The preparation and performance of alginate/polyurethane complex microspheres
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We first synthesize the polyurethane solution,then mix the polyurethane solution and sodium alginate solution with certain volume ratio,prepare the sodium alginate/polyurethane blend microspheres by condensation phase separation method.We give a study on the balling situation,swelling and water content of the blend microspheres.The results show that when the percentage mass content of PU in the blend solution is 10%,30%,50%,we can prepare the better morphology microspheres;with the increasing of the percentage mass content of PU in the blend solution,the water content of the blend microspheres decreased;the blens microspheres swells slower than the microspheres prepared by SA solution in the phosphate buffer solution(pH6.86).Keywords:
Sodium alginate
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AbstractGelatin microspheres are prepared by emulsification of a aqueous gelatin solution in a oily phase containing a surfactant, gelation by cooling, dehydration by isopropanol and cross-linking by formaldehyde. The pH, the gelatin concentration in the aqueous solution and the surfactant concentration in the oily phase have some influence on the size distribution of unloaded and loaded microspheres and on the drug contents of microspheres.
Gelatin
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Gelatin/chitosan (Gel/Cs) microspheres were fabricated through an emulsification-solvent evaporation technique using saturated glutaraldehyde as a cross-linking reagent. The influences of the concentration of the emulsifier, stirring speed, and water/oil ratio on particle size and surface morphology were investigated. The experimental results indicated that the particle size of the microspheres decreased with increasing concentration of the emulsifier; however, the microsphere size did not change when the concentration of the emulsifier exceeded 0.016 g·mL−1. The particle diameter of the microspheres decreased with increasing stirring speed and increased with increasing water/oil ratio. The concentration of an acetone/water solution had an obvious effect on the morphologies of the Gel/Cs microspheres during the course of dehydration; the surface of the microspheres became smooth when dehydrated by an acetone solution with a volume ratio of 3:1.
Glutaraldehyde
Gelatin
Surface-area-to-volume ratio
Particle (ecology)
Morphology
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Objective:To prepare 20(S)-protopanaxadiol polylactic acid-glycolic acid(PLGA)microspheres.Method:20(S)-protopanaxadiol PLGA microspheres were prepared by emulsion-solvent evaporation method,with polyvinyl alcohol(PVA)as emulsifier,mixture of ethyl acetate and methylene chloride as oil phase.Based on single factor test,with composite score of microspheres yield,encapsulation efficiency and drug-loading as index,formulation technology was optimized by orthogonal test,then to investigate its in vitro release characteristics.Result:Optimized formulation technology was as following:volume ratio of O/W 1:50,the mass fraction of PVA 0.5%,feeding dosage 20 mg.These prepared microspheres had round appearance with average particle size of about 1.16 μm,microspheres yield of 35.58%,encapsulation efficiency of 41.76%,drug loading of 19.61%.In vitro release of these microspheres within the first 0.5 h was 18.24%,and cumulative release was up to 98.99% in 192h.Conclusion:This optimized formulation and preparation technology was stable and feasible.These prepared microspheres had significant sustained release effect.
PLGA
Polylactic Acid
Glycolic acid
Polyvinyl Alcohol
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The preparation of gelatin microspheres is one of the contents in pharmaceutics experiment courses. However,the microspheres prepared by original method are usually adhesive,too small in particle size,and the preparation efficiency is relatively low. To improve the outcome of experimental class study,the original method for preparation of gelatin microspheres were adjusted in this study. New formulation and process were applied,including the change of oil phase,the concentration and usage of gelatin solution,water-oil ratio,and a different kind of cross-linking agent. In addition,the order of mixing each component was adjusted,as well as the manner of dehydration washing. As a result,the microspheres prepared by the new method showed better properties: transparent and spherical with good appearance,dispersed well and with proper particle size. Furthermore,the amount of microspheres prepared and the preparation efficiency both increased.
Gelatin
Pharmaceutics
Particle (ecology)
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Chitosan microspheres were prepared by emulsion-dispersed chemical-crosslinking method and by using glutaradelhye as crosslinking agent, vacuum-pump oil and paraffin oil mixture as oil phase. The influence of emulsifers on the formation of chitosan microspheres was investigated. The results show that kinds and concentration of emulsifers affect the formation of chitosan microspheres. Under conditions of span-80 and magnesium stearate mixture with mass ration 3:1 as emulsifier, and the total concentration of emulsifier ranged from 10 g/L to 20 g/L, chitosan microspheres are gained with good spherical shape and diameters ranged from 1 m to 5 m.
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Objective:To prepare an X-ray developable alginate-barium sulfate microspheres as material for embolic agent.Methods:The emulsification-internal gelation technique was used to prepare alginate microspheres and the orthogonal design was adopted to optimize the technique.The diameter,shape,dispersibility,stability,suspension property,coating ratio and developability under X-ray of the microspheres were examined.Results:The average diameter of the microspheres was(53.08±32.72)μm;they were well distributed and had a round shape.The ratio of the destroyed microspheres was(2.0±1.1)% after heated at 100℃for 2 h,(86.0±19.2)% after frozen at-4℃ for 24 h,(39.0±14.7)% after vibrated at 37℃ for 24 h,and(10.3±3.2)% after irradiated with ~(60)Co(10kGy)for 0.5 h.The ratio of sedimentation volume in 0.25% suspension of sodium alginate microspheres was(0.92±0.018).The coating rate was(69.2±13.2)% when the feeding amount of barium sulfate was 2.0 g,and the result of X-ray development was good.Conclusion:Alginate-chitosan can be used for the preparation of barium sulfate microspheres;and the emulsification-internal gelation technique can prepare the microspheres with good dispersibility and shape.
Barium sulfate
Suspension
Glass microsphere
Barium
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Objective To prepare blend microspheres natural polymers alginate and starch and to study their controlled release performance on berberine hydrochloride.Methods A modified emulsification/gelation method was applied to prepare blend microspheres.Shape of those microspheres was observed with optical microscope.Drug distribution inside the Microspheres was observed with CLSM.Encapsulation efficiency was determined by UV-spectrophotometer.Drug release performance in two medium was also tested.Results Microspheres appeared to be spherical and well dispersed in water.Encapsulation efficiency was higher than 80%.Microspheres was found to have a certain effect on the controlled release of berberine hydrochloride.Conclusion Blend microspheres with good performance were prepared with alginate and starch.
Berberine hydrochloride
Hydrochloride
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Microparticle
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Polyvinyl Alcohol
Foaming agent
Aqueous two-phase system
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Novel PVA-SA based microspheres,prepared by polymers solution blending method,were developed for the delivery of drug.The parameters such as the concentration of SA,PVA and CaCl2,mass ratio of PVA to SA and dry method were adjusted to improve the properties of blend microspheres.The water content,swelling rate,drug loading rate,entrapment efficiency and PTIR analysis were carried out to characterize the composite microspheres.The effects of the ratio of PVA to SA of blend microspheres on the sustained release behavior were also discussed.The results show that,when SA concentration is 6%,PVA concentration is 10% and CaCl2 concentration is 5%,and the mass ratio of PVA and SA is 1∶3,blend microspheres with excellent properties can be prepared.The microspheres have high drug loading rate of 30.24%,entrapment efficient of 90.11%,good sustained release behavior and may be used as a special drug delivery system.
Polyvinyl Alcohol
Sodium alginate
Vinyl alcohol
Entrapment
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