The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Xianghong Wang - One of the best experts on this subject based on the ideXlab platform.
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influence of different sugars on pullulan production and activities of α phosphoglucose mutase udpg pyrophosphorylase and glucosyltransferase involved in pullulan synthesis in aureobasidium Pullulans y68
Carbohydrate Polymers, 2008Co-Authors: Xiaohui Duan, Lin Wang, Xianghong WangAbstract:Effects of different sugars on pullulan production, UDP-glucose level, and activities of α-phosphoglucose mutase, UDPG-pyrophosphorylase and glucosyltransferase in Aureobasidium Pullulans Y68 were examined. It was found that more pullulan was produced when the yeast strain was grown in the medium containing glucose than when it was cultivated in the medium supplementing other sugars. Our results demonstrate that when more pullulan was synthesized, less UDP-glucose was left in the cells of A. Pullulans Y68. However, it was observed that more pullulan was synthesized, the cells had higher activities of α-phosphoglucose mutase, UDPG-pyrophosphorylase and glycosyltransferase. Therefore, high pullulan yield is related to high activities of α-phosphoglucose mutase, UDPG-pyrophosphorylase and glucosyltransferase in A. Pullulans Y68 grown on different sugars. A pathway of pullulan biosynthesis in A. pullulan Y68 was proposed based on the results of this study and those from other researchers. This study will be helpful to metabolism-engineer the yeast strain to further enhance pullulan yield.
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influence of different sugars on pullulan production and activities of α phosphoglucose mutase udpg pyrophosphorylase and glucosyltransferase involved in pullulan synthesis in aureobasidium Pullulans y68
Carbohydrate Polymers, 2008Co-Authors: Xiaohui Duan, Zhenming Chi, Lin Wang, Xianghong WangAbstract:Effects of different sugars on pullulan production, UDP-glucose level, and activities of α-phosphoglucose mutase, UDPG-pyrophosphorylase and glucosyltransferase in Aureobasidium Pullulans Y68 were examined. It was found that more pullulan was produced when the yeast strain was grown in the medium containing glucose than when it was cultivated in the medium supplementing other sugars. Our results demonstrate that when more pullulan was synthesized, less UDP-glucose was left in the cells of A. Pullulans Y68. However, it was observed that more pullulan was synthesized, the cells had higher activities of α-phosphoglucose mutase, UDPG-pyrophosphorylase and glycosyltransferase. Therefore, high pullulan yield is related to high activities of α-phosphoglucose mutase, UDPG-pyrophosphorylase and glucosyltransferase in A. Pullulans Y68 grown on different sugars. A pathway of pullulan biosynthesis in A. pullulan Y68 was proposed based on the results of this study and those from other researchers. This study will be helpful to metabolism-engineer the yeast strain to further enhance pullulan yield.
Laurent J. Feldman - One of the best experts on this subject based on the ideXlab platform.
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Tubular cationized pullulan hydrogels as local reservoirs for plasmid DNA
Journal of Biomedical Materials Research Part A, 2007Co-Authors: Aurélie San Juan, Grégory Ducrocq, Hanna Hlawaty, Isabelle Bataille, Erwann Guénin, Didier Letourneur, Laurent J. FeldmanAbstract:1 - ArticleIn the present study, we measured the ability of various cationized pullulan tubular hydrogels to retain plasmid DNA, and tested the ability of retained plasmid DNA to transfect vascular smooth muscle cells (VSMCs). Cationized Pullulans were obtained by grafting at different charge densities ethylamine (EA) or diethylaminoethyl-amine (DEAE) on the pullulan backbone. Polymers were characterized by elemental analysis, acid-base titration, size exclusion chromatography, Fourier-transform infrared spectroscopy, and proton nuclear magnetic resonance. The complexation of cationized Pullulans in solution with plasmid DNA was evidenced by fluorescence quenching with PicoGreen. Cationized Pullulans were then chemically crosslinked with phosphorus oxychloride to obtain tubular cationized pullulan hydrogels. Native pullulan tubes did not retain loaded plasmid DNA. In contrast, the ability of cationized pullulan tubes to retain plasmid DNA was dependent on both the amine content and the type of amine. The functional integrity of plasmid DNA in cationized pullulan tubes was demonstrated by in vitro transfection of VSMCs. Hence, cationized pullulan hydrogels can be designed as tubular structures with high affinity for plasmid DNA, which may provide new biomaterials to enhance the efficiency of local arterial gene transfer strategies. (c) 2007 Wiley Periodicals, Inc
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Tubular cationized pullulan hydrogels as local reservoirs for plasmid DNA.
Journal of biomedical materials research. Part A, 2007Co-Authors: Aurélie San Juan, Grégory Ducrocq, Hanna Hlawaty, Isabelle Bataille, Erwann Guénin, Didier Letourneur, Laurent J. FeldmanAbstract:In the present study, we measured the ability of various cationized pullulan tubular hydrogels to retain plasmid DNA, and tested the ability of retained plasmid DNA to transfect vascular smooth muscle cells (VSMCs). Cationized Pullulans were obtained by grafting at different charge densities ethylamine (EA) or diethylaminoethylamine (DEAE) on the pullulan backbone. Polymers were characterized by elemental analysis, acid-base titration, size exclusion chromatography, Fourier-transform infrared spectroscopy, and proton nuclear magnetic resonance. The complexation of cationized Pullulans in solution with plasmid DNA was evidenced by fluorescence quenching with PicoGreen. Cationized Pullulans were then chemically crosslinked with phosphorus oxychloride to obtain tubular cationized pullulan hydrogels. Native pullulan tubes did not retain loaded plasmid DNA. In contrast, the ability of cationized pullulan tubes to retain plasmid DNA was dependent on both the amine content and the type of amine. The functional integrity of plasmid DNA in cationized pullulan tubes was demonstrated by in vitro transfection of VSMCs. Hence, cationized pullulan hydrogels can be designed as tubular structures with high affinity for plasmid DNA, which may provide new biomaterials to enhance the efficiency of local arterial gene transfer strategies.
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Tubular cationized pullulan hydrogels as local reservoirs for plasmid DNA
Journal of Biomedical Materials Research Part A, 2007Co-Authors: Aurélie San Juan, Grégory Ducrocq, Hanna Hlawaty, Isabelle Bataille, Erwann Guénin, Didier Letourneur, Laurent J. FeldmanAbstract:In the present study, we measured the ability of various cationized pullulan tubular hydrogels to retain plasmid DNA, and tested the ability of retained plasmid DNA to transfect vascular smooth muscle cells (VSMCs). Cationized Pullulans were obtained by grafting at different charge densities ethylamine (EA) or diethylaminoethyl-amine (DEAE) on the pullulan backbone. Polymers were characterized by elemental analysis, acid-base titration, size exclusion chromatography, Fourier-transform infrared spectroscopy, and proton nuclear magnetic resonance. The complexation of cationized Pullulans in solution with plasmid DNA was evidenced by fluorescence quenching with PicoGreen. Cationized Pullulans were then chemically crosslinked with phosphorus oxychloride to obtain tubular cationized pullulan hydrogels. Native pullulan tubes did not retain loaded plasmid DNA. In contrast, the ability of cationized pullulan tubes to retain plasmid DNA was dependent on both the amine content and the type of amine. The functional integrity of plasmid DNA in cationized pullulan tubes was demonstrated by in vitro transfection of VSMCs. Hence, cationized pullulan hydrogels can be designed as tubular structures with high affinity for plasmid DNA, which may provide new biomaterials to enhance the efficiency of local arterial gene transfer strategies. (c) 2007 Wiley Periodicals, Inc.
J.m. Catchmark - One of the best experts on this subject based on the ideXlab platform.
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effects of initial ammonium ion concentration on pullulan production by aureobasidium Pullulans and its modeling
Journal of Food Engineering, 2011Co-Authors: Kuan-chen Cheng, J.m. Catchmark, Ali Demirci, Virendra M PuriAbstract:Pullulan fermentations by Aureobasidium Pullulans with various initial ammonium ion concentrations were evaluated in a 2-L bioreactor. The results demonstrated that A. Pullulans produced highest pullulan (23.1 g/L) when the initial ammonium sulfate was 7 at 5 g/L. The purity of produced pullulan was 94.6%. Seven gram per liter of ammonium sulfate produced more biomass due to the higher level of nitrogen source, but the pullulan-degrading enzyme activity was detected after the depletion of sucrose, which reduced pullulan concentration. From the results of fed-batch fermentation, addition of 10 g/L of sucrose suppressed A. Pullulans from producing pullulan-degrading enzyme. Additionally, the modified-Gompertz equation demonstrated its generality to fit all pullulan production, biomass production, and sucrose consumption curves at three ammonium sulfate levels. After incorporating the degrading factor, a re-modified-Gompertz equation was obtained that can adequately describe the decrease of pullulan at the late fermentation stage.
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continuous pullulan fermentation in a biofilm reactor
Applied Microbiology and Biotechnology, 2011Co-Authors: Kuan-chen Cheng, Ali Demirci, J.m. CatchmarkAbstract:Biofilm is a natural form of cell immobilization in which microorganisms attach onto solid support. In this study, a pigment-reduced pullulan-producing strain, Aureobasidium Pullulans (ATCC 201253), was used for continuous pullulan fermentation in a plastic composite support (PCS) biofilm reactor. Optimal conditions for the continuous pullulan production were determined by evaluating the effects of the feeding medium with various concentrations of ammonium sulfate and sucrose and dilution rate. Pullulan concentration and production rate reached maximum (8.3 g/l and 1.33 g/l/h) when 15 g/l of sucrose, 0.9 g/l of ammonium sulfate, and 0.4 g/l of yeast extract were applied in the medium, and the dilution rate was at 0.16 h−1. The purity of produced pullulan was 93.0%. The ratio of hyphal cells of A. Pullulans increased when it was grown on the PCS shaft. Overall, the increased pullulan productivity can be achieved through biomass retention by using PCS biofilm reactor.
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Continuous Pullulan Fermentation in a PCS Biofilm Reactor
Applied Microbiology and Biotechnology, 2011Co-Authors: Kuan-chen Cheng, Ali Demirci, J.m. CatchmarkAbstract:Biofilms are natural form of cell immobilization in which microorganisms attach onto solid support. In this study, a pigment-reduced pullulan-producing strain, Aureobasidium Pullulans (ATCC 201253), was used for continuous pullulan fermentation in a Plastic Composite Support (PCS) biofilm reactor. Optimal conditions for the continuous pullulan production were determined by evaluating the effects of the feeding medium (concentrations of ammonium sulfate and sucrose) and dilution rate. Pullulan concentration and production rate reached maximum (8.3 g/l and 1.33 g/l/h) when 15 g/l of sucrose, 0.9 g/l of ammonium sulfate and 0.4 g/l of yeast extract were applied in the medium, and the dilution rate was at 0.16 h-1. For system stability evaluation, A. Pullulans produced equal amount of pullulan after 60 residence times, and the purity of produced pullulan was 93.0%. The ratio of hyphal form cells on the PCS increased since the solid support is more suitable for the attachment of filamentous cells. Overall, the increased pullulan productivity can be achieved through biomass retention by using PCS biofilm reactor.
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Pullulan: Biosynthesis, production, and applications
Applied Microbiology and Biotechnology, 2011Co-Authors: Kuan-chen Cheng, Ali Demirci, J.m. CatchmarkAbstract:Pullulan is a linear glucosic polysaccharide produced by the polymorphic fungus Aureobasidium Pullulans, which has long been applied for various applications from food additives to environmental remediation agents. This review article presents an overview of pullulan's chemistry, biosynthesis, applications, state-of-the-art advances in the enhancement of pullulan production through the investigations of enzyme regulations, molecular properties, cultivation parameters, and bioreactor design. The enzyme regulations are intended to illustrate the influences of metabolic pathway on pullulan production and its structural composition. Molecular properties, such as molecular weight distribution and pure pullulan content, of pullulan are crucial for pullulan applications and vary with different fermentation parameters. Studies on the effects of environmental parameters and new bioreactor design for enhancing pullulan production are getting attention. Finally, the potential applications of pullulan through chemical modification as a novel biologically active derivative are also discussed.
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modeling of pullulan fermentation by using a color variant strain of aureobasidium Pullulans
Journal of Food Engineering, 2010Co-Authors: Kuan-chen Cheng, J.m. Catchmark, Ali Demirci, Virendra M PuriAbstract:Abstract Pullulan, which is comprised of glucose units, is a simple linear polysaccharide produced by Aureobasidium Pullulans. Pullulan has long been used in various applications such as blood plasma substitutes, food additives, adhesive additives, flocculants, and even environmental pollution control agents. Mathematical models of biomass, pullulan, and sucrose profiles during fermentation not only provide information about the kinetic-metabolic nature of pullulan, but also facilitate the control and optimization of pullulan production. In this study, several models were modified and tested in order to describe biomass, pullulan, and sucrose profiles during batch fermentation using a color variant strain of A. Pullulans. The results demonstrated that the modified Gompertz model can serve as a universal equation to fit biomass production, pullulan production, and sucrose consumption. Furthermore, validation of this modified Gompertz model indicated that biomass (slope = 1.00, R2 = 0.991), pullulan (slope = 1.10, R2 = 0.991), and sucrose (slope = 0.96, R2 = 0.991) were all predicted accurately.
Kuan-chen Cheng - One of the best experts on this subject based on the ideXlab platform.
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effects of initial ammonium ion concentration on pullulan production by aureobasidium Pullulans and its modeling
Journal of Food Engineering, 2011Co-Authors: Kuan-chen Cheng, J.m. Catchmark, Ali Demirci, Virendra M PuriAbstract:Pullulan fermentations by Aureobasidium Pullulans with various initial ammonium ion concentrations were evaluated in a 2-L bioreactor. The results demonstrated that A. Pullulans produced highest pullulan (23.1 g/L) when the initial ammonium sulfate was 7 at 5 g/L. The purity of produced pullulan was 94.6%. Seven gram per liter of ammonium sulfate produced more biomass due to the higher level of nitrogen source, but the pullulan-degrading enzyme activity was detected after the depletion of sucrose, which reduced pullulan concentration. From the results of fed-batch fermentation, addition of 10 g/L of sucrose suppressed A. Pullulans from producing pullulan-degrading enzyme. Additionally, the modified-Gompertz equation demonstrated its generality to fit all pullulan production, biomass production, and sucrose consumption curves at three ammonium sulfate levels. After incorporating the degrading factor, a re-modified-Gompertz equation was obtained that can adequately describe the decrease of pullulan at the late fermentation stage.
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continuous pullulan fermentation in a biofilm reactor
Applied Microbiology and Biotechnology, 2011Co-Authors: Kuan-chen Cheng, Ali Demirci, J.m. CatchmarkAbstract:Biofilm is a natural form of cell immobilization in which microorganisms attach onto solid support. In this study, a pigment-reduced pullulan-producing strain, Aureobasidium Pullulans (ATCC 201253), was used for continuous pullulan fermentation in a plastic composite support (PCS) biofilm reactor. Optimal conditions for the continuous pullulan production were determined by evaluating the effects of the feeding medium with various concentrations of ammonium sulfate and sucrose and dilution rate. Pullulan concentration and production rate reached maximum (8.3 g/l and 1.33 g/l/h) when 15 g/l of sucrose, 0.9 g/l of ammonium sulfate, and 0.4 g/l of yeast extract were applied in the medium, and the dilution rate was at 0.16 h−1. The purity of produced pullulan was 93.0%. The ratio of hyphal cells of A. Pullulans increased when it was grown on the PCS shaft. Overall, the increased pullulan productivity can be achieved through biomass retention by using PCS biofilm reactor.
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Continuous Pullulan Fermentation in a PCS Biofilm Reactor
Applied Microbiology and Biotechnology, 2011Co-Authors: Kuan-chen Cheng, Ali Demirci, J.m. CatchmarkAbstract:Biofilms are natural form of cell immobilization in which microorganisms attach onto solid support. In this study, a pigment-reduced pullulan-producing strain, Aureobasidium Pullulans (ATCC 201253), was used for continuous pullulan fermentation in a Plastic Composite Support (PCS) biofilm reactor. Optimal conditions for the continuous pullulan production were determined by evaluating the effects of the feeding medium (concentrations of ammonium sulfate and sucrose) and dilution rate. Pullulan concentration and production rate reached maximum (8.3 g/l and 1.33 g/l/h) when 15 g/l of sucrose, 0.9 g/l of ammonium sulfate and 0.4 g/l of yeast extract were applied in the medium, and the dilution rate was at 0.16 h-1. For system stability evaluation, A. Pullulans produced equal amount of pullulan after 60 residence times, and the purity of produced pullulan was 93.0%. The ratio of hyphal form cells on the PCS increased since the solid support is more suitable for the attachment of filamentous cells. Overall, the increased pullulan productivity can be achieved through biomass retention by using PCS biofilm reactor.
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Pullulan: Biosynthesis, production, and applications
Applied Microbiology and Biotechnology, 2011Co-Authors: Kuan-chen Cheng, Ali Demirci, J.m. CatchmarkAbstract:Pullulan is a linear glucosic polysaccharide produced by the polymorphic fungus Aureobasidium Pullulans, which has long been applied for various applications from food additives to environmental remediation agents. This review article presents an overview of pullulan's chemistry, biosynthesis, applications, state-of-the-art advances in the enhancement of pullulan production through the investigations of enzyme regulations, molecular properties, cultivation parameters, and bioreactor design. The enzyme regulations are intended to illustrate the influences of metabolic pathway on pullulan production and its structural composition. Molecular properties, such as molecular weight distribution and pure pullulan content, of pullulan are crucial for pullulan applications and vary with different fermentation parameters. Studies on the effects of environmental parameters and new bioreactor design for enhancing pullulan production are getting attention. Finally, the potential applications of pullulan through chemical modification as a novel biologically active derivative are also discussed.
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modeling of pullulan fermentation by using a color variant strain of aureobasidium Pullulans
Journal of Food Engineering, 2010Co-Authors: Kuan-chen Cheng, J.m. Catchmark, Ali Demirci, Virendra M PuriAbstract:Abstract Pullulan, which is comprised of glucose units, is a simple linear polysaccharide produced by Aureobasidium Pullulans. Pullulan has long been used in various applications such as blood plasma substitutes, food additives, adhesive additives, flocculants, and even environmental pollution control agents. Mathematical models of biomass, pullulan, and sucrose profiles during fermentation not only provide information about the kinetic-metabolic nature of pullulan, but also facilitate the control and optimization of pullulan production. In this study, several models were modified and tested in order to describe biomass, pullulan, and sucrose profiles during batch fermentation using a color variant strain of A. Pullulans. The results demonstrated that the modified Gompertz model can serve as a universal equation to fit biomass production, pullulan production, and sucrose consumption. Furthermore, validation of this modified Gompertz model indicated that biomass (slope = 1.00, R2 = 0.991), pullulan (slope = 1.10, R2 = 0.991), and sucrose (slope = 0.96, R2 = 0.991) were all predicted accurately.
Aurélie San Juan - One of the best experts on this subject based on the ideXlab platform.
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Tubular cationized pullulan hydrogels as local reservoirs for plasmid DNA
Journal of Biomedical Materials Research Part A, 2007Co-Authors: Aurélie San Juan, Grégory Ducrocq, Hanna Hlawaty, Isabelle Bataille, Erwann Guénin, Didier Letourneur, Laurent J. FeldmanAbstract:1 - ArticleIn the present study, we measured the ability of various cationized pullulan tubular hydrogels to retain plasmid DNA, and tested the ability of retained plasmid DNA to transfect vascular smooth muscle cells (VSMCs). Cationized Pullulans were obtained by grafting at different charge densities ethylamine (EA) or diethylaminoethyl-amine (DEAE) on the pullulan backbone. Polymers were characterized by elemental analysis, acid-base titration, size exclusion chromatography, Fourier-transform infrared spectroscopy, and proton nuclear magnetic resonance. The complexation of cationized Pullulans in solution with plasmid DNA was evidenced by fluorescence quenching with PicoGreen. Cationized Pullulans were then chemically crosslinked with phosphorus oxychloride to obtain tubular cationized pullulan hydrogels. Native pullulan tubes did not retain loaded plasmid DNA. In contrast, the ability of cationized pullulan tubes to retain plasmid DNA was dependent on both the amine content and the type of amine. The functional integrity of plasmid DNA in cationized pullulan tubes was demonstrated by in vitro transfection of VSMCs. Hence, cationized pullulan hydrogels can be designed as tubular structures with high affinity for plasmid DNA, which may provide new biomaterials to enhance the efficiency of local arterial gene transfer strategies. (c) 2007 Wiley Periodicals, Inc
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Tubular cationized pullulan hydrogels as local reservoirs for plasmid DNA.
Journal of biomedical materials research. Part A, 2007Co-Authors: Aurélie San Juan, Grégory Ducrocq, Hanna Hlawaty, Isabelle Bataille, Erwann Guénin, Didier Letourneur, Laurent J. FeldmanAbstract:In the present study, we measured the ability of various cationized pullulan tubular hydrogels to retain plasmid DNA, and tested the ability of retained plasmid DNA to transfect vascular smooth muscle cells (VSMCs). Cationized Pullulans were obtained by grafting at different charge densities ethylamine (EA) or diethylaminoethylamine (DEAE) on the pullulan backbone. Polymers were characterized by elemental analysis, acid-base titration, size exclusion chromatography, Fourier-transform infrared spectroscopy, and proton nuclear magnetic resonance. The complexation of cationized Pullulans in solution with plasmid DNA was evidenced by fluorescence quenching with PicoGreen. Cationized Pullulans were then chemically crosslinked with phosphorus oxychloride to obtain tubular cationized pullulan hydrogels. Native pullulan tubes did not retain loaded plasmid DNA. In contrast, the ability of cationized pullulan tubes to retain plasmid DNA was dependent on both the amine content and the type of amine. The functional integrity of plasmid DNA in cationized pullulan tubes was demonstrated by in vitro transfection of VSMCs. Hence, cationized pullulan hydrogels can be designed as tubular structures with high affinity for plasmid DNA, which may provide new biomaterials to enhance the efficiency of local arterial gene transfer strategies.
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Tubular cationized pullulan hydrogels as local reservoirs for plasmid DNA
Journal of Biomedical Materials Research Part A, 2007Co-Authors: Aurélie San Juan, Grégory Ducrocq, Hanna Hlawaty, Isabelle Bataille, Erwann Guénin, Didier Letourneur, Laurent J. FeldmanAbstract:In the present study, we measured the ability of various cationized pullulan tubular hydrogels to retain plasmid DNA, and tested the ability of retained plasmid DNA to transfect vascular smooth muscle cells (VSMCs). Cationized Pullulans were obtained by grafting at different charge densities ethylamine (EA) or diethylaminoethyl-amine (DEAE) on the pullulan backbone. Polymers were characterized by elemental analysis, acid-base titration, size exclusion chromatography, Fourier-transform infrared spectroscopy, and proton nuclear magnetic resonance. The complexation of cationized Pullulans in solution with plasmid DNA was evidenced by fluorescence quenching with PicoGreen. Cationized Pullulans were then chemically crosslinked with phosphorus oxychloride to obtain tubular cationized pullulan hydrogels. Native pullulan tubes did not retain loaded plasmid DNA. In contrast, the ability of cationized pullulan tubes to retain plasmid DNA was dependent on both the amine content and the type of amine. The functional integrity of plasmid DNA in cationized pullulan tubes was demonstrated by in vitro transfection of VSMCs. Hence, cationized pullulan hydrogels can be designed as tubular structures with high affinity for plasmid DNA, which may provide new biomaterials to enhance the efficiency of local arterial gene transfer strategies. (c) 2007 Wiley Periodicals, Inc.
