pH-Dependent Micellization of Poly(2-vinylpyridine)-<i>block</i>-poly(ethylene oxide)

Martin, Thomas; Procházka, Karel; Munk, Petr; Webber, S. E.

doi:10.1021/ma960629f

Cited by 260 publications

(265 citation statements)

References 20 publications

(20 reference statements)

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“…Webber et al also studied the influence of pH on the micellization of P2VP-b-PEO diblocks. Titration light scattering data showed that both P2VP and PEO are soluble in water at pH lower than 5 and that P2VP turns insoluble with formation of micelles at higher pH [17].…”

Section: Resultsmentioning

confidence: 99%

Morphology of core-shell-corona aqueous micelles: II. Addition of core-forming homopolymer

Liangcai

Gohy

Willet

et al. 2004

Polymer

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The poly(styrene)-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) triblock copolymer PS 200 -b-P2VP 140 -b-PEO 590 , where the subscripts refer to the number average degrees of polymerization, forms spherical micelles in water, that consist of a PS core, a pH-responsive P2VP shell and a PEO corona. This triblock has been added with homo-PS before micellization in order to increase the volume fraction of the core-forming block. The length of the added homo-PS has been varied with respect to the length of the PS core-forming block: much shorter, much longer and approximately the same. The structure of the micelles has been investigated by transmission electron microscopy, static and dynamic light scattering. Homo-PS phase separates whenever its length is larger than the one of the PS core-forming chains; otherwise this phenomenon occurs beyond a critical concentration that depends on molecular weight. The addition of homo-PS has no influence on the morphology of the micelles and on the characteristic size of both the PS core and the P2VP shell, although the hydrodynamic diameter of the micelles is decreased. Substitution of styrene for homopolystyrene results in transition from a spherical to a dominant rod-like morphology.

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Section: Resultsmentioning

confidence: 99%

Morphology of core-shell-corona aqueous micelles: II. Addition of core-forming homopolymer

Liangcai

Gohy

Willet

et al. 2004

Polymer

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“…are observed at pH > 5 [11,13]. In the case of CSC micelles formed by PS-b-P2VP-b-PEO copolymers, a change in pH is expected to modify deeply conformation and water-solubility of the P2VP blocks.…”

Section: Nm Nmmentioning

confidence: 99%

“…3. The water-solubility of the P2VP block strongly depends on pH [11], the block being hydrophobic and non-soluble in water at pH > 5 and ionized and water-soluble at pH < 5. Although the ionization/deprotonation of P2VP is a complex process [12], it allows for the reversible micellization of P2VP-b-PEO diblocks.…”

Section: Nm 100 Nmmentioning

confidence: 99%

pH Dependence of the morphology of aqueous micelles formed by polystyrene-block-poly(2-vinylpyridine)-blockpoly( ethylene oxide) copolymers

Willet

Varshney²,

Zhang³

et al. 2002

E-Polymers

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Abstract:The morphology of micelles formed by two polystyrene-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) (PS-b-P2VP-b-PEO) copolymers was studied in water by dynamic light scattering and transmission electron microscopy. Spherical micelles were observed that consist of a PS core, a P2VP shell and a PEO corona. The characteristic size of core, shell and corona depends on the copolymer composition. An important increase in micellar size occurs at pH < 5 as a result of P2VP block protonation. The reversibility of this pH effect depends on copolymer composition, too. The conformation of the PEO block plays an important role in this pH driven morphological transition.

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“…In spite of good colloidal and drug-solubilizing properties, the low drug loading efficiency and use of organic solvents for drug loading are still significant concerns in the polymeric micelle formulations [10][11][12]. Thus, this study focuses on the solvent-free system for PTX loading based on a pH-dependent micellization [13][14][15][16] and hydrotropic effect for PTX solubilization in aqueous media [10,[17][18][19].…”

Section: Introductionmentioning

confidence: 99%

A new hydrotropic block copolymer micelle system for aqueous solubilization of paclitaxel

Huh

Min

Lee

et al. 2008

Journal of Controlled Release

106

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Paclitaxel (PTX), a potent anti-cancer drug, is poorly soluble in water, and this has been a major limitation in developing patient friendly formulations for clinical applications. Recent studies on polymeric micelles, especially hydrotropic polymer micelles, have suggested an alternative formulation of PTX based on their high loading capacity and physical stability in aqueous media. The present study aims at aqueous solubilization of PTX in polymer micelles without using any organic solvents that is usually required for solubilization in polymer micelles. Poly(ethylene glycol) was used as a hydrophilic block and, as a hydrotropic block, poly(4-(2-vinylbenzyloxy-Npicolylnicotinamide)) (P(2-VBOPNA)) was synthesized by atom transfer radical polymerization. The hydrotropic block copolymers did not form a micellar structure at pH 2 or below due to protonation of PNA groups, but the aqueous solubility of PTX increased significantly by the hydrotropic activity of P(2-VBOPNA). At pH values higher than 2, the PTX solubility increased even further due to deprotonation of 2-VBOPNA, leading to effective polymer micellization. A longer hydrotropic block resulted in higher aqueous PTX solubility, and slightly slower release rate from the micelles. The hydrotropic block copolymers synthesized in this study are able to form PTXloaded polymeric micelles in aqueous solution without using any organic solvents.

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pH-Dependent Micellization of Poly(2-vinylpyridine)-block-poly(ethylene oxide)

Cited by 260 publications

References 20 publications

Morphology of core-shell-corona aqueous micelles: II. Addition of core-forming homopolymer

Morphology of core-shell-corona aqueous micelles: II. Addition of core-forming homopolymer

pH Dependence of the morphology of aqueous micelles formed by polystyrene-block-poly(2-vinylpyridine)-blockpoly( ethylene oxide) copolymers

A new hydrotropic block copolymer micelle system for aqueous solubilization of paclitaxel

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