CO_(2) flooding is a vital development method for enhanced oil recovery in low-permeability reservoirs,However,micro-fractures are developed in low-permeability reservoirs,which are essential oil flow channels but can...CO_(2) flooding is a vital development method for enhanced oil recovery in low-permeability reservoirs,However,micro-fractures are developed in low-permeability reservoirs,which are essential oil flow channels but can also cause severe CO_(2) gas channeling problems.Therefore,anti-gas channeling is a necessary measure to improve the effect of CO_(2) flooding.The kind of anti-gas channeling refers to the plugging of fractures in the deep formation to prevent CO_(2) gas channeling,which is different from the wellbore leakage.Polymer microspheres have the characteristics of controllable deep plugging,which can achieve the profile control of low-permeability fractured reservoirs.In acidic environments with supercritical CO_(2),traditional polymer microspheres have poor expandability and plugging properties.Based on previous work,a systematic evaluation of the expansion performance,dispersion rheological properties,stability,deep migration,anti-CO_(2) channeling and enhanced oil recovery ability of a novel acid-resistant polymer microsphere(DCNPM-A)was carried out under CQ oilifield conditions(salinity of85,000 mg/L,80℃,pH=3).The results show that the DCNPM-A microsphere had a better expansion performance than the traditional microsphere,with a swelling rate of 13.5.The microsphere dispersion with a concentration of 0.1%-0.5%had the advantages of low viscosity,high dispersion and good injectability in the low permeability fractured core.In the acidic environment of supercritical CO_(2),DCNPM-A microspheres showed excellent stability and could maintain strength for over 60 d with less loss.In core experiments,DCNPM-A microspheres exhibited delayed swelling characteristics and could effectively plug deep formations.With a plugging rate of 95%,the subsequent enhanced oil recovery of CO_(2) flooding could reach 21.03%.The experimental results can provide a theoretical basis for anti-CO_(2)channeling and enhanced oil recovery in low-permeability fractured reservoirs.展开更多
Background:In facial plastic surgery,patients with nasal deformity are often treated by rib cartilage transplantation.In recent years,cartilage tissue engineering has developed as an alternative to complex surgery for...Background:In facial plastic surgery,patients with nasal deformity are often treated by rib cartilage transplantation.In recent years,cartilage tissue engineering has developed as an alternative to complex surgery for patients with minor nasal defects via injection of nasal filler material.In this study,we prepared an injectable nasal filler material containing poly-L-l actic acid(PLLA)porous microspheres(PMs),hyaluronic acid(HA)and adipose-derived mesenchymal stem cells(ADMSCs).Methods:We seeded ADMSCs into as-prepared PLLA PMs using our newly invented centrifugation perfusion technique.Then,HA was mixed with ADMSC-i ncorporated PLLA PMs to form a hydrophilic and injectable cell delivery system(ADMSCincorporated PMH).Results:We evaluated the biocompatibility of PMH in vitro and in vivo.PMH has good injectability and provides a favorable environment for the proliferation and chondrogenic differentiation of ADMSCs.In vivo experiments,we observed that PMH has good biocompatibility and cartilage regeneration ability.Conclusion:In this study,a injectable cell delivery system was successfully constructed.We believe that PMH has potential application in cartilage tissue engineering,especially in nasal cartilage regeneration.展开更多
Drug-loaded microspheres are significant for the development of modern pharmaceutical products. It is well known that the taken of aspirin for long-term increases the risk of serious gastrointestinal complications, th...Drug-loaded microspheres are significant for the development of modern pharmaceutical products. It is well known that the taken of aspirin for long-term increases the risk of serious gastrointestinal complications, therefore a controllable delivery of aspirin is of importance to lighten those side effects. In this work, poly(lactic acid)(PLA) was chosen as the carrier to prepare PLA-aspirin microspheres by using the traditional and the improved solvent evaporation methods. It was found that no matter which experimental condition was, the encapsulation efficiency of aspirin was higher by using the improved method than that of the traditional method. Specifically, when the concentration of polyvinyl alcohol = 1%(mass),the polymer concentration = 1:20, the oil/water rate = 1:2.5, PLA-aspirin microspheres were obtained via the improved method with a high yield of 82.83%(mass) and an encapsulation efficiency of 44.09%. PLAaspirin microspheres were then prepared continuously using the improved method, which further enhanced the encapsulation efficiency to 54.56%. Approximate 85% aspirin released from microspheres within 7 days. Obvious degradation which was represented by reduction on hardness was observed by soaking microspheres in PBS for 60 days. This work is of interest because it provides a continuous route to prepare PLA-aspirin microspheres continuously with a high drug encapsulation efficiency.展开更多
Aim Ciprofloxacin polylactic acid microspheres (CFX-PLA-MS) were preparedusing solvent evaporation method from a solid-in-oil-in-water emulsion system. Methods Orthogonalexperiment was used to optimize the method of C...Aim Ciprofloxacin polylactic acid microspheres (CFX-PLA-MS) were preparedusing solvent evaporation method from a solid-in-oil-in-water emulsion system. Methods Orthogonalexperiment was used to optimize the method of CFX-PLA-MS preparation. Microspheres werecharacterized in terms of morphology, size, encapsulation efficiency, drug loading and in vitro drugrelease. Results The physical state of CFX-PLA-MS was determined by scanning electron microscopy(SEM) and differential scanning calorimetry (DSC) . Microspheres formed were spherical with smoothsurfaces. Drug was enveloped in microspheres without mixing physically with PLA. The averageparticle size was 280.80 ± 0.15 μm, with over 90% of microspheres falling in the range of 250 -390 μm. The encapsulation efficiency was 65.8% ± 0.58% and the drug loading was 34.1% ± 0.51% .In vitro release study revealed a profile of sustained release of Ciprofloxacin from CFX-PLA-MS. Theaccumulated release percentage and half-life (T_(1/2) of Ciprofloxacin microspheres were 84.0% in53.2 h, and 31.9 h, respectively. Higuchi equation was Q= -0.0043 + 0.003 9 t^(1/2), r = 0.9941.Conclusion Ciprofloxacin microspheres have been successfully prepared and sustained release of CFXfrom microspheres is achieved.展开更多
A variety of neurotrophic factors have been shown to repair the damaged peripheral nerve. However, in clinical practice, nerve growth factor, neurotrophin-3 and brain-derived neuro- trophic factor are all peptides or ...A variety of neurotrophic factors have been shown to repair the damaged peripheral nerve. However, in clinical practice, nerve growth factor, neurotrophin-3 and brain-derived neuro- trophic factor are all peptides or proteins that may be rapidly deactivated at the focal injury site; their local effective concentration time following a single medication cannot meet the required time for spinal axons to regenerate and cross the glial scar. In this study, we produced polymer sustained-release microspheres based on the polylactic-co-glycolic acid copolymer; the micro- spheres at 300-pm diameter contained nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor. Six microspheres were longitudinally implanted into the sciatic nerve at the anastomosis site, serving as the experimental group; while the sciatic nerve in the control group was subjected to the end-to-end anastomosis using 10/0 suture thread. At 6 weeks after implanta- tion, the lower limb activity, weight of triceps surae muscle, sciatic nerve conduction velocity and the maximum amplitude were obviously better in the experimental group than in the control group. Compared with the control group, more regenerating nerve fibers were observed and dis- tributed in a dense and ordered manner with thicker myelin sheaths in the experimental group. More angiogenesis was also visible. Experimental findings indicate that polylactic-co-glycolic acid composite microspheres containing nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor can promote the restoration of sciatic nerve in rats after injury.展开更多
High-performance liquid chromatography (HPLC) was employed to determine drug release rates based on emamectin benzoate concentrations in the medium. Release kinetics equations were used to fit the drug release behav...High-performance liquid chromatography (HPLC) was employed to determine drug release rates based on emamectin benzoate concentrations in the medium. Release kinetics equations were used to fit the drug release behavior. The effects of particle size and release medium pH on the release rate were also investigated. The indoor toxicity of emamectin benzoate-loaded polylactic acid microspheres on the diamondback moth larva (Plutella xylostella) was studied to explore drug sustained-release performance. In acidic and neutral media, the drug release behavior of the microspheres was in accord with the first-order kinetics equation. Increasing the spray dosage of emamectin benzoate-loaded polylactic acid microspheres initially resulted in an equivalent insecticidal efficacy with the conventional emamectin benzoate microemulsion. However, the drug persistence period was four-fold longer than that observed using the conventional formulation. The developed emamectin benzoate-loaded polylactic acid microspheres showed dramatic sustained-release performance. A treatment threshold of greater than 35 mg mL-1 was established for an efficient accumulated release concentration of emamectin benzoate-loaded microspheres.展开更多
Monodisperse poly(poly(ethyleneglycol) methyl ether acrylate-co-acrylic acid) (poly(PEGMA-co-AA)) microspheres were prepared by distillation-precipitation polymerization with divinylbenzene (DVB) as crosslin...Monodisperse poly(poly(ethyleneglycol) methyl ether acrylate-co-acrylic acid) (poly(PEGMA-co-AA)) microspheres were prepared by distillation-precipitation polymerization with divinylbenzene (DVB) as crosslinker with 2,2'- azobisisobutyronitrile (AIBN) as initiator in neat acetonitrile without stirring. Under various reaction conditions, four distinct morphologies including the sol, microemulsion, microgels and microspheres were formed during the distillation of the solvent from the reaction system. A 2D morphological map was established as a function of crosslinker concentration and the polar monomer AA concentration, in comonomer feed in the transition between the morphology domains. The effect of the covalent crosslinker DVB on the morphology of the polymer network was investigated in detail at AA fraction of 40 vol%. The ratios of acid to ethylene oxide units presenting in the comonomers dramatically affected the polymer-polymer interaction and hence the morphology of the resultant polymer network. The covalent crosslinking by DVB and the hydrogen bonding crosslinking between two acid units as well as between the acid and ethylene oxide unit played key roles in the formation of monodisperse polymer microspheres.展开更多
AIM: To prepare polylactic acid microspheres of Erythromycin for Lung targeting. METHEDS: The orthogonal test design was used to optimize the technology of preparation. The character of the microspheres, drug release ...AIM: To prepare polylactic acid microspheres of Erythromycin for Lung targeting. METHEDS: The orthogonal test design was used to optimize the technology of preparation. The character of the microspheres, drug release in vitro, stability and tissue distribution were examined. RESULTS: The Erythromycin polylactic acid microspheres was regular in its morphology. Drug was enveloped in microspheres but not physically mixed with PDLLA. The average particle size was 11.65mm with over 94% of the microspheres being in the range of 5~20mm; The drug loading and the incorporation efficiency were 18% and 60% respectively. The microspheres were stable for three month at 4℃ and room temperature. The in vitro release properties could be expressed by the Higuchi抯 equation: y = 28.067 + 3.8515t1/2 (r = 0.9834). Comparing with injection, the drug in microspheres was more concentrated in lung tissue. CONCLUSION: Erythromycin polylactic acid microspheres showed significant sustained release and lung targeting.展开更多
BACKGROUND: Nogo A antigen is the major inhibiting factor blocking regeneration of the injured spinal cord. Neutralizing Nogo A antigens using Nogo A antibodies may help promote neurite regeneration and nervous funct...BACKGROUND: Nogo A antigen is the major inhibiting factor blocking regeneration of the injured spinal cord. Neutralizing Nogo A antigens using Nogo A antibodies may help promote neurite regeneration and nervous function recovery. For successful regeneration, sustained release of the antibody from a biodegradable material loaded with Nogo A antibodies to the injury site is required. OBJECTIVE: To compare the therapeutic effects of poly lactic-co-glycolic acid (PLGA)-Nogo A antibody delayed-release microspheres and Nogo A antibody alone on spinal regeneration in Sprague-Dawley rats with complete transverse injury to the spinal cord. DESIGN, TIME AND SETTING: A randomized, controlled animal trial was performed at the Pharmacological Laboratory of West China Center of Medical Sciences, Sichuan University, between October 2007 and January 2008. MATERIALS: Goat anti-rat Nogo A monoclonal antibody was purchased from Santa, American; goat anti-rat neurofilament 200 monoclonal antibody was from Zhongshan Goldenbridge, Beijing, China; PLGA-Nogo A antibody delayed-release microspheres were provided by the College of Pharmacy, Sichuan University. METHODS: A total of 36 adult female Sprague Dawley rats were used to establish models of completely transected spinal cord injury, at T10. Animals were randomly divided into three groups (n=12): model, Nogo A antibody alone, and Nogo A antibody delayed-release microsphere groups. After transverse injury of the spinal cord, 50 μ L normal saline solution, 50 μL normal saline solution containing 50μL g Nogo A antibody, and 50 μL normal saline solution containing 50 μg Nogo A antibody microspheres were administered to the respective groups at the injury site. MAIN OUTCOME MEASURES: The expression of Nogo A and neurofilament 200 in injured spinal cord was tested immunohistochemically, and motor function of rats was assessed by Basso-Beattie-Bresnahan (BBB) locomotor rating scale. RESULTS: Four weeks after injury, expression of Nogo A in microsphere group was significantly less than model and Nogo A antibody alone groups (P 〈 0.05); while there was no significant difference between model and Nogo A antibody alone groups (P 〉 0.05). Ten weeks after injury, microsphere group showed a significantly greater expression of neurofilament 200 than model and Nogo A antibody alone groups (P 〈 0.05); while no significant difference was found between model and Nogo A antibody alone groups (P 〉 0.05). At postoperative weeks 5 and 6, the score of BBB locomotor rating scale in microsphere group was significantly greater than the model group (P 〈 0.05), and at postoperative weeks 7 10, the score was much greater than model and Nogo A antibody alone groups (P 〈 0.05). CONCLUSION: Nogo A antibody delayed-release microspheres decreased Nogo A expression, increased neurofilament 200 expression in the injured spinal cord of rats, and promoted recovery of motor function through sustained drug release over a long-term period.展开更多
Biodegradable polymer poly(lactic-co-glycolic acid)(PLGA) was used to encapsulate the pharmacological activity metabolite of tolterodine by means of O/W emulsion solvent evaporation method via homogenization in th...Biodegradable polymer poly(lactic-co-glycolic acid)(PLGA) was used to encapsulate the pharmacological activity metabolite of tolterodine by means of O/W emulsion solvent evaporation method via homogenization in the emulsification process. The influences of preparation parameters were investigated. The results indicate that increa- sing PLGA concentration from 15% to 40% made the encapsulation efficiency of 5-hydroxymethyl derivative of tol- terodine(5-HMT) increased from 55.39% to 76.32%, and the particle size increased from 34.33 μm to 70,78 lain. In addition, when homogenization speed increased from 850 r/min to 2300 r/min, both particle size and encapsulation efficiency of microspheres decreased. An increase in the volume of aqueous phase led to higher encapsulation efficiency and bigger particle size. Increasing temperature made encapsulation efficiency and particle size change significantly. While reaction temperature increased from 20 ℃ to 50 ℃, the encapsulation efficiency decreased from 70.44% to 24.07%, and particle size increased from 38.66 μm to 69.38 μm. High reaction temperature(over 40 ℃) may lead to porous surface of microspheres. Porous surface, encapsulation efficiency and particle size influenced on the in vitro release of 5-HMT together.展开更多
The aim of the present study was to develop a novel long-acting Poly(lactic-co-glycolic acid)(PLGA)-based microspheres formulation of Bisdemethoxycurcum(BDMC) by emulsionsolvent evaporation method. Meanwhile, the effe...The aim of the present study was to develop a novel long-acting Poly(lactic-co-glycolic acid)(PLGA)-based microspheres formulation of Bisdemethoxycurcum(BDMC) by emulsionsolvent evaporation method. Meanwhile, the effects of the volume ratio of the dispersed phase and continuous phase, the concentration of PLGA and PVA, the theoretical drug loading and stirring speed were investigated. The mean diameter of the microspheres was 8.5 μm and the size distribution was narrow. The encapsulation efficiency(EE) and drug loading efficiency(DLE) of BDME loaded PLGA microspheres(BDMC-PLGA-MS) was 94.18% and 8.14%,respectively. In an in vitro study of drug release, it can be concluded that the BDMC-PLGAMS exhibited sustained and long-term release properties for 96 h. Stability studies suggested that the microspheres we prepared had a very good stability. Furthermore, the results of an in vivo study indicated that the BDMC-PLGA-MS had sustained release effect and was mainly distributed in the lung tissue, and less distribution in other tissues, which indicated that microspheres could be an effective parenteral carrier for the delivery of BDMC in lung cancer treatment.展开更多
[Objectives]To prepare donepezil hydrochloride microspheres and evaluate their quality.[Methods]The donepezil hydrochloride microspheres were prepared by emulsification-solvent evaporation method.The morphology was ob...[Objectives]To prepare donepezil hydrochloride microspheres and evaluate their quality.[Methods]The donepezil hydrochloride microspheres were prepared by emulsification-solvent evaporation method.The morphology was observed by scanning electron microscopy and the particle size distribution was determined by Laser Diffraction Method.The encapsulation efficiency,drug loading capacity,and in vitro release were determined by HPLC.[Results]The prepared donepezil hydrochloride microspheres were spherical with the average particle diameter of 15.927 μm.The drug loading capacity was 35.62%.The encapsulation efficiency was 90.32%.The drug release in vitro lasted for14 d.The release curve accorded with the first-order kinetic equation.[Conclusions]The prepared donepezil hydrochloride microspheres performed good sustained release effect in vitro,and it was expected to be used for research on Parkinson's disease.展开更多
The purpose of this study was to evaluate the effect of poly(lactide-co-glycolic acid) delayed-release microspheres,which were prepared using glial cell line-derived neurotrophic factor(GDNF),on the delayed-releas...The purpose of this study was to evaluate the effect of poly(lactide-co-glycolic acid) delayed-release microspheres,which were prepared using glial cell line-derived neurotrophic factor(GDNF),on the delayed-release,controllability,and protection of GDNF activity.The present study is the first to combine chondroitinase ABC,GDNF,and Nogo A antibody delayed-release microspheres for the treatment of spinal cord injury.Results show that the combined therapy of chondroitinase ABC,GDNF,and Nogo A antibody microspheres can increase the immunoreaction of neurofilament 200 in the injured spinal cord,and this therapeutic effect was better than chondroitinase ABC,GDNF,or Nogo A antibody microspheres administered singularly.展开更多
The combination of micro-carriers and polymer scaffolds as promising bone grafts have attracted considerable interest in recent decades.The poly(L-lactic acid)/poly(lactic-co-glycolic acid)/polycaprolactone(PLLA/PLGA/...The combination of micro-carriers and polymer scaffolds as promising bone grafts have attracted considerable interest in recent decades.The poly(L-lactic acid)/poly(lactic-co-glycolic acid)/polycaprolactone(PLLA/PLGA/PCL)composite scaffold with porous structure was fabricated by thermally induced phase separation(TIPS).Dexamethasone(DEX)was incorporated into PLGA microspheres and then loaded on the PLLA/PLGA/PCL scaffoldtopreparethedesiredcompositescaffold.The physicochemical properties of the prepared composite scaffold were characterized.The morphology of rat bone marrow mesenchymal stem cells(BMSCs)grown on scaffolds was observed using scanning electron microscope(SEM)and fluorescence microscope.The resultsshowedthatthePLLA/PLGA/PCLscaffoldhad interconnected macropores and biomimetic nanofibrous structure.In addition,DEX can be released from scaffold in a sustained manner.More importantly,DEX loaded composite scaffold can effectively support the proliferation of BMSCs as indicated by fluorescence observation and cell proliferation assay.The results suggested that the prepared PLLA/PLGA/PCL composite scaffold incorporating drug-loaded PLGA microspheres could hold great potential for bone tissue engineering applications.展开更多
The present study aims to investigate the motional dynamics of risperidone within polylactic co-glycolic acid(PLGA)microsphere by employing solution state'H and 19F nuclear magnetic resonance(NMR)measurements.Risp...The present study aims to investigate the motional dynamics of risperidone within polylactic co-glycolic acid(PLGA)microsphere by employing solution state'H and 19F nuclear magnetic resonance(NMR)measurements.Risperidone,a second-generation fluorinated antipsychotic drug used for the treatment of schizophrenia is commercially marketed as PLGA microsphere formulation resulting in prolonged release of the drug in solution.Although the current trend in the pharmaceutical market is to develop drug formulation with long-acting release(LAR)products,complete physicochemical characterization of such formulations are scarce.Especially the effects of microsphere encapsulation on the motional properties and diffusion behavior of the drugs are not discussed adequately in any of the earlier reports.We therefore,have employed NMR relaxation and diffusion measurements to decipher the interaction of PLGA cavity water with risperidone.A detailed analysis of NMR relaxation rates confirmed the event of encapsulation and the presence of local motion in the non-fluorinated end of risperidone.Further,the relaxation data indicated a significant alteration in 19F chemical shift anisotropy(CSA)and CSA/dipole-dipole(DD)cross-correlated relaxation mechanism and decreased effect of solvent relaxation pointing out reduced water concentration within the microsphere cavity.'H and 19F diffusion coefficients of risperidone led to the information about hydrodynamic radius of risperidone in free and encapsulated states.Measurement of hydrodynamic radius supported the presence of limited water in PLGA cavity allowing higher translational mobility of risperidone after the encapsulation.展开更多
基金supported by the Fund of State Key Laboratory of Deep Oil and Gas,China University of Petroleum (East China) (SKLDOG2024-ZYRC-06)Key Program of National Natural Science Foundation of China (52130401)+2 种基金National Natural Science Foundation of China (52104055,52250410349)Major Science and Technology Project of China National Petroleum Corporation Limited (2021ZZ01-08)Shandong Provincial Natural Science Foundation,China (ZR2021ME171)。
文摘CO_(2) flooding is a vital development method for enhanced oil recovery in low-permeability reservoirs,However,micro-fractures are developed in low-permeability reservoirs,which are essential oil flow channels but can also cause severe CO_(2) gas channeling problems.Therefore,anti-gas channeling is a necessary measure to improve the effect of CO_(2) flooding.The kind of anti-gas channeling refers to the plugging of fractures in the deep formation to prevent CO_(2) gas channeling,which is different from the wellbore leakage.Polymer microspheres have the characteristics of controllable deep plugging,which can achieve the profile control of low-permeability fractured reservoirs.In acidic environments with supercritical CO_(2),traditional polymer microspheres have poor expandability and plugging properties.Based on previous work,a systematic evaluation of the expansion performance,dispersion rheological properties,stability,deep migration,anti-CO_(2) channeling and enhanced oil recovery ability of a novel acid-resistant polymer microsphere(DCNPM-A)was carried out under CQ oilifield conditions(salinity of85,000 mg/L,80℃,pH=3).The results show that the DCNPM-A microsphere had a better expansion performance than the traditional microsphere,with a swelling rate of 13.5.The microsphere dispersion with a concentration of 0.1%-0.5%had the advantages of low viscosity,high dispersion and good injectability in the low permeability fractured core.In the acidic environment of supercritical CO_(2),DCNPM-A microspheres showed excellent stability and could maintain strength for over 60 d with less loss.In core experiments,DCNPM-A microspheres exhibited delayed swelling characteristics and could effectively plug deep formations.With a plugging rate of 95%,the subsequent enhanced oil recovery of CO_(2) flooding could reach 21.03%.The experimental results can provide a theoretical basis for anti-CO_(2)channeling and enhanced oil recovery in low-permeability fractured reservoirs.
基金supported by grants from the CAMS Innovation Fund for Medical Sciences(2021-I2M-1-052)Tianjin Natural Science Foundation for Jingjinji Collaboration(23JCZXJC00240)+2 种基金Capital's Funds for Health Improvement and Research(CFH:2022-2-5072)Tianjin Hospital Fund for Science and Technology(Tjyy2109)the Open Fund of Tianjin Key Laboratory of Biomedical Materials(2022BMEKFKT002)。
文摘Background:In facial plastic surgery,patients with nasal deformity are often treated by rib cartilage transplantation.In recent years,cartilage tissue engineering has developed as an alternative to complex surgery for patients with minor nasal defects via injection of nasal filler material.In this study,we prepared an injectable nasal filler material containing poly-L-l actic acid(PLLA)porous microspheres(PMs),hyaluronic acid(HA)and adipose-derived mesenchymal stem cells(ADMSCs).Methods:We seeded ADMSCs into as-prepared PLLA PMs using our newly invented centrifugation perfusion technique.Then,HA was mixed with ADMSC-i ncorporated PLLA PMs to form a hydrophilic and injectable cell delivery system(ADMSCincorporated PMH).Results:We evaluated the biocompatibility of PMH in vitro and in vivo.PMH has good injectability and provides a favorable environment for the proliferation and chondrogenic differentiation of ADMSCs.In vivo experiments,we observed that PMH has good biocompatibility and cartilage regeneration ability.Conclusion:In this study,a injectable cell delivery system was successfully constructed.We believe that PMH has potential application in cartilage tissue engineering,especially in nasal cartilage regeneration.
基金financially supported by National Natural Science Foundation of China (22068018)Yunnan Ten Thousand Talents Plan Young & Elite Talents Project。
文摘Drug-loaded microspheres are significant for the development of modern pharmaceutical products. It is well known that the taken of aspirin for long-term increases the risk of serious gastrointestinal complications, therefore a controllable delivery of aspirin is of importance to lighten those side effects. In this work, poly(lactic acid)(PLA) was chosen as the carrier to prepare PLA-aspirin microspheres by using the traditional and the improved solvent evaporation methods. It was found that no matter which experimental condition was, the encapsulation efficiency of aspirin was higher by using the improved method than that of the traditional method. Specifically, when the concentration of polyvinyl alcohol = 1%(mass),the polymer concentration = 1:20, the oil/water rate = 1:2.5, PLA-aspirin microspheres were obtained via the improved method with a high yield of 82.83%(mass) and an encapsulation efficiency of 44.09%. PLAaspirin microspheres were then prepared continuously using the improved method, which further enhanced the encapsulation efficiency to 54.56%. Approximate 85% aspirin released from microspheres within 7 days. Obvious degradation which was represented by reduction on hardness was observed by soaking microspheres in PBS for 60 days. This work is of interest because it provides a continuous route to prepare PLA-aspirin microspheres continuously with a high drug encapsulation efficiency.
基金National Natural Science Foundation of Guangdong Province (020885,980504).
文摘Aim Ciprofloxacin polylactic acid microspheres (CFX-PLA-MS) were preparedusing solvent evaporation method from a solid-in-oil-in-water emulsion system. Methods Orthogonalexperiment was used to optimize the method of CFX-PLA-MS preparation. Microspheres werecharacterized in terms of morphology, size, encapsulation efficiency, drug loading and in vitro drugrelease. Results The physical state of CFX-PLA-MS was determined by scanning electron microscopy(SEM) and differential scanning calorimetry (DSC) . Microspheres formed were spherical with smoothsurfaces. Drug was enveloped in microspheres without mixing physically with PLA. The averageparticle size was 280.80 ± 0.15 μm, with over 90% of microspheres falling in the range of 250 -390 μm. The encapsulation efficiency was 65.8% ± 0.58% and the drug loading was 34.1% ± 0.51% .In vitro release study revealed a profile of sustained release of Ciprofloxacin from CFX-PLA-MS. Theaccumulated release percentage and half-life (T_(1/2) of Ciprofloxacin microspheres were 84.0% in53.2 h, and 31.9 h, respectively. Higuchi equation was Q= -0.0043 + 0.003 9 t^(1/2), r = 0.9941.Conclusion Ciprofloxacin microspheres have been successfully prepared and sustained release of CFXfrom microspheres is achieved.
基金financially supported by a grant from the Natural Science Foundation of Hunan Province of China,No.13JJ6016
文摘A variety of neurotrophic factors have been shown to repair the damaged peripheral nerve. However, in clinical practice, nerve growth factor, neurotrophin-3 and brain-derived neuro- trophic factor are all peptides or proteins that may be rapidly deactivated at the focal injury site; their local effective concentration time following a single medication cannot meet the required time for spinal axons to regenerate and cross the glial scar. In this study, we produced polymer sustained-release microspheres based on the polylactic-co-glycolic acid copolymer; the micro- spheres at 300-pm diameter contained nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor. Six microspheres were longitudinally implanted into the sciatic nerve at the anastomosis site, serving as the experimental group; while the sciatic nerve in the control group was subjected to the end-to-end anastomosis using 10/0 suture thread. At 6 weeks after implanta- tion, the lower limb activity, weight of triceps surae muscle, sciatic nerve conduction velocity and the maximum amplitude were obviously better in the experimental group than in the control group. Compared with the control group, more regenerating nerve fibers were observed and dis- tributed in a dense and ordered manner with thicker myelin sheaths in the experimental group. More angiogenesis was also visible. Experimental findings indicate that polylactic-co-glycolic acid composite microspheres containing nerve growth factor, neurotrophin-3 and brain-derived neurotrophic factor can promote the restoration of sciatic nerve in rats after injury.
基金supported by the National Key Research and Development Program of China (2016YFD0200502, 2017YFD0200301)
文摘High-performance liquid chromatography (HPLC) was employed to determine drug release rates based on emamectin benzoate concentrations in the medium. Release kinetics equations were used to fit the drug release behavior. The effects of particle size and release medium pH on the release rate were also investigated. The indoor toxicity of emamectin benzoate-loaded polylactic acid microspheres on the diamondback moth larva (Plutella xylostella) was studied to explore drug sustained-release performance. In acidic and neutral media, the drug release behavior of the microspheres was in accord with the first-order kinetics equation. Increasing the spray dosage of emamectin benzoate-loaded polylactic acid microspheres initially resulted in an equivalent insecticidal efficacy with the conventional emamectin benzoate microemulsion. However, the drug persistence period was four-fold longer than that observed using the conventional formulation. The developed emamectin benzoate-loaded polylactic acid microspheres showed dramatic sustained-release performance. A treatment threshold of greater than 35 mg mL-1 was established for an efficient accumulated release concentration of emamectin benzoate-loaded microspheres.
基金This work was supported in part by the National Science Foundation of China (No. 20504015)the starting project for young teachers from the Ministry of Education, China.
文摘Monodisperse poly(poly(ethyleneglycol) methyl ether acrylate-co-acrylic acid) (poly(PEGMA-co-AA)) microspheres were prepared by distillation-precipitation polymerization with divinylbenzene (DVB) as crosslinker with 2,2'- azobisisobutyronitrile (AIBN) as initiator in neat acetonitrile without stirring. Under various reaction conditions, four distinct morphologies including the sol, microemulsion, microgels and microspheres were formed during the distillation of the solvent from the reaction system. A 2D morphological map was established as a function of crosslinker concentration and the polar monomer AA concentration, in comonomer feed in the transition between the morphology domains. The effect of the covalent crosslinker DVB on the morphology of the polymer network was investigated in detail at AA fraction of 40 vol%. The ratios of acid to ethylene oxide units presenting in the comonomers dramatically affected the polymer-polymer interaction and hence the morphology of the resultant polymer network. The covalent crosslinking by DVB and the hydrogen bonding crosslinking between two acid units as well as between the acid and ethylene oxide unit played key roles in the formation of monodisperse polymer microspheres.
基金Guangdong Provincial Natural Science Foundation of China
文摘AIM: To prepare polylactic acid microspheres of Erythromycin for Lung targeting. METHEDS: The orthogonal test design was used to optimize the technology of preparation. The character of the microspheres, drug release in vitro, stability and tissue distribution were examined. RESULTS: The Erythromycin polylactic acid microspheres was regular in its morphology. Drug was enveloped in microspheres but not physically mixed with PDLLA. The average particle size was 11.65mm with over 94% of the microspheres being in the range of 5~20mm; The drug loading and the incorporation efficiency were 18% and 60% respectively. The microspheres were stable for three month at 4℃ and room temperature. The in vitro release properties could be expressed by the Higuchi抯 equation: y = 28.067 + 3.8515t1/2 (r = 0.9834). Comparing with injection, the drug in microspheres was more concentrated in lung tissue. CONCLUSION: Erythromycin polylactic acid microspheres showed significant sustained release and lung targeting.
基金the National Natural Science Foundation of China,No.30471759
文摘BACKGROUND: Nogo A antigen is the major inhibiting factor blocking regeneration of the injured spinal cord. Neutralizing Nogo A antigens using Nogo A antibodies may help promote neurite regeneration and nervous function recovery. For successful regeneration, sustained release of the antibody from a biodegradable material loaded with Nogo A antibodies to the injury site is required. OBJECTIVE: To compare the therapeutic effects of poly lactic-co-glycolic acid (PLGA)-Nogo A antibody delayed-release microspheres and Nogo A antibody alone on spinal regeneration in Sprague-Dawley rats with complete transverse injury to the spinal cord. DESIGN, TIME AND SETTING: A randomized, controlled animal trial was performed at the Pharmacological Laboratory of West China Center of Medical Sciences, Sichuan University, between October 2007 and January 2008. MATERIALS: Goat anti-rat Nogo A monoclonal antibody was purchased from Santa, American; goat anti-rat neurofilament 200 monoclonal antibody was from Zhongshan Goldenbridge, Beijing, China; PLGA-Nogo A antibody delayed-release microspheres were provided by the College of Pharmacy, Sichuan University. METHODS: A total of 36 adult female Sprague Dawley rats were used to establish models of completely transected spinal cord injury, at T10. Animals were randomly divided into three groups (n=12): model, Nogo A antibody alone, and Nogo A antibody delayed-release microsphere groups. After transverse injury of the spinal cord, 50 μ L normal saline solution, 50 μL normal saline solution containing 50μL g Nogo A antibody, and 50 μL normal saline solution containing 50 μg Nogo A antibody microspheres were administered to the respective groups at the injury site. MAIN OUTCOME MEASURES: The expression of Nogo A and neurofilament 200 in injured spinal cord was tested immunohistochemically, and motor function of rats was assessed by Basso-Beattie-Bresnahan (BBB) locomotor rating scale. RESULTS: Four weeks after injury, expression of Nogo A in microsphere group was significantly less than model and Nogo A antibody alone groups (P 〈 0.05); while there was no significant difference between model and Nogo A antibody alone groups (P 〉 0.05). Ten weeks after injury, microsphere group showed a significantly greater expression of neurofilament 200 than model and Nogo A antibody alone groups (P 〈 0.05); while no significant difference was found between model and Nogo A antibody alone groups (P 〉 0.05). At postoperative weeks 5 and 6, the score of BBB locomotor rating scale in microsphere group was significantly greater than the model group (P 〈 0.05), and at postoperative weeks 7 10, the score was much greater than model and Nogo A antibody alone groups (P 〈 0.05). CONCLUSION: Nogo A antibody delayed-release microspheres decreased Nogo A expression, increased neurofilament 200 expression in the injured spinal cord of rats, and promoted recovery of motor function through sustained drug release over a long-term period.
基金Supported by Key Projects in the National Science & Technology Pillar Program During the Eleventh Five-Year Plan Period 2009,China(No.ZX9103-122)
文摘Biodegradable polymer poly(lactic-co-glycolic acid)(PLGA) was used to encapsulate the pharmacological activity metabolite of tolterodine by means of O/W emulsion solvent evaporation method via homogenization in the emulsification process. The influences of preparation parameters were investigated. The results indicate that increa- sing PLGA concentration from 15% to 40% made the encapsulation efficiency of 5-hydroxymethyl derivative of tol- terodine(5-HMT) increased from 55.39% to 76.32%, and the particle size increased from 34.33 μm to 70,78 lain. In addition, when homogenization speed increased from 850 r/min to 2300 r/min, both particle size and encapsulation efficiency of microspheres decreased. An increase in the volume of aqueous phase led to higher encapsulation efficiency and bigger particle size. Increasing temperature made encapsulation efficiency and particle size change significantly. While reaction temperature increased from 20 ℃ to 50 ℃, the encapsulation efficiency decreased from 70.44% to 24.07%, and particle size increased from 38.66 μm to 69.38 μm. High reaction temperature(over 40 ℃) may lead to porous surface of microspheres. Porous surface, encapsulation efficiency and particle size influenced on the in vitro release of 5-HMT together.
文摘The aim of the present study was to develop a novel long-acting Poly(lactic-co-glycolic acid)(PLGA)-based microspheres formulation of Bisdemethoxycurcum(BDMC) by emulsionsolvent evaporation method. Meanwhile, the effects of the volume ratio of the dispersed phase and continuous phase, the concentration of PLGA and PVA, the theoretical drug loading and stirring speed were investigated. The mean diameter of the microspheres was 8.5 μm and the size distribution was narrow. The encapsulation efficiency(EE) and drug loading efficiency(DLE) of BDME loaded PLGA microspheres(BDMC-PLGA-MS) was 94.18% and 8.14%,respectively. In an in vitro study of drug release, it can be concluded that the BDMC-PLGAMS exhibited sustained and long-term release properties for 96 h. Stability studies suggested that the microspheres we prepared had a very good stability. Furthermore, the results of an in vivo study indicated that the BDMC-PLGA-MS had sustained release effect and was mainly distributed in the lung tissue, and less distribution in other tissues, which indicated that microspheres could be an effective parenteral carrier for the delivery of BDMC in lung cancer treatment.
基金Supported by National Innovative Training Program for College Students(201610443020)
文摘[Objectives]To prepare donepezil hydrochloride microspheres and evaluate their quality.[Methods]The donepezil hydrochloride microspheres were prepared by emulsification-solvent evaporation method.The morphology was observed by scanning electron microscopy and the particle size distribution was determined by Laser Diffraction Method.The encapsulation efficiency,drug loading capacity,and in vitro release were determined by HPLC.[Results]The prepared donepezil hydrochloride microspheres were spherical with the average particle diameter of 15.927 μm.The drug loading capacity was 35.62%.The encapsulation efficiency was 90.32%.The drug release in vitro lasted for14 d.The release curve accorded with the first-order kinetic equation.[Conclusions]The prepared donepezil hydrochloride microspheres performed good sustained release effect in vitro,and it was expected to be used for research on Parkinson's disease.
基金the National Natural Science Foundation of China, No. 30471759
文摘The purpose of this study was to evaluate the effect of poly(lactide-co-glycolic acid) delayed-release microspheres,which were prepared using glial cell line-derived neurotrophic factor(GDNF),on the delayed-release,controllability,and protection of GDNF activity.The present study is the first to combine chondroitinase ABC,GDNF,and Nogo A antibody delayed-release microspheres for the treatment of spinal cord injury.Results show that the combined therapy of chondroitinase ABC,GDNF,and Nogo A antibody microspheres can increase the immunoreaction of neurofilament 200 in the injured spinal cord,and this therapeutic effect was better than chondroitinase ABC,GDNF,or Nogo A antibody microspheres administered singularly.
基金National Natural Science Foundations of China(Nos.31271028,31570984)Innovation Program of Shanghai Municipal Education Commission,China(No.13ZZ051)+2 种基金International Cooperation Fund of the Science and Technology Commission of Shanghai Municipality,China(No.15540723400)Open Foundation of State Key Laboratory for Modification of Chemical Fibers and Polymer Materials,China(No.LK1416)“111 Project” Biomedical Textile Materials Science and Technology,China(No.B07024)
文摘The combination of micro-carriers and polymer scaffolds as promising bone grafts have attracted considerable interest in recent decades.The poly(L-lactic acid)/poly(lactic-co-glycolic acid)/polycaprolactone(PLLA/PLGA/PCL)composite scaffold with porous structure was fabricated by thermally induced phase separation(TIPS).Dexamethasone(DEX)was incorporated into PLGA microspheres and then loaded on the PLLA/PLGA/PCL scaffoldtopreparethedesiredcompositescaffold.The physicochemical properties of the prepared composite scaffold were characterized.The morphology of rat bone marrow mesenchymal stem cells(BMSCs)grown on scaffolds was observed using scanning electron microscope(SEM)and fluorescence microscope.The resultsshowedthatthePLLA/PLGA/PCLscaffoldhad interconnected macropores and biomimetic nanofibrous structure.In addition,DEX can be released from scaffold in a sustained manner.More importantly,DEX loaded composite scaffold can effectively support the proliferation of BMSCs as indicated by fluorescence observation and cell proliferation assay.The results suggested that the prepared PLLA/PLGA/PCL composite scaffold incorporating drug-loaded PLGA microspheres could hold great potential for bone tissue engineering applications.
文摘The present study aims to investigate the motional dynamics of risperidone within polylactic co-glycolic acid(PLGA)microsphere by employing solution state'H and 19F nuclear magnetic resonance(NMR)measurements.Risperidone,a second-generation fluorinated antipsychotic drug used for the treatment of schizophrenia is commercially marketed as PLGA microsphere formulation resulting in prolonged release of the drug in solution.Although the current trend in the pharmaceutical market is to develop drug formulation with long-acting release(LAR)products,complete physicochemical characterization of such formulations are scarce.Especially the effects of microsphere encapsulation on the motional properties and diffusion behavior of the drugs are not discussed adequately in any of the earlier reports.We therefore,have employed NMR relaxation and diffusion measurements to decipher the interaction of PLGA cavity water with risperidone.A detailed analysis of NMR relaxation rates confirmed the event of encapsulation and the presence of local motion in the non-fluorinated end of risperidone.Further,the relaxation data indicated a significant alteration in 19F chemical shift anisotropy(CSA)and CSA/dipole-dipole(DD)cross-correlated relaxation mechanism and decreased effect of solvent relaxation pointing out reduced water concentration within the microsphere cavity.'H and 19F diffusion coefficients of risperidone led to the information about hydrodynamic radius of risperidone in free and encapsulated states.Measurement of hydrodynamic radius supported the presence of limited water in PLGA cavity allowing higher translational mobility of risperidone after the encapsulation.