Piezoelectric materials that generate electrical signals in response to mechanical strain can be used in tissue engineering to stimulate cell proliferation. Poly （vinylidene fluoride-trifluoroethylene） （P（VDF-TrF...Piezoelectric materials that generate electrical signals in response to mechanical strain can be used in tissue engineering to stimulate cell proliferation. Poly （vinylidene fluoride-trifluoroethylene） （P（VDF-TrFE））, a piezoelectric polymer, is widely used in biomaterial applications. We hypothesized that incorporation of zinc oxide （ZnO） nanoparticles into the P（VDF-TrFE） matrix could promote adhesion, migration, and proliferation of cells, as well as blood vessel formation （angiogenesis）. In this study, we fabricated and comprehensively characterized a novel electrospun P（VDF-TrFE）/ZnO nanocomposite tissue engineering scaffold. We analyzed the morphological features of the polymeric matrix by scanning electron microscopy, and utilized Fourier transform infrared spectroscopy, X-ray diffraction, and differential scanning calorimetry to examine changes in the crystalline phases of the copolymer due to addition of the nanoparticles. We detected no or minimal adverse effects of the biomaterials with regard to blood compatibility in vitro, biocompatibility, and cytotoxicity, indicating that P（VDF-TrFE）/ZnO nanocomposite scaffolds are suitable for tissue engineering applications. Interestingly, human mesenchymal stem cells （hMSCs） and human umbilical vein endothelial cells cultured on the nanocomposite scaffolds exhibited higher cell viability, adhesion, and proliferation compared to cells cultured on tissue culture plates or neat P（VDF-TrFE） scaffolds. Nanocomposite scaffolds implanted into rats with or without hMSCs did not elicit immunological responses, as assessed by macroscopic analysis and histology. Importantly, nanocomposite scaffolds promoted angiogenesis, which was increased in scaffolds pre-seeded with hMSCs. Overall, our results highlight the potential of these novel P（VDF-TrFE）/ZnO nanocomposites for use in tissue engineering, due to their biocompatibility and ability to promote cell adhesion and angiogenesis.展开更多
Vinylidene fluoride-trifluoroethylene copolymer films of molar ratio 70/30 with thickness of about 1μm have been deposited from solution in ethyl methyl ketone to a glass substrate with an aluminum electrode by spin ...Vinylidene fluoride-trifluoroethylene copolymer films of molar ratio 70/30 with thickness of about 1μm have been deposited from solution in ethyl methyl ketone to a glass substrate with an aluminum electrode by spin coating.The solution has been filtrated through a PTFE membrane filter with pore size 0.2μm directly before spin coating or it has been used as is(unfiltrated).After deposition of a top electrode,the samples have been polarized by hysteresis loops with an electric field amplitude of about 100 V/μm.In samples,annealed at temperature 145°C for 3 h,a high remanent polarization of about 7.5μC/cm2 has been achieved,without significant differences between samples fabricated of filtrated or unfiltrated solution.Spherulitic lamella are growing in films fabricated of filtrated solution when they are heated above the melting temperature to 159°C for 3 min before the further annealing process at 145°C.These films show substantially lower remanent polarization below 4μC/cm2.Pyroelectric images recorded with a pyroelectric laser scanning microscope show that the spherulites have very small pyroelectric activity,i.e.,the spherulites consist of flat-on lamella.In contrast,no spherulitic lamella are growing in films fabricated of unfiltrated solution heated above the melting temperature,melted and annealed under the same conditions.An explanation for this observation is that filtrating changes the structure of the copolymer in solution from polymer coil to rod.Copolymer rods deposited on a substrate will crystallize in flat-on lamella when heated above the melting temperature,in contrast to copolymer coils which crystallize in edge-on lamella.展开更多
A microfabrication process for poly(vinylidene fluoride-trifluoroethylene)(P(VDF-TrFE)) based flexible piezoelectric devices is proposed using heat controlled spin coating and reactive ion etching(RIE) techniques.Dry ...A microfabrication process for poly(vinylidene fluoride-trifluoroethylene)(P(VDF-TrFE)) based flexible piezoelectric devices is proposed using heat controlled spin coating and reactive ion etching(RIE) techniques.Dry etching of P(VDF-TrFE) in CF 4 +O2 plasma is found to be more effective than that using SF 6 +O2 or Ar+O2 feed gas with the same radiofrequency power and pressure conditions.A maximum etching rate of 400 nm/min is obtained using the CF 4 +O2 plasma with an oxygen concentration of 60% at an antenna power of 200 W and a platen power of 20 W.The oxygen atoms and fluorine atoms are found to be responsible for the chemical etching process.Microstructuring of P(VDF-TrFE) with a feature size of 10 m is achieved and the patterned films show a high remanent polarization of 63.6mC/m 2.展开更多
Surface acoustic wave(SAW) devices have been utilized for the sensing of chemical and biological phenomena in microscale for the past few decades. In this study, SAW device was fabricated by electrospinning poly(vinyl...Surface acoustic wave(SAW) devices have been utilized for the sensing of chemical and biological phenomena in microscale for the past few decades. In this study, SAW device was fabricated by electrospinning poly(vinylidenefluoride-co-trifluoroethylene)(P(VDF-TrFE)) incorporated with zinc oxide(ZnO) nanoparticles over the delay line area of the SAW device. The morphology, composition, and crystallinity of P(VDF-TrFE)/ZnO nanocomposites were investigated. After measurement of SAW frequency response, it was found that the insertion loss of the SAW devices incorporated with ZnO nanoparticles was much less than that of the neat polymer-deposited device. The fabricated device was expected to be used in acoustic biosensors to detect and quantify the cell proliferation in cell culture systems.展开更多
During the past decades,transition metal dichalcogenides(TMDs) have received special focus for their unique properties in photoelectric detection.As one important member of TMDs,MoS2 has been made into photodetector p...During the past decades,transition metal dichalcogenides(TMDs) have received special focus for their unique properties in photoelectric detection.As one important member of TMDs,MoS2 has been made into photodetector purely or combined with other materials,such as graphene,ionic liquid,and ferroelectric materials.Here,we report a gate-free MoS2 phototransistor combined with organic ferroelectric material poly(vinylidene fluoride-trifluoroethylene)(P(VDF-TrFE)).In this device,the remnant polarization field in P(VDF-TrFE) is obtained from the piezoelectric force microscope(PFM) probe with a positive or negative bias,which can turn the dipoles from disorder to be the same direction.Then,the MoS2 channel can be maintained at an accumulated state with downward polarization field modulation and a depleted state with upward polarization field modulation.Moreover,the P(VDF-TrFE) segregates MoS2 from oxygen and water molecules around surroundings,which enables a cleaner surface state.As a photodetector,an ultra-low dark current of 10^–11 A,on/off ration of more than 10^4 and a fast photoresponse time of 120 μs are achieved.This work provides a new method to make high-performance phototransistors assisted by the ferroelectric domain which can operate without a gate electrode and demonstrates great potential for ultra-low power consumption applications.展开更多
文摘Piezoelectric materials that generate electrical signals in response to mechanical strain can be used in tissue engineering to stimulate cell proliferation. Poly （vinylidene fluoride-trifluoroethylene） （P（VDF-TrFE））, a piezoelectric polymer, is widely used in biomaterial applications. We hypothesized that incorporation of zinc oxide （ZnO） nanoparticles into the P（VDF-TrFE） matrix could promote adhesion, migration, and proliferation of cells, as well as blood vessel formation （angiogenesis）. In this study, we fabricated and comprehensively characterized a novel electrospun P（VDF-TrFE）/ZnO nanocomposite tissue engineering scaffold. We analyzed the morphological features of the polymeric matrix by scanning electron microscopy, and utilized Fourier transform infrared spectroscopy, X-ray diffraction, and differential scanning calorimetry to examine changes in the crystalline phases of the copolymer due to addition of the nanoparticles. We detected no or minimal adverse effects of the biomaterials with regard to blood compatibility in vitro, biocompatibility, and cytotoxicity, indicating that P（VDF-TrFE）/ZnO nanocomposite scaffolds are suitable for tissue engineering applications. Interestingly, human mesenchymal stem cells （hMSCs） and human umbilical vein endothelial cells cultured on the nanocomposite scaffolds exhibited higher cell viability, adhesion, and proliferation compared to cells cultured on tissue culture plates or neat P（VDF-TrFE） scaffolds. Nanocomposite scaffolds implanted into rats with or without hMSCs did not elicit immunological responses, as assessed by macroscopic analysis and histology. Importantly, nanocomposite scaffolds promoted angiogenesis, which was increased in scaffolds pre-seeded with hMSCs. Overall, our results highlight the potential of these novel P（VDF-TrFE）/ZnO nanocomposites for use in tissue engineering, due to their biocompatibility and ability to promote cell adhesion and angiogenesis.
文摘Vinylidene fluoride-trifluoroethylene copolymer films of molar ratio 70/30 with thickness of about 1μm have been deposited from solution in ethyl methyl ketone to a glass substrate with an aluminum electrode by spin coating.The solution has been filtrated through a PTFE membrane filter with pore size 0.2μm directly before spin coating or it has been used as is(unfiltrated).After deposition of a top electrode,the samples have been polarized by hysteresis loops with an electric field amplitude of about 100 V/μm.In samples,annealed at temperature 145°C for 3 h,a high remanent polarization of about 7.5μC/cm2 has been achieved,without significant differences between samples fabricated of filtrated or unfiltrated solution.Spherulitic lamella are growing in films fabricated of filtrated solution when they are heated above the melting temperature to 159°C for 3 min before the further annealing process at 145°C.These films show substantially lower remanent polarization below 4μC/cm2.Pyroelectric images recorded with a pyroelectric laser scanning microscope show that the spherulites have very small pyroelectric activity,i.e.,the spherulites consist of flat-on lamella.In contrast,no spherulitic lamella are growing in films fabricated of unfiltrated solution heated above the melting temperature,melted and annealed under the same conditions.An explanation for this observation is that filtrating changes the structure of the copolymer in solution from polymer coil to rod.Copolymer rods deposited on a substrate will crystallize in flat-on lamella when heated above the melting temperature,in contrast to copolymer coils which crystallize in edge-on lamella.
文摘A microfabrication process for poly(vinylidene fluoride-trifluoroethylene)(P(VDF-TrFE)) based flexible piezoelectric devices is proposed using heat controlled spin coating and reactive ion etching(RIE) techniques.Dry etching of P(VDF-TrFE) in CF 4 +O2 plasma is found to be more effective than that using SF 6 +O2 or Ar+O2 feed gas with the same radiofrequency power and pressure conditions.A maximum etching rate of 400 nm/min is obtained using the CF 4 +O2 plasma with an oxygen concentration of 60% at an antenna power of 200 W and a platen power of 20 W.The oxygen atoms and fluorine atoms are found to be responsible for the chemical etching process.Microstructuring of P(VDF-TrFE) with a feature size of 10 m is achieved and the patterned films show a high remanent polarization of 63.6mC/m 2.
基金the Agence Nationale de la Recherche for the financial support (ANR-12-BS09021)the Department of Biotechnology (DBT), Government of India, New Delhi, for the financial support through MSUB IPLSARE Program (BT/PR4800/INF/22/152/2012)
文摘Surface acoustic wave(SAW) devices have been utilized for the sensing of chemical and biological phenomena in microscale for the past few decades. In this study, SAW device was fabricated by electrospinning poly(vinylidenefluoride-co-trifluoroethylene)(P(VDF-TrFE)) incorporated with zinc oxide(ZnO) nanoparticles over the delay line area of the SAW device. The morphology, composition, and crystallinity of P(VDF-TrFE)/ZnO nanocomposites were investigated. After measurement of SAW frequency response, it was found that the insertion loss of the SAW devices incorporated with ZnO nanoparticles was much less than that of the neat polymer-deposited device. The fabricated device was expected to be used in acoustic biosensors to detect and quantify the cell proliferation in cell culture systems.
基金supported by the Major State Basic Research Development Program (Grant Nos. 2016YFA0203900, 2016YFB0400801 and 2015CB921600)Key Research Project of Frontier Sciences of Chinese Academy of Sciences (Nos. QYZDB-SSW-JSC016, QYZDY-SSW-JSC042)+2 种基金Strategic Priority Research Program of Chinese Academy of Sciences (XDPB12, XDB 3000000)Natural Science Foundation of China (Grant Nos. 61521001, 61574151, 61574152, 61674158, 61722408, 61734003 and 61835012)Natural Science Foundation of Shanghai (Grant No. 16ZR1447600, 17JC1400302)
文摘During the past decades,transition metal dichalcogenides(TMDs) have received special focus for their unique properties in photoelectric detection.As one important member of TMDs,MoS2 has been made into photodetector purely or combined with other materials,such as graphene,ionic liquid,and ferroelectric materials.Here,we report a gate-free MoS2 phototransistor combined with organic ferroelectric material poly(vinylidene fluoride-trifluoroethylene)(P(VDF-TrFE)).In this device,the remnant polarization field in P(VDF-TrFE) is obtained from the piezoelectric force microscope(PFM) probe with a positive or negative bias,which can turn the dipoles from disorder to be the same direction.Then,the MoS2 channel can be maintained at an accumulated state with downward polarization field modulation and a depleted state with upward polarization field modulation.Moreover,the P(VDF-TrFE) segregates MoS2 from oxygen and water molecules around surroundings,which enables a cleaner surface state.As a photodetector,an ultra-low dark current of 10^–11 A,on/off ration of more than 10^4 and a fast photoresponse time of 120 μs are achieved.This work provides a new method to make high-performance phototransistors assisted by the ferroelectric domain which can operate without a gate electrode and demonstrates great potential for ultra-low power consumption applications.
