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BACKGROUND: Anti-tuberculous chemotherapy is the main method for treating bone and joint tuberculosis. However, systemic administration hardly maintains the effective drug concentration in the focus area, and the therapeutic efficacy is unsatisfactory. OBJECTIVE: To prepare a chitosan-gelatin/poly(lactic-co-glycolic acid) combined with drug-loaded hydrogel, which can release anti-tuberculosis drugs in situ for a long time and promote osteogenesis. METHODS: Isoniazid, a hydrophilic anti-tuberculosis drug, and a hydrophobic stromal cell derived factor-1 were loaded into poly(lactic-co-glycolic acid) by double emulsion method to prepare drug-loaded poly(lactic acid co-glycolic acid) microspheres, which were then mixed into chitosan gelatin/poly(lactic acid co-glycolic acid) combined with drug-loaded hydrogel. The ability of drug delivery and anti-tuberculosis of poly(lactic acid co-glycolic acid) microspheres and chitosan gelatin/poly(lactic acid co-glycolic acid) combined with drug-loaded hydrogels in vitro were tested. MC3T3-E1 cells were inoculated on the surface of microspheres and hydrogel respectively. The biocompatibility was detected by cell counting kit-8 assay. The osteogenetic activity was detected by alkaline phosphatase activity. RESULTS AND CONCLUSION: (1) The burst release of isoniazid in the microspheres was about 23.3% in 1 hour, 42.6% in 2 days, and then it entered the sustained-release stage in the later 25 days. The burst release of stromal cell derived factor was about 19.8% in 1 hour, 44.7% in 2 days, and then it entered the sustained-release stage in the next 25 days. The release of isoniazid and stromal cell-derived factor in the combined drug-loaded hydrogel was 8.3% and 8.5% in the first hour, respectively. The cumulative release rates on the second day were 15.2% and 17.6%, respectively, which were much lower than that of poly(lactic acid co-glycolic acid) microspheres. (2) After 4 weeks in vitro, the antibacterial diameter of the combined drug-loaded hydrogel was much larger than that of the drug-loaded microspheres, and the antibacterial rate was higher than that of the drug-loaded microspheres (P < 0.05). (3) The combined drug-loaded hydrogel and the drug-loaded microspheres had good cytocompatibility and cell viability was about 100%. (4) After 5 and 10 days of culture, there was no significant difference in the activity of alkaline phosphatase on the surface of drug-loaded hydrogel and drug-loaded microspheres. (5) These results show that the in situ chitosan-gelatin/poly(lactic acid co-glycolic acid) combined with drug-loaded hydrogel can be used for treating tuberculosis and other bone and joint infections.
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ABSTRACT: The aim of this research was to perform a systematic review to identify the most frequent uses of PLA/ PGA in alveolar bone regeneration and their results. A study was designed to answer the question: What are the most frequent uses of PLA/PLGA and their copolymers in alveolar bone regeneration?. A systematic search was done on MEDLINE, EMBASE and LILACS from April 1993 to December 2017. The search string used on MEDLINE was: (((polylactic acid) OR PLA) OR PLA-based copolymers) OR PLA blends) OR PLA scaffolds)) AND ((("Bone Regeneration"[Mesh]) OR bone regeneration) OR guided bone regeneration). The search was complemented by a manual review of the references from the articles included. Most of the studies selected were weak and, regarding the most frequent uses of PLA/PGA, 13 studies used it as a resorbable membrane, two as an absorbable mesh, one as an absorbable screw and three as filling material. Based on our results, the authors consider that PLA/PGA requires a delicate relation between the mechanical resistance and the degradation process. PLA/PGA does not interrupt bone regeneration; however, the influence in cellular events related to bone regeneration and later osseointegration have not been identified.
RESUMEN: El objetivo de esta revisión fue realizar una revisión sistemática de la literatura para identificar los usos más frecuentes de PLA/PGA en regeneración ósea en área maxilofacial y sus resultados. Se diseñó un estudio para responder a la pregunta: ¿Cuáles son los usos más frecuentes de PLA/PLGA y sus copolímeros en regeneración ósea en el sector maxilofacial?. Los estudios seleccionados fueron en su mayoría débiles y sobre los usos más frecuentes de PLA/PGA, 13 estudios lo utilizaron como membrana reabsorbible, 2 estudios como malla absorbible, un estudio como tornillo absorbible y 3 estudios como material de relleno. En base a nuestros resultados, los autores estiman que PLA/PGA requiere una delicada relación entre la resistencia mecánica que ofrece y la degradación que se produce; PLA/ PGA no interrumpe la regeneración ósea, sin embargo, no se ha identificado la potencialidad o influencia que presenta en los eventos celulares de la regeneración y posterior oseointegración.
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Humans , Polyethylene Glycols/chemistry , Dental Implants , Alveolar Bone Loss/surgery , Bone Substitutes , Alveolar Ridge Augmentation/methods , Bone Regeneration , Bone TransplantationABSTRACT
Objective To investigate the efficacy ofpoly (lactic acid co castor oil) microspheres containing ropivacaine for sciatic nerve block of mice.Methods A total of 150 Kunming male mice were randomly assigned into 3 groups,namely placebo microspheres (lactic acid co castor oil) group (group A,n=50),ropivacaine injection group (group B,n=50) and ropivacaine microspheres group (group C,n=50).After sevoflurane anesthesia,the mouse was fixed on the operating table and the bilateral sciatic nerve was exposed.The corresponding preparations were implanted or injected near the sciatic nerve.Five mice were randomly selected from each group for the next experiments.Paw withdrawal thermal latency,the ability to splay and flex of the hind paw and plasma ropivacaine concentration were measured 10min,30min,1h,3h,5h,7h,10h,15h,30h and 48h after drug administration.Results The anesthetic effect of group C began to work at 3h.Compared with group B,the duration of sciatic nerve sensory block of group C was significantly longer and the effect of motor block was weaker.No anesthetic effect was observed in group A.The sensory and motor block of group B reached the peak at 1h,and the pharmacodynamics subsided at 7h.Compared with group B,the concentration of ropivacaine in group C increased slowly,and the peak value at 10h after administration was gradually decreased.Conclusions Ropivacaine loading poly (lactic acid co castor oil) microspheres can significantly extend the effect of ropivacaine on sciatic nerve sensory block.Compared with ropivacaine injection,motor block effect of ropivacaine loading poly (lactic acid co castor oil) microspheres is reduced and its plasma ropivacaine concentration fluctuation range is small.
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Thermodynamically immiscible poly(lactic acid) (PLA) and poly(ε-caprolactone) (PCL) were blended and solution-cast by adding the 3% compatibilizer (tributyl citrate, TBC) of the PCL weight. In the PLA/PCL composition range of 99/1–95/5 wt%, mechanical properties of the PLA/PCL films with TBC were always superior to those of the films without TBC. The tensile strength of 42.9 ± 3.5 MPa and the elongation at break of 10.3 ± 2.7% were observed for the 93/7 PLA/PCL films without TBC, indicating that PCL addition is effective for strength and ductility. However, the tensile strength of 54.1 ± 3.4 MPa and the elongation at break of 8.8 ± 1.8% were found for the 95/5 PLA/PCL with TBC, indicating that the effect of co-addition of PCL and TBC on mechanical properties of the films is more pronounced. No cytotoxicity was observed for the PLA/PCL films regardless of TBC addition.
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Cell Proliferation , Citric Acid , Tensile StrengthABSTRACT
Objective:To synthesize poly (2-ethyl-2-oxazoline)-poly(lactic acid) copolymer (PEOz-PLA), prepare pH-sensitive paclitaxel-loaded polymeric micelles, and evaluate the in vitro properties. Methods: The structures of all the synthesized copolymers were confirmed by 1 HNMR and Fourier transform infrared spectroscopy ( FTIR) . The drug-loaded micelles were prepared by a dialysis method. The micelles solution was freeze-dried and the lyoprotectants were screened. The critical micelle concentrations ( CMC) of the copolymers were measured by pyrene fluorescent probe technique. The distribution of particle size was measured by dynamic light scat-tering ( DLS) . The in vitro release behavior of the loaded micelles at different pH conditions was studied by a dialysis method. Re-sults:The CMC of micelles was 25. 63 mg·ml-1 . When 10% polyethylene glycol 4000 was used as the lyoprotectant, the re-solubili-ty of micelles was good and the distribution of particle size was narrow. The drug loading rate of micelles was 8. 12% and the encapsu-lation efficiency was 69. 33%. The average particle size of freeze-dried micelles was 183. 7 nm. The in vitro release of the drug-loaded micelles showed that the drug released slowly at pH 7. 4 and fast at pH 5. 0, which indicated that the change of pH could affect the drug release. Conclusion:The preparation of PEOz-PLA polymer micelles is simple. The particle size, entrapment efficiency and drug loading are controllable. The micelles have a certain sustained-release effect, which provides basis for further pharmacological study and clinical application.
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Objective:To observe the repair effect of nano hydroxyapatite/magnesium(nHA-Mg)porous composite material modified by poly lactic acid/glycolic acid copolymer(PLGA) on the jaw bone defect of rabbits,and to elucidate the mechanisms preliminary.Methods:The mandibular defect models of 10 mm×5 mm×1 mm in the 18 rabbits were established.Nine rabbits were selected and implanted with nHA-Mg composite materials modified by PLGA in the left as experimental group and the right as blank control group;the other nine were implanted with nHA-Mg in the left as positive control group and the right as blank control group.The rabbits were sacrificed at 4, 8, 12 weeks (respectively 3 of experimental group and positive control group every time)and the mandibular defect areas were intercepted and observed by imaging and histological examination;the sizes of the newborn trabecula area and residual materials in experimental group and positive control group were compared.Results:Compared with positive control group and blank control group, the percentage of newborn trabecula area of the rabbits in experimental group was increased (P0.05).The imaging results showed that the new bone formation can be observed in experimental group and better than positive control group and blank control group.The paraffin section results indicated that there were visible vascular tissue and newborn trabecula,the osteoblasts gathered around the bone trabecula;a lot of pits were located in the bone trabecula, and the pits contained osteocytes in experimental group.As the prolongation of time,thickened newborn trabecula, dense arrangement and trend of converting to lamellar bone were observed in experimental group.The hard tissue section results showed that the remaining amount of materials in experimental group was more than that in positive control group.Conclusion:nHA-Mg porous composite materials modified by PLGA can effectively reduce the rate of degradation in the body, promote osteogenesis and guide the bone regeneration.
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Objective To prepare a innovative VP3 gene‐loaded ultrasound microbubble decorated with TATp and SDF‐1 , having the extracellular accumulation and intracellular permeation function ,and characterize their property .Methods VP3 gene‐loaded ultrasound microbubbles were prepared with the method of W/O/W double emulsion .SDF‐1 and TATp were covalently con‐gjugated to the surface of poly‐lactic/acid‐glycolic acid(PLGA) microbubble though thioether bonds to prepare gene‐loaded targeted ultrasound mirobubbles .Their particle size ,distribution and surface potential were determined by Malvern measuring instrument . The conjugation status of TATp and SDF‐1 were evaluated by flow cytometry and confocal microscopy .Their DNA protection were identified by digestion reaction test .The vitro targeting capacity was preliminarily assessed by light microscopy and flow cytometry , and the vitro ultrasound imaging was investigated under high frequency imaging condition .Results The gene‐loaded targeted ultra‐sound mirobubbles showed regularly sphericity .The diameter was (536 .00 ± 16 .55)nm ,and showed a narrow distribution .The zeta potential was(-0 .08 ± 0 .08)mV .The average gene loading was 0 .62% ,with the average rate of 36 .13% gene encapsulation effi‐ciency .The DNA protective effect sustained 60 min without damage .Connection rate of TATp and SDF‐1 coupled with PLGA mi‐crobubbles surface was 69 .84% .The vitro targeting study showed that more targeted microbubbles stably clustered together in the tongue SCC‐15 cell membranes with the connection rate of 91 .44% ,while non‐targeted microbubbles combination rate was 12 .96% .Moreover ,the vitro ultrasound imaging was tiny dot ,even high echo .Conclusion TATp‐SDF‐1‐VP3‐PEG‐PLGA micro‐bubbles were prepared successfully ,which can efficiently target to tongue SCC‐15 cells ,and pass through the cell membranes at a short time in company with outstanding ultrasound imagings in vitro .
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Bio-based materials are new materials or chemicals with renewable biomass as raw materials such as grain, legume, straw, bamboo and wood powder. This class of materials includes bio-based polymer, biobased fiber, glycotechnology products, biobased rubber and plastics produced by biomass thermoplastic processing and basic biobased chemicals, for instance, bio-alcohols, organic acids, alkanes, and alkenes, obtained by bio-synthesis, bio-processing and bio-refinery. Owing to its environmental friendly and resource conservation, bio-based materials are becoming a new dominant industry taking the lead in the world scientific and technological innovation and economic development. An overview of bio-based materials development is reported in this special issue, and the industrial status and research progress of the following aspects, including biobased fiber, polyhydroxyalkanoates, biodegradable mulching film, bio-based polyamide, protein based biomedical materials, bio-based polyurethane, and modification and processing of poly(lactic acid), are introduced.
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Biomass , Biotechnology , Organic Chemicals , Plastics , Polymers , RubberABSTRACT
Poly (lactic acid) (PLA) is a polymer synthesized from lactic acid with good biocompatibility and biodegradability. At present, PLA manufactured on industrial scale is mainly synthesized from L-lactic acid. The obtained products have good transparency but poor heat resistance. Adding nucleating agents could increase the crystallinity of PLA, to improve heat resistance. We reviewed the progress of research on organic and inorganic nucleating agents that can be used for PLA synthesis.
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Chemical Industry , Lactic Acid , Polyesters , Chemistry , PolymersABSTRACT
Poly lactic acid (PLA)/Poly (butyleneadipate-co-terephthalate)(PBAT) and glyceryl triacetate (GTA) blend were prepared by torque rheometer, and the effect of GTA on thermodynamical performance, mechanical properties and microstructure of PLA/PBAT composites were studied using differential scanning calorimeter(DSC), dynamic mechanical analysis(DMA), universal testing machine, impact testing machine and scanning electron microscope(SEM). After adding GTA, Tg values of the two phases gradually became closer, blends cold crystallization temperature and melting temperature decreased. When with 3 phr GTA, the dispersed phase particle size of PLA/PBAT blend decreased. Mechanics performance test showed that the elongation at break and impact strength of the PLA/PBAT blend was greatly increased with 3 phr GTA, and the elongation at break increased 2.6 times, improved from 17.7% to 64.1%.
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Acetates , Chemistry , Calorimetry, Differential Scanning , Crystallization , Lactic Acid , Polyesters , Chemistry , Polymers , TemperatureABSTRACT
Increasing bioactivity and mechanical properties of polymers to produce more suitable scaffold for tissue engineering is a recurrent goal in the development of new biomedical materials. In this study, collagen-functionalized poly (lactic acid), PLA, was obtained by means of a simple grafting route, and electrospun scaffolds were produced to grow cells in vitro; their bioactivity was compared with scaffolds made of physical blends of PLA and collagen. Grafting was verified via nuclear magnetic resonance, attenuated total reflection-Fourier transform infrared and X-ray photoelectron spectroscopy. The cell adhesion performance of the scaffolds was studied using macrophages. Elastic modulus (74.7 megapascals) and tensile strength (3.0 megapascals) of the scaffold made from PLA grafted with collagen were substantially higher than the scaffolds made from physical blends of collagen and PLA: 32 and 2.16 megapascals, respectively, implying a more resistant material because of the chemical bond of the polypeptide to PLA. Besides, the fibers had more uniform diameter without defects. Scaffolds made from PLA grafted with collagen presented four-fold increase in cell adhesion than those of PLA blended with collagen. Furthermore, cell spreading within the scaffolds occurred only when collagen-functionalized poly (lactic acid) was used. These results open a new option for the easy tailoring of nanofiber-based scaffolds in three dimensions for tissue engineering.
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Cell Adhesion , Collagen , Elastic Modulus , In Vitro Techniques , Macrophages , Magnetic Resonance Spectroscopy , Photoelectron Spectroscopy , Polymers , Tensile Strength , Tissue Engineering , TransplantsABSTRACT
Biodegradable poly (lactic acid) films containing Lapatinib were prepared by spreading polymer / Lapatinib solution on the non-solvent surface. Different drug loading polymer films can be obtained by controlling the weight ratios of drug and polymer. The synthesized Lapatinib loaded PLA films were evaluated by different parameters such as drug loading, encapsulation efficiency, surface morphology, differential scanning calorimetry, powder X-ray diffractometry and In vitro drug release kinetics. Various combinations of the polymer-drug weight ratios were used to achieve In vitro release of drug over a period of 30-35 days, with initial burst release < 25% and a steady release rate over the entire period of release. Furthermore the drug release rate of the film could be controlled by the drug loading content and pH of the release medium. Our results suggest that these Lapatinib loaded PLA film formulations could constitute a promising approach for the controlled drug delivery applications. This is the first study which shows the in-vitro release profile of Lapatinib using a polymeric delivery system.
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Poly (L-lactic acid) (PLA) nanoparticles have the approval of the main institutions for drugs administration and therapeutics. However, the use of lactic acid polymer is controversial because lactic acid has been proposed as an energy source for cancer cells. The aim of this study was to evaluate the cytotoxic, apoptotic and cell cycle properties of PLA and CuSO4-loaded PLA biodegradable nanoparticles on MKN-45 gastric adenocarcinoma cell line. PLA nanoparticles for the delivery of the anticancer active principle CuSO4 were obtained using the double emulsion method. PLA and CuSO4 loaded PLA nanoparticles were morphologically characterized and their size determined using transmission electron microscopy (TEM). The cytotoxicity of this drug delivery system was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay; apoptosis was evaluated using YO-PRO-1/Propidium Iodide and cell cycle analysis throughout flow cytometry. CuSO4-loaded PLA nanoparticles were effective inhibitors of MKN45 cancer cell growth. They increased cytotoxicity and apoptosis, and induced G1/Go cell cycle arrest;whereas the anticancer activity was increased using a 96 h treatment of a minimal (1mM) concentration of CuSO4 loaded in 40 µM PLA nanoparticles. The treatment with 40 µM lactic acid and PLA (40 µM) did not increase the rate of cell survival assays related to the control, which indicate that PLA use as a polymer carrier not induce proliferation of MKN-45 cancer cells. Our research presents novel data about the effect of PLA nanoparticles and CuSO4 on gastric cancer cell line MKN45.
Las nanopartículas de ácido poli L-láctico (PLA) tienen la aprobación de las principales instituciones de administración de medicamentos y terapéutica. Sin embargo, el uso de polímero de ácido láctico es controvertido ya que el ácido láctico se ha propuesto como una fuente de energía para las células cancerosas. El objetivo de este estudio fue evaluar las propiedades citotóxicas, la apoptosis y sobre el ciclo celular de las nanoparticulas de PLA biodegradable y de estas PLA nanopartículas cargadas con CuSO4 en la línea celular de adenocarcinoma gástrico MKN-45. Las nanopartículas de PLA para la administración del principio activo CuSO4 contra el cáncer se obtuvieron utilizando el método de doble emulsión. Las nanopartículas de PLA y PLA cargadas con CuSO4 se caracterizan morfológicamente y su tamaño fue determinaron usando microscopía electrónica de transmisión (TEM). Se evaluó la citotoxicidad de este sistema de administración de fármacos utilizando la 3 - (4,5-dimetiltiazol-2-il) -2,5-ensayo difeniltetrazolio (MTT); la apoptosis se evaluó usando yoduro de propidio/YO-PRO-1 y el análisis de ciclo celular por citometría de flujo. Las nanopartículas cargadas con CuSO4-PLA fueron eficaces inhibidores del crecimiento de las células MKN-45 cancerosas. Aumentaron citotoxicidad y la apoptosis, e inducen la detención del ciclo celular en G1/Go, mientras que la actividad contra el cáncer se incrementó con el uso de un tratamiento de 96 horas con una concentración mínima (1 mM) de CuSO4 cargado en nanopartículas con 40 µM de PLA. El tratamiento con 40 µM de ácido láctico y 40 µM PLA no aumentó la tasa de supervivencia de células en relación con el control, lo que indica que el uso de PLA como un polímero portador que no induce la proliferación de células de cáncer MKN-45. Nuestro estudio presenta nuevos datos sobre el efecto de las nanopartículas de PLA con CuSO4 en la línea celular de cáncer gástrico MKN-45.
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Humans , Polymers , Stomach Neoplasms , Adenocarcinoma , Lactic Acid , Antineoplastic Agents/administration & dosage , Stomach Neoplasms/pathology , Adenocarcinoma/pathology , Cell Survival , Apoptosis , Copper Sulfate , Cell Line, Tumor/drug effects , Microscopy, Electron, Transmission , Emulsions , NanoparticlesABSTRACT
Objective To investigate the preparation of a polycaprolactone (PCL)/poly (lactic acid-glycolic acid) (PLGA) degradable ureteral stent and its degradation ability in vitro.Methods From December 2010 to September 2012,degradable ureteral stent was fabricated by electrospinning,using different concentration of PCL/PLGA (5％,10％,15％,20％,25％,30％).The structure of stent was scanned by electron microscopy (SEM).The Instron system was used to test the mechanical property of those stents.The PCL/PLGA stents of different concentration (5％,15％,25％) were immerged into the urine to assess their degradable ability 7,14,21,28,35,42,49,56 days later.Results The inner diameter of the white tubular scaffold was 1.5 mm and the outer diameter was 2.0 mm.The SEM results showed that the scaffold had been made by nanofiber with the structure of multi-porous.The tension test showed that the mechanical property was enhanced with the increasing in the proportion of the PCL.The lowest stress at break was found in 5％ PCL/PLGA stent,while it was still sufficient for the mechanical criteria of degradable biomaterial.The degradation curves of different ratio of PCL/PLGA stent were close to a straight line.The 5％ PCL/PLGA stent collapsed into pieces within 28 d.The 15％ and 25％ PCL/PLGA collapsed within 42 d and 56 d,respectively.Conclusion The PCL/PLGA biodegradable ureteral stent has a good mechanical property and the degradation time can fully meet the demand of a ureteral stent.
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OBJECTIVE: 1H-NMR (Nuclear Magnetic Resonance Method) was used to quantitatively determine the MePEG (me-thoxy polyethylene glycol) content and chain density on MePEG-PLGA-NP surface, and study the influences of MePEG molecular weights and proportion on the chemical and physical properties of MePEG-PLGA-NP surface. METHODS: MePEG-PLGA-NP were prepared by self-emulsion solvent diffusion method with methoxy polyethylene glycol-poly(lactic acid-hydroxyl acid) copolymer (Me-PEG-PLGA) as the carriers. And the particle average size and Zeta potential were characterized. 1H-NMR method were used to ascertain the composition of the MePEG-PLGA copolymer and determine the MePEG content and chain density on the MePEG-PLGA-NP surface, and compared with colorimetric assay. RESULTS: The composition of MePEG-PLGA copolymer are basically the same with the labelled amount. When the Molecular weight is at the same, along with the increase of proportion of MePEG, the average size of MePEG-PLGA-NP decrease, the absolute value of the Zeta potential also decrease gradually, MePEG content on particles surface (α) increase gradually, the MePEG chain density on nanoparticles surface (δ) increase gradually, the distance between two adjacent MePEG chains on the surface of the particles (D) decrease; When there is the same proportions, with MePEG chain length increases, nanoparticles are not significantly different on the particle average size and the Zeta potential, whereas α increase gradually, the δ decreases, and D increases; Theavalue of the same MePEG-PLGA-NP determined by colorimetric assay is higher than which is determined by 1H-NMR. CONCLUSION: 1H-NMR method can be used to quantitatively determine the MePEG content and chain density on MePEG-PLGA-NP surface; Compared with the traditional method, the results determined by 1H-NMR method are more accurate. With the experimental limits, MePEG molecular weighs and proportion have influences on the chemical and physical properties of MePEG-PLGA NP surface, such as mean size, Zeta potential and the MePEG content and chain density on nanoparticles surface. Copyright 2012 by the Chinese Pharmaceutical Association.
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Sustained release drug delivery from microparticles is an excellent alternative for daily protein/peptide drug administration protocol. Poly(lactic acid) (PLA) and poly(lactic-co-glycolic acid) (PLGA) are the most commonly used polymer carriers in the development of protein/peptide microspheres. Basically there are three preparation methods for PLA/PLGA microspheres: the solvent extraction/evaporation based multiple emulsion (W/O/W emulsion) method, the phase separation method and the spray drying method. The stability of the protein/pipetide loaded, encapsulation efficiency, and the burst effect of the microspheres are key problems usually met in the preparation of microspheres. In this review the preparation techniques and progress in the development of protein/pipetide microspheres which aimed to stabilize protein/peptide structural integrity, keep the bioactivity of drugs, increase the encapsulation efficiency and improve the release profile were summarized and evaluated.
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Se sintetizó lacturo por medio de la policondensación de ácido láctico a 180 °C y 5,3 kPa durante 120 minutos, y una posterior depolimerización a 220 °C y 5,3 kPa durante 40 minutos usando cloruro de estaño dihidratado como catalizador. Se utilizó un sistema novedoso de reacción y separación, recolectando el lacturo sólido y dejando en fase vapor el agua y el ácido láctico, garantizando así una alta pureza del producto y evitando reacciones reversibles.
Lactide was synthesized by polycondenzation of lactic acid at 180 °C and a 5.3 kPa for 120 minutes, and a subsequent depolymerization at 220 °C and 5.3 kPa for 40 minutes using dehydrated tin chloride as catalyst. A new reaction separation system was used, collecting the lactide in solid form and leaving water and lactic acid as vapor. This guarantees a high purity product and avoids any reversible reaction of lactide.
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Objective To observe the in vivo degradation of poly-DL-lactic acid ureteral stent in canine and the pathological change in canine ureter.Methods Poly-DL-lactic acid ureteral stent was inserted into 19 canine ureters,respectively.The stents were taken out every two weeks with their degradation observed with electronic microscopy and their molecular weight change detected by gel permeation chromatography.Pathological change in ureteral tissue specimens stained with hematoxylin and eosin was observed by light microscopy.Results The molecular weight of poly-DL-lactic acid ureteral stent was decreased to 8 033 seven weeks after degradation from 68 900 before degradation,with a degradation rate of 88.3%.Electronic microscopy showed that the number of pores in stent was gradually increased and their diameter became larger.The stent was degraded.The main pathological change observed in canine ureter tissue was non-specific inflammation.Conclusion Poly-DL-lactic acid ureteral stent is good in degradation property and tissue compatibility in vivo.
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OBJECTIVE:To prepare the gene recombined human interferon-alpha poly(lactic acid-co-glycolic)microspheres and study its physicochemical properties.METHODS:Interferon-? microspheres were prepared by W/O/W solvent extraction technique;the in vitro release of microspheres were examined;the rudimental organic solvent was determined with GC-MS.RESULTS:The IFN-?-MS were regular in their morphology,and the particle size distribution was narrow.The average diameter was 45.54?m.The encapsulation rate and the loading efficiency were 83.49% and 8.03%,and the in vitro accumulative release rate was 80.32% in 30 days.The in vitro interferon-? release from the microspheres was best described using Higuchi diffusion model.The rudimental of dichloromethane was less than 0.05%.CONCLUSIONS:The prepared IFN-?-MS is very good in all aspects of its physicochemical properties.