they were used to fabricate a scaffold by selective laser sintering. Detailedly, PLLA particles were first functionalized by dopamine oxide polymerization, which introduced abundance active catechol groups on the particle surface, and subsequently, the catechol groups concentrated Ca2+ ions by chelation in a simulated body fluid solution, and then, Ca2+ ions absorbed PO43- ions through electrostatic interactions for in situ nucleation of HAP. The results indicated that HAP was homogeneously generated on the PLLA particle surface, and HAP and PLLA exhibited good interfacial bonding in the HAP/PLLA scaffolds. Meanwhile, the scaffolds displayed excellent bioactivity by inducing apatite precipitation and provided a good environment for human bone mesenchymal stem cell attachment, proliferation, and osteogenic differentiation. More importantly, the ingrowth of blood vessel and the formation of new bone could be stimulated by the scaffolds in vivo, and the bone volume fraction and bone mineral density increased by 44.44 and 41.73% compared with the pure PLLA scaffolds, respectively. Serum biochemical indexes fell within the normal range, which indicated that there was no harmful effect on the normal functioning of the body after implanting the scaffold.
Assuntos
Durapatita/química , Células-Tronco Mesenquimais/citologia , Poliésteres/química , Alicerces Teciduais/química , Densidade Óssea , Regeneração Óssea , Durapatita/síntese química , Humanos , Estrutura Molecular , Osteogênese , Tamanho da Partícula , Propriedades de Superfície , Engenharia TecidualRESUMO
Graphene oxide (GO) can improve the degradation resistance of biomedical Mg alloy because of its excellent impermeability and outstanding chemical inertness. However, the weak interfacial bonding between GO and Mg matrix leads to easily detaching during degradation. In this study, in situ reaction induced by TiO2 took place in the AZ61-GO biocomposite to enhance the interfacial bonding between GO and Mg matrix. For the specific process, TiO2 was uniformly and tightly deposited onto the GO surface by hydrothermal reaction (TiO2/GO) first and then used for fabricating AZ61-TiO2/GO biocomposites by selective laser melting (SLM). Results showed that TiO2 was in situ reduced by magnesiothermic reaction during SLM process, and the reduzate Ti, on the one hand, reacted with Al in the AZ61 matrix to form TiAl2 and, on the other hand, reacted with GO to form TiC at the AZ61-GO interface. Owing to the enhanced interfacial bonding, the AZ61-TiO2/GO biocomposite showed 12.5% decrease in degradation rate and 10.1% increase in compressive strength as compared with the AZ61-GO biocomposite. Moreover, the AZ61-TiO2/GO biocomposite also showed good cytocompatibility because of the slowed degradation. These findings may provide guidance for the interfacial enhancement in GO/metal composites for biomedical applications.
Assuntos
Ligas/química , Materiais Revestidos Biocompatíveis/química , Grafite/química , Titânio/química , Ligas/toxicidade , Linhagem Celular Tumoral , Materiais Revestidos Biocompatíveis/toxicidade , Grafite/toxicidade , Humanos , Magnésio/química , Magnésio/toxicidade , Titânio/toxicidadeRESUMO
Magnesium-based biomaterials are attracting increasingly more attention for orthopedic applications based on their appropriate mechanical properties, biodegradability, and favorable biocompatibility. However, the high corrosion rate of these materials remains to be addressed. In this study, porous ß-Ca3(PO4)2/Mg-Zn (ß-TCP/Mg-Zn) composites were fabricated via a powder metallurgy method. The ß-TCP/Mg-Zn composites with 6% porosity exhibited optimal mechanical properties, and thus, they were selected for surface modification. A novel dopamine/gelatin/recombinant human bone morphogenetic protein-2 (rhBMP-2) coating with demonstrated stability was prepared to further improve the corrosion resistance of the composite and enhance early osteoinductivity. The homogeneously coated ß-TCP/Mg-Zn composite showed significantly improved corrosion resistance according to electrochemical and immersion tests. In addition, extracts from the dopamine/gelatin/rhBMP-2-coated ß-TCP/Mg-Zn composite not only facilitated cell proliferation but also significantly enhanced the osteogenic differentiation of Sprague-Dawley rat bone marrow-derived mesenchymal stem cells in vitro. Furthermore, in vivo experiments were performed to evaluate the biodegradation, histocompatibility, and osteoinductive potential of the coated composite. No obvious pathological changes in the vital visceral organs were observed after implantation, and radiography and hematoxylin-eosin staining showed strong promotion of new bone formation, matched composite degradation and bone regeneration rates, and complete absorption of the released hydrogen gas. Collectively, these results indicate that the dopamine/gelatin/rhBMP-2-coated ß-TCP/Mg-Zn composite offers improved corrosion resistance, favorable biocompatibility, and enhanced osteoinductive potential for use in the fabrication of orthopedic implants.
Assuntos
Osso e Ossos , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/farmacologia , Teste de Materiais , Próteses e Implantes , Animais , Proteína Morfogenética Óssea 2 , Fosfatos de Cálcio , Dopamina , Feminino , Gelatina , Magnésio , Masculino , Células-Tronco Mesenquimais , Coelhos , Ratos , ZincoRESUMO
The slow degradation of Fe severely restricts its application in bone repair although it possesses good biocompatibility and high mechanical properties. In this study, carbon nanotubes (CNTs) were introduced to accelerate Fe biodegradation: (I) CNTs acted as cathodes to induce galvanic corrosion owing to their differences in corrosion potential; (II) The large specific surface area of CNTs increased area ratios of cathode to anode; (III) The excellent electrical conductivity of CNTs allowed significant levels of electron transfer through the cathode in galvanic corrosion. Consequently, the degradation rate of Fe/CNTs composites greatly increased by 74% with the increase of CNTs (0.3-0.9â¯wt%). Further addition of CNTs would lead to corrosion holes and cracks due to localized corrosion. Besides, cell culture experiments showed that MG-63 cells could normally proliferate to maintain their population, indicating good cytocompatibility of Fe/CNTs composites. The results proved that the incorporation of CNTs into Fe was an effective approach to develop Fe-based bone implants with enhanced degradation rates.
Assuntos
Ferro/química , Nanotubos de Carbono/química , Biodegradação Ambiental , Linhagem Celular Tumoral , Sobrevivência Celular , Corrosão , Eletroquímica , Dureza , Humanos , Nanotubos de Carbono/ultraestrutura , Tamanho da Partícula , Difração de Raios XRESUMO
Mg-5.6Zn-0.5Zr alloy (ZK60) tends to degrade too rapid for orthopedic application, in spite of its natural degradation, suitable strength and good biocompatibility. In this study, Nd was alloyed with ZK60 via laser melting method to enhance its corrosion resistance. The microstructure features, mechanical properties and corrosion behaviors of ZK60-xNd (x = 0, 1.8, 3.6, 5.4 wt.%) were investigated. Results showed that laser melted ZK60-xNd were composed of fine É-Mg grains and intermetallic phases along grain boundaries. And the precipitated intermetallic phases experienced successive changes: divorced island-like MgZn phase â honeycomb-like T phase â coarsened and agglomerated W phase with Nd increasing. It was worth noting that ZK60-3.6Nd with honeycomb-like T phase exhibited an optimal corrosion behavior with a corrosion rate of 1.56 mm year-1. The improved corrosion behavior was ascribed to: (I) dense surface film caused by the formation of Nd2O3 hindered the invasion of immersion solution; (II) the three-dimensional honeycomb structure of intermetallic phases formed a tight barrier to restrain the propagation of corrosion. Moreover, ZK60-3.6Nd exhibited good biocompatibility. It was suggested that ZK60-3.6Nd was a preferable candidate for biodegradable bone implant.
Assuntos
Ligas , Interface Osso-Implante , Neodímio/química , Implantes Absorvíveis , Animais , Osso e Ossos , Linhagem Celular Tumoral , Corrosão , Humanos , Teste de Materiais , Fenômenos Mecânicos , Osteossarcoma , Propriedades de Superfície , ZircônioRESUMO
The poor bonding strength between biopolymer and bioceramic has remained an unsolved issue. In this study, graphene oxide (GO) was introduced as an interface phase to improve the interfacial bonding between polyetheretherketone (PEEK) and hydroxyapatite (HAP) for tissue engineering scaffolds. On the one hand, the conjugated structure of GO could form strong π-π stacking interaction with the benzene rings in PEEK. On the other hand, GO with a negatively charge resulting from oxygen functional groups could adsorb the positively charged calcium atoms (C sites) of HAP. Consequently, the dispersibility and compatibility of HAP in the PEEK matrix increased with increasing GO content up to 1 wt%. At this time, the compressive strength and modulus of scaffolds increased by 79.45% and 42.07%, respectively. Furthermore, the PEEK-HAP with GO (PEEK-HAP/GO) scaffolds possessed the ability to induce formation of bone-like apatite. And they could support cellular adhesion, proliferation as well as osteogenic differentiation. More importantly, in vivo bone defect repair experiments showed that new bone formed throughout the scaffolds at 60 days after implantation. All these results suggested that the PEEK-HAP/GO scaffolds have a promising potential for bone tissue engineering application.
Assuntos
Durapatita/química , Grafite/química , Cetonas/química , Polietilenoglicóis/química , Engenharia Tecidual/métodos , Alicerces Teciduais/química , Adsorção , Animais , Apatitas/química , Benzofenonas , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Osso e Ossos/efeitos dos fármacos , Osso e Ossos/metabolismo , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Força Compressiva , Humanos , Osteogênese/efeitos dos fármacos , Óxidos/química , Polímeros , Coelhos , Aderências TeciduaisRESUMO
Incorporating boron nitride nanotubes (BNNTs) into ceramic matrices is a promising strategy for obtaining multifunctional composites. In this study, the application of BNNTs in reinforcing ß-tricalcium phosphate (ß-TCP) scaffolds manufactured using laser sintering is demonstrated. BNNTs contribute to the effective inhibition of both grain growth and phase transformation in ß-TCP. Moreover, they can strengthen the grain boundaries and boost the fracture mode transition from intergranular to transgranular. BNNTs play an active role in reinforcing ß-TCP in terms of load transfer and energy absorption by the synergistic mechanisms of pull-out, peel-off, crack bridging and deflection. With a BNNT content of 4 wt%, the elastic modulus, hardness, compressive strength and fracture toughness of ß-TCP increase by 46%, 39%, 109% and 35%, respectively. Umbilical cord mesenchymal stem cells (UC-MSCs) were isolated with high purity, and surface molecule characterization revealed that they were CD90+, CD29+, CD73+, CD31-, CD34- and CD45-. UC-MSCs on BNNTs/ß-TCP scaffolds were characterized by more positive Alizarin Red staining as well as up-regulated expression of osteoblast markers, as revealed by quantitative real-time reverse transcriptase polymerase chain reaction analysis and immunofluorescence staining. These results are the first to demonstrate that BNNTs promote the osteogenic differentiation of UC-MSCs, indicating good osteoinductive properties for use in bone scaffolds. This study paves the way for the potential use of a BNNT/ß-TCP scaffold in bone repair.
Assuntos
Compostos de Boro/farmacologia , Fosfatos de Cálcio/farmacologia , Diferenciação Celular/efeitos dos fármacos , Células-Tronco Mesenquimais/citologia , Nanotubos/química , Osteogênese/efeitos dos fármacos , Alicerces Teciduais/química , Materiais Biocompatíveis/farmacologia , Biomarcadores/metabolismo , Humanos , Células-Tronco Mesenquimais/efeitos dos fármacos , Células-Tronco Mesenquimais/metabolismo , Nanotubos/ultraestrutura , Estresse Mecânico , Cordão Umbilical/citologiaRESUMO
Osteogenesis is a complex multi-step process involving the differentiation of mesenchymal stem cells (MSCs) into osteoblast progenitor cells, preosteoblasts, osteoblasts and osteocytes, and the crosstalk between multiple cell types for the formation and remodeling of bone. The signaling regulatory networks during osteogenesis include various components, including growth factors, transcription factors, micro (mi)RNAs and effectors, a number of which form feedback loops controlling the balance of osteogenic differentiation by positive or negative regulation. miRNAs have been found to be important regulators of osteogenic signaling pathways in multiple aspects and multiple signaling pathways. The present review focusses on the progress in elucidating the role of miRNA in the osteogenesis signaling networks of MSCs as a substitute for bone implantation the the field of bone tissue engineering. In particular, the review classifies which miRNAs promote or suppress the osteogenic process, and summarizes which signaling pathway these miRNAs are involved in. Improvements in knowledge of the characteristics of miRNAs in osteogenesis provide an important step for their application in translational investigations of bone tissue engineering and bone disease.
Assuntos
Diferenciação Celular , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , MicroRNAs/genética , Osteogênese , Transdução de Sinais , Animais , Diferenciação Celular/genética , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Osteogênese/genética , Interferência de RNARESUMO
A synergetic effect between carbon nanotubes (CNTs) and graphene on diopside (Di) scaffolds was demonstrated. 3D network architecture in the matrix was formed through the 1D CNTs inlaid among the 2D graphene platelets (GNPs). The mechanical properties of the CNTs/GNPs/Di scaffolds were significantly improved compared with the CNTs/Di scaffolds and GNPs/Di scaffolds. In addition, the scaffolds exhibited excellent apatite-forming ability, a modest degradation rate, and stable mechanical properties in simulated body fluid (SBF). Moreover, cell culturing tests indicated that the scaffolds supported the cells attachment and proliferation. Taken together, the CNTs/GNPs/Di scaffolds offered great potential for bone tissue engineering.
Assuntos
Grafite/farmacologia , Nanotubos de Carbono/química , Ácido Silícico/farmacologia , Alicerces Teciduais/química , Materiais Biocompatíveis/farmacologia , Morte Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Forma Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Força Compressiva/efeitos dos fármacos , Humanos , Peso Molecular , Nanotubos de Carbono/ultraestrutura , Espectroscopia de Infravermelho com Transformada de Fourier , Estresse MecânicoRESUMO
The biological properties of porous poly (vinylidene fluoride) (PVDF) scaffolds fabricated by selective laser sintering were tailored through nano-sized 58s bioactive glass. The results showed that 58s bioactive glass distributed evenly in the PVDF matrix. There were some exposed particles on the surface which provided attachment sites for biological response. It was confirmed that the scaffolds had highly bioactivity by the formation of bone-like apatite in simulated body fluid. And the bone-like apatite became dense with the increase in 58s bioactive glass and culture time. Moreover, the scaffolds were suitable for cell adhesion and proliferation compared with the PVDF scaffolds without 58s bioactive glass. The research showed that the PVDF/58s bioactive glass scaffolds had latent application in bone tissue engineering.
Assuntos
Substitutos Ósseos/química , Vidro/química , Nanoestruturas/química , Polivinil/química , Alicerces Teciduais/química , Apatitas/química , Substitutos Ósseos/síntese química , Linhagem Celular Tumoral , Sobrevivência Celular , Humanos , Lasers , Teste de Materiais , Porosidade , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios XRESUMO
Nano SiO2 and MgO particles were incorporated into ß-tricalcium phosphate (ß-TCP) scaffolds to improve the mechanical and biological properties. The porous cylindrical ß-TCP scaffolds doped with 0.5 wt % SiO2, 1.0 wt % MgO, 0.5 wt % SiO2 + 1.0 wt % MgO were fabricated via selective laser sintering respectively and undoped ß-TCP scaffold was also prepared as control. The phase composition and mechanical strength of the scaffolds were evaluated. X-ray diffraction analysis indicated that the phase transformation from ß-TCP to α-TCP was inhibited after the addition of MgO. The compressive strength of scaffold was improved from 3.12 ± 0.36 MPa (ß-TCP) to 5.74 ± 0.62 MPa (ß-TCP/SiO2), 9.02 ± 0.55 MPa (ß-TCP/MgO) and 10.43 ± 0.28 MPa (ß-TCP/SiO2/MgO), respectively. The weight loss and apatite-forming ability of the scaffolds were evaluated by soaking them in simulated body fluid. The results demonstrated that both SiO2 and MgO dopings slowed down the degradation rate and improved the bioactivity of ß-TCP scaffolds. In vitro cell culture studies indicated that SiO2 and MgO dopings facilitated cell attachment and proliferation. Combined addition of SiO2 and MgO were found optimal in enhancing both the mechanical and biological properties of ß-TCP scaffold.
Assuntos
Materiais Biocompatíveis/química , Fosfatos de Cálcio/química , Óxido de Magnésio/química , Dióxido de Silício/química , Alicerces Teciduais/química , Linhagem Celular Tumoral , Proliferação de Células , Humanos , Teste de Materiais/métodos , Microscopia Eletrônica de Varredura , Porosidade , Propriedades de Superfície , Engenharia Tecidual/métodos , Difração de Raios XRESUMO
Carbon nanotubes are ideal candidates for the mechanical reinforcement of ceramic due to their excellent mechanical properties, high aspect ratio and nanometer scale diameter. In this study, the effects of multi-walled carbon nanotubes (MWCNTs) on the mechanical properties of diopside (Di) scaffolds fabricated by selective laser sintering were investigated. Results showed that compressive strength and fracture toughness improved significantly with increasing MWCNTs from 0.5 to 2 wt %, and then declined with increasing MWCNTs to 5 wt %. Compressive strength and fracture toughness were enhanced by 106% and 21%, respectively. The reinforcing mechanisms were identified as crack deflection, MWCNTs crack bridging and pull-out. Further, the scaffolds exhibited good apatite-formation ability and supported adhesion and proliferation of cells in vitro.
Assuntos
Nanotubos de Carbono/química , Ácido Silícico/química , Alicerces Teciduais/química , Osso e Ossos/fisiologia , Linhagem Celular Tumoral , Humanos , Teste de Materiais/métodos , Propriedades de Superfície , Resistência à Tração/fisiologia , Engenharia Tecidual/métodosRESUMO
In this study, nano-hydroxyapatite scaffolds with high mechanical strength and an interconnected porous structure were prepared using NTSS for the first time. The first step was performed using a laser characterized by the rapid heating to skip the surface diffusion and to obtain the driving force for grain boundary diffusion. Additionally, the interconnected porous structure was achieved by SLS. The second step consisted of isothermal heating in a furnace at a lower temperature (T2) than that of the laser beam to further increase the density and to suppress grain growth by exploiting the difference in kinetics between grain-boundary diffusion and grain-boundary migration. The results indicated that the mechanical properties first increased and then decreased as T2 was increased from 1050 to 1250°C. The optimal fracture toughness, compressive strength and stiffness were 1.69â MPam(1/2), 18.68â MPa and 245.79â MPa, respectively. At the optimal point, the T2 was 1100°C, the grain size was 60â nm and the relative density was 97.6%. The decrease in mechanical properties was due to the growth of grains and the decomposition of HAP. The cytocompatibility test results indicated that cells adhered and spread well on the scaffolds. A bone-like apatite layer formed, indicating good bioactivity.
Assuntos
Substitutos Ósseos/química , Durapatita/química , Nanoestruturas/química , Alicerces Teciduais/química , Linhagem Celular Tumoral , Força Compressiva , Dureza , Humanos , Teste de Materiais , Nanoestruturas/ultraestrutura , Porosidade , Espectroscopia de Infravermelho com Transformada de Fourier , Estresse Mecânico , Propriedades de Superfície , Engenharia Tecidual , Difração de Raios XRESUMO
Graphene is a novel material and currently popular as an enabler for the next-generation nanocomposites. Here, we report the use of graphene to improve the mechanical properties of nano-58S bioactive glass for bone repair and regeneration. And the composite scaffolds were fabricated by a homemade selective laser sintering system. Qualitative and quantitative analysis demonstrated the successful incorporation of graphene into the scaffold without obvious structural damage and weight loss. The optimum compressive strength and fracture toughness reached 48.65 ± 3.19 MPa and 1.94 ± 0.10 MPa · m(1/2) with graphene content of 0.5 wt%, indicating significant improvements by 105% and 38% respectively. The mechanisms of pull-out, crack bridging, crack deflection and crack tip shielding were found to be responsible for the mechanical enhancement. Simulated body fluid and cell culture tests indicated favorable bioactivity and biocompatibility of the composite scaffold. The results suggest a great potential of graphene/nano-58S composite scaffold for bone tissue engineering applications.
Assuntos
Vidro/química , Grafite/química , Linhagem Celular Tumoral , Força Compressiva , Humanos , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Termogravimetria , Engenharia Tecidual , Alicerces TeciduaisRESUMO
Cracks often occur when nano-hydroxyapatite bone scaffolds are fabricated with selective laser sintering, which affect the performance of scaffolds. In this study, a small amount of poly (l-lactide acid) (PLLA) was added into nano-hydroxyapatite (nano-HAP) powder by mechanical blending in order to improve the sintering properties. The nano-HAP powder combined with 1wt percent PLLA was sintered under different laser power (5W, 7.5W, 10W, 12.5W, 15W and 20W). The fabricated scaffolds were characterized using Scanning Electron Microscope (SEM), X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Micro Hardness Tester. The results showed that nano-HAP particles grew up quickly with the laser power increasing, and there were many strip-like cracks on the surface of sintering zone. The cracks gradually reduced until disappeared when the laser power increased to 15W, together with a great improvement of density. Large pores were observed on the specimen when the laser power further increases, accompanied with the decomposition of HAP into β-tricalcium phosphate (β-TCP) and tetracalcium phosphate (TTCP). And the optimum parameters were eventually obtained with laser power of 15W, scanning speed of 1000 mm/min, powder bed temperature of 150ºC, laser spot diameter of 2 mm and layer thickness of 0.2 mm. We summarized that the molten PLLA enhanced the particle rearrangement of nano-HAP by capillary force and may absorb thermal stress in laser sintering process, while PLLA would be oxidized gradually until completely excluded from the sintered nano-HAP scaffolds, which was confirmed by FTIR analysis. This study provides a novel method to improve the sintering properties of nano-HAP with no adverse effects which would be used in the application of bone tissue engineering potentially.
Assuntos
Substitutos Ósseos , Hidroxiapatitas/química , Nanoestruturas/química , Poliésteres/química , Espectroscopia de Infravermelho com Transformada de Fourier , Dureza , Temperatura Alta , Porosidade , Engenharia Tecidual , Alicerces TeciduaisRESUMO
Gas heating has been widely used in the process of fused biconical tapering. However, as the instability and asymmetric flame temperature of gas heating exist, the performance of the optical devices fabricated by this method was affected. To overcome the problems resulting from gas combustion, an electric heater is designed and manufactured using a metal-ceramic (MoSi(2)) as a heating material. Our experimental data show that the fused-taper machine with an electric heater has improved the performance of optical devices by increasing the consistency of the extinction ratio, excess loss, and the splitting ratio over that of the previous gas heating mode. Microcrystallizations and microcracks were observed at the fused region of the polarization-maintaining (PM) fiber coupler and at the taper region with scanning electron microscopy and atomic force microscopy respectively. The distribution of the microcrystallizations and microcracks are nonuniform along the fiber with gas heating, while their distribution is rather uniform with electric heating. These findings show that the novel optical fiber coupler with an electric heater has improved the performance of optical fiber devices by affecting the consistency of the optical parameters and micromorphology of the surface of PM fiber.