Structure and properties of bioabsorbable polyglycolide (PGA) and poly(glycolide-co-lactide) (PGA-co-PLA)fibers were investigated during several industrial processing stages and in vitro degradation by means of wide-a...Structure and properties of bioabsorbable polyglycolide (PGA) and poly(glycolide-co-lactide) (PGA-co-PLA)fibers were investigated during several industrial processing stages and in vitro degradation by means of wide-angle X-raydiffraction (WAXD), dynamic mechanical analysis (DMA) and mechanical property tests. In the orientation stage, the PGAfibers were found to have higher degrees of crystallinity than corresponding PGA-co-PLA samples produced under similarconditions. In the hot-stretching and post-annealing stages, after fibers were braided, PGA samples were found to gain morecrystallinity and higher T_g than PGA-co-PLA samples. The higher crystallinity in PGA fibers resulted in a slower rate ofdegradation. DMA results showed that a great deal of internal stress that was built during orientation and hot-stretchingstages was released in the post-annealing stage for a1l PGA and PGA-co-PLA samples. During earlier stages of in vitrodegradation, both PGA and PGA-co-PLA samples exhibited the typical cleavage-induced crystallization mechanism. Theheat shrinkage in the glass transition area was found to disappear after 6-8 days of degradation for all PGA and PGA-co-PLAsamples, indicating the amorphous portions of the polymers lost orientation after a short period in the buffer solution, mostlikely due to relaxation of the cleaved chains.展开更多
For monomer reactivity ratios study, the copolymerization of D,L-3-methylglycolide (MG) with glycolide (GA) or D,L-lactide (LA) was carried out in bulk to a certain low conversion in the presence of stannous octoate a...For monomer reactivity ratios study, the copolymerization of D,L-3-methylglycolide (MG) with glycolide (GA) or D,L-lactide (LA) was carried out in bulk to a certain low conversion in the presence of stannous octoate at 140 degrees C. The copolymer compositions were determined by H-1 NMR spectroscopy. The monomer reactivity ratios were evaluated by Fineman-Ross method, Kelen-Tudos method and linear least-squares method. The monomer reactivity ratios of D,L-3-methylglycolide and glycolide or D,L-lactide are r(mg)= 0.73, r(ga)= 1.47; r(mg)= 1.71, r(la)= 0.92, respectively.展开更多
A novel polyester containing glycolic acid(GA)and 2 hydro 2 oxo 1,3,2 dioxaphosphorinane(TMP)was prepared by ring opening polymerization.The composition and the structure of the titled polymer were investigated by 1...A novel polyester containing glycolic acid(GA)and 2 hydro 2 oxo 1,3,2 dioxaphosphorinane(TMP)was prepared by ring opening polymerization.The composition and the structure of the titled polymer were investigated by 1H NMR, 13 C NMR,FT IR,EA,and VPO.The influence of time on total conversion and molecular weight was also studied.展开更多
Poly （ l- lactide- co-glycolide ） （ PLGA ） with different compositions was prepared using stannous octaoate as catalyst by bulk ring-opening copolymerization of l-lactide and glycolide. The structure and properti...Poly （ l- lactide- co-glycolide ） （ PLGA ） with different compositions was prepared using stannous octaoate as catalyst by bulk ring-opening copolymerization of l-lactide and glycolide. The structure and properties of the PLGA copolymers were cbaracterized by means of attenuated total reflectance-Fourier transform infrared （ATR-FTIR）, ^1H NMR, differential scanning calorimeter （ DSC and X-ray diffraction （XRD） methods, The experimented results indicate that the synthetic conditions and the composition of copolymers have art obvious influence on the structure of PLGA copolymers, The degradation rate of eopolymers increased with the increasing of the glycolide component in the copolymers.展开更多
Electrospun aligned ultrafine fibers of poly( lactide-coglycolide)( PLGA) can be used to construct biomimetic scaffolds for engineering those structurally anisotropic and dense tissues( e. g.,tendon,ligament,etc.). Bu...Electrospun aligned ultrafine fibers of poly( lactide-coglycolide)( PLGA) can be used to construct biomimetic scaffolds for engineering those structurally anisotropic and dense tissues( e. g.,tendon,ligament,etc.). But the acidic degradation products of the PLGA could result in p H decrease in the vicinity of the scaffolds,which may give rise to biocompatibility concerns. To address the noted problem, this study was designed to evaluate the p Hcompensation capacity of using Lysine( Lys) —a kind of basic amino acid on the acidic degradation products of PLGA. Ultrafine PLGA( 50∶ 50) fibers with 0,10%,20%,and 30% by weight of Lys loadings were prepared by a stable jet electrospinning( SJES)approach. The morphology,structure,and mechanical properties of the electrospun aligned fibrous mats of Lys-incorporated PLGA( 50∶50) were characterized by scanning electron microscope( SEM),Fourier transform infrared spectroscopy( FTIR),and tensile testing,respectively. Thereafter,the fibrous PLGA( 50 ∶50) scaffolds were subjected to degradation by being immersed in phosphate buffered saline( PBS,p H 6. 86) solution at 37 ℃ for 5weeks. Our results show that the formed Lys / PLGA composite ultrafine fibers have a well-aligned and uniform morphology with a fineness of ca. 1 #m in diameter. Introduction of Lys led to increased mechanical performance; that is,when the Lys loading is less than 30%,tensile strength and Young's modulus of the aligned Lys / PLGA fibers reached up to the impressive values of 84. 5 MPa and 2. 4 GPa,respectively. Degradation results show that the p H of the PLGA group fell to 5. 6 in 5 weeks while the p H of the Lys /PLGA groups with 10%,20%, and 30% of Lys loadings was maintained at 6. 3, 6. 5 and 6. 7, respectively. This work demonstrated that incorporation of Lys into electrospun PLGA fibers could be an effective approach in mediating the p H decrease caused by the acidic degradation products of the PLGA.展开更多
PLGA thin films were prepared onto implantable devices by the electrospray and pressurized spray method. Thin films with structural gradients were obtained by controlling four parameters consisting of solution conce...PLGA thin films were prepared onto implantable devices by the electrospray and pressurized spray method. Thin films with structural gradients were obtained by controlling four parameters consisting of solution concentration, applied voltage, air pressure , and deposition time. The surface morphologies of the deposited films were observed using scanning electron microscopy （SEM）. The image analysis revealed the control factors on the preparation of PLGA thin films. The beaded structure is ensily formed with a decrease in polymer concentration while the fibrous structure is easily formed with an increuse in polymer concentration. With the increase in applied voltage, the surface morphologies changed continnously from a small amount of fibrous shape to a large fibrous one： a small amount of.fibrous shape at 10 kV, more fibers with non-uniform diameter at 20 kV, and most fibers with uniform diameter at 30 kV. Low air pressure（0.1 MPa ） corresponded to round particles while high air pressure （0.3 MPa ） corresponded to fiat particles. The change in thickness from 5.34 to 10.1μm was a result of deposition time increasing from 5 to 10 s. From our above work, films of the bead or fiber structures can be obtained by changing electrical parameters to impropvc tbe biocompntibility of the film.展开更多
The purposes of this research were to synthesize and characterize star-shaped poly lactide-co-glycolide-β-cyclo-dextrin (PLGA-β-CD) copolymer by reacting L-lactide, glycolide and β-cyclodextrin in the presence of s...The purposes of this research were to synthesize and characterize star-shaped poly lactide-co-glycolide-β-cyclo-dextrin (PLGA-β-CD) copolymer by reacting L-lactide, glycolide and β-cyclodextrin in the presence of stannous octoate as a catalyst. The structure of PLGA-β-CD copolymer was confirmed with 1H-NMR, 13C-NMR and FT-IR spectra. Albumin as a model peptide drug was encapsulated within nanoparticles made of PLGA-β-CD with a modified double emulsion method. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) photomicrographs showed that the nanoparticles have the mean diameter within the range of 80 - 210 nm. Also they were almost spherical in shape. Effects of the experimental parameters, such as copolymer composition, copolymer concentration, and reaction temperature, on particular size and encapsulation efficiency were investigated.展开更多
Background Glaucoma filtering surgery （GFS） is the most common procedure performed in the treatment of glaucoma.Although antiscarring agents help prevent postsurgical scarring and improve glaucoma surgical outcomes,...Background Glaucoma filtering surgery （GFS） is the most common procedure performed in the treatment of glaucoma.Although antiscarring agents help prevent postsurgical scarring and improve glaucoma surgical outcomes,they may be associated with an increased incidence of severe and potentially blinding complications.Poly（DL-lactide-co-glycolide） （PDLLA/GA） is a bioresorbable polymer,which can be prepared with a large range of physical,mechanical,and biological properties and has been widely used in medicine,including as an absorbable suture and a drug carrier and especially as a scaffold in tissue engineering.This study aimed to evaluate the effect of PDLLA/GA on scar formation after glaucoma filtration surgery （GFS）.Methods Forty-eight New Zealand white rabbits were divided into two groups randomly and GFS was performed on the right eye of each.PDLLA/GA membranes were put under the sclera flap for evaluation.GFS with no membrane inserted served as control.Clinical evaluations of intraocular pressure （lOP） and the presence of a filtration bleb were performed at intervals （3 days,1,2,4,8,12,20,and 24 weeks） postoperatively.At each time point,three eyes per group were excised to observe histological changes such as inflammation and scar formation and the expression of collagen type Ⅳ,proliferating cell nuclear antigen （PCNA）,matrix metalloproteinase-9 （MMP-9）,and tissue inhibitor of metalloproteinase-1 （TIMP-1）.The expression of connective tissue growth factor （CTGF） mRNA was determined by reverse transcription-polymerase chain reaction.Results The lower lOP level and an effective bleb were maintained for a long time after GFS in the PDLLA/GA group.The histological analysis showed less inflammation and scar formation,weaker expression of collagen type Ⅳ and PCNA,more intense MMP-9 and TIMP-1,slightly elevated ratio of MMP-9 and TIMP-1,and a smaller increase in CTGF mRNA postoperatively in the PDLLA/GA group but less than the control group （P ＜0.05）.Conclusion PDLLA/GA membranes may be promising for preventing fibrosis after GFS.展开更多
An electrospun poly（lactide-co-glycolide） （PLGA） membrane was prepared and used to perform the anti-adhesion of Achilles tendon. Throughout the experiments, the membrane showed an appropriate degradation rate, and...An electrospun poly（lactide-co-glycolide） （PLGA） membrane was prepared and used to perform the anti-adhesion of Achilles tendon. Throughout the experiments, the membrane showed an appropriate degradation rate, and the pH values of degradation media were maintained at around 7.4. Simultaneously, the excellent biocompatibility of the membrane in vitro and in vivo was confirmed by live/dead and histopathological analyses. Meanwhile, the membrane can reduce tendon adhesion significantly and promote functional recovery effectively. The encouraging results were further demonstrated by hematoxylin and eosin （H＆E）, and Masson＇s trichrome stainings, and type I collagen immunohistochemical analysis. It was concluded that the model treated with the electrospun PLGA membrane was significantly better with respect to the adhesion prevention and tissue repair than that without treatment. Considering the results of degradation and adhesion prevention efficacy, the electrospun PLGA membrane would be a great candidate for the prevention of postoperative tendon adhesion.展开更多
A composite construct comprising of a bone mesenchymal stem cell (BMSC) sheet, plasmid DNA, encoding human bone morphogenic protein-2 (hBMP-2), and poly(lactide-co-glycolide)/hydroxyapatite (PLGA/HA) sponge was design...A composite construct comprising of a bone mesenchymal stem cell (BMSC) sheet, plasmid DNA, encoding human bone morphogenic protein-2 (hBMP-2), and poly(lactide-co-glycolide)/hydroxyapatite (PLGA/HA) sponge was designed and employed in the restoration of rat calvarial defects. To improve gene transfection efficiency, a cationic chitosan derivative, N,N,N,-trimethyl chitosan chloride (TMC), was employed as the vector. The TMC/DNA complexes had a transfection efficiency of 13% in rat BMSCs, resulting in heterogeneous hBMP-2 expression in a 10-d culture period in vitro. In vivo culture of the composite constructs was performed by implantation into rat full-thickness calvarial defects, using constructs lacking pDNA-hBMP-2 or BMSC sheets as controls. Significantly higher heterogeneous expression of hBMP-2 was detected in vivo at 2 weeks for the cell sheet/DNA complex/scaffold constructs, compared with the constructs lacking pDNA-hBMP-2 or BMSC sheets. New bone formation was evident as early as 4 weeks in the experimental constructs. At 8 weeks, partial bridging of calvarial defects was observed in the experimental constructs, which was significantly better than the constructs lacking pDNA-hBMP-2 or BMSC sheets. Therefore, the combination of the PLGA/HA scaffold with BMSC sheets and gene therapy vectors is effective at enhancing bone formation.展开更多
This study aimed to prepare and characterize itraconazole (ITCZ)- or miconazole (MCZ)-loaded poly (lactide-co-glycolide) (PLGA) microparticles (MP) using a co-grinding method with ball milling, which is a solvent-free...This study aimed to prepare and characterize itraconazole (ITCZ)- or miconazole (MCZ)-loaded poly (lactide-co-glycolide) (PLGA) microparticles (MP) using a co-grinding method with ball milling, which is a solvent-free and convenient procedure. PLGA MP was prepared by grinding for 60 min, and the fixed theoretical drug loading was set at 9.1% and 16.7% for both drugs. The obtained loading efficiency for both drugs was estimated to be approximately 100%. The average diameters of the drug-loaded PLGA MP were approximately 20 - 35 μm. Powder X-ray diffraction (PXRD) or differential scanning calorimetry (DSC) confirmed amorphization of ITCZ and MCZ in ITCZ- or MCZ-loaded PLGA MP in all formulations. The drug release percentage from 9.1%-loaded ITCZ-PLGA7505 MP at 24 h was almost 50%, which was higher than that of ITCZ powder. The drug release percentage from MCZ-loaded PLGA7505 MP at 4 h was over 80%, which was higher than that of MCZ powder. This enhancement of release rate is caused by the amorphization of ITCZ or MCZ in the PLGA matrix. MCZ-loaded PLGA7510 MP showed a sustained release profile up to 24 h, suggesting that MCZ exists in an amorphous form in the PLGA matrix;however, the release rate declined owing to the large molecular weight of PLGA. Therefore, the release enhancement of antifungal drugs loaded on PLGA MP could be achieved by their amorphization using a co-grinding method with ball milling.展开更多
聚乙交酯丙交酯类共聚物(PGLA)聚合工艺中,催化剂多采用锡基催化剂,过量的残留锡(Sn)会对人体造成生物毒害。因此,为有效监控聚合工艺中生产物料的Sn含量,需要建立一套准确并快速的检测方法。通过优化微波消解条件和配方,并配合电感耦...聚乙交酯丙交酯类共聚物(PGLA)聚合工艺中,催化剂多采用锡基催化剂,过量的残留锡(Sn)会对人体造成生物毒害。因此,为有效监控聚合工艺中生产物料的Sn含量,需要建立一套准确并快速的检测方法。通过优化微波消解条件和配方,并配合电感耦合等离子体发射光谱(ICP-OES)法,建立了可用于测定PGLA产品中Sn含量的分析方法。称取0.10 g PGLA试样,以7 mL 65%~68%硝酸(HNO3)为消解液,消解温度最高为220℃。采用内标法进行定性定量分析,样品重复度好,RSD为3.65%。加标回收率在112%~115%,满足PGLA试样中的Sn含量分析需求,为工艺优化和产品质量控制提供了一种简单、实用的分析方法。展开更多
基金This research was made possible by a Johnson & Johnson CORD Internship Award funded by Ethicon. BH and BF thank the National Science Foundation for partial financial support (DMR-0098104).
文摘Structure and properties of bioabsorbable polyglycolide (PGA) and poly(glycolide-co-lactide) (PGA-co-PLA)fibers were investigated during several industrial processing stages and in vitro degradation by means of wide-angle X-raydiffraction (WAXD), dynamic mechanical analysis (DMA) and mechanical property tests. In the orientation stage, the PGAfibers were found to have higher degrees of crystallinity than corresponding PGA-co-PLA samples produced under similarconditions. In the hot-stretching and post-annealing stages, after fibers were braided, PGA samples were found to gain morecrystallinity and higher T_g than PGA-co-PLA samples. The higher crystallinity in PGA fibers resulted in a slower rate ofdegradation. DMA results showed that a great deal of internal stress that was built during orientation and hot-stretchingstages was released in the post-annealing stage for a1l PGA and PGA-co-PLA samples. During earlier stages of in vitrodegradation, both PGA and PGA-co-PLA samples exhibited the typical cleavage-induced crystallization mechanism. Theheat shrinkage in the glass transition area was found to disappear after 6-8 days of degradation for all PGA and PGA-co-PLAsamples, indicating the amorphous portions of the polymers lost orientation after a short period in the buffer solution, mostlikely due to relaxation of the cleaved chains.
基金This work was supported by the Key Project of the National Natural Science Foundation of China!(59833 140).
文摘For monomer reactivity ratios study, the copolymerization of D,L-3-methylglycolide (MG) with glycolide (GA) or D,L-lactide (LA) was carried out in bulk to a certain low conversion in the presence of stannous octoate at 140 degrees C. The copolymer compositions were determined by H-1 NMR spectroscopy. The monomer reactivity ratios were evaluated by Fineman-Ross method, Kelen-Tudos method and linear least-squares method. The monomer reactivity ratios of D,L-3-methylglycolide and glycolide or D,L-lactide are r(mg)= 0.73, r(ga)= 1.47; r(mg)= 1.71, r(la)= 0.92, respectively.
文摘A novel polyester containing glycolic acid(GA)and 2 hydro 2 oxo 1,3,2 dioxaphosphorinane(TMP)was prepared by ring opening polymerization.The composition and the structure of the titled polymer were investigated by 1H NMR, 13 C NMR,FT IR,EA,and VPO.The influence of time on total conversion and molecular weight was also studied.
文摘Poly （ l- lactide- co-glycolide ） （ PLGA ） with different compositions was prepared using stannous octaoate as catalyst by bulk ring-opening copolymerization of l-lactide and glycolide. The structure and properties of the PLGA copolymers were cbaracterized by means of attenuated total reflectance-Fourier transform infrared （ATR-FTIR）, ^1H NMR, differential scanning calorimeter （ DSC and X-ray diffraction （XRD） methods, The experimented results indicate that the synthetic conditions and the composition of copolymers have art obvious influence on the structure of PLGA copolymers, The degradation rate of eopolymers increased with the increasing of the glycolide component in the copolymers.
基金Fundamental Research Funds for the Central Universities,China(No.14D110519)Pujiang Talent Program Funded by theScience and Technology Commission of Shanghai M unicipality,China(No.10PJ1400200)National Natural Science Foundation of China(No.51073032)
文摘Electrospun aligned ultrafine fibers of poly( lactide-coglycolide)( PLGA) can be used to construct biomimetic scaffolds for engineering those structurally anisotropic and dense tissues( e. g.,tendon,ligament,etc.). But the acidic degradation products of the PLGA could result in p H decrease in the vicinity of the scaffolds,which may give rise to biocompatibility concerns. To address the noted problem, this study was designed to evaluate the p Hcompensation capacity of using Lysine( Lys) —a kind of basic amino acid on the acidic degradation products of PLGA. Ultrafine PLGA( 50∶ 50) fibers with 0,10%,20%,and 30% by weight of Lys loadings were prepared by a stable jet electrospinning( SJES)approach. The morphology,structure,and mechanical properties of the electrospun aligned fibrous mats of Lys-incorporated PLGA( 50∶50) were characterized by scanning electron microscope( SEM),Fourier transform infrared spectroscopy( FTIR),and tensile testing,respectively. Thereafter,the fibrous PLGA( 50 ∶50) scaffolds were subjected to degradation by being immersed in phosphate buffered saline( PBS,p H 6. 86) solution at 37 ℃ for 5weeks. Our results show that the formed Lys / PLGA composite ultrafine fibers have a well-aligned and uniform morphology with a fineness of ca. 1 #m in diameter. Introduction of Lys led to increased mechanical performance; that is,when the Lys loading is less than 30%,tensile strength and Young's modulus of the aligned Lys / PLGA fibers reached up to the impressive values of 84. 5 MPa and 2. 4 GPa,respectively. Degradation results show that the p H of the PLGA group fell to 5. 6 in 5 weeks while the p H of the Lys /PLGA groups with 10%,20%, and 30% of Lys loadings was maintained at 6. 3, 6. 5 and 6. 7, respectively. This work demonstrated that incorporation of Lys into electrospun PLGA fibers could be an effective approach in mediating the p H decrease caused by the acidic degradation products of the PLGA.
文摘PLGA thin films were prepared onto implantable devices by the electrospray and pressurized spray method. Thin films with structural gradients were obtained by controlling four parameters consisting of solution concentration, applied voltage, air pressure , and deposition time. The surface morphologies of the deposited films were observed using scanning electron microscopy （SEM）. The image analysis revealed the control factors on the preparation of PLGA thin films. The beaded structure is ensily formed with a decrease in polymer concentration while the fibrous structure is easily formed with an increuse in polymer concentration. With the increase in applied voltage, the surface morphologies changed continnously from a small amount of fibrous shape to a large fibrous one： a small amount of.fibrous shape at 10 kV, more fibers with non-uniform diameter at 20 kV, and most fibers with uniform diameter at 30 kV. Low air pressure（0.1 MPa ） corresponded to round particles while high air pressure （0.3 MPa ） corresponded to fiat particles. The change in thickness from 5.34 to 10.1μm was a result of deposition time increasing from 5 to 10 s. From our above work, films of the bead or fiber structures can be obtained by changing electrical parameters to impropvc tbe biocompntibility of the film.
文摘The purposes of this research were to synthesize and characterize star-shaped poly lactide-co-glycolide-β-cyclo-dextrin (PLGA-β-CD) copolymer by reacting L-lactide, glycolide and β-cyclodextrin in the presence of stannous octoate as a catalyst. The structure of PLGA-β-CD copolymer was confirmed with 1H-NMR, 13C-NMR and FT-IR spectra. Albumin as a model peptide drug was encapsulated within nanoparticles made of PLGA-β-CD with a modified double emulsion method. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) photomicrographs showed that the nanoparticles have the mean diameter within the range of 80 - 210 nm. Also they were almost spherical in shape. Effects of the experimental parameters, such as copolymer composition, copolymer concentration, and reaction temperature, on particular size and encapsulation efficiency were investigated.
文摘Background Glaucoma filtering surgery （GFS） is the most common procedure performed in the treatment of glaucoma.Although antiscarring agents help prevent postsurgical scarring and improve glaucoma surgical outcomes,they may be associated with an increased incidence of severe and potentially blinding complications.Poly（DL-lactide-co-glycolide） （PDLLA/GA） is a bioresorbable polymer,which can be prepared with a large range of physical,mechanical,and biological properties and has been widely used in medicine,including as an absorbable suture and a drug carrier and especially as a scaffold in tissue engineering.This study aimed to evaluate the effect of PDLLA/GA on scar formation after glaucoma filtration surgery （GFS）.Methods Forty-eight New Zealand white rabbits were divided into two groups randomly and GFS was performed on the right eye of each.PDLLA/GA membranes were put under the sclera flap for evaluation.GFS with no membrane inserted served as control.Clinical evaluations of intraocular pressure （lOP） and the presence of a filtration bleb were performed at intervals （3 days,1,2,4,8,12,20,and 24 weeks） postoperatively.At each time point,three eyes per group were excised to observe histological changes such as inflammation and scar formation and the expression of collagen type Ⅳ,proliferating cell nuclear antigen （PCNA）,matrix metalloproteinase-9 （MMP-9）,and tissue inhibitor of metalloproteinase-1 （TIMP-1）.The expression of connective tissue growth factor （CTGF） mRNA was determined by reverse transcription-polymerase chain reaction.Results The lower lOP level and an effective bleb were maintained for a long time after GFS in the PDLLA/GA group.The histological analysis showed less inflammation and scar formation,weaker expression of collagen type Ⅳ and PCNA,more intense MMP-9 and TIMP-1,slightly elevated ratio of MMP-9 and TIMP-1,and a smaller increase in CTGF mRNA postoperatively in the PDLLA/GA group but less than the control group （P ＜0.05）.Conclusion PDLLA/GA membranes may be promising for preventing fibrosis after GFS.
基金financially supported by the National Natural Science Foundation of China(Nos.51303174,51321062,51233004,51390484,51273196,and 51203153)the Scientific Development Program of Jilin Province(No.20140520050JH)
文摘An electrospun poly（lactide-co-glycolide） （PLGA） membrane was prepared and used to perform the anti-adhesion of Achilles tendon. Throughout the experiments, the membrane showed an appropriate degradation rate, and the pH values of degradation media were maintained at around 7.4. Simultaneously, the excellent biocompatibility of the membrane in vitro and in vivo was confirmed by live/dead and histopathological analyses. Meanwhile, the membrane can reduce tendon adhesion significantly and promote functional recovery effectively. The encouraging results were further demonstrated by hematoxylin and eosin （H＆E）, and Masson＇s trichrome stainings, and type I collagen immunohistochemical analysis. It was concluded that the model treated with the electrospun PLGA membrane was significantly better with respect to the adhesion prevention and tissue repair than that without treatment. Considering the results of degradation and adhesion prevention efficacy, the electrospun PLGA membrane would be a great candidate for the prevention of postoperative tendon adhesion.
基金supported by the National Natural Science Foundation of China (20934003)the Science Technology Program of Zhejiang Province (2009C14003, 2009C13020)the National Basic Research Program of China (2011CB606203)
文摘A composite construct comprising of a bone mesenchymal stem cell (BMSC) sheet, plasmid DNA, encoding human bone morphogenic protein-2 (hBMP-2), and poly(lactide-co-glycolide)/hydroxyapatite (PLGA/HA) sponge was designed and employed in the restoration of rat calvarial defects. To improve gene transfection efficiency, a cationic chitosan derivative, N,N,N,-trimethyl chitosan chloride (TMC), was employed as the vector. The TMC/DNA complexes had a transfection efficiency of 13% in rat BMSCs, resulting in heterogeneous hBMP-2 expression in a 10-d culture period in vitro. In vivo culture of the composite constructs was performed by implantation into rat full-thickness calvarial defects, using constructs lacking pDNA-hBMP-2 or BMSC sheets as controls. Significantly higher heterogeneous expression of hBMP-2 was detected in vivo at 2 weeks for the cell sheet/DNA complex/scaffold constructs, compared with the constructs lacking pDNA-hBMP-2 or BMSC sheets. New bone formation was evident as early as 4 weeks in the experimental constructs. At 8 weeks, partial bridging of calvarial defects was observed in the experimental constructs, which was significantly better than the constructs lacking pDNA-hBMP-2 or BMSC sheets. Therefore, the combination of the PLGA/HA scaffold with BMSC sheets and gene therapy vectors is effective at enhancing bone formation.
文摘This study aimed to prepare and characterize itraconazole (ITCZ)- or miconazole (MCZ)-loaded poly (lactide-co-glycolide) (PLGA) microparticles (MP) using a co-grinding method with ball milling, which is a solvent-free and convenient procedure. PLGA MP was prepared by grinding for 60 min, and the fixed theoretical drug loading was set at 9.1% and 16.7% for both drugs. The obtained loading efficiency for both drugs was estimated to be approximately 100%. The average diameters of the drug-loaded PLGA MP were approximately 20 - 35 μm. Powder X-ray diffraction (PXRD) or differential scanning calorimetry (DSC) confirmed amorphization of ITCZ and MCZ in ITCZ- or MCZ-loaded PLGA MP in all formulations. The drug release percentage from 9.1%-loaded ITCZ-PLGA7505 MP at 24 h was almost 50%, which was higher than that of ITCZ powder. The drug release percentage from MCZ-loaded PLGA7505 MP at 4 h was over 80%, which was higher than that of MCZ powder. This enhancement of release rate is caused by the amorphization of ITCZ or MCZ in the PLGA matrix. MCZ-loaded PLGA7510 MP showed a sustained release profile up to 24 h, suggesting that MCZ exists in an amorphous form in the PLGA matrix;however, the release rate declined owing to the large molecular weight of PLGA. Therefore, the release enhancement of antifungal drugs loaded on PLGA MP could be achieved by their amorphization using a co-grinding method with ball milling.
文摘聚乙交酯丙交酯类共聚物(PGLA)聚合工艺中,催化剂多采用锡基催化剂,过量的残留锡(Sn)会对人体造成生物毒害。因此,为有效监控聚合工艺中生产物料的Sn含量,需要建立一套准确并快速的检测方法。通过优化微波消解条件和配方,并配合电感耦合等离子体发射光谱(ICP-OES)法,建立了可用于测定PGLA产品中Sn含量的分析方法。称取0.10 g PGLA试样,以7 mL 65%~68%硝酸(HNO3)为消解液,消解温度最高为220℃。采用内标法进行定性定量分析,样品重复度好,RSD为3.65%。加标回收率在112%~115%,满足PGLA试样中的Sn含量分析需求,为工艺优化和产品质量控制提供了一种简单、实用的分析方法。
