The spraying-dried HA （ ASD ） was employed. ASD was plasma-sprayed onto ice to obtain hollow HA microspheres. The particle size of the sample was determined with a particle size analyzer. The morphology and structur...The spraying-dried HA （ ASD ） was employed. ASD was plasma-sprayed onto ice to obtain hollow HA microspheres. The particle size of the sample was determined with a particle size analyzer. The morphology and structure of the samples were measured by scanning electron microscope and X-ray powder diffraction. The in vitro biodegradability of samples was evaluated by immersion tests in Ringer＇ s solution （RS） and simulated body fluid （SBF）. The samples were immersed respectively in RS and SBF for a period. The Ca^2＋ ion concentration in the solutions was determined by Atomic Adsorption Spectrum. By plasma spraying hollow HA microspheres were obtained. The hollow microspheres consisted mainly of low crystalline and amorphous HA, and had better biodegradability.展开更多
Aim Polylactic acid (PLA) or polylactide-co-glycolide (PLGA) was used asbiodegradable and biocom-patible carriers to achieve sustained release ofestradial-PLGA/PLA-Microspheres (E_2-PLGA/PLA-MS). THF was added in the ...Aim Polylactic acid (PLA) or polylactide-co-glycolide (PLGA) was used asbiodegradable and biocom-patible carriers to achieve sustained release ofestradial-PLGA/PLA-Microspheres (E_2-PLGA/PLA-MS). THF was added in the organic phase to study itseffects on the properties of MS. Methods MS were formed by an emulsification-solvent extractionmethod with mixture of ethyl acetate (EtoAc) and tetrahydrofuran (THF) as the organic solvents, andthen the properties and in vitro drug release behavior were examined. Results The results indicatedthat the drug loading efficiency decreased when THF added, but when the ratio of EtoAc was more than50% , there was no obvious effect of THF ratio, but the particle size increased accordingly. Thecarriers' properties and the drug contents were the main factors influencing the in vitro drugrelease. Conclusions By controlling the technology and formulation, we can get sustained-release E_2biodegradable microsperes with proper particle size, drug content and low burst-release, althoughTHF with readily solubility in water was used in the organic phase.展开更多
The lipophilic hydroxyapatite(HA)nanorods were firstly synthesized by the solvothermal method using calcium oleate as the precursor.As-synthesized HA nanorods had an average aspect ratio of 11.4 with 18.4 wt%oleic aci...The lipophilic hydroxyapatite(HA)nanorods were firstly synthesized by the solvothermal method using calcium oleate as the precursor.As-synthesized HA nanorods had an average aspect ratio of 11.4 with 18.4 wt%oleic acid attached on the surface.Then the hydroxyapatite/polylactic acid(HA/PLA)nanocomposites were prepared by dispersing the HA nanorods in PLA using dichloromethane(CH_(2)Cl_(2))as the volatile solvent.The influence of the HA content on the properties of the HA/PLA nanocomposites was investigated.It is found that the nanocomposite with 2 wt%HA exhibits the optimal mechanical properties.The tensile strength and elongation at break are 59.4 MPa and 18.19%,respectively.The values are enhanced by 13%and 184.2%compared with that of the pure PLA.The higher HA addition results in the decrease in the mechanical properties due to the aggregation of HA nanorods.The thermal properties of the HA/PLA nanocomposites were also examined.It is found that the thermal stability and crystallization transition temperature are decreased while the glass transition temperature and melting temperature remain basically unchanged with the increasing HA content up to 10 wt%.展开更多
In order to prepare cellulose nanocrystals( CNCs)-coated polylactide( PLA) microspheres for the use of drug delivery and tissue engineering,a Pickering emulsion route was applied. The stable Pickering emulsions were p...In order to prepare cellulose nanocrystals( CNCs)-coated polylactide( PLA) microspheres for the use of drug delivery and tissue engineering,a Pickering emulsion route was applied. The stable Pickering emulsions were prepared using CNCs as efficient stabilizers without any additional surfactant. The microspheres were successfully fabricated after volatilization of the solvent. What's more,the size of microspheres could be controlled by fabrication parameters.展开更多
Hyaluronan (HA), the consistent glycosaminoglycans in extracellular matrix, is a kind of biomaterials with wonderful biocompatibility. To develop drug release system (DDS) with HA as drug carrier is a new hotspot in t...Hyaluronan (HA), the consistent glycosaminoglycans in extracellular matrix, is a kind of biomaterials with wonderful biocompatibility. To develop drug release system (DDS) with HA as drug carrier is a new hotspot in the field of pharmaceutics. In this paper, we applied technique of ultrosound and reversed phase (Water/Oil) emulsification to develop dexamethasone (DEX)-HA-STMP cross-linking microspheres (DEX-HA MS) with STMP as cross-linker. DEX-HA MS has a wonderful shape and property of dispersion. There is a negative correlation between diameter of DEX-HA MS and the content of cross-linker, or the content of emulsifier, and a positive correlation between the diameter and CHA . When CHA≤1%,DEX/HA≤1/10 (g/g),there is a positive correlation between the factors mentioned below and drug loading (DL%)/loading efficiency (LE%),the content of STMP, the content of emulsifier,CHA and the content of DEX. DEX-HA-MS can realize function of slow release. In vitro drug release experiment shows that cumulative release (CR%) of DEX-HA MS fits in with pervasion-corrosion equation, and there is a negative correlation between the content of STMP, CHA and CR%, a positive correlation between emulsifier and CR%. When DEX/HA≤1/5 (g/g) there is a negative correlation between the content of DEX and CR%.展开更多
Nonporous and porous C/PLA/nano-HA composites were fabricated by the process of solvent blending and freeze-drying technique, and the effect of porous structure on the mechanical properties of C/PLA/nano-HA composites...Nonporous and porous C/PLA/nano-HA composites were fabricated by the process of solvent blending and freeze-drying technique, and the effect of porous structure on the mechanical properties of C/PLA/nano-HA composites scaffold was investigated and analyzed. The results show that the effects of porous structure on the bending strength, modulus and curves of stress and strain were obvious. Compared with nonporous sample, the curves of stress and strain of porous sample show more rough, and alternative phenomenon of stress increase and stress relaxation appears. It is strongly suggested that the fracture model of C/PLA/nano-HA composites scaffold transforms from the local to global load due to the porous structure.展开更多
BACKGROUND:The implantation of released chemotherapeutic drugs,which takes biodegradable polymer as vector,into the tumor site can get high concentration and release the drug for a long time,it can directly act on the...BACKGROUND:The implantation of released chemotherapeutic drugs,which takes biodegradable polymer as vector,into the tumor site can get high concentration and release the drug for a long time,it can directly act on the tumor cells,and reduce the general toxicity.OBJECTIVE:To explore the in vitro and in vivo course of 1,3-bis(2-chloroethyl)-1-nitrosourea(BCNU)sustained-release from BCNU-loaded polylactide(PLA)microspheres(MS)and location in rat brain tissue.DESIGN:A repetitive measurement.SETTING:Central Pharmacy,General Hospital of Chinese People’s Armed Police Forces.MATERIALS:Thirty male SD rats were used.PLA(Mr5000,batch number:KSL8377)was produced by Wako Pure Chemical Inc.,Ltd.(Japan);BCNU(batch number:021121)by Tianjin Jinyao Amino Acid Co.,Ltd.;BCNU-PLA-MS was prepared by the method of solvent evaporation and pressed into tablets(10 mg/tablet).High-performance liquid chromatography(HPLC)Agilent 1100(USA);LS9800 liquid-scintillation radiometric apparatus(Beckman).Chromatographic conditions:Elite Hypersil ODS2 C18 chromatographic column(5μm,4.6 mm×150 mm);Mobile phase:methanol:water(50:50),flow rate was 1.0 mL per minute,wave length of ultraviolet detection was 237 nm,and the inlet amount of samples was 10μL.METHODS:The experiments were carried out in the experimental animal center of the General Hospital of Chinese Armed Police from May 2004 to July 2005.①In vitro BCNU-PLA-MS release test:BCNU-PLA-MS was prepared by the method of solvent evaporation,then placed in 0.1 mol/L phosphate buffered solution(PBS,pH 7.4,37℃),part of MS were taken out at 1,2,3,7,10 and 15 days respectively,and the rest amount of BCNU in MS was determined by HPLC,then the curve of BCNU-PLA-MS release was drawn.②In vivo BCNU-PLA-MS release and distribution test:The rats were anesthetized,then BCNU-PLA-MS were implanted to the site 1 mm inferior to the cortex of frontal lobe.Five rats were killed postoperatively at 4 hours,1,2,3,7 and 15 days,the residual MS was removed from the brain tissue.The rest amount of BCNU was determined with HLPC,and the curve of BCNU-PLA-MS release was drawn as compared with the amount of BCNU in the implanted tablets.Besides,brain tissues(1 g)at the implanted side and the contralateral one were obtained respectively,blood sample(0.5 mL)was also collected,3H-BCNU was counted radioactively in radioactive liquid flash solution.The distributions of BCNU-PLA-MS in normal rat brain tissue and serum were detected.The analysis of variance was applied to compare the intergroup differences of the measurement data.MAIN OUTCOME MEASURES:①Characteristics of BCNU-PLA-MS release in phosphate buffered solution(PBS)and rat brain tissue;②Distributions of BCNU-PLA-MS in normal rat brain tissue and serum.RESULTS:①Release of BCNU-PLA-MS in PBS and rat brain tissue:The BCNU released from BCNU-PLA-MS could be sustained for over 2 weeks both in PBS and brain tissue.In PBS,the released rate of BCNU was over 15%at 24 hours,nearly 50%at 72 hours and over 90%at 15 days.In brain tissue,the released rate was 8%at 4 hours,16%at 24 hours,60%at 72 hours,respectively,and BCNU could be sustained released for over 15 days.②Distributions of BCNU-PLA-MS in normal rat brain tissue and serum:The concentrations of BCNU in the ipsilateral brain tissue were 6 to 70 times higher than those in the contralateral one.The concentrations of BCNU in the ipsilateral brain tissue were obviously higher than those in serum and contralateral brain tissue(F=103.47,P<0.01).CONCLUSION:BCNU-PLA-MS can increase the drug concentration in targeted brain tissue,decrease that in the non-targeted brain tissue,reduce general toxic and side effects,and have good releasing function.展开更多
文摘The spraying-dried HA （ ASD ） was employed. ASD was plasma-sprayed onto ice to obtain hollow HA microspheres. The particle size of the sample was determined with a particle size analyzer. The morphology and structure of the samples were measured by scanning electron microscope and X-ray powder diffraction. The in vitro biodegradability of samples was evaluated by immersion tests in Ringer＇ s solution （RS） and simulated body fluid （SBF）. The samples were immersed respectively in RS and SBF for a period. The Ca^2＋ ion concentration in the solutions was determined by Atomic Adsorption Spectrum. By plasma spraying hollow HA microspheres were obtained. The hollow microspheres consisted mainly of low crystalline and amorphous HA, and had better biodegradability.
文摘Aim Polylactic acid (PLA) or polylactide-co-glycolide (PLGA) was used asbiodegradable and biocom-patible carriers to achieve sustained release ofestradial-PLGA/PLA-Microspheres (E_2-PLGA/PLA-MS). THF was added in the organic phase to study itseffects on the properties of MS. Methods MS were formed by an emulsification-solvent extractionmethod with mixture of ethyl acetate (EtoAc) and tetrahydrofuran (THF) as the organic solvents, andthen the properties and in vitro drug release behavior were examined. Results The results indicatedthat the drug loading efficiency decreased when THF added, but when the ratio of EtoAc was more than50% , there was no obvious effect of THF ratio, but the particle size increased accordingly. Thecarriers' properties and the drug contents were the main factors influencing the in vitro drugrelease. Conclusions By controlling the technology and formulation, we can get sustained-release E_2biodegradable microsperes with proper particle size, drug content and low burst-release, althoughTHF with readily solubility in water was used in the organic phase.
基金the Foundation of Hubei Province Key Laboratory of Green Materials for Light Industry,Hubei University of Technology。
文摘The lipophilic hydroxyapatite(HA)nanorods were firstly synthesized by the solvothermal method using calcium oleate as the precursor.As-synthesized HA nanorods had an average aspect ratio of 11.4 with 18.4 wt%oleic acid attached on the surface.Then the hydroxyapatite/polylactic acid(HA/PLA)nanocomposites were prepared by dispersing the HA nanorods in PLA using dichloromethane(CH_(2)Cl_(2))as the volatile solvent.The influence of the HA content on the properties of the HA/PLA nanocomposites was investigated.It is found that the nanocomposite with 2 wt%HA exhibits the optimal mechanical properties.The tensile strength and elongation at break are 59.4 MPa and 18.19%,respectively.The values are enhanced by 13%and 184.2%compared with that of the pure PLA.The higher HA addition results in the decrease in the mechanical properties due to the aggregation of HA nanorods.The thermal properties of the HA/PLA nanocomposites were also examined.It is found that the thermal stability and crystallization transition temperature are decreased while the glass transition temperature and melting temperature remain basically unchanged with the increasing HA content up to 10 wt%.
基金National Key Technology R&D Program of China(No.2014BAC13B02)National Natural Science Foundation of China(No.51403035)+1 种基金Programme of Introducing Talents of Discipline to Universities,China(No.105-07-005735)the Fundamental Research Funds for the Central Universities,China(No.15D110510)
文摘In order to prepare cellulose nanocrystals( CNCs)-coated polylactide( PLA) microspheres for the use of drug delivery and tissue engineering,a Pickering emulsion route was applied. The stable Pickering emulsions were prepared using CNCs as efficient stabilizers without any additional surfactant. The microspheres were successfully fabricated after volatilization of the solvent. What's more,the size of microspheres could be controlled by fabrication parameters.
文摘Hyaluronan (HA), the consistent glycosaminoglycans in extracellular matrix, is a kind of biomaterials with wonderful biocompatibility. To develop drug release system (DDS) with HA as drug carrier is a new hotspot in the field of pharmaceutics. In this paper, we applied technique of ultrosound and reversed phase (Water/Oil) emulsification to develop dexamethasone (DEX)-HA-STMP cross-linking microspheres (DEX-HA MS) with STMP as cross-linker. DEX-HA MS has a wonderful shape and property of dispersion. There is a negative correlation between diameter of DEX-HA MS and the content of cross-linker, or the content of emulsifier, and a positive correlation between the diameter and CHA . When CHA≤1%,DEX/HA≤1/10 (g/g),there is a positive correlation between the factors mentioned below and drug loading (DL%)/loading efficiency (LE%),the content of STMP, the content of emulsifier,CHA and the content of DEX. DEX-HA-MS can realize function of slow release. In vitro drug release experiment shows that cumulative release (CR%) of DEX-HA MS fits in with pervasion-corrosion equation, and there is a negative correlation between the content of STMP, CHA and CR%, a positive correlation between emulsifier and CR%. When DEX/HA≤1/5 (g/g) there is a negative correlation between the content of DEX and CR%.
基金Project(30870609) supported by the National Natural Science Foundation of ChinaProjects(KJ081205 KJ091213) supported by the Natural Science Foundation of Chongqing Education Committee, China
文摘Nonporous and porous C/PLA/nano-HA composites were fabricated by the process of solvent blending and freeze-drying technique, and the effect of porous structure on the mechanical properties of C/PLA/nano-HA composites scaffold was investigated and analyzed. The results show that the effects of porous structure on the bending strength, modulus and curves of stress and strain were obvious. Compared with nonporous sample, the curves of stress and strain of porous sample show more rough, and alternative phenomenon of stress increase and stress relaxation appears. It is strongly suggested that the fracture model of C/PLA/nano-HA composites scaffold transforms from the local to global load due to the porous structure.
文摘BACKGROUND:The implantation of released chemotherapeutic drugs,which takes biodegradable polymer as vector,into the tumor site can get high concentration and release the drug for a long time,it can directly act on the tumor cells,and reduce the general toxicity.OBJECTIVE:To explore the in vitro and in vivo course of 1,3-bis(2-chloroethyl)-1-nitrosourea(BCNU)sustained-release from BCNU-loaded polylactide(PLA)microspheres(MS)and location in rat brain tissue.DESIGN:A repetitive measurement.SETTING:Central Pharmacy,General Hospital of Chinese People’s Armed Police Forces.MATERIALS:Thirty male SD rats were used.PLA(Mr5000,batch number:KSL8377)was produced by Wako Pure Chemical Inc.,Ltd.(Japan);BCNU(batch number:021121)by Tianjin Jinyao Amino Acid Co.,Ltd.;BCNU-PLA-MS was prepared by the method of solvent evaporation and pressed into tablets(10 mg/tablet).High-performance liquid chromatography(HPLC)Agilent 1100(USA);LS9800 liquid-scintillation radiometric apparatus(Beckman).Chromatographic conditions:Elite Hypersil ODS2 C18 chromatographic column(5μm,4.6 mm×150 mm);Mobile phase:methanol:water(50:50),flow rate was 1.0 mL per minute,wave length of ultraviolet detection was 237 nm,and the inlet amount of samples was 10μL.METHODS:The experiments were carried out in the experimental animal center of the General Hospital of Chinese Armed Police from May 2004 to July 2005.①In vitro BCNU-PLA-MS release test:BCNU-PLA-MS was prepared by the method of solvent evaporation,then placed in 0.1 mol/L phosphate buffered solution(PBS,pH 7.4,37℃),part of MS were taken out at 1,2,3,7,10 and 15 days respectively,and the rest amount of BCNU in MS was determined by HPLC,then the curve of BCNU-PLA-MS release was drawn.②In vivo BCNU-PLA-MS release and distribution test:The rats were anesthetized,then BCNU-PLA-MS were implanted to the site 1 mm inferior to the cortex of frontal lobe.Five rats were killed postoperatively at 4 hours,1,2,3,7 and 15 days,the residual MS was removed from the brain tissue.The rest amount of BCNU was determined with HLPC,and the curve of BCNU-PLA-MS release was drawn as compared with the amount of BCNU in the implanted tablets.Besides,brain tissues(1 g)at the implanted side and the contralateral one were obtained respectively,blood sample(0.5 mL)was also collected,3H-BCNU was counted radioactively in radioactive liquid flash solution.The distributions of BCNU-PLA-MS in normal rat brain tissue and serum were detected.The analysis of variance was applied to compare the intergroup differences of the measurement data.MAIN OUTCOME MEASURES:①Characteristics of BCNU-PLA-MS release in phosphate buffered solution(PBS)and rat brain tissue;②Distributions of BCNU-PLA-MS in normal rat brain tissue and serum.RESULTS:①Release of BCNU-PLA-MS in PBS and rat brain tissue:The BCNU released from BCNU-PLA-MS could be sustained for over 2 weeks both in PBS and brain tissue.In PBS,the released rate of BCNU was over 15%at 24 hours,nearly 50%at 72 hours and over 90%at 15 days.In brain tissue,the released rate was 8%at 4 hours,16%at 24 hours,60%at 72 hours,respectively,and BCNU could be sustained released for over 15 days.②Distributions of BCNU-PLA-MS in normal rat brain tissue and serum:The concentrations of BCNU in the ipsilateral brain tissue were 6 to 70 times higher than those in the contralateral one.The concentrations of BCNU in the ipsilateral brain tissue were obviously higher than those in serum and contralateral brain tissue(F=103.47,P<0.01).CONCLUSION:BCNU-PLA-MS can increase the drug concentration in targeted brain tissue,decrease that in the non-targeted brain tissue,reduce general toxic and side effects,and have good releasing function.
