The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Yuri F Zuev - One of the best experts on this subject based on the ideXlab platform.
-
Micellization in sodium deoxycholate solutions
Colloid Journal, 2012Co-Authors: L. R. Bogdanova, O. I. Gnezdilov, B. Z. Idiyatullin, R. Kh. Kurbanov, Yuri F Zuev, O. G. Us’yarovAbstract:NMR self-diffusion, tensiometry, and measurement of solubilization capacity are employed to comparatively study micellization in aqueous solutions of a facial amphiphilic compound, sodium deoxycholate (NaDC), and a conventional Micelle-forming sodium dodecyl sulfate. Based on the two-state model, which is commonly used to analyze the data of NMR diffusometry, a method is proposed for determining variable sizes of NaDC Micelles. It is shown that, in the concentration range from the critical Micelle concentration to 0.1 M, the sizes of NaDC Micelles monotonically increase. At comparable sizes of molecules of the examined surfactants, NaDC Micelles are characterized by noticeably smaller aggregation numbers and solubilization capacity than sodium dodecyl sulfate due to the rigid structure of NaDC molecules, their facial amphiphilicity, and a low value of hydrophilic-lipophilic balance.
-
effect of surface potential of reverse Micelle on enzyme substrate complex formation
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2008Co-Authors: Elena A Ermakova, Natalia L Zakhartchenko, Yuri F ZuevAbstract:Abstract The influence of the electrostatic potential of reverse Micelle on the enzyme–substrate complex formation have been studied within the framework of the encounter complex (EC) formation theory. Reverse Micelles have a multiple-factor effect on encapsulated substances and on mechanisms of their interaction. The action of individual constituents on the overall micellar effect was analyzed by means of Brownian dynamics simulation. The effects of surface potential in charged and neutral reverse Micelles, of the size and of the ionic strength of micellar core on the probability to form the reaction complex between serine protease (trypsin) and specific substrate Nα-benzoyl- l -arginine ethyl ester was examined. It was shown that negative potential of Micelle increases the probability of EC formation and the positive potential decreases it. Orientation of substrate in electrostatic field of Micelle depends on the value and the sign of surface potential.
-
Effect of surface potential of reverse Micelle on enzyme–substrate complex formation
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2008Co-Authors: Elena A Ermakova, Natalia L Zakhartchenko, Yuri F ZuevAbstract:Abstract The influence of the electrostatic potential of reverse Micelle on the enzyme–substrate complex formation have been studied within the framework of the encounter complex (EC) formation theory. Reverse Micelles have a multiple-factor effect on encapsulated substances and on mechanisms of their interaction. The action of individual constituents on the overall micellar effect was analyzed by means of Brownian dynamics simulation. The effects of surface potential in charged and neutral reverse Micelles, of the size and of the ionic strength of micellar core on the probability to form the reaction complex between serine protease (trypsin) and specific substrate Nα-benzoyl- l -arginine ethyl ester was examined. It was shown that negative potential of Micelle increases the probability of EC formation and the positive potential decreases it. Orientation of substrate in electrostatic field of Micelle depends on the value and the sign of surface potential.
Vladimir P Torchilin - One of the best experts on this subject based on the ideXlab platform.
-
Polymeric Micelles: polyethylene glycol-phosphatidylethanolamine (PEG-PE)-based Micelles as an example.
Methods of Molecular Biology, 2010Co-Authors: Rupa R. Sawant, Vladimir P TorchilinAbstract:: One of the renowned nanosized pharmaceutical carriers for delivery of poorly soluble drugs, especially, in cancer, is Micelles, which are self-assembled colloidal particles with a hydrophobic core and hydrophilic shell. Among the Micelle-forming compounds, Micelles made of polyethylene glycol-phosphatidylethanolamine (PEG-PE) have gained more attention due to some attractive properties such as good stability, longevity, and ability to accumulate in the areas with an abnormal vasculature via the enhanced permeability and retention effect (into the areas with leaky vasculature, such as tumors). Additionally these Micelles can be made "targeted" by attaching specific targeting ligand molecules to the Micelle surface or can be comprised of stimuli-responsive amphiphilic block copolymers. Addition of second component such as surfactant or another hydrophobic material to the main Micelle forming material further improves the solubilizing capacity of Micelles without compromising their stability. Micelles carrying various contrast agents may become the imaging agents of choice in different imaging modalities. Here, we have discussed various protocols for preparation and evaluation of PEG-PE-based Micelles.
-
Micellar nanocarriers: Pharmaceutical perspectives
Pharmaceutical Research, 2007Co-Authors: Vladimir P TorchilinAbstract: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. © 2006 Springer Science+Business Media, Inc.
-
Micellar Nanocarriers: Pharmaceutical Perspectives
Pharmaceutical Research, 2006Co-Authors: Vladimir P TorchilinAbstract: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.
-
structure and design of polymeric surfactant based drug delivery systems
Journal of Controlled Release, 2001Co-Authors: Vladimir P TorchilinAbstract:The review concentrates on the use of polymeric Micelles as pharmaceutical carriers. Micellization of biologically active substances is a general phenomenon that increases the bioavailability of lipophilic drugs and nutrients. Currently used low-molecular-weight pharmaceutical surfactants have low toxicity and high solubilization power towards poorly soluble pharmaceuticals. However, Micelles made of such surfactants usually have relatively high critical Micelle concentration (CMC) and are unstable upon strong dilution (for example, with the blood volume upon intravenous administration). On the other hand, amphiphilic block co-polymers are also known to form spherical Micelles in solution. These Micelles have very high solubilization capacity and rather low CMC value that makes them very stable in vivo. Amphiphilic block co-polymers suitable for Micelle preparation are described and various types of polymeric Micelles are considered as well as mechanisms of their formation, factors influencing their stability and disintegration, their loading capacity towards various poorly soluble pharmaceuticals, and their therapeutic potential. The basic mechanisms underlying Micelle longevity and steric protection in vivo are considered with a special emphasis on long circulating drug delivery systems. Advantages and disadvantages of Micelles when compared with other drug delivery systems are considered. New polymer–lipid amphiphilic compounds such as diacyillipid–polyethylene glycol, are described and discussed. These compounds are very attractive from a practical point of view, since they easily micellize yielding extremely stable Micelles with very high loading capacity. Micelle passive accumulation in the areas with leaky vasculature (tumors, infarct zones) is discussed as an important physiology-based mechanism of drug delivery into certain target zones. Targeted polymeric Micelles prepared by using thermo- or pH-sensitive components or by attaching specific targeted moieties (such as antibodies) to their outer surface are described as well as their preparation and some in vivo properties. The fast growing field of diagnostic Micelles is analyzed. Polymeric Micelles are considered loaded with various agents for gamma, magnetic resonance, and computed tomography imaging. Their in vitro and in vivo properties are discussed and the results of the initial animal experiments are presented.
André Brodkorb - One of the best experts on this subject based on the ideXlab platform.
-
the casein Micelle historical aspects current concepts and significance
International Dairy Journal, 2008Co-Authors: André BrodkorbAbstract:Abstract The caseins, a group of unique milk-specific acid-insoluble phosphoproteins, represent ≈80% of the total protein in the milk of cattle and other commercial dairy species. Owing to their commercial importance, the caseins have been studied very extensively and are probably the best characterized food protein system. It has been recognized since the work of Schubler in 1818 that the caseins exist in milk as large particles suspended in the aqueous phase (milk serum). Initially, the casein particles were usually referred to as “calcium caseinate–calcium phosphate particles”. The term “casein Micelle” was introduced in 1921 and the two terms were used interchangeably for several years but since about 1960, the latter term has been used exclusively. It has been suggested that the calcium caseinate–phosphate particles are not true Micelles. The term “Micelle” was introduced by Nageli and Schwendener [Nageli, C.W., & Schwendener, W. (1877). Das Mikroskop: Theorie und Anwendung Desselben (2nd ed.). Leipzig: W. Engelmann] for microparticles of cellulose in plant cells visible in the light microscope; later, it was used for various other types of aggregates. Owing to the importance of the casein Micelles for many of the physico-chemical properties of milk and dairy products, their structure and properties and the effects of compositional and processing factors thereon have been studied extensively. Since the discovery of the Micelle-stabilizing protein, κ-casein, in 1956, several models of the casein Micelle have been proposed and refined. This review will focus on the following aspects: introduction and use of the term “Micelle”, early views on the stability of casein in milk, introduction of the term “casein Micelle” for the calcium phosphate–calcium caseinate particles in milk, and the structure and stability of casein Micelles.
-
The casein Micelle: Historical aspects, current concepts and significance
International Dairy Journal, 2008Co-Authors: P. F. Fox, André BrodkorbAbstract:The caseins, a group of unique milk-specific acid-insoluble phosphoproteins, represent ≈80% of the total protein in the milk of cattle and other commercial dairy species. Owing to their commercial importance, the caseins have been studied very extensively and are probably the best characterized food protein system. It has been recognized since the work of Schübler in 1818 that the caseins exist in milk as large particles suspended in the aqueous phase (milk serum). Initially, the casein particles were usually referred to as "calcium caseinate-calcium phosphate particles". The term "casein Micelle" was introduced in 1921 and the two terms were used interchangeably for several years but since about 1960, the latter term has been used exclusively. It has been suggested that the calcium caseinate-phosphate particles are not true Micelles. The term "Micelle" was introduced by Nägeli and Schwendener [Nägeli, C.W., & Schwendener, W. (1877). Das Mikroskop: Theorie und Anwendung Desselben (2nd ed.). Leipzig: W. Engelmann] for microparticles of cellulose in plant cells visible in the light microscope; later, it was used for various other types of aggregates. Owing to the importance of the casein Micelles for many of the physico-chemical properties of milk and dairy products, their structure and properties and the effects of compositional and processing factors thereon have been studied extensively. Since the discovery of the Micelle-stabilizing protein, κ-casein, in 1956, several models of the casein Micelle have been proposed and refined. This review will focus on the following aspects: introduction and use of the term "Micelle", early views on the stability of casein in milk, introduction of the term "casein Micelle" for the calcium phosphate-calcium caseinate particles in milk, and the structure and stability of casein Micelles. © 2008 Elsevier Ltd. All rights reserved.
Adi Eisenberg - One of the best experts on this subject based on the ideXlab platform.
-
block copolymer Micelles as delivery vehicles of hydrophobic drugs Micelle cell interactions
Journal of Drug Targeting, 2006Co-Authors: Radoslav Savic, Adi Eisenberg, Dusica MaysingerAbstract:One-third of drugs in development are water insoluble and one-half fail in trials because of poor pharmacokinetics. Block copolymer Micelles are nanosized particles that can solubilize hydrophobic drugs and alter their kinetics in vitro and in vivo. However, block copolymer Micelles are not solely passive drug containers that simply solubilize hydrophobic drugs; cells internalize Micelles. To facilitate the development of advanced, controlled, micellar drug delivery vehicles, we have to understand the fate of Micelles and Micelle-incorporated drugs in cells and in vivo. With Micelle-based drug formulations recently reaching clinical trials, the impetus for answers is ever so strong and detailed studies of interactions of Micelles and cells are starting to emerge. Most notably, the question arises: Is the internalization of block copolymer Micelles carrying small molecular weight drugs an undesired side effect or a useful means of improving the effectiveness of the incorporated drugs?
-
multiple morphologies and characteristics of crew cut Micelle like aggregates of polystyrene b poly acrylic acid diblock copolymers in aqueous solutions
Journal of the American Chemical Society, 1996Co-Authors: Adi EisenbergAbstract:Crew-cut Micelle-like aggregates of various morphologies prepared from polystyrene-b-poly(acrylic acid), PS-b-PAA, diblock copolymers under near-equilibrium conditions, were studied by transmission electron microscopy (TEM). The insoluble block (PS) contents in the copolymers ranged from 80 to 98 wt %. In spherical Micelles, the Micelle cores, formed by aggregation of the PS blocks, were generally monodisperse. A comparison between star and crew-cut Micelles showed that the latter are distinguished by a low density of corona chains on the core surface and a low degree of stretching of the PS blocks in the cores. As the PAA content in block copolymer decreased, the morphology of the aggregates changed progressively from spheres to cylinders, to bilayers (both vesicles and lamellae), and eventually to compound Micelles consisting of an assembly of inverted Micelles surrounded by a hydrophilic surface. The compound Micelles are believed to be a new morphology for block copolymers. The addition of homopolysty...
Elena A Ermakova - One of the best experts on this subject based on the ideXlab platform.
-
effect of surface potential of reverse Micelle on enzyme substrate complex formation
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2008Co-Authors: Elena A Ermakova, Natalia L Zakhartchenko, Yuri F ZuevAbstract:Abstract The influence of the electrostatic potential of reverse Micelle on the enzyme–substrate complex formation have been studied within the framework of the encounter complex (EC) formation theory. Reverse Micelles have a multiple-factor effect on encapsulated substances and on mechanisms of their interaction. The action of individual constituents on the overall micellar effect was analyzed by means of Brownian dynamics simulation. The effects of surface potential in charged and neutral reverse Micelles, of the size and of the ionic strength of micellar core on the probability to form the reaction complex between serine protease (trypsin) and specific substrate Nα-benzoyl- l -arginine ethyl ester was examined. It was shown that negative potential of Micelle increases the probability of EC formation and the positive potential decreases it. Orientation of substrate in electrostatic field of Micelle depends on the value and the sign of surface potential.
-
Effect of surface potential of reverse Micelle on enzyme–substrate complex formation
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2008Co-Authors: Elena A Ermakova, Natalia L Zakhartchenko, Yuri F ZuevAbstract:Abstract The influence of the electrostatic potential of reverse Micelle on the enzyme–substrate complex formation have been studied within the framework of the encounter complex (EC) formation theory. Reverse Micelles have a multiple-factor effect on encapsulated substances and on mechanisms of their interaction. The action of individual constituents on the overall micellar effect was analyzed by means of Brownian dynamics simulation. The effects of surface potential in charged and neutral reverse Micelles, of the size and of the ionic strength of micellar core on the probability to form the reaction complex between serine protease (trypsin) and specific substrate Nα-benzoyl- l -arginine ethyl ester was examined. It was shown that negative potential of Micelle increases the probability of EC formation and the positive potential decreases it. Orientation of substrate in electrostatic field of Micelle depends on the value and the sign of surface potential.
