The Influence of Emulsifers on the Formation of Chitosan Microspheres
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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.Cite
Hydroxypropyl chitosan was synthesized from chitosan and propylene oxide,and use it as the shell material,insulin as thecore,prepared for microspheres,the average particle size was 13.34 μm.And by IR,DSC and scanning electron microscope,the structure of the product was characterized.The results showed that,when mixing speed for 400 r/min,the dosage of HPCS for w(HPCS) = 8%,glutaraldehyde volume fraction φ = 0.25%(on the liquid paraffin),the microspheres are smooth surface,compact,with a proper average size.The microsphere were stable at room temperature and with higher embedding rate.
Glutaraldehyde
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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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Hydroxypropyl chitosan was synthesized from chitosan and propylene oxide.Using it as the shell material,insulin as the core was prepared microspheres single-pool preparation and the performance of microspheres was studied.Microspheres was prepored by single coacervation.The microspheres chemical structure was characterized by IR,XRD and DCS,morphology was observation using optical microscopy and scanning electron microscopic and the stability of microspheres was inspected.When stirring speed was 400 r/min,crosslinker dosage 0.15 mL,hydroxypropyl-chitosan concentration was 8 %,the shape of microspheres were better,encapsulation efficiency was 63 %,particle size was medium and distribution narrow was scope.The stability was appropriate under a variety of environmental.Microspheres of hydroxypropyl chitosan coated insulin performance studies was showed that the microspheres met the medical need.
Coacervate
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Chitosan (CS) microspheres loaded with levofloxacin (LOF) were prepared by emulsion crosslinking technique and the experimental parameters were optimized by orthogonal tests. The influences of various factors on the combination properties of chitosan microspheres were discussed. The optimal preparation condition was 98000 chitosan molecular weight, 30mg/ml chitosan concentration, 5:1 volume ratio of oil to water, 1:1 molar ratio of amino group of chitosan to aldehyde group of glutaraldehyde (GA), 1500 rpm stirring rate, 2:1 mass ratio of chitosan to levofloxacin and 1 h crosslinking time. The CS microspheres prepared under optimal parameters had spherical morphology with 1.59 μm of average geometric diameter and 0.99 of span, its loading capacity (LC) and association efficiency (AE) values were 21.71% and 80.49% respectively. In vitro release profile showed the levofloxacin released fast initially, and then slowly from the microspheres with T 90 occurring at 188.5h and its delivery behavior conformed to First-Order release kinetics model.
Glutaraldehyde
Mass fraction
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Genipin
Surface-area-to-volume ratio
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The shrimp shell was used as raw materials to prepare chitosan.Chitosan microspheres and Ceftezole Sodium for Injection drug were prepared by RP-suspension crosslinking legal system.The influences of acetic acid concentration,chitosan concentration,chitosan deacetylation,the amount of emulsifier,oil-water ratio,cross-linking density,reaction time,stirring speed and other factors on microspheres average size and grain size dispersity were studied.
Dispersity
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The Fe3O4 nanoparticles were prepared by co-precipitation and modified by oleic acid and the composite chitosan magnetic microspheres containing Fe3O4 nanoparticles were prepared using the emulsification cross-linking technique by adding proper amount of glutaraldehyde into chitosan solution.The results demonstrated that the chitosan concentration,NaOH amount and stirring speed of the suspension medium were the most effective parameters for the size,size distribution,morphology and magnetism of magnetic chitosan microspheres.The SEM,IR and DLS indicated that the diameter of the microspheres was about 348.5 nm and the microspheres were uniformly disperse.The magnetic test showed that the microspheres had good magnetic responsiveness and the functional groups on the surface.
Glutaraldehyde
Magnetism
Morphology
Suspension
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The factors affecting the preparation of chitosan microspheres,such as viscosity-average molecular weight and concentration of chitosan,ratio of ethyl acetate and NaOH,agglomerating time,were studied and the method of preparing porous chitosan microspheres was optimized using the surface,inner configurations and shape of chitosan microsphere obtained by scanning electron microscope as index.The optimum conditions for preparing porous chitosan microspheres were as follows: the carrier was chitosan with viscosity-average molecular weight of 448.4 kDa and concentration of 2.5%,3.0% NaOH as clotted solution,ratio of ethyl acetate and NaOH solution was 5%,agglomerating for 3h.
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Purpose:hydroxypropyl chitosan was synthesized from chitosan and propylene oxide, and use it as the shell material, insulin as the core, prepared for microspheres, the average particle size was 13.34μm. Method: the chemical structure of hydroxypropyl chitosan and the microspheres was characterized by IR; thermal stability of hydroxypropyl chitosan microspheres and coated insulin microspheres coated with it was inspected by TG; morphology of different microsphere in liquids and dried microspheres was observed using both optical microscopy and scanning electron microscopy; insulin standard curve and deter mination of encapsulation efficiency of microspheres was determined by UV; the stability of the microspheres at room temperature,in simulated gastric juice and in simulated intestinal fluid was inspected. Results: the microspheres are surface smooth, dense, with a proper average size and narrow distribution. The yield and encapsulation efficiency reached 93% and 61.3% respectively. The microsphere were stable at room temperature. Conclusion: the microspheres have the efficacy of slow- release according to the stability.
Thermal Stability
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The experimentation used composite crosslinker (formaldehyde and glutaraldehyde) to prepare tetracycline hydrochloridel chitosan sustained-release microspheres by emulsion cross-linking method. In order to select the optimum technology for preparing chitosan sustained-release microspheres,the influencing factors of drug-carried microspheres were analysed,including the types of chitosan,the mass ratio of raw materials,the dosage of crosslinking agent and the emulsifying speeds. Moreover,the experimentation researched the modality of microspheres by scanning electron microscope and chatelier-type microscope.And the in-vitro release characteristics of microspheres were investigated under the conditions of pH=7.4 and temperature is 37℃. The results suggest that prepared with emulsion cross-linking method in this test, the sphericity of microspheres was good, the diameter of microspheres was from 5-50μm. The drugloading was 26.9%, and the enbedding ratio was 56.3%, and the in vitro release of tetracycline hydrochloridel from the microspheres is sustained.
Glutaraldehyde
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