One-Step Surface Modification of Poly(lactide-co-glycolide) Microparticles with Heparin

Cui, Chengji; Schwendeman, Steven P.

doi:10.1007/s11095-007-9378-1

Cited by 5 publications

(6 citation statements)

References 46 publications

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“…The mean volume-based diameter and size distribution of the particles were determined by a Microtrac® S3500 (North Largo, FL) particle size analyzer after dispersing the freeze-dried microspheres in a 0.2% w/v aqueous solution of PVA. The polydispersity indices of all formulations were calculated as the ratio of volume-averaged mean particle size to number-averaged mean particle size [25]. The zeta potential was measured by Zeta potential analyzer V. 3.40 (Brookhaven Instruments Corp. Holtsville, NY) after dispersing the formulations in PBS buffer.…”

Section: Particle Characterizationmentioning

confidence: 99%

Inhalable large porous microspheres of low molecular weight heparin: In vitro and in vivo evaluation

Rawat

Majumder²,

Ahsan

2008

Journal of Controlled Release

125

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This study tests the feasibility of large porous particles as long-acting carriers for pulmonary delivery of low molecular weight heparin (LMWH). Microspheres were prepared with a biodegradable polymer, poly(lactic-co-glycolic acid) (PLGA), by a double-emulsion-solvent-evaporation technique. The drug entrapment efficiencies of the microspheres were increased by modifying them with three different additivespolyethyleneimine (PEI), Span 60 and stearylamine. The resulting microspheres were evaluated for morphology, size, zeta potential, density, in vitro drug-release properties, cytotoxicity, and for pulmonary absorption in vivo. Scanning electron microscopic examination suggests that the porosity of the particles increased with the increase in aqueous volume fraction. The amount of aqueous volume fraction and the type of core-modifying agent added to the aqueous interior had varying degrees of effect on the size, density and aerodynamic diameter of the particles. When PEI was incorporated in the internal aqueous phase, the entrapment efficiency was increased from 16.22+/-1.32% to 54.82+/-2.79%. The amount of drug released in the initial burst phase and the release-rate constant for the core-modified microspheres were greater than those for the plain microspheres. After pulmonary administration, the half-life of the drug from the PEI- and stearylamine-modified microspheres was increased by 5- to 6-fold compared to the drug entrapped in plain microspheres. The viability of Calu-3 cells was not adversely affected when incubated with the microspheres. Overall, the data presented here suggest that the newly developed porous microspheres of LMWH have the potential to be used in a form deliverable by dry-powder inhaler as an alternative to multiple parenteral administrations of LMWH.

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Section: Particle Characterizationmentioning

confidence: 99%

Inhalable large porous microspheres of low molecular weight heparin: In vitro and in vivo evaluation

Rawat

Majumder²,

Ahsan

2008

Journal of Controlled Release

125

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“…Heparin-mediated delivery of BMP-2 has also resulted in a wide range of effects in vivo, with studies demonstrating variable amounts of mineralization in both ectopic and orthotopic sites [25, 37–39], reflecting an inconsistent ability to form functional bone. Furthermore, the majority of these materials consist of relatively small amounts of heparin immobilized within a larger bulk material [23, 24, 40–43], which may attenuate heparin’s ability to effectively bind and present growth factors. As a result, previous reports on heparin-containing biomaterials may significantly underestimate the amount of BMP-2 that can be delivered via heparin binding.…”

Section: Introductionmentioning

confidence: 99%

Heparin microparticle effects on presentation and bioactivity of bone morphogenetic protein-2

et al. 2014

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Biomaterials capable of providing localized and sustained presentation of bioactive proteins are critical for effective therapeutic growth factor delivery. However, current biomaterial delivery vehicles commonly suffer from limitations that can result in low retention of growth factors at the site of interest or adversely affect growth factor bioactivity. Heparin, a highly sulfated glycosaminoglycan, is an attractive growth factor delivery vehicle due to its ability to reversibly bind positively charged proteins, provide sustained delivery, and maintain protein bioactivity. This study describes the fabrication and characterization of heparin methacrylamide (HMAm) microparticles for recombinant growth factor delivery. HMAm microparticles were shown to efficiently bind several heparin-binding growth factors (e.g. bone morphogenetic protein-2 (BMP-2), vascular endothelial growth factor (VEGF), and basic fibroblast growth factor (FGF-2)), including a wide range of BMP-2 concentrations that exceeds the maximum binding capacity of other common growth factor delivery vehicles, such as gelatin. BMP-2 bioactivity was assessed on the basis of alkaline phosphatase (ALP) activity induced in skeletal myoblasts (C2C12). Microparticles loaded with BMP-2 stimulated comparable C2C12 ALP activity to soluble BMP-2 treatment, indicating that BMP-2-loaded microparticles retain bioactivity and potently elicit a functional cell response. In summary, our results suggest that heparin microparticles stably retain large amounts of bioactive BMP-2 for prolonged periods of time, and that presentation of BMP-2 via heparin microparticles can elicit cell responses comparable to soluble BMP-2 treatment. Consequently, heparin microparticles present an effective method of delivering and spatially retaining growth factors that could be used in a variety of systems to enable directed induction of cell fates and tissue regeneration.

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“…It was well known that poly (vinyl alcohol) (PVA) is one of the polymeric materials for making emulsifier. PVA possesses good hydrophilicity and other advantages, and it is well established as an effective emulsifier for the PLGA o/w emulsion system [10]. Fig.…”

Section: Evaluation Methods Of Microspheres Compositive Quality Indic...mentioning

confidence: 99%

“…With the emulsifier increased, the viscosity of the solution increased obviously, which induced the collision of the microspheres was hard to occur and prevented from their adhesions. Therefore, the microspheres distribution was more even and the particle size was smaller [10]. However, with further increase in PVA concentration up to 0.150 g/ml, it was difficult S to stir and form uniform microspheres due to too high viscosity.…”

Section: Evaluation Methods Of Microspheres Compositive Quality Indic...mentioning

confidence: 99%

Preparation of Sea Buckthorn Oil-Plga Microspheres via the Emulsion-Solvent Evaporation Process Coupling Ultrasonic Treatment

Liu

et al. 2011

AMR

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The optimal preparation conditions of sea buckthorn oil-poly (lactic-co-glycolic acid) (PLGA) microspheres were studied via the emulsion-solvent evaporation process coupling ultrasonic treatment, using polyvinyl alcohol (PVA) as the emulsifier, PLGA as the wall material, a mixture of dichloromethane and ethyl acetate as the oil phase. The research discussed the effects of the PVA concentration, the PLGA dosage, ultrasonic power and ultrasonic time on comprehensive quality index (S) of sea buckthorn oil-PLGA microspheres. The orthogonal experimental design L9(34) with the factor analysis was applied to optimize preparation conditions. The experimental date showed that the optimal technology preparation conditions for sea buckthorn oil-PLGA microspheres were as follows: the concentration of PVA 0.125 g/ml, PLGA loading 125 mg, ultrasonic time 10 min, and ultrasonic power 180W. It resulted in sea buckthorn oil-PLGA microspheres that were in more regular and smaller shape, and with a better comprehensive quality index.

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One-Step Surface Modification of Poly(lactide-co-glycolide) Microparticles with Heparin

Abstract: PLGA microparticles were successfully surface-modified with heparin. Univalent salts and amino acid complexes of heparin, as effective emulsifiers, can become surface-immobilized in PLGA microspheres.

Cited by 5 publications

References 46 publications

Inhalable large porous microspheres of low molecular weight heparin: In vitro and in vivo evaluation

Inhalable large porous microspheres of low molecular weight heparin: In vitro and in vivo evaluation

Heparin microparticle effects on presentation and bioactivity of bone morphogenetic protein-2

Preparation of Sea Buckthorn Oil-Plga Microspheres via the Emulsion-Solvent Evaporation Process Coupling Ultrasonic Treatment

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