chitosan and plga microspheres as drug delivery ... - UniCA Eprints

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7. RFP Loaded PLGA Coated Chitosan Microspheres Obtained by WSD Method7.2.3. Surface ChargeZeta potential of microparticles differed significantly between uncoated PLGA and chitosancoatedPLGA microspheres (Table 7.2). Chitosan coating shifted the negative zeta potential ofpure PLGA microspheres to positive values, in relation to the used chitosan concentration.Increasing chitosan concentrations shifted the zeta potential from negative to highly positivevalues, as a consequence of the increasing amount of free ionizable amino groups. But zetapotential is also affected by the presence of RFP. In fact RFP encapsulated microparticlesshowed an increased zeta potential value. For instance, encapsulation of RFP shifted the zetapotential of uncoated PLGA particles from 2.80mV to -4.80 mV, whereas for chitosan-coatedparticles the zeta potential values changed from 4mV to 14mV, and from 19mV to 37mV forthe lowest chitosan concentration and the highest chitosan concentration respectively (Table7.2). It means that the zeta potential of the PLGA particles was affected by chitosanconcentration in the external phase.7.2.4. Entrapment Efficiency (E%)Figure 3 shows encapsulation efficiency (E%) of prepared microspheres. In the present part ofthe work the influence of chitosan coating concentration on the RFP entrapment in PLGAcoated chitosan microspheres was evaluated. The presence of chitosan coating onmicrospheres enhanced E%, which increased as chitosan concentration increased.In fact the highest E% were found for formulations with the highest amount of chitosan (0.5%and 0.75%). It has been reported that added hydrophilic polymers to primary emulsion as astabilizer could prevent loss of drug from the external phase.The presence of chitosan on particle surface is probably capable of preventing drug leakagesduring preparation but in particular during purification process (273).Figure 7.2 also shows that freeze-drying of microparticles did not result in statisticallyrelevant RFP leakage from any of the prepared microspheres.110
7. RFP Loaded PLGA Coated Chitosan Microspheres Obtained by WSD Method10080% RFP6040200No chit 0,1% chit 0,25% chit 0,5% chit 0,75% chitE% before FD E% after FDFigure 7.2: Entrapment Efficiency (E%) of Rfp-Loaded Plga Coated ChitosanMicrosferes7.2.5. Nebulization Studies of Chitosan MicrospheresNebulization studies carried out to evaluate stability and suitability of chitosan coated PLGAparticles for pulmonary/nasal administration.Nebulization led to a reduction of mean particle diameter, but not a reduction of P.I.These results demonstrate that the prepared microspheres had a multimodal distribution andthat nebulization led to a separation of the particles in all the three stages of the usedimpinger.Table 7.3: Particle Size of RFP-Loaded PLGA Coated Chitosan Microspheres Beforeand After NebulizationFormulationParticle Size (nm± SD)Before nebulizationP.I ± SDParticle Size(nm ± SD)After nebulizationP.I ± SDNo Chit. 2535 ± 58,01 0.506 ± 0,055 1463 ± 50,33 0,637 ± 0,0180,1% Chit. 2900 ± 59.54 0.571 ± 0.018 1746 ± 25,16 0,558 ± 0,0390,25% Chit. 2807 ± 85.89 0.459 ± 0.053 1786 ± 38,15 0,523 ± 0,0840,5% Chit. 2567 ± 19.76 0.494 ± 0.059 1700 ± 32,28 0,754 ± 0,0920,75% Chit. 1407 ± 51.23 0.392 ± 0.020 1266 ± 32,14 0,756 ± 0,098111
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European Union Ministero dell’Uni
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Table Of Contents1. GENERAL INTRODU
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7.1.4. Release Studies/Stability St
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1. General Introduction1.1. Pulmona
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1. General Introductionmucosa, and
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1. General Introductionis the fact
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1.3. Lung Anatomy1. General Introdu
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1. General Introductionhighly vascu
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201. General Introductionliquid (84
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1. General IntroductionAerosol size
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1. General Introductionof numerous
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1. General Introductionintermittent
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1. General Introductionsphere prepa
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1. General Introductionit, respecti
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1. General Introductionthe subject
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1. General IntroductionA. zahoor et
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2. Chitosan And PLGA2.1. Chitosan a
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2. Chitosan And PLGAfor the prepara
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2. Chitosan And PLGAmainly controll
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2. Chitosan And PLGAAt present, a n
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2. Chitosan And PLGAneed to be a go
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2. Chitosan And PLGAdichloromethane
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3. Aim of the Work49
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3. Aim of the WorkBiodegradable mic
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4. RFP Loaded Chitosan Microspheres
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