Poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) composite hydrogel specimens were prepared with 15% PVA and 1%,2%, 3%, 4% and 5% HA by repeated freezing-thawing. The tests of static and dynamic mechanical properties wer...Poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) composite hydrogel specimens were prepared with 15% PVA and 1%,2%, 3%, 4% and 5% HA by repeated freezing-thawing. The tests of static and dynamic mechanical properties were carried out todiscuss the influence of different contents of HA and freezing-thawing cycles on the mechanical properties of PVA/HA compositehydrogel. The results of static mechanical tests showed that the PVA/HA composite hydrogel with 3% HA and ninefreezing-thawing cycles had excellent stress relaxation properties, higher relaxation ratio, lower stress equilibrium value andpresented better properties of creep and recovery. The results of dynamic mechanical test showed that the PVA/HA compositehydrogel with nine freezing-thawing cycles had higher storage modulus and loss modulus, so was the PVA/HA compositehydrogel with 3% HA.展开更多
A novel poly（N-isopropylacrylamide）-based sandwich-typed hydrogel, which was featured with both ends of linear poly（N-isopropylaerylamide） （PNIPAM） chains being grafted onto cross-linked PNIPAM chains, was succe...A novel poly（N-isopropylacrylamide）-based sandwich-typed hydrogel, which was featured with both ends of linear poly（N-isopropylaerylamide） （PNIPAM） chains being grafted onto cross-linked PNIPAM chains, was successfully prepared in a three-step process by a method of sequential synthesis. The proposed hydrogel displays faster and hydration/dehydration dynamic response to temperature cycling owing to linear PNIPAM chains to form big-pore structure. This work may lead to high attraction for targeting drug delivery systems, polymeric pump, sensors and so on.展开更多
The thermal aging behavior of poly （ vinyl alcohol ） （ PVA ） hydrogel was studied at four different temperatures of 40 ℃, 50 ℃, 60 ℃ and 70 ℃ in one year. The samples of PVA hydrogel were closely covered by pl...The thermal aging behavior of poly （ vinyl alcohol ） （ PVA ） hydrogel was studied at four different temperatures of 40 ℃, 50 ℃, 60 ℃ and 70 ℃ in one year. The samples of PVA hydrogel were closely covered by plastic film. The changes of their chemical structures and physical properties during aging were measured through different measurable techniques including tensile testing, gel permeation chromatography （ GPC ）, viscosity analysis, and Fourier transform infrared （FTIR） spec- trum. The results showed that the molecular weight of PVA in hydrogel changed little with time and temperature. FTIR spectra of PVA in all the samples were similar to those of the original samples. The tensile strength of PVA hydrogel didn＇t change until the 330th days.展开更多
Background: Recent research into skin injury and wound healing has focused mainly on post‐trauma hemostasis, infection prevention, dermal regeneration and angiogenesis. However, less attention has been paid to air pe...Background: Recent research into skin injury and wound healing has focused mainly on post‐trauma hemostasis, infection prevention, dermal regeneration and angiogenesis. However, less attention has been paid to air permeability and moisture loss prevention which also play important roles in injury healing. Methods: In the present work, we prepared a hyaluronic acid‐poloxamer (HA‐POL) hydrogel and tested the therapeutic effect of the hydrogel on skin‐wound healing. Results: The HA‐POL hydrogel transformed from sol to gel at 30°C, close to body temperature, and had stable moisturizing properties. HA‐POL hydrogel promoted skin‐wound healing and increased protein accumulation in the wound area. HA‐POL hydrogel allowed greater air permeability than Band‐aid, a typical wound covering. Results from transwell assays showed that the HA‐POL hydrogel effectively isolated skin‐wounds from bacterial invasion. Conclusion: This work demonstrates the advantages of using HA‐POL gel materials in the treatment of cutaneous wounds.展开更多
Hydroxyapatite/titania (HA/TiO2) double layers were coated onto Ti scaffolds throughout for orthopaedic applications by sol-gel method. Differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and X-ra...Hydroxyapatite/titania (HA/TiO2) double layers were coated onto Ti scaffolds throughout for orthopaedic applications by sol-gel method. Differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and X-ray diffractometry (XRD) were used for the characterisation of the phase transformations of the dried gels and coated surface structures. Scanning electron microscope (SEM) equipped with energy dispersive spectrometry (EDS) was used for the observation and evaluation of the morphology and phases of the surface layers and for the assessment of the in vitro tests. The in vitro assessments were performed by soaking the HA/TiO2 double coated samples into the simulated body fluid (SBF) for various periods. The TiO2 dipping-coating method at a speed of 12 cm/min, followed by a heat treatment at 600 ℃ for 20 min. The HA la lyaeyre wr wasa ssu cbosaetqeude bnytl ya dipping-coated on the outer surface at the same speed and then heat-treated at difference temperatures. The results indicat that the HA phase begins to crystallize after a heat treatment at 560 ℃. The crystallinity increases obviously at 760 ℃. SEM observations find no delamination or crack at the interfaces of HA/TiO2 and TiO2/Ti. The HA/TiO2 coated Ti scaffolds displays excellent bone-like apatite forming ability when it is soaked into SBF. Ti scaffolds after HA/TiO2 double coatings can be anticipated as promising implant materials for orthopaedic展开更多
New IPN hydrogels composed of diallyldimethylammonium chloride (DADMAC) and natural macromolecule, kappa-carrageenan (KC) were prepared by gamma irradiation and their properties were studied, The results show that bot...New IPN hydrogels composed of diallyldimethylammonium chloride (DADMAC) and natural macromolecule, kappa-carrageenan (KC) were prepared by gamma irradiation and their properties were studied, The results show that both the gel strength and the swelling capacity of the IPN hydrogels were enhanced significantly as compared with those of the pure hydrogels of PDADMAC.展开更多
Nano-hydroxyapatite reinforced poly（vinyl alcohol） gel（nano-HA/PVA gel） composites has been proposed as a promising biomaterial,especially used as an articular cartilage repair biomaterial.In this paper,nano-HA/PV...Nano-hydroxyapatite reinforced poly（vinyl alcohol） gel（nano-HA/PVA gel） composites has been proposed as a promising biomaterial,especially used as an articular cartilage repair biomaterial.In this paper,nano-HA/PVA gel composite was prepared by in situ synthesis method and incorporation with freeze-thaw cycle process.The microstructure and morphology were investigated by X-ray diffraction,TEM,SEM and FTIR.The results showed that the size of HA particles synthesized in PVA solution was on the nanometer scale.Both the size and crystallinity of HA particles synthesized in PVA solution decreased compared with that of HA synthesized in distilled water.The nano-HA particles were distributed in PVA matrix uniformly due to the effect of PVA solution as a dispersant while low content of HA particles in the composites.On the contrary,with high content of nano-HA particles in the composites,the particles tended to aggregate.The result of FT-IR analysis indicated that the chemical bond between nano-HA particles and PVA matrix existed.The conformation and degree of tacticity of PVA molecule changed because of the addition of HA particles.Furthermore,the interfacial strength of the composites was improved due to the interaction between nano-HA particle and PVA matrix and this was beneficial to improving the mechanical properties of the composites.展开更多
Macroporous hydrogels are water-swollen polymer networks with porous structures beyond the mesh size.They provide high specific surface areas and hieratical mass transfer channels which are desired for emerging applic...Macroporous hydrogels are water-swollen polymer networks with porous structures beyond the mesh size.They provide high specific surface areas and hieratical mass transfer channels which are desired for emerging applications including cell culturing,bio-separation,and drug delivery.A variety of approaches have been developed to fabricate macroporous hydrogels,including gas foaming,porogen templating,phase separation,3D printing,etc.Alternatively,ice templating utilizes the crystallization of water as the porogenation mechanism which doesn't need the leaching of porogens.展开更多
A combination of the viscoelastic properties of hyaluronic acid(HA)and the elastic properties of star shaped 8-arm poly(ethylene glycol)(8-arm PEG)was used to design in-situ forming hydrogels.Hydrogels were prepared b...A combination of the viscoelastic properties of hyaluronic acid(HA)and the elastic properties of star shaped 8-arm poly(ethylene glycol)(8-arm PEG)was used to design in-situ forming hydrogels.Hydrogels were prepared by the enzymatic crosslinking of a partially tyramine modified 8-arm PEG and a tyramine conjugated HA using horseradish peroxidase in the presence of hydrogen peroxide.Hydrogels of the homopolymer conjugates and mixtures thereof were rapidly formed within seconds under physiological conditions at low polymer and enzyme concentrations.Elastic hydrogels with high gel content(≥95%)and high storage moduli(up to 22.4 kPa)were obtained.An in vitro study in the presence of hyaluronidase(100 U/mL)revealed that with increasing PEG content the degradation time of the hybrid hydrogels increased up to several weeks,whereas hydrogels composed of only hyaluronic acid degraded within 2 weeks.Human mesenchymal stem cells(hMSCs)incorporated in the hybrid hydrogels remained viable as shown by a PrestoBlue and a live-dead assay,confirming the biocompatibility of the constructs.The production of an extracellular matrix by re-differentiation of encapsulated human chondrocytes was followed over a period of 28 days.Gene expression indicated that these highly elastic hydrogels induced an enhanced production of collagen type II.At low PEG-TA/HA-TA ratios a higher expression of SOX 9 and ACAN was observed.These results indicate that by modulating the ratio of PEG/HA,injectable hydrogels can be prepared applicable as scaffolds for tissue regeneration applications.展开更多
Developing a meniscus substitute mimicking the anisotropic mechanics(higher circumferential tensile modulus and lower compressive modulus)of native tissue remains a great challenge.In this work,based on the pendant gr...Developing a meniscus substitute mimicking the anisotropic mechanics(higher circumferential tensile modulus and lower compressive modulus)of native tissue remains a great challenge.In this work,based on the pendant group structure-dependent H-bonding strengthening mechanism,two kinds of amide-based H-bonding crosslinked hydrogels with distinct mechanical behaviors,that is,the flexible poly(N-acryloyl glycinamide)(PNAGA)and the ultra-stiff poly(N-acryloylsemicarbazide)(PNASC)hydrogels are employed to construct the biomimetic meniscus substitute.To this end,a gel microparticle-based self-thickening strategy is first proposed to fabricate PNASC(GMP-PNASC)high-modulus hydrogels skeleton by extrusion printing technology in mimicking the collagen fibers in native meniscus to resist the circumferential tensile stress.Then,the PNAGA hydrogel is infused into the PNASC skeleton to replicate the proteoglycan,providing a lower compressive modulus.By regulating the structural features at the interior and peripheral regions,the GMP-PNASC/PNAGA hydrogel meniscus scaffold with the higher tensile modulus(87.28±6.06 MPa)and lower compressive modulus(2.11±0.28 MPa)can be constructed.In vivo outcome at 12 weeks post-implantation of rabbit’s medial meniscectomy model confirms the effects of GMP-PNASC/PNAGA meniscus scaffold on alleviating the wear of articular cartilage and ameliorating the development of osteoarthritis(OA).展开更多
基金supported by National Natural Science Foundation of China(Grant No.50875252)Program for New Century Excellent TaIents in University (Grant No.NCET-06-0479)Natural Science Foundation of Jiangsu Proyince (Grant No.BK2008005)
文摘Poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) composite hydrogel specimens were prepared with 15% PVA and 1%,2%, 3%, 4% and 5% HA by repeated freezing-thawing. The tests of static and dynamic mechanical properties were carried out todiscuss the influence of different contents of HA and freezing-thawing cycles on the mechanical properties of PVA/HA compositehydrogel. The results of static mechanical tests showed that the PVA/HA composite hydrogel with 3% HA and ninefreezing-thawing cycles had excellent stress relaxation properties, higher relaxation ratio, lower stress equilibrium value andpresented better properties of creep and recovery. The results of dynamic mechanical test showed that the PVA/HA compositehydrogel with nine freezing-thawing cycles had higher storage modulus and loss modulus, so was the PVA/HA compositehydrogel with 3% HA.
基金Funded by the National Natural Science Foundation of China (20976202)the Natural Science Foundation of Hubei Province (2009CDB161)
文摘A novel poly（N-isopropylacrylamide）-based sandwich-typed hydrogel, which was featured with both ends of linear poly（N-isopropylaerylamide） （PNIPAM） chains being grafted onto cross-linked PNIPAM chains, was successfully prepared in a three-step process by a method of sequential synthesis. The proposed hydrogel displays faster and hydration/dehydration dynamic response to temperature cycling owing to linear PNIPAM chains to form big-pore structure. This work may lead to high attraction for targeting drug delivery systems, polymeric pump, sensors and so on.
文摘The thermal aging behavior of poly （ vinyl alcohol ） （ PVA ） hydrogel was studied at four different temperatures of 40 ℃, 50 ℃, 60 ℃ and 70 ℃ in one year. The samples of PVA hydrogel were closely covered by plastic film. The changes of their chemical structures and physical properties during aging were measured through different measurable techniques including tensile testing, gel permeation chromatography （ GPC ）, viscosity analysis, and Fourier transform infrared （FTIR） spec- trum. The results showed that the molecular weight of PVA in hydrogel changed little with time and temperature. FTIR spectra of PVA in all the samples were similar to those of the original samples. The tensile strength of PVA hydrogel didn＇t change until the 330th days.
基金Beijing Municipal Natural Science Foundation, Grant/Award Number: 7142131
文摘Background: Recent research into skin injury and wound healing has focused mainly on post‐trauma hemostasis, infection prevention, dermal regeneration and angiogenesis. However, less attention has been paid to air permeability and moisture loss prevention which also play important roles in injury healing. Methods: In the present work, we prepared a hyaluronic acid‐poloxamer (HA‐POL) hydrogel and tested the therapeutic effect of the hydrogel on skin‐wound healing. Results: The HA‐POL hydrogel transformed from sol to gel at 30°C, close to body temperature, and had stable moisturizing properties. HA‐POL hydrogel promoted skin‐wound healing and increased protein accumulation in the wound area. HA‐POL hydrogel allowed greater air permeability than Band‐aid, a typical wound covering. Results from transwell assays showed that the HA‐POL hydrogel effectively isolated skin‐wounds from bacterial invasion. Conclusion: This work demonstrates the advantages of using HA‐POL gel materials in the treatment of cutaneous wounds.
文摘Hydroxyapatite/titania (HA/TiO2) double layers were coated onto Ti scaffolds throughout for orthopaedic applications by sol-gel method. Differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and X-ray diffractometry (XRD) were used for the characterisation of the phase transformations of the dried gels and coated surface structures. Scanning electron microscope (SEM) equipped with energy dispersive spectrometry (EDS) was used for the observation and evaluation of the morphology and phases of the surface layers and for the assessment of the in vitro tests. The in vitro assessments were performed by soaking the HA/TiO2 double coated samples into the simulated body fluid (SBF) for various periods. The TiO2 dipping-coating method at a speed of 12 cm/min, followed by a heat treatment at 600 ℃ for 20 min. The HA la lyaeyre wr wasa ssu cbosaetqeude bnytl ya dipping-coated on the outer surface at the same speed and then heat-treated at difference temperatures. The results indicat that the HA phase begins to crystallize after a heat treatment at 560 ℃. The crystallinity increases obviously at 760 ℃. SEM observations find no delamination or crack at the interfaces of HA/TiO2 and TiO2/Ti. The HA/TiO2 coated Ti scaffolds displays excellent bone-like apatite forming ability when it is soaked into SBF. Ti scaffolds after HA/TiO2 double coatings can be anticipated as promising implant materials for orthopaedic
文摘New IPN hydrogels composed of diallyldimethylammonium chloride (DADMAC) and natural macromolecule, kappa-carrageenan (KC) were prepared by gamma irradiation and their properties were studied, The results show that both the gel strength and the swelling capacity of the IPN hydrogels were enhanced significantly as compared with those of the pure hydrogels of PDADMAC.
基金Funded by the Natural Science Research of Key Projects of Anhui Provincial Universities (No. KJ2010A099)
文摘Nano-hydroxyapatite reinforced poly（vinyl alcohol） gel（nano-HA/PVA gel） composites has been proposed as a promising biomaterial,especially used as an articular cartilage repair biomaterial.In this paper,nano-HA/PVA gel composite was prepared by in situ synthesis method and incorporation with freeze-thaw cycle process.The microstructure and morphology were investigated by X-ray diffraction,TEM,SEM and FTIR.The results showed that the size of HA particles synthesized in PVA solution was on the nanometer scale.Both the size and crystallinity of HA particles synthesized in PVA solution decreased compared with that of HA synthesized in distilled water.The nano-HA particles were distributed in PVA matrix uniformly due to the effect of PVA solution as a dispersant while low content of HA particles in the composites.On the contrary,with high content of nano-HA particles in the composites,the particles tended to aggregate.The result of FT-IR analysis indicated that the chemical bond between nano-HA particles and PVA matrix existed.The conformation and degree of tacticity of PVA molecule changed because of the addition of HA particles.Furthermore,the interfacial strength of the composites was improved due to the interaction between nano-HA particle and PVA matrix and this was beneficial to improving the mechanical properties of the composites.
基金supported by the National Natural Science Foundation of China(grant Nos.52273112,U20A6001,22105167)the Start-up funding of Ningbo Research Institute of Zhejiang University(grant No.20201203Z0193).
文摘Macroporous hydrogels are water-swollen polymer networks with porous structures beyond the mesh size.They provide high specific surface areas and hieratical mass transfer channels which are desired for emerging applications including cell culturing,bio-separation,and drug delivery.A variety of approaches have been developed to fabricate macroporous hydrogels,including gas foaming,porogen templating,phase separation,3D printing,etc.Alternatively,ice templating utilizes the crystallization of water as the porogenation mechanism which doesn't need the leaching of porogens.
基金support by a grant from the Dutch government to the Netherlands Institute for Regenerative Medicine(NIRM,Grant No.FES0908)support of the Netherlands Organisation for Scientific Research(NWO)P15-23(Project 1)“Activating resident stem cells”and EFRO OPOost 00867 Orthros TR.
文摘A combination of the viscoelastic properties of hyaluronic acid(HA)and the elastic properties of star shaped 8-arm poly(ethylene glycol)(8-arm PEG)was used to design in-situ forming hydrogels.Hydrogels were prepared by the enzymatic crosslinking of a partially tyramine modified 8-arm PEG and a tyramine conjugated HA using horseradish peroxidase in the presence of hydrogen peroxide.Hydrogels of the homopolymer conjugates and mixtures thereof were rapidly formed within seconds under physiological conditions at low polymer and enzyme concentrations.Elastic hydrogels with high gel content(≥95%)and high storage moduli(up to 22.4 kPa)were obtained.An in vitro study in the presence of hyaluronidase(100 U/mL)revealed that with increasing PEG content the degradation time of the hybrid hydrogels increased up to several weeks,whereas hydrogels composed of only hyaluronic acid degraded within 2 weeks.Human mesenchymal stem cells(hMSCs)incorporated in the hybrid hydrogels remained viable as shown by a PrestoBlue and a live-dead assay,confirming the biocompatibility of the constructs.The production of an extracellular matrix by re-differentiation of encapsulated human chondrocytes was followed over a period of 28 days.Gene expression indicated that these highly elastic hydrogels induced an enhanced production of collagen type II.At low PEG-TA/HA-TA ratios a higher expression of SOX 9 and ACAN was observed.These results indicate that by modulating the ratio of PEG/HA,injectable hydrogels can be prepared applicable as scaffolds for tissue regeneration applications.
基金the support for this work from the National Key Research and Development Program(Grant No.2018YFA0703100)the National Nature Science Foundation of China(Grant No.51733006).
文摘Developing a meniscus substitute mimicking the anisotropic mechanics(higher circumferential tensile modulus and lower compressive modulus)of native tissue remains a great challenge.In this work,based on the pendant group structure-dependent H-bonding strengthening mechanism,two kinds of amide-based H-bonding crosslinked hydrogels with distinct mechanical behaviors,that is,the flexible poly(N-acryloyl glycinamide)(PNAGA)and the ultra-stiff poly(N-acryloylsemicarbazide)(PNASC)hydrogels are employed to construct the biomimetic meniscus substitute.To this end,a gel microparticle-based self-thickening strategy is first proposed to fabricate PNASC(GMP-PNASC)high-modulus hydrogels skeleton by extrusion printing technology in mimicking the collagen fibers in native meniscus to resist the circumferential tensile stress.Then,the PNAGA hydrogel is infused into the PNASC skeleton to replicate the proteoglycan,providing a lower compressive modulus.By regulating the structural features at the interior and peripheral regions,the GMP-PNASC/PNAGA hydrogel meniscus scaffold with the higher tensile modulus(87.28±6.06 MPa)and lower compressive modulus(2.11±0.28 MPa)can be constructed.In vivo outcome at 12 weeks post-implantation of rabbit’s medial meniscectomy model confirms the effects of GMP-PNASC/PNAGA meniscus scaffold on alleviating the wear of articular cartilage and ameliorating the development of osteoarthritis(OA).
