Polymer Micelles with Hydrophobic Core and Ionic Amphiphilic Corona. 2. Starlike Distribution of Charged and Nonpolar Blocks in Corona

Evgeny A. Lysenko; Alevtina I. Kulebyakina; Pavel S. Chelushkin; Artem M. Rumyantsev; Elena Yu. Kramarenko; Alexander B. Zezin

doi:10.1021/la302606a

Effect of Molecular Architecture on Associating Behavior of Star-Like Amphiphilic Polymers Consisting of Plural Poly(ethylene oxide) and One Alkyl Chain

Polymers ◽

10.3390/polym13030460 ◽

2021 ◽

Vol 13 (3) ◽

pp. 460

Author(s):

Daisuke Kugimoto ◽

Aoi Taniguchi ◽

Masaki Kinoshita ◽

Isamu Akiba

Keyword(s):

Ethylene Oxide ◽

Average Molecular Weight ◽

Amphiphilic Polymers ◽

Hydrophobic Core ◽

Molecular Architecture ◽

Polymer Micelles ◽

The Core ◽

X Ray Scattering ◽

Poly Ethylene Oxide ◽

Poly Ethylene

Associating behavior of star-like amphiphilic polymers consisting of two or three poly(ethylene oxide) (PEO) chains and one stearyl chain (C18) was investigated. Although the aggregation number (Nagg) of linear analogue of amphiphilic polymers monotonically decreased with increasing number-average molecular weight of PEO (Mn,PEO), the Nagg of micelles of star-like amphiphilic polymers with Mn,PEO = 550 g/mol was smaller than that with Mn,PEO = 750 g/mol, whereas that with Mn,PEO ≥ 750 g/mol showed general Mn,PEO dependence. Small-angle X-ray scattering analyses revealed that the occupied area of one PEO chain on the interface between hydrophobic core and corona layer in the micelles of star-like polymers was much narrower than that in the linear amphiphilic polymers. This result indica ted the PEO chains of star-like polymers partially took unfavorable conformation near the core–corona interface in polymer micelles. The effect of local conformation of PEO chains near the interface on the associating behavior became significant as Mn,PEO decreased. Therefore, in polymer micelles of star-like amphiphilic polymers containing PEO with Mn,PEO = 550 g/mol, the enlargement of occupied area of PEO on the core–corona interface should be caused to avoid the formation of unfavorable conformations of partial PEO chains, resulting in a decrease in Naggs.

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Anomalous Small-Angle X-ray Scattering Study of Structure of Polymer Micelles Having Bromines in Hydrophobic Core

Macromolecules ◽

10.1021/ma300461d ◽

2012 ◽

Vol 45 (15) ◽

pp. 6150-6157 ◽

Cited By ~ 18

Author(s):

Isamu Akiba ◽

Atsuro Takechi ◽

Megumi Sakou ◽

Masashi Handa ◽

Yuya Shinohara ◽

...

Keyword(s):

Small Angle ◽

Hydrophobic Core ◽

Polymer Micelles ◽

X Ray ◽

X Ray Scattering ◽

Scattering Study ◽

Ray Scattering

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Effective oxidation protection of polymer micelles for copper nanoparticles in water

RSC Advances ◽

10.1039/c4ra00304g ◽

2014 ◽

Vol 4 (27) ◽

pp. 14193-14196 ◽

Cited By ~ 3

Author(s):

Hang Lu ◽

Li Yu ◽

Bo Yang ◽

Jianing Si ◽

Jianzhong Du

Keyword(s):

Block Copolymer ◽

Copper Nanoparticles ◽

Diffusion Barrier ◽

Copper Nanoparticle ◽

Hydrophobic Core ◽

Polymer Micelles ◽

Oxidation Protection ◽

Water Dispersible ◽

Copolymer Micelle

Copper nanoparticles are often susceptible to rapid oxidation in water. We report a water-dispersible and long-term stable copper nanoparticle protected by a block copolymer micelle that can effectively inhibit the access of oxygen to the copper inside its hydrophobic core, providing a sufficient diffusion barrier against oxidation in water.

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ASAXS Study on Spatial Distribution of Hydrophobic Compounds in Polymer Micelles

Acta Crystallographica Section A Foundations and Advances ◽

10.1107/s2053273314084198 ◽

2014 ◽

Vol 70 (a1) ◽

pp. C1580-C1580

Author(s):

Isamu Akiba ◽

Ryosuke Nakanishi ◽

Masaki Kugimoto ◽

Daisuke Kugimoto ◽

Yusuke Sanada ◽

...

Keyword(s):

Spatial Distribution ◽

Hydrophobic Core ◽

Polymer Micelle ◽

Polymer Micelles ◽

Small Droplet ◽

Chemical Structures ◽

Hydrophobic Compounds ◽

Drug Compounds ◽

Resonant Term ◽

Highly Hydrophobic

In drug delivery system (DDS) using polymer micelles as drug carrier, DDS properties are related to spatial distribution of drug compounds in the micelles [1]. Because the spatial distribution of drug compounds should strongly depend on interactions and solubility of drug compounds in the micelles, elucidation of the relation between chemical structures of drug compounds and their spatial distribution in the micelle is much important. Thus, in this study, we examine to elucidate the relation between chemical features and spatial distribution of drug compounds in polymer micelles by using anomalous small-angle X-ray scattering (ASAXS). To apply the ASAXS near bromine K-edge for analysis [2] of spatial distribution of drug compounds in polymer micelles, we employ 4 different bromine-labeled hydrophobic compounds as model drug compounds and polymer micelles composed of poly(dimethylaminoethyl methacrylate)-block-poly(methyl methacrylate) (PDMAEMA-b-PMMA). Figure shows SAXS and resonant term obtained from ASAXS near bromine K-edge for the polymer micelles containing 9-bromofluorene (BrF). The domain size estimated from the resonant term is much smaller than that of hydrophobic PMMA core of the micelle. Therefore, When BrF, which is highly hydrophobic and scarcely dissolved in hydrophobic PMMA, is incorporated in the polymer micelle, BrF forms small droplet in the hydrophobic core composed of PMMA. For the micelles incorporating bromobenzene, which as similar properties of BrF, similar result is obtained. On the other hand, 4-bromobenzyl alcohol and ethyl 2-bromoethyl propionate, which are miscible with PMMA, are homogeneously dispersed in the PMMA core of the micelles. These results indicate that highly hydrophobic compounds forms small droplet in hydrophobic core, and introduction of polarity to the compounds causes expansion of the area existing the hydrophobic compounds in polymer micelle.

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More Is Less: Curcumin and Paclitaxel Formulations Using Poly(2-Oxazoline) and Poly(2-Oxazine) Based Amphiphiles Bearing Linear and Branched C9 Side Chains

10.26434/chemrxiv.5883109 ◽

2018 ◽

Author(s):

Michael M. Lübtow ◽

Larissa Keßler ◽

Thomas Lorson ◽

Niklas Gangloff ◽

Marius Kirsch ◽

...

Keyword(s):

Triblock Copolymers ◽

Side Chain ◽

Side Chains ◽

General Strategy ◽

Loading Capacity ◽

Hydrophobic Core ◽

Polymer Micelles ◽

Drug Solubilization ◽

Solubilization Capacity ◽

Insoluble Compounds

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Helvetica} <p>A known limitation of polymer micelles for the formulation of hydrophobic drugs is their low loading capacity, which rarely exceeds 20 wt.%. One general strategy to overcome this limitation is to increase the amphiphilic contrast, i.e. to make the hydrophobic core of the micelles more hydrophobic. However, we reported earlier that for poly(2-oxazoline) based amphiphilic triblock copolymers, a minimal amphiphilic contrast is beneficial, which was tentatively attributed to possible side chain crystallization. Here, we revisit this subject in more detail using more hydrophobic side chains that are either linear (nonyl) or branched (3-ethylheptyl), the latter of which should not crystallize. Moreover, we investigate two different backbones within the hydrophobic block, in particular poly(2-oxazoline) and poly(2-oxazine), for the solubilization and co-solubilization of the two highly water insoluble compounds curcumin and paclitaxel. Even though high loading capacities could be achieved for curcumin within poly(2-oxazine) based triblock copolymers, the solubilization capacity of all investigated polymers with longer side chains was significantly lower compared to poly(2-oxazoline)s and poly(2-oxazine)s with shorter side chains. Although the even lower loading capacity for paclitaxel could be somehow attenuated by co-formulating curcumin, this study corroborates that in the case of poly(2-oxazoline) and poly(2-oxazine) based polymer micelles, an increased amphiphilic contrast leads to less drug solubilization.</p>

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More Is Less: Curcumin and Paclitaxel Formulations Using Poly(2-Oxazoline) and Poly(2-Oxazine) Based Amphiphiles Bearing Linear and Branched C9 Side Chains

10.26434/chemrxiv.5883109.v1 ◽

2018 ◽

Cited By ~ 1

Author(s):

Michael M. Lübtow ◽

Larissa Keßler ◽

Thomas Lorson ◽

Niklas Gangloff ◽

Marius Kirsch ◽

...

Keyword(s):

Triblock Copolymers ◽

Side Chain ◽

Side Chains ◽

General Strategy ◽

Loading Capacity ◽

Hydrophobic Core ◽

Polymer Micelles ◽

Drug Solubilization ◽

Solubilization Capacity ◽

Insoluble Compounds

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Helvetica} <p>A known limitation of polymer micelles for the formulation of hydrophobic drugs is their low loading capacity, which rarely exceeds 20 wt.%. One general strategy to overcome this limitation is to increase the amphiphilic contrast, i.e. to make the hydrophobic core of the micelles more hydrophobic. However, we reported earlier that for poly(2-oxazoline) based amphiphilic triblock copolymers, a minimal amphiphilic contrast is beneficial, which was tentatively attributed to possible side chain crystallization. Here, we revisit this subject in more detail using more hydrophobic side chains that are either linear (nonyl) or branched (3-ethylheptyl), the latter of which should not crystallize. Moreover, we investigate two different backbones within the hydrophobic block, in particular poly(2-oxazoline) and poly(2-oxazine), for the solubilization and co-solubilization of the two highly water insoluble compounds curcumin and paclitaxel. Even though high loading capacities could be achieved for curcumin within poly(2-oxazine) based triblock copolymers, the solubilization capacity of all investigated polymers with longer side chains was significantly lower compared to poly(2-oxazoline)s and poly(2-oxazine)s with shorter side chains. Although the even lower loading capacity for paclitaxel could be somehow attenuated by co-formulating curcumin, this study corroborates that in the case of poly(2-oxazoline) and poly(2-oxazine) based polymer micelles, an increased amphiphilic contrast leads to less drug solubilization.</p>

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