The biodegradable polymer demonstrates significant potential for addressing the critical environmental challenges associated with oil spills;however, the cellular film structure and hydrophobic characteristics of the ...The biodegradable polymer demonstrates significant potential for addressing the critical environmental challenges associated with oil spills;however, the cellular film structure and hydrophobic characteristics of the polymer restrict their efficacy. In this study, a biodegradable thin membrane composed of a blend of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(caprolactone) (PCL) was fabricated utilizing the electrospinning technique. The membrane exhibited an adsorption capacity for cooking oil of 10.8 g/g, and Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the anticipated chemical structures, revealing no evidence of chemical interactions between PHBV and PCL. This research presents an environmentally friendly and straightforward approach for fabricating biodegradable membrane structure with exceptional oil-water separation capabilities.展开更多
Poly(3-hydroxybutyrate-co-lactate)[P(3HB-co-LA)]is a highly promising valuable biodegradable material with good biocompatibility and degradability.Vibrio natriegens,owing to its fast-growth,wide substrate spectrum cha...Poly(3-hydroxybutyrate-co-lactate)[P(3HB-co-LA)]is a highly promising valuable biodegradable material with good biocompatibility and degradability.Vibrio natriegens,owing to its fast-growth,wide substrate spectrum characteristics,was selected to produce P(3HB-co-LA).Herein,the crucial role of acetyltransferase PN96-18060 for PHB synthesis in V.natriegens was identified.Heterologous pathway of P(3HB-co-LA)was introduced into V.natriegens successfully,in addition,overexpression of the dldh gene led to 1.84 fold enhancement of the lactate content in P(3HB-co-LA).Finally,the production of P(3HB-co-LA)was characterized under different carbon sources.The lactate fraction in P(3HB-co-LA)was increased to 28.3 mol%by the modification,about 1.84 times of that of the control.This is the first successful case of producing the P(3HB-co-LA)in V.natriegens.Collectively,this study showed that V.natriegens is an attractive host organism for producing P(3HB-co-LA)and has great potential to produce other co-polymers.展开更多
Poly(lactate-co-3-hydroxybutyrate)[P(LA-co-3HB)]is a high-molecular-weight biomaterial with excellent biocompatibility and biodegradability.In this study,the properties of P(LA-co-3HB)were examined and found to be aff...Poly(lactate-co-3-hydroxybutyrate)[P(LA-co-3HB)]is a high-molecular-weight biomaterial with excellent biocompatibility and biodegradability.In this study,the properties of P(LA-co-3HB)were examined and found to be affected by its lactate fraction.The efficiency of lactyl-CoA biosynthesis from intracellular lactate significantly affected the microbial synthesis of P(LA-co-3HB).Two CoA transferases from Anaerotignum lactatifermentans and Bacillota bacterium were selected for use in copolymer biosynthesis from 11 candidates.We found that cotAl enhanced the lactate fraction by 31.56%compared to that of the frequently used modified form of propionyl-CoA transferase from Anaerotignum propionicum.In addition,utilizing xylose as a favorable carbon source and blocking the lactate degradation pathway further enhanced the lactate fraction to 30.42 mol%and 52.84 mol%,respectively.Furthermore,when a 5 L bioreactor was used for fermentation utilizing xylose as a carbon source,the engineered strain produced 60.60 wt%P(46.40 mol%LA-co-3HB),which was similar to the results of our flask experiments.Our results indicate that the application of new CoA transferases has great potential for the biosynthesis of other lactate-based copolymers.展开更多
The present study deals with the kinetics of improved poly(3-hydroxybutyrate)(PHB)production by an L-cysteine HCl-depressed mutant of Bacillus licheniformis.Production of biodegradable polymers is to eliminate use of ...The present study deals with the kinetics of improved poly(3-hydroxybutyrate)(PHB)production by an L-cysteine HCl-depressed mutant of Bacillus licheniformis.Production of biodegradable polymers is to eliminate use of materials derived from petrochemicals and also because of their environmental impact.For the current study,mutant strain(NA-21)&wild-type(IIB-isl19)were used for PHB production.Submerged culture with two-stage fermentation technique was used for PHB production.Results indicated that PHB production was improved with 300 mM of-HNO2.The superior mutant strain(NA-21)resulted in 2-fold more PHB as compared to the wild-type(IIB-isl9).It was selected,and resistance against L-cysteine HCl was developed.At 4 ppm concentration of L-cysteine HCl,PHB production by mutant strain(NA-cys4)was higher than its wild counterpart by 5.7-fold.Kinetic study of parameters including specific growth rate(μh−1),growth(Yx/s,Ys/x),product yield coefficients(Yp/s,Yp/x),volumetric rate constants(Qp,Qs,Qx)and specific rate constants(qp,qs,qx),were also accomplished.Moreover,Yp/x,Qp and qp=μ×Yp/x were found to be very significant as 1.254±0.06(g/g biomass),0.134±0.01(g/l/h)and 0.168±0.01(g/g/h),respectively.The effect of fatty acids on PHB production highlighted the improvement in PHB production by 1.94-fold.The highest PHB production during the study was 16.35±3.12 g/l which highlighted its significance(p≤0.05)and impact on the overall process.The variation in PBH yield between wild-type and mutant B.licheniformis is possibly because of induced DNA interstrand thus making unstable thymidine-thymidine dymers.From the results,it was concluded that improved PHB production on industrial scale is fairly possible and it holds the potential to contribute significantly to plastic circularity in the future.展开更多
AIM: To establish the potential of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) as a material for tendon repair. METHODS: The biocompatibility of PHBHHx with both rat tenocytes (rT) and human mesenchymal ste...AIM: To establish the potential of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) as a material for tendon repair. METHODS: The biocompatibility of PHBHHx with both rat tenocytes (rT) and human mesenchymal stem cells (hMSC) was explored by monitoring adhesive characteristics on films of varying weight/volume ratios coupled to a culture atmosphere of either 21% O2 (air) or 2% O2 (physiological normoxia). The diameter and stiffness of PHBHHx films was established using optical coherence tomography and mechanical testing, respectively. RESULTS: Film thickness correlated directly with weight/volume PHBHHx (r2 = 0.9473) ranging from 0.1 mm (0.8% weight/volume) to 0.19 mm (2.4% weight/volume). Film stiffness on the other hand displayed a biphasic response which increased rapidly at values > 1.6% weight/volume. Optimal cell attachment of rT required films of ≥ 1.6% and ≥ 2.0% weight/volume PHBHHx in 2% O2 and 21% O2 respectively. A qualitative adhesion increase was noted for hMSC in films ≥ 1.2% weight/volume, becoming significant at 2% weight/volume in 2% O2. An increase in cell adhesion was also noted with ≥ 2% weight/volume PHBHHx in 21% O2. Cell migration into films was not observed. CONCLUSION: This evaluation demonstrates that PHBHHx is a suitable polymer for future cell/polymer replacement strategies in tendon repair.展开更多
The miscibility and crystallization of solution casting biodegradable poly（3-hydroxybuty- rate）/poly（ethylene succinate） （PHB/PES） blends was investigated by differential scanning calorimetry, rheology, and opti...The miscibility and crystallization of solution casting biodegradable poly（3-hydroxybuty- rate）/poly（ethylene succinate） （PHB/PES） blends was investigated by differential scanning calorimetry, rheology, and optical microscopy. The blends showed two glass transition temperatures and a depression of melting temperature of PHB with compositions in phase diagram, which indicated that the blend was partially miscible. The morphology observation supported this result. It was found that the PHB and PES can crystallize simultaneously or upon stepwise depending on the crystallization temperatures and compositions. The spherulite growth rate of PHB increased with increasing of PES content. The influence of compositions on the spherulitic growth rate for the partially miscible polymer blends was discussed.展开更多
Poly-3-hydroxybutyrate （PHB） can be produced by various species of bacteria. Among the possible carbon sources, both methane and methanol could be a suitable substrate for the production of PHB. Methane is cheap and...Poly-3-hydroxybutyrate （PHB） can be produced by various species of bacteria. Among the possible carbon sources, both methane and methanol could be a suitable substrate for the production of PHB. Methane is cheap and plentiful not only as natural gas, but also as biogas. Methanol can also maintain methanotrophic activity in some conditions. The methanotrophic strain Methylosinus trichosporium IMV3011 can accumulate PHB with methane and methanol in a brief nonsterile process. Liquid methanol （0.1%） was added to improve the oxidization of methane. The studies were carried out using shake flasks. Cultivation was performed in two stages： a continuous growth phase and a PHB accumulation phase under the conditions short of essential nutrients （ammonium, nitrate, phosphorus, copper, iron （Ⅲ）, magnesium or ethylenediamine tetraacetate （EDTA）） in batch culture. It was found that the most suitable growth time for the cell is 144 h. Then an optimized culture condition for second stage was determined, in which the PHB concentration could be much increased to 0.6 g/L. In order to increase PHB content, citric acid was added as an inhibitor of tricarboxylic acid cycle （TCA）. It was found that citric acid is favorable for the PHB accumulation, and the PHB yield was increased to 40% （w/w） from the initial yield of 12% （w/w） after nutrient deficiency cultivation. The PHB produced is of very high quality with molecular weight up to 1.5 × 10^6Da.展开更多
Biosynthesis and thermal properties of poly（3-hydroxybutyrate-co-3-hydroxyvalerate） （PHBV） with different HV （hydrovalerate） content produced by a Bacillus cereus strain were investigated. A large variety of HV ...Biosynthesis and thermal properties of poly（3-hydroxybutyrate-co-3-hydroxyvalerate） （PHBV） with different HV （hydrovalerate） content produced by a Bacillus cereus strain were investigated. A large variety of HV contents （up to about 90 mol%） of PHBV could be produced by this strain. Combined nitrogen sources containing both yeast extract and ammonium sulphate were better for cell growth and polyhydroxyalkanoates （PHA） production than either yeast extract or ammonium sulphate alone. Propionic acid is more favorable for the production of HV content than that of valeric acid. Finally, thermal properties of PHBV produced by this strain are found close to the results of other groups.展开更多
Tissue engineered scaffold is one of the hopeful therapies for the patients with organ or tissue damages. The key element for a tissue engineered scaffold material is high biocompatibility. Herein the poly (3-hydroxyb...Tissue engineered scaffold is one of the hopeful therapies for the patients with organ or tissue damages. The key element for a tissue engineered scaffold material is high biocompatibility. Herein the poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) film was irradiated by the low temperature atmospheric plasma and then coated by the silk fibroins (SF). After plasma treatment, the surface of PHBHHx film became rougher and more hydrophilic than that of original film. The experiment of PHBHHx flushed by phosphate buffer solution (PBS) proves that the coated SF shows stronger immobilization on the plasma-treated film than that on the untreated film. The cell viability assay demonstrates that SF-coated PHBHHx films treated by the plasma significantly supports the proliferation and growth of the human smooth muscle cells (HSMCs). Furthermore, the scanning electron microscopy and hemotoylin and eosin (HE) staining show that HSMCs formed a cell sub-monolayer and secreted a large amount of extracellular matrix (ECM) on the films after one week's culture. The silk fibroins modify the plasma-treated PHBHHx film, providing a material potentially applicable in the cardiovascular tissue engi-neering.展开更多
Poly(3-hydroxybutyrate) (PHB) is an intracellular carbon and energy storage material accumulated by many kinds of microorganism under unfavorable growth conditions. For the production of PHB, Alcaligenes eutrophus has...Poly(3-hydroxybutyrate) (PHB) is an intracellular carbon and energy storage material accumulated by many kinds of microorganism under unfavorable growth conditions. For the production of PHB, Alcaligenes eutrophus has been widely used because it is easy to grow, and its physiological and biochemical changes during the PHB synthesis is understood in details. A very high concentration and productivity of PHB could be obtained by fed-batch culture of Alcaligenes eutrophus with phosphate limitation in 50 L fermenter.展开更多
Porous poly(3 hydroxybutyrate)(PHB) membranes were prepared by microemulsion templates. The influence of microemulsion templates on pore size and porosity of the PHB membranes were studied. Preliminary studies showed...Porous poly(3 hydroxybutyrate)(PHB) membranes were prepared by microemulsion templates. The influence of microemulsion templates on pore size and porosity of the PHB membranes were studied. Preliminary studies showed that the pore size made by microemulsion templates were smaller and were estimated in the range of 100~500 nanometer. In this research, the ultraviolet/visible light spectrometer was applied in the investigation of H 2O/Span85 Tween60/chloroform reserve microemulsion. Surfactant content(P) and water content(R) were optimized. Furthermore, the effects of variation of P and R on the pore size and porosity of PHB films were discussed.展开更多
Poly (3-hydroxybutyrate-co-3-hydroxyvalerate)/Organophilic montmorillonite (PHBV/OMMT) nanocomposites were prepared and the biodegradability of the PHBV/OMMT nanocomposites was studied by a cultivation degrading metho...Poly (3-hydroxybutyrate-co-3-hydroxyvalerate)/Organophilic montmorillonite (PHBV/OMMT) nanocomposites were prepared and the biodegradability of the PHBV/OMMT nanocomposites was studied by a cultivation degrading method in soil suspension. The relationship between structure and biodegradability of PHBV/OMMT nanocomposites was investigated. The results showed that the biodegradability of PHBV/OMMT nanocomposites decreased with increasing amount of OMMT and it was related to the number of PHBV degrading microorganisms in degradation environment, the anti-microbial property of OMMT and the degree of crystallinity of the nanocomposites.展开更多
Blends of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and poly(butylene succinate-adipate) (PBSA), both biodegradable semicrystalline polyesters, were prepared with the ratio of PHBHHx/PBSA ranging from 80/...Blends of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and poly(butylene succinate-adipate) (PBSA), both biodegradable semicrystalline polyesters, were prepared with the ratio of PHBHHx/PBSA ranging from 80/20 to 20/80 by melt mixing method. Differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), dynamic mechanical thermal analysis (DMA), polarizing optical microscopy (POM) and wide angle X-ray diffractometer (WAXD) were used to study the miscibility and crystallization behavior of PHBHHx/PBSA blends. Experimental results indicate that PHBHHx is immiscible with PBSA as shown by the almost unchanged glass transition temperature and the biphasic melt.展开更多
文摘The biodegradable polymer demonstrates significant potential for addressing the critical environmental challenges associated with oil spills;however, the cellular film structure and hydrophobic characteristics of the polymer restrict their efficacy. In this study, a biodegradable thin membrane composed of a blend of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(caprolactone) (PCL) was fabricated utilizing the electrospinning technique. The membrane exhibited an adsorption capacity for cooking oil of 10.8 g/g, and Fourier-transform infrared spectroscopy (FTIR) analysis confirmed the anticipated chemical structures, revealing no evidence of chemical interactions between PHBV and PCL. This research presents an environmentally friendly and straightforward approach for fabricating biodegradable membrane structure with exceptional oil-water separation capabilities.
基金supported by the National Natural Science Foundation of China(22278137)the National Key R&D Program of China(2021YFC2103500)Partially supported by Open Funding Project of the State Key Laboratory of Bioreactor Engineering.
文摘Poly(3-hydroxybutyrate-co-lactate)[P(3HB-co-LA)]is a highly promising valuable biodegradable material with good biocompatibility and degradability.Vibrio natriegens,owing to its fast-growth,wide substrate spectrum characteristics,was selected to produce P(3HB-co-LA).Herein,the crucial role of acetyltransferase PN96-18060 for PHB synthesis in V.natriegens was identified.Heterologous pathway of P(3HB-co-LA)was introduced into V.natriegens successfully,in addition,overexpression of the dldh gene led to 1.84 fold enhancement of the lactate content in P(3HB-co-LA).Finally,the production of P(3HB-co-LA)was characterized under different carbon sources.The lactate fraction in P(3HB-co-LA)was increased to 28.3 mol%by the modification,about 1.84 times of that of the control.This is the first successful case of producing the P(3HB-co-LA)in V.natriegens.Collectively,this study showed that V.natriegens is an attractive host organism for producing P(3HB-co-LA)and has great potential to produce other co-polymers.
基金supported by the National Natural Science Foundation of China(22278137)the National Key R&D Program of China(2021YFC2103500)Partially supported by Open Funding Project of the State Key Laboratory of Bioreactor Engineering.
文摘Poly(lactate-co-3-hydroxybutyrate)[P(LA-co-3HB)]is a high-molecular-weight biomaterial with excellent biocompatibility and biodegradability.In this study,the properties of P(LA-co-3HB)were examined and found to be affected by its lactate fraction.The efficiency of lactyl-CoA biosynthesis from intracellular lactate significantly affected the microbial synthesis of P(LA-co-3HB).Two CoA transferases from Anaerotignum lactatifermentans and Bacillota bacterium were selected for use in copolymer biosynthesis from 11 candidates.We found that cotAl enhanced the lactate fraction by 31.56%compared to that of the frequently used modified form of propionyl-CoA transferase from Anaerotignum propionicum.In addition,utilizing xylose as a favorable carbon source and blocking the lactate degradation pathway further enhanced the lactate fraction to 30.42 mol%and 52.84 mol%,respectively.Furthermore,when a 5 L bioreactor was used for fermentation utilizing xylose as a carbon source,the engineered strain produced 60.60 wt%P(46.40 mol%LA-co-3HB),which was similar to the results of our flask experiments.Our results indicate that the application of new CoA transferases has great potential for the biosynthesis of other lactate-based copolymers.
基金the Researchers Supporting Project,King Saud University,Riyadh,Saudi Arabia for funding this work through the project number(RSP-2024R437).
文摘The present study deals with the kinetics of improved poly(3-hydroxybutyrate)(PHB)production by an L-cysteine HCl-depressed mutant of Bacillus licheniformis.Production of biodegradable polymers is to eliminate use of materials derived from petrochemicals and also because of their environmental impact.For the current study,mutant strain(NA-21)&wild-type(IIB-isl19)were used for PHB production.Submerged culture with two-stage fermentation technique was used for PHB production.Results indicated that PHB production was improved with 300 mM of-HNO2.The superior mutant strain(NA-21)resulted in 2-fold more PHB as compared to the wild-type(IIB-isl9).It was selected,and resistance against L-cysteine HCl was developed.At 4 ppm concentration of L-cysteine HCl,PHB production by mutant strain(NA-cys4)was higher than its wild counterpart by 5.7-fold.Kinetic study of parameters including specific growth rate(μh−1),growth(Yx/s,Ys/x),product yield coefficients(Yp/s,Yp/x),volumetric rate constants(Qp,Qs,Qx)and specific rate constants(qp,qs,qx),were also accomplished.Moreover,Yp/x,Qp and qp=μ×Yp/x were found to be very significant as 1.254±0.06(g/g biomass),0.134±0.01(g/l/h)and 0.168±0.01(g/g/h),respectively.The effect of fatty acids on PHB production highlighted the improvement in PHB production by 1.94-fold.The highest PHB production during the study was 16.35±3.12 g/l which highlighted its significance(p≤0.05)and impact on the overall process.The variation in PBH yield between wild-type and mutant B.licheniformis is possibly because of induced DNA interstrand thus making unstable thymidine-thymidine dymers.From the results,it was concluded that improved PHB production on industrial scale is fairly possible and it holds the potential to contribute significantly to plastic circularity in the future.
基金Supported by EPSRC Doctoral Training Centre in Regenerative Medicine and the HYANJI Scaffold Project (European Commission Framework 7 program)
文摘AIM: To establish the potential of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) as a material for tendon repair. METHODS: The biocompatibility of PHBHHx with both rat tenocytes (rT) and human mesenchymal stem cells (hMSC) was explored by monitoring adhesive characteristics on films of varying weight/volume ratios coupled to a culture atmosphere of either 21% O2 (air) or 2% O2 (physiological normoxia). The diameter and stiffness of PHBHHx films was established using optical coherence tomography and mechanical testing, respectively. RESULTS: Film thickness correlated directly with weight/volume PHBHHx (r2 = 0.9473) ranging from 0.1 mm (0.8% weight/volume) to 0.19 mm (2.4% weight/volume). Film stiffness on the other hand displayed a biphasic response which increased rapidly at values > 1.6% weight/volume. Optimal cell attachment of rT required films of ≥ 1.6% and ≥ 2.0% weight/volume PHBHHx in 2% O2 and 21% O2 respectively. A qualitative adhesion increase was noted for hMSC in films ≥ 1.2% weight/volume, becoming significant at 2% weight/volume in 2% O2. An increase in cell adhesion was also noted with ≥ 2% weight/volume PHBHHx in 21% O2. Cell migration into films was not observed. CONCLUSION: This evaluation demonstrates that PHBHHx is a suitable polymer for future cell/polymer replacement strategies in tendon repair.
基金ACKNOWLEDGMENT This work was supported by the Key Science Foundation of Education Ministry of China and the Anhui Science Foundation.
文摘The miscibility and crystallization of solution casting biodegradable poly（3-hydroxybuty- rate）/poly（ethylene succinate） （PHB/PES） blends was investigated by differential scanning calorimetry, rheology, and optical microscopy. The blends showed two glass transition temperatures and a depression of melting temperature of PHB with compositions in phase diagram, which indicated that the blend was partially miscible. The morphology observation supported this result. It was found that the PHB and PES can crystallize simultaneously or upon stepwise depending on the crystallization temperatures and compositions. The spherulite growth rate of PHB increased with increasing of PES content. The influence of compositions on the spherulitic growth rate for the partially miscible polymer blends was discussed.
基金New Century Excellent Talents in University of China(NCET-05-0358)the National Natural Science Foundation of China(20625308)
文摘Poly-3-hydroxybutyrate （PHB） can be produced by various species of bacteria. Among the possible carbon sources, both methane and methanol could be a suitable substrate for the production of PHB. Methane is cheap and plentiful not only as natural gas, but also as biogas. Methanol can also maintain methanotrophic activity in some conditions. The methanotrophic strain Methylosinus trichosporium IMV3011 can accumulate PHB with methane and methanol in a brief nonsterile process. Liquid methanol （0.1%） was added to improve the oxidization of methane. The studies were carried out using shake flasks. Cultivation was performed in two stages： a continuous growth phase and a PHB accumulation phase under the conditions short of essential nutrients （ammonium, nitrate, phosphorus, copper, iron （Ⅲ）, magnesium or ethylenediamine tetraacetate （EDTA）） in batch culture. It was found that the most suitable growth time for the cell is 144 h. Then an optimized culture condition for second stage was determined, in which the PHB concentration could be much increased to 0.6 g/L. In order to increase PHB content, citric acid was added as an inhibitor of tricarboxylic acid cycle （TCA）. It was found that citric acid is favorable for the PHB accumulation, and the PHB yield was increased to 40% （w/w） from the initial yield of 12% （w/w） after nutrient deficiency cultivation. The PHB produced is of very high quality with molecular weight up to 1.5 × 10^6Da.
基金This work was financially supported by the Hong Kong Polytechnic University (Grant YD37)the Research Grant Council of the Hong Kong Special Administration Region, China (Nos. Polyu5272/01M, Polyu5257/02M, Polyu5403/03M)
文摘Biosynthesis and thermal properties of poly（3-hydroxybutyrate-co-3-hydroxyvalerate） （PHBV） with different HV （hydrovalerate） content produced by a Bacillus cereus strain were investigated. A large variety of HV contents （up to about 90 mol%） of PHBV could be produced by this strain. Combined nitrogen sources containing both yeast extract and ammonium sulphate were better for cell growth and polyhydroxyalkanoates （PHA） production than either yeast extract or ammonium sulphate alone. Propionic acid is more favorable for the production of HV content than that of valeric acid. Finally, thermal properties of PHBV produced by this strain are found close to the results of other groups.
文摘Tissue engineered scaffold is one of the hopeful therapies for the patients with organ or tissue damages. The key element for a tissue engineered scaffold material is high biocompatibility. Herein the poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) film was irradiated by the low temperature atmospheric plasma and then coated by the silk fibroins (SF). After plasma treatment, the surface of PHBHHx film became rougher and more hydrophilic than that of original film. The experiment of PHBHHx flushed by phosphate buffer solution (PBS) proves that the coated SF shows stronger immobilization on the plasma-treated film than that on the untreated film. The cell viability assay demonstrates that SF-coated PHBHHx films treated by the plasma significantly supports the proliferation and growth of the human smooth muscle cells (HSMCs). Furthermore, the scanning electron microscopy and hemotoylin and eosin (HE) staining show that HSMCs formed a cell sub-monolayer and secreted a large amount of extracellular matrix (ECM) on the films after one week's culture. The silk fibroins modify the plasma-treated PHBHHx film, providing a material potentially applicable in the cardiovascular tissue engi-neering.
文摘Poly(3-hydroxybutyrate) (PHB) is an intracellular carbon and energy storage material accumulated by many kinds of microorganism under unfavorable growth conditions. For the production of PHB, Alcaligenes eutrophus has been widely used because it is easy to grow, and its physiological and biochemical changes during the PHB synthesis is understood in details. A very high concentration and productivity of PHB could be obtained by fed-batch culture of Alcaligenes eutrophus with phosphate limitation in 50 L fermenter.
文摘Porous poly(3 hydroxybutyrate)(PHB) membranes were prepared by microemulsion templates. The influence of microemulsion templates on pore size and porosity of the PHB membranes were studied. Preliminary studies showed that the pore size made by microemulsion templates were smaller and were estimated in the range of 100~500 nanometer. In this research, the ultraviolet/visible light spectrometer was applied in the investigation of H 2O/Span85 Tween60/chloroform reserve microemulsion. Surfactant content(P) and water content(R) were optimized. Furthermore, the effects of variation of P and R on the pore size and porosity of PHB films were discussed.
基金The National Natural Science Foundation of China (No. 20374032) Chinese Education Ministry Foundation for N & T Joint Academy
文摘Poly (3-hydroxybutyrate-co-3-hydroxyvalerate)/Organophilic montmorillonite (PHBV/OMMT) nanocomposites were prepared and the biodegradability of the PHBV/OMMT nanocomposites was studied by a cultivation degrading method in soil suspension. The relationship between structure and biodegradability of PHBV/OMMT nanocomposites was investigated. The results showed that the biodegradability of PHBV/OMMT nanocomposites decreased with increasing amount of OMMT and it was related to the number of PHBV degrading microorganisms in degradation environment, the anti-microbial property of OMMT and the degree of crystallinity of the nanocomposites.
基金The National Natural Science Foundation of China (No. 20374032) and Tianjin Science and Technology Key Project (No. 05YFSZSF02200)
文摘Blends of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and poly(butylene succinate-adipate) (PBSA), both biodegradable semicrystalline polyesters, were prepared with the ratio of PHBHHx/PBSA ranging from 80/20 to 20/80 by melt mixing method. Differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), dynamic mechanical thermal analysis (DMA), polarizing optical microscopy (POM) and wide angle X-ray diffractometer (WAXD) were used to study the miscibility and crystallization behavior of PHBHHx/PBSA blends. Experimental results indicate that PHBHHx is immiscible with PBSA as shown by the almost unchanged glass transition temperature and the biphasic melt.
