Uniform double-walled polymer microspheres of controllable shell thickness

Berkland, Cory; Pollauf, Emily; Pack, Daniel W.; Kim, Kyekyoon

doi:10.1016/j.jconrel.2004.01.018

Cited by 121 publications

(82 citation statements)

References 32 publications

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“…Their protocol used two polymers to form a core and shell morphology through phase separation. 29 Since then, core-shell microspheres have been developed for controlled size distribution, 30 improved release kinetics, and enhanced biocompatibility and toxicological safety, etc. 31 However, the above researchers investigated the core-shell microsphere system for protein delivery using the water-in-oil-in-water (W/O/W) and water-in-oil-in-oil Table 6 β-galactosidase activity from core-shell microspheres (n = 5, P = 0.75)…”

Section: Discussionmentioning

confidence: 99%

Controlled-release and preserved bioactivity of proteins from (self-assembled) core-shell double-walled microspheres

Yuan¹,

Liu²

2012

IJN

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Abstract:In order to address preserved protein bioactivities and protein sustained-release problems, a method for preparing double-walled microspheres with a core (protein-loaded nanoparticles with a polymer-suspended granule system-formed core) and a second shell (a polymerformed shell) for controlled drug release and preserved protein bioactivities has been developed using (solid-in-oil phase-in-hydrophilic oil-in-water (S/O/O h /W)) phases. The method, based on our previous microsphere preparation method (solid-in-oil phase-in-hydrophilic oil-in-water (S/O/O h /W), employs different concentric poly(D,L-lactide-co-glycolide), poly(D,L-lactide), and protein-loaded nanoparticles to produce a suspended liquid which then self-assembles to form shell-core microspheres in the hydrophilic oil phase, which are then solidified in the water phase. Variations in the preparation parameters allowed complete encapsulation by the shell phase, including the efficient formation of a poly(D,L-lactide) shell encapsulating a protein-loaded nanoparticle-based poly(D,L-lactide-co-glycolide) core. This method produces core-shell doublewalled microspheres that show controlled protein release and preserved protein bioactivities for 60 days. Based upon these results, we concluded that the core-shell double-walled microspheres might be applied for tissue engineering and therapy for chronic diseases, etc.

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Section: Discussionmentioning

confidence: 99%

Controlled-release and preserved bioactivity of proteins from (self-assembled) core-shell double-walled microspheres

Yuan¹,

Liu²

2012

IJN

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“…39,41,43 Previously, PPFfabricated particles were utilized to better control and understand the release profiles of small molecule drugs by comparing a range of particle sizes encapsulating drugs of various solubility in water. 41,44,45 For all formulations studied to date, an initial burst of drug was absent, although for small microspheres encapsulating a model drug with high water solubility (>8 mg/mL), rapid diffusion and complete release after only a few days were often noted.…”

Section: Discussionmentioning

confidence: 99%

“…Dextran and BSA are most likely released by restricted diffusion through water-filled pores connected to the particle surface, which can be described by Fickian diffusion with an effective diffusivity, leading to an analogous linear plot of release versus t 0. 43 . Such plots of our data suggest that the slow phases of F-Dex and R-BSA release are controlled by diffusion for all spheres sizes, and a conventional ''initial burst''-defined as a rapid release, faster than that accounted for by simple diffusion, in the first 1-2 days-was not observed (Fig.…”

Section: In Vitro Release Of F-dex and R-bsamentioning

confidence: 99%

Macromolecule Release from Monodisperse PLG Microspheres: Control of Release Rates and Investigation of Release Mechanism

Berkland

Pollauf

Raman

et al. 2007

Journal of Pharmaceutical Sciences

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“…3 and 4) suggest that the canola oil had a similar affinity for the aqueous extraction phase as PLGA. The thermodynamics of this phenomena, which considers interfacial tension effects on spreading coefficients, have been addressed thoroughly in the context of microencapsulation by Mathiowitz and others [30,31] as well as in other previous reports [20,32]. The two competing effects are the rate at which the boundary is moving (convection), and the rate at which the oil is diffusing through the medium.…”

Section: Dynamics Of Oil Distribution In a Forming Particlementioning

confidence: 99%

“…Concurrently, an ultrasonic transducer (Branson Ultrasonics) controlled by a frequency generator (Hewlett Packard model 3325A) disrupted the emerging polymer jet into uniform droplets. For more details on this Precision Particle Fabrication technology, please see references [7][8][9][19][20][21][22]. The streams flowed into a beaker containing approximately 200-300 mL of 1% PVA, and the particles were stirred at room temperature for three hours, filtered, and rinsed with distilled water.…”

Section: Preparation Of Microspheres and Nanocipromentioning

confidence: 99%

NanoCipro encapsulation in monodisperse large porous PLGA microparticles

Arnold

Gorman

Schieber

et al. 2007

Journal of Controlled Release

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119

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Pulmonary drug delivery of controlled release formulations may provide an effective adjunct approach to orally delivered antibiotics for clearing persistent lung infections. Dry powder formulations for this indication should possess characteristics including; effective deposition to infected lung compartments, persistence at the infection site, and steady release of antibiotic. Large porous particles (∼10-15 μm) have demonstrated effective lung deposition and enhanced lung residence as a result of their large diameter and reduced clearance by macrophages in comparison to small microparticles (∼1-5 μm). In this report, Precision Particle Fabrication technology was used to create monodisperse large porous particles of poly(D,L-lactic-co-glycolic acid) (PLGA) utilizing oils as extractable porogens. After extraction, the resulting large porous PLGA particles exhibited a low density and a web-like or hollow interior depending on porogen concentration and type, respectively. Ciprofloxacin nanoparticles (nanoCipro) created by homogenization in dichloromethane, possessed a polymorph with a decreased melting temperature. Encapsulating nanoCipro in large porous PLGA particles resulted in a steady release of ciprofloxacin that was extended for larger particle diameters and for the solid particle morphology in comparison to large porous particles. The encapsulation efficiency of nanoCipro was quite low and factors impacting the entrapment of nanoparticles during particle formation were elucidated. A dry powder formulation with the potential to control particle deposition and sustain release to the lung was developed and insight to improve nanoparticle encapsulation is discussed.

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Uniform double-walled polymer microspheres of controllable shell thickness

Cited by 121 publications

References 32 publications

Controlled-release and preserved bioactivity of proteins from (self-assembled) core-shell double-walled microspheres

Controlled-release and preserved bioactivity of proteins from (self-assembled) core-shell double-walled microspheres

Macromolecule Release from Monodisperse PLG Microspheres: Control of Release Rates and Investigation of Release Mechanism

NanoCipro encapsulation in monodisperse large porous PLGA microparticles

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