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Polymeric Particles (polymeric + particle)
Selected AbstractsTailored composite polymer,metal nanoparticles by miniemulsion polymerization and thiol-ene functionalizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2010Kim Y. van Berkel Abstract A simple and modular synthetic approach, based on miniemulsion polymerization, has been developed for the fabrication of composite polymer,metal nanoparticle materials. The procedure produces well-defined composite structures consisting of gold, silver, or MnFe2O4 nanoparticles (,10 nm in diameter) encapsulated within larger spherical nanoparticles of poly(divinylbenzene) (,100 nm in diameter). This methodology readily permits the incorporation of multiple metal domains into a single polymeric particle, while still preserving the useful optical and magnetic properties of the metal nanoparticles. The morphology of the composite particles is retained upon increasing the inorganic content and also upon redispersion in organic solvents. Finally, the ability to tailor the surface chemistry of the composite nanoparticles and incorporate steric stabilizing groups using simple thiol-ene chemistry is demonstrated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1594,1606, 2010 [source] Designer Biomaterials for NanomedicineADVANCED FUNCTIONAL MATERIALS, Issue 24 2009Nishit Doshi Abstract Nanotechnology has had tremendous impact on medical science and has resulted in phenomenal progress in the field of drug delivery and diagnostics. A wide spectrum of novel nanomaterials including polymeric particles, liposomes, quantum dots, and iron oxide particles have been developed for applications in therapeutic delivery and diagnostics. This has resulted in control over the rate and period of delivery and targeting of drugs to specific organs in the human body. This feature article focuses on the delivery of drugs using polymeric particles. The size, choice of polymer, surface chemistry, shape, and mechanical properties of the particles are parameters that critically affect particle function. Numerous biomaterials and fabrication techniques have been developed in the last decade that focus on novel design parameters, such as shape and mechanical properties and the interplay of these parameters with the size and surface chemistry of particles. Recent advances with particular focus on the importance of particle shape are highlighted, and the challenges that are yet to be fulfilled are underscored. [source] Multifaceted and Nanobored Particle Arrays Sculpted Using Colloidal Lithography,ADVANCED FUNCTIONAL MATERIALS, Issue 1 2006D.-G. Choi Abstract A novel method of fabricating multifaceted and nanobored particle arrays via colloidal lithography using colloidal-crystal layers as masks for anisotropic reactive-ion etching (RIE) is reported. The shape of the sculpted particles is dependent on the crystal orientation relative to the etchant flow, the number of colloidal layers, the RIE conditions, and the matrix (or mask) structure in colloidal lithography. Arrays of non-spherical particles with sculpted shapes, which to date could not otherwise be produced, are fabricated using a tilted anisotropic RIE process and the layer-by-layer growth of a colloidal mask. These non-spherical particles and their ordered arrays can be used for antireflection surfaces, biosensors, and nanopatterning masks, as well as non-spherical building blocks for novel colloidal crystals. In addition, polymeric particles with patterned holes of controlled depths obtained by the present method can be applied to the fabrication of functional composite particles. [source] The Synthesis and Assembly of Polymeric Microparticles Using MicrofluidicsADVANCED MATERIALS, Issue 41 2009Dhananjay Dendukuri Abstract The controlled synthesis of micrometer-sized polymeric particles bearing features such as nonspherical shapes and spatially segregated chemical properties is becoming increasingly important. Such particles can enable fundamental studies on self-assembly and suspension rheology, as well as be used in applications ranging from medical diagnostics to photonic devices. Microfluidics has recently emerged as a very promising route to the synthesis of such polymeric particles, providing fine control over particle shape, size, chemical anisotropy, porosity, and core/shell structure. This progress report summarizes microfluidic approaches to particle synthesis using both droplet- and flow-lithography-based methods, as well as particle assembly in microfluidic devices. The particles formed are classified according to their morphology, chemical anisotropy, and internal structure, and relevant examples are provided to illustrate each of these approaches. Emerging applications of the complex particles formed using these techniques and the outlook for such processes are discussed. [source] Experimental problems in the application of UV/visible based methods as the quantification tool for the entrapped/released insulin from PLGA carriersJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2009V.L. Lassalle Abstract BACKGROUND: Controlled release of medicaments from biodegradable polymers remains the most convenient way for their sustained release. Although a number of articles have been published, experimental work involving the preparation of polymer-based carriers and release procedures are not described with sufficient level of detail to allow other researchers to reproduce the experiments and to compare published results with their own. In this contribution the experimental background of the entrapment and release of insulin from PLGA carriers is described and the problems found at each step related to UV/Visible method used to quantify them are addressed in detail. RESULTS: The quantification of entrapped insulin by UV/visible methods was affected by aggregation. The design of the release experiment influenced the results regarding the entrapment efficiency (EE) and the maximum percentage of released insulin. It was also found that the presence of colloidal polymeric particles, insufficient centrifugation times and the kind of solvent used in the release test might lead to mistakes in the percentage of liberated insulin when UV/visible based methods are employed. CONCLUSIONS: This contribution demonstrates that serious discrepancies in the EE and percentage of released protein may arise if some key experimental factors are not taken into account. Therefore, the analysis presented here tries to point out important aspects of this topic currently not reported, unnoticed or not properly analyzed in the open literature. The results are useful for the entrapment of any protein on any polymeric device using UV/visible based methods to quantify them. Copyright © 2009 Society of Chemical Industry [source] Preparation and characterization of a customized cellulose acetate butyrate dispersion for controlled drug deliveryJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 6 2002Siva Vaithiyalingam Abstract The purpose of the present experiment was to prepare and characterize the aqueous-based pseudolatex system of cellulose acetate butyrate (CAB) for controlled drug delivery. Aqueous pseudolatex systems are advantageous over organic-based coating systems because these systems are devoid of criteria pollutants such as carbon monoxide, nitrogen oxides, nonmethane volatile organic compounds, and sulfur dioxide. Pseudolatex was prepared with CAB and polyvinyl alcohol (stabilizer) by a polymer emulsification technique. The stability of pseudolatex was evaluated. Particle size was measured and rheological experiments were conducted. The glass transition temperature, microscopic free volume, permeation coefficient, and mechanical properties of plasticized pseudolatex films were estimated. Surface roughness of coating on inert Nu-Pareil® beads (Ingredient Technology Corp., Mahwah, NJ) was measured as a function of coating weight gain. The CAB Pseudolatex was found to be stabilized by steric forces. From intrinsic viscosity, the thickness of the stabilization layer was estimated. An increase in polymeric particles proportionately decreased the thickness of the stabilization layer. All the essential properties of a coating membrane such as microscopic free-volume fraction, permeability coefficient, mechanical properties, and glass transition temperature were fairly controllable as a function of plasticizer concentration. The pseudolatex dispersion of CAB was stable with negligible sedimentation volume and a particle size of 300 nm. Because CAB is water insoluble and non-ionizable, this pseudolatex can be used for pH-independent coating. The films obtained were strong and flexible for controlled drug delivery applications. Coating with the CAB dispersion reduced the surface roughness of beads but it remained stable as a function of increase in coating weight gain. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:1512,1522, 2002 [source] Characterization of the interactions between polymethacrylate-based aqueous polymeric dispersions and aluminum lakesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 12 2001Nasser Nyamweya Abstract Instability in film coating formulations can arise from interactions between aluminum lake pigments and aqueous polymeric dispersions. The purpose of this study was to characterize the interactions between three polymethacrylate-based aqueous polymeric dispersions (Eudragit® RS 30 D, Eudragit® L 30 D-55, and Eudragit® NE 30 D) and aluminum lakes. Particle size measurements, pH stability profiles, zeta potential measurements, and microscopy were used to study mixed dispersions of the polymeric latices and the lakes. Interactions leading to dispersion instability were related to the surface charge of the components in the formulation. Interactions between the ionic polymers and the lakes arose from instability of the lakes outside a certain pH range resulting in the release of electrolytes, which led to aggregation of the polymeric particles. Interactions between the nonionic polymer and the lakes were related to the polymer modifying the surface charge of the lakes, resulting in aggregation of the pigment particles. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1937,1947, 2001 [source] From polymeric particles to multifunctional nanocapsules for biomedical applications using the miniemulsion processJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 3 2010Katharina Landfester Abstract The miniemulsions process represents a versatile tool for the formation of polymeric nanoparticles consisting of different kinds of polymer as obtained by a variety of polymerization types ranging from radical, anionic, cationic, enzymatic polymerization to polyaddition, and polycondensation. The process perfectly allows the encapsulation of hydrophilic and hydrophobic liquids and solids in polymeric shells, molecularly dissolved dyes or other components. In combination with a specific functionalization of the nanoparticles' or nanocapsules' surfaces and the possibility to release substances in a defined way from the interior, complex nanoparticles or nanocapsules are obtained, which are ideally suited for application in biomedical application as marker and targeted drug-delivery system. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 493,515, 2010 [source] Recent advances in controlled/living radical polymerization in emulsion and dispersionJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2008Jung Kwon Oh Abstract Effective ways to conduct controlled/living radical polymerization (CRP) in emulsion systems are necessary for commercial latex production without significant modification of current industrial facilities. Conducting CRP in emulsion media is more complicated and more challenging than its application in homogeneous bulk. These challenges come from the intrinsic kinetics of emulsion polymerization. They include mass transport, slow chain growth mechanism, and exit of short radicals from polymeric particles. This review describes the recent developments of CRP in heterogeneous dispersion, including miniemulsion, microemulsion, dispersion, and especially emulsion. Various approaches for conducting emulsion CRP are detailed, including controlled seeded emulsion polymerization, nanoprecipitation, use of short oligomers as macroinitiators for in situ block copolymerization, and RAFT-mediated self-assembly. In addition many remaining challenges of the current methods barring wide spread industrial application of emulsion CRP are also suggested. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6983,7001, 2008 [source] Synthesis of polymeric core,shell particles using surface-initiated living free-radical polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2007Sarav B. Jhaveri Abstract An easy and novel approach to the synthesis of functionalized nanostructured polymeric particles is reported. The surfactant-free emulsion polymerization of methyl methacrylate in the presence of the crosslinking reagent 2-ethyl-2-(hydroxy methyl)-1,3-propanediol trimethacrylate was used to in situ crosslink colloid micelles to produce stable, crosslinked polymeric particles (diameter size , 100,300 nm). A functionalized methacrylate monomer, 2-methacryloxyethyl-2,-bromoisobutyrate, containing a dormant atom transfer radical polymerization (ATRP) living free-radical initiator, which is termed an inimer (initiator/monomer), was added to the solution during the polymerization to functionalize the surface of the particles with ATRP initiator groups. The surface-initiated ATRP of different monomers was then carried out to produce core,shell-type polymeric nanostructures. This versatile technique can be easily employed for the design of a wide variety of polymeric shells surrounding a crosslinked core while keeping good control over the sizes of the nanostructures. The particles were characterized with scanning electron microscopy, transmission electron microscopy, optical microscopy, dynamic light scattering, and Raman spectroscopy. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1575,1584, 2007 [source] Preparation and characterization of self-dispersible polymeric microspheres,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 7-8 2006Ke Min Abstract Monodispersed OEGMA/St polymeric particles were prepared through soap-free emulsion polymerization, then surface modification was conducted by atom transfer radical polymerization (ATRP), and nano-size hairy shell of OEGMA/St particles were obtained. By hydrolysis, the grafting chains of the hairy particles were successfully cut down from the core particles. Through gel permeation chromatography (GPC) and transmission electron microscopy (TEM) measurements, the density of grafting chains was calculated. Experimental results showed that the hairy shell on the surface of the particles could dramatically improve the particles dispersibility in organic solvents. Copyright © 2006 John Wiley & Sons, Ltd. [source] |