Polymeric micelles - a new generation of colloidal drug carriers.
01 Sep 1999-European Journal of Pharmaceutics and Biopharmaceutics (Elsevier)-Vol. 48, Iss: 2, pp 101-111
TL;DR: This review examines the chemical nature of polymeric micelles as well as the methods used to characterize them with regard to drug delivery and potential medical applications, especially in cancer chemotherapy, are described and discussed.
About: This article is published in European Journal of Pharmaceutics and Biopharmaceutics.The article was published on 1999-09-01. It has received 1200 citations till now. The article focuses on the topics: Critical micelle concentration & Drug carrier.
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TL;DR: The surface mechanisms, which affords red blood cells long-circulatory lives and the ability of specific microorganisms to evade macrophage recognition, are explored and the rational approaches in the design as well as the biological performance of such constructs are assessed.
Abstract: The rapid recognition of intravenously injected colloidal carriers, such as liposomes and polymeric nanospheres from the blood by Kupffer cells, has initiated a surge of development for "Kupffer cell-evading" or long-circulating particles. Such carriers have applications in vascular drug delivery and release, site-specific targeting (passive as well as active targeting), as well as transfusion medicine. In this article we have critically reviewed and assessed the rational approaches in the design as well as the biological performance of such constructs. For engineering and design of long-circulating carriers, we have taken a lead from nature. Here, we have explored the surface mechanisms, which affords red blood cells long-circulatory lives and the ability of specific microorganisms to evade macrophage recognition. Our analysis is then centered where such strategies have been translated and fabricated to design a wide range of particulate carriers (e.g., nanospheres, liposomes, micelles, oil-in-water emulsions) with prolonged circulation and/or target specificity. With regard to the targeting issues, attention is particularly focused on the importance of physiological barriers and disease states.
3,413 citations
Cites background from "Polymeric micelles - a new generati..."
...…acid)-poly(methyl methacrylate) as well as those that have been used in particle coatings (e.g., poloxamers, poloxamines, PEG-PLA, PEG-PLGA) also self-disperse in water to form spherical polymeric micelles with diameters in the size range of 15 to 80 nm (Yokoyama, 1992; Jones and Leroux, 1999)....
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TL;DR: C encapsulated individual nanocrystals in phospholipid block–copolymer micelles acted as in vitro fluorescent probes to hybridize to specific complementary sequences and were followed to the tadpole stage, allowing lineage-tracing experiments in embryogenesis.
Abstract: Fluorescent semiconductor nanocrystals (quantum dots) have the potential to revolutionize biological imaging, but their use has been limited by difficulties in obtaining nanocrystals that are biocompatible. To address this problem, we encapsulated individual nanocrystals in phospholipid block-copolymer micelles and demonstrated both in vitro and in vivo imaging. When conjugated to DNA, the nanocrystal-micelles acted as in vitro fluorescent probes to hybridize to specific complementary sequences. Moreover, when injected into Xenopus embryos, the nanocrystal-micelles were stable, nontoxic (<5 x 10(9) nanocrystals per cell), cell autonomous, and slow to photobleach. Nanocrystal fluorescence could be followed to the tadpole stage, allowing lineage-tracing experiments in embryogenesis.
3,049 citations
TL;DR: This review will discuss some recent trends in using micelles as pharmaceutical carriers, including lipid-core micells, which may become the imaging agents of choice in different imaging modalities.
Abstract: Micelles, self-assembling nanosized colloidal particles with a hydrophobic core and hydrophilic shell are currently successfully used as pharmaceutical carriers for water-insoluble drugs and demonstrate a series of attractive properties as drug carriers. Among the micelle-forming compounds, amphiphilic copolymers, i.e., polymers consisting of hydrophobic block and hydrophilic block, are gaining an increasing attention. Polymeric micelles possess high stability both in vitro and in vivo and good biocompatibility, and can solubilize a broad variety of poorly soluble pharmaceuticals many of these drug-loaded micelles are currently at different stages of preclinical and clinical trials. Among polymeric micelles, a special group is formed by lipid-core micelles, i.e., micelles formed by conjugates of soluble copolymers with lipids (such as polyethylene glycol-phosphatidyl ethanolamine conjugate, PEG-PE). Polymeric micelles, including lipid-core micelles, carrying various reporter (contrast) groups may become the imaging agents of choice in different imaging modalities. All these micelles can also be used as targeted drug delivery systems. The targeting can be achieved via the enhanced permeability and retention (EPR) effect (into the areas with the compromised vasculature), by making micelles of stimuli-responsive amphiphilic block-copolymers, or by attaching specific targeting ligand molecules to the micelle surface. Immunomicelles prepared by coupling monoclonal antibody molecules to p-nitrophenylcarbonyl groups on the water-exposed termini of the micelle corona-forming blocks demonstrate high binding specificity and targetability. This review will discuss some recent trends in using micelles as pharmaceutical carriers.
1,685 citations
Cites background from "Polymeric micelles - a new generati..."
...same type (A-B-type copolymers), or can form alternating blocks with different hydrophobicity (A-B-A type copolymers) (23)....
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...achieving extended circulation time, favorable biodistribution and lower toxicity of a drug (23,31,47)....
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TL;DR: The review concentrates on the use of polymeric micelles as pharmaceutical carriers and the basic mechanisms underlying micelle longevity and steric protection in vivo are considered with a special emphasis on long circulating drug delivery systems.
1,670 citations
TL;DR: This review covers the principles, advantages, and drawbacks of passive and active targeting based on various polymer and magnetic iron oxide nanoparticle carriers with drug attached by both covalent and noncovalent pathways.
Abstract: Targeted delivery combined with controlled drug release has a pivotal role in the future of personalized medicine. This review covers the principles, advantages, and drawbacks of passive and active targeting based on various polymer and magnetic iron oxide nanoparticle carriers with drug attached by both covalent and noncovalent pathways. Attention is devoted to the tailored conjugation of targeting ligands (e.g., enzymes, antibodies, peptides) to drug carrier systems. Similarly, the approaches toward controlled drug release are discussed. Various polymer–drug conjugates based, for example, on polyethylene glycol (PEG), N-(2-hydroxypropyl)methacrylamide (HPMA), polymeric micelles, and nanoparticle carriers are explored with respect to absorption, distribution, metabolism, and excretion (ADME scheme) of administrated drug. Design and structure of superparamagnetic iron oxide nanoparticles (SPION) and condensed magnetic clusters are classified according to the mechanism of noncovalent drug loading involving...
1,241 citations
References
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Book•
01 Jan 1977
TL;DR: Colloid and surface chemistry - scope and variables sedimentation and diffusion and their equilibrium solution thermodynamics - osmotic and Donnan equilibria the rheology of dispersions static and dynamic light scattering and other radiation scattering surface tension and contact angle - application to pure substances adsorption from solution and monolayer formation colloidal structures in surfactant solutions - association colloids adsorction at gas-solid interfaces van der Waals forces the electrical double layer and double-layer interactions electrophoresis and other electrokinetic phenomena electrostatic and polymer-induced
Abstract: Colloid and surface chemistry - scope and variables sedimentation and diffusion and their equilibrium solution thermodynamics - osmotic and Donnan equilibria the rheology of dispersions static and dynamic light scattering and other radiation scattering surface tension and contact angle - application to pure substances adsorption from solution and monolayer formation colloidal structures in surfactant solutions - association colloids adsorption at gas-solid interfaces van der Waals forces the electrical double layer and double-layer interactions electrophoresis and other electrokinetic phenomena electrostatic and polymer-induced colloid stability appendix A - examples of expansions encountered in this book appendix B - units - CGS-SI interconversions appendix C - statistics of discrete and continuous distributions of data appendix D - list of worked-out examples
4,177 citations
"Polymeric micelles - a new generati..." refers methods in this paper
...The cmc can be determined by several methods and the reader is referred to specialized textbooks for further information on this topic [50,51]....
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TL;DR: In this article, it was shown that in the presence of polar solvents, there is a significant enhancement in the intensity of the 0-0 vibronic band at the expense of other bands.
Abstract: The fluorescence intensities for various vibronic fine structures in the pyrene monomer fluorescence show strong solvent dependence. In the presence of polar solvents, there is a significant enhancement in the intensity of the 0--0 vibronic band at the expense of other bands. This strong perturbation in the vibronic band intensities is more dependent on the solvent dipole moment than on the bulk solvent dielectric constant. This suggests the operation of some specific solute--solvent dipole--dipole interaction mechanism. The strong perturbation of the vibronic band intensities has been used as a probe to accurately determine critical micelle concentrations and also to investigate the extent of water penetration in micellar systems.
3,271 citations
"Polymeric micelles - a new generati..." refers background in this paper
...Pyrene is a condensed aromatic hydrocarbon that is highly hydrophobic and sensitive to the polarity of the surrounding environment [57]....
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...The apparent cmc can be obtained from the plot of the ̄uorescence of pyrene, the I1/I3 ratio from emission spectra or the I333/I338 ratio from excitation spectra, against concentration: a major change in the slope indicates the onset of micellization [57] (Fig....
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...When micelles are formed, pyrene partitions preferentially toward the hydrophobic domain afforded by the micellar core and thus, experiences a non-polar environment [57]....
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TL;DR: In this paper, a lower critical solution temperature of poly(N-isopropyl acrylamide was found to be due to an entropy effect, which was attributed to the formation of nonpolar and intermolecular hydrogen bonds.
Abstract: Aqueous solutions of poly(N-isopropyl acrylamide) show a lower critical solution temperature. The thermodynamic properties of the system have been evaluated from the phase diagram and the heat absorbed during phase separation and the phenomenon is ascribed to be primarily due to an entropy effect. From viscosity, sedimentation, and light-scattering studies of solutions close to conditions of phase separation, it appears that aggregation due to formation of nonpolar and intermolecular hydrogen bonds is important. In addition, a weakening of the ordering effect of the water-amide hydrogen bonds as the temperature is raised contributes to the stability of the two-phase system.
2,698 citations
TL;DR: A needle-like solid is obtained on drying of aqueous solutions of the spherical micelles of the highly asymmetric polystyrene-poly-(acrylic acid) block copolymers prepared in a low molecular weight solvent system.
Abstract: The observation by transmission electron microscopy of six different stable aggregate morphologies is reported for the same family of highly asymmetric polystyrene-poly-(acrylic acid) block copolymers prepared in a low molecular weight solvent system. Four of the morphologies consist of spheres, rods, lamellae, and vesicles in aqueous solution, whereas the fifth consists of simple reverse micelle-like aggregates. The sixth consists of up to micrometer-size spheres in aqueous solution that have hydrophilic surfaces and are filled with the reverse micelle-like aggregates. In addition, a needle-like solid, which is highly birefringent, is obtained on drying of aqueous solutions of the spherical micelles. This range of morphologies is believed to be unprecedented for a block copolymer system.
2,279 citations
"Polymeric micelles - a new generati..." refers background in this paper
...Recently, Zhang and Eisenberg [27,102] have described a variety of polymeric micelles with different morphologies, opening very interesting perspectives in drug delivery....
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...Several studies describe the use of non-or poorly biodegradable polymers such as polystyrene (Pst) [26,27] or poly(methyl methacrylate) (PMMA) [28] as constituents of the inner core....
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Journal Article•
TL;DR: Tumor vessels in the model found that tumor vessels in this model were permeable to liposomes of up to 400 nm in diameter, suggesting that the cutoff size of the pores is between 400 and 600nm in diameter.
Abstract: Molecular size is one of the key determinants of transvascular transport of therapeutic agents in tumors. However, there are no data in the literature on the molecular size dependence of microvascular permeability in tumors. Therefore, we measured microvascular permeability to various macromolecules in the human colon adenocarcinoma LS174T transplanted in dorsal skin chambers in severe combined immunodeficient mice. These molecules were fluorescently labeled and injected i.v. into mice. The microvascular permeability was calculated from the fluorescence intensity measured by the intravital fluorescence microscopy technique. The value of permeability varied approximately 2-fold in the range of molecular weight from 25,000 to 160,000. These data indicate that tumor vessels are less permselective than normal vessels, presumably due to large pores in the vessel wall. The transport of macromolecules appears to be limited by diffusion through these pores. The cutoff size of the pores was estimated by observations of transvascular transport of sterically stabilized liposomes of 100-600 nm in diameter. We found that tumor vessels in our model were permeable to liposomes of up to 400 nm in diameter, suggesting that the cutoff size of the pores is between 400 and 600 nm in diameter.
1,747 citations
"Polymeric micelles - a new generati..." refers background in this paper
...Large pores exist and may account for the perivascular accumulation of macromolecules and colloidal drug carriers [89,90]....
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