Glucose-induced sphere to ellipsoid transition of polyoxyethylene–polyoxypropylene block copolymer micelles in aqueous solutions

Kaizu, Kazuhiro; Alexandridis, Paschalis

doi:10.1016/j.colsurfa.2014.10.061

Cited by 22 publications

(23 citation statements)

References 61 publications

(149 reference statements)

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“…Micelles of Pluronic ® P85 (EO 27 PO 39 EO 27 ) have been observed to transition from spheres to rods [ 59 , 60 ] and prolate ellipsoids [ 61 ] at high temperature (around 70 °C). Additives such as polar organic solvents [ 62 , 63 , 64 , 65 , 66 ], urea [ 67 ] and salts [ 68 ] are known to influence micellization properties and micelle structure by changing the solvent quality. As shown in Figure 2 , the micellization boundary for Pluronic ® P105 (EO 27 PO 56 EO 27 ) can be drastically influenced by the addition to water of cosolvents, which alter the amount of hydration available for the PEO and PPO blocks [ 69 ].…”

Section: Poloxamer Self-assembly In Aqueous Solutionsmentioning

confidence: 99%

Formulation of Poloxamers for Drug Delivery

Bodratti

Alexandridis

2018

JFB

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443

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Poloxamers, also known as Pluronics®, are block copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), which have an amphiphilic character and useful association and adsorption properties emanating from this. Poloxamers find use in many applications that require solubilization or stabilization of compounds and also have notable physiological properties, including low toxicity. Accordingly, poloxamers serve well as excipients for pharmaceuticals. Current challenges facing nanomedicine revolve around the transport of typically water-insoluble drugs throughout the body, followed by targeted delivery. Judicious design of drug delivery systems leads to improved bioavailability, patient compliance and therapeutic outcomes. The rich phase behavior (micelles, hydrogels, lyotropic liquid crystals, etc.) of poloxamers makes them amenable to multiple types of processing and various product forms. In this review, we first present the general solution behavior of poloxamers, focusing on their self-assembly properties. This is followed by a discussion of how the self-assembly properties of poloxamers can be leveraged to encapsulate drugs using an array of processing techniques including direct solubilization, solvent displacement methods, emulsification and preparation of kinetically-frozen nanoparticles. Finally, we conclude with a summary and perspective.

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Section: Poloxamer Self-assembly In Aqueous Solutionsmentioning

confidence: 99%

Formulation of Poloxamers for Drug Delivery

Bodratti

Alexandridis

2018

JFB

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443

267

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“…Some polar organic solvents, such as ethanol and 1-propanol, act as cosolvents that are able to decrease the cohesive forces in the solvent mixture and increase the solubility of the PEO-PPO-PEO block copolymer molecules, resulting in increased critical micelle concentration (CMC). Other solvents, such as glycerol, favor the micellization and decrease CMC due to a contraction (dehydration) of PEO blocks [ 17 ], depending on the solvent quality in the mixed solvents [ 12 , 16 , 19 , 21 , 22 ].…”

Section: Introductionmentioning

confidence: 99%

Micellization Thermodynamics of Pluronic P123 (EO20PO70EO20) Amphiphilic Block Copolymer in Aqueous Ethylammonium Nitrate (EAN) Solutions

Alexandridis

2017

Polymers

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Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers (commercially available as Pluronics or Poloxamers) can self-assemble into various nanostructures in water and its mixtures with polar organic solvents. Ethylammonium nitrate (EAN) is a well-known protic ionic liquid that is expected to affect amphiphile self-assembly due to its ionic nature and hydrogen bonding ability. By proper design of isothermal titration calorimetry (ITC) experiments, we determined the enthalpy and other thermodynamic parameters of Pluronic P123 (EO 20 PO 70 EO 20 ) micellization in aqueous solution at varied EAN concentration. Addition of EAN promoted micellization in a manner similar to increasing temperature, e.g., the addition of 1.75 M EAN lowered the critical micelle concentration (CMC) to the same extent as a temperature increase from 20 to 24 • C. The presence of EAN disrupts the water solvation around the PEO-PPO-PEO molecules through electrostatic interactions and hydrogen bonding, which dehydrate PEO and promote micellization. At EAN concentrations lower than 1 M, the PEO-PPO-PEO micellization enthalpy and entropy increase with EAN concentration, while both decrease above 1 M EAN. Such a change can be attributed to the formation by EAN of semi-ordered nano-domains with water at higher EAN concentrations. Pyrene fluorescence suggests that the polarity of the mixed solvent decreased linearly with EAN addition, whereas the polarity of the micelle core remained unaltered. This work contributes to assessing intermolecular interactions in ionic liquid + polymer solutions, which are relevant to a number of applications, e.g., drug delivery, membrane separations, polymer electrolytes, biomass processing and nanomaterial synthesis.

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“…In this sense, we can make some qualitative descriptions about the structure of the system at different concentrations. This can include micelle formation and micelle shape transitions (Kaizu and Alexandridis, ). For all of the surfactants tested here, the relative viscosity initially decreases with surfactant concentration before increasing again.…”

Section: Resultsmentioning

confidence: 99%

“…Changes in the viscosity of a surfactant solution above the CMC may indicate micelle shape changes such as sphere to ellipsoid (Kaizu and Alexandridis, ). This is demonstrated in Fig.…”

Section: Resultsmentioning

confidence: 99%

Self‐Assembly of Polyethylene Glycol Ether Surfactants in Aqueous Solutions: The Effect of Linker between Alkyl and Ethoxylate

Bodratti

Cheng

Kong

et al. 2019

J Surfact & Detergents

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The aqueous self‐assembly behavior of two homologous series of poly(ethylene oxide) (PEO)‐containing nonionic surfactants based on a C10‐Guerbet hydrophobe is reported. The two families of surfactants, alkyl ethoxylates and alkyl alkoxylates, are commercially available from BASF under the trade name Lutensol® XP‐series and XL‐series, respectively. The latter incorporate propylene oxide (PO) units in the surfactant chain. Dye solubilization was used to determine the critical micellization concentration (CMC) of each surfactant at 22 and 50 °C. The PO‐containing alkyl alkoxylates displayed lower CMC values, which were also more sensitive to temperature. The Gibbs free energy, enthalpy, and entropy of micellization were computed from the CMC data and used to identify the contribution of each surfactant moiety (alkyl chain, PO unit, and PEO block) in controlling the CMC. The micellization properties are compared with compositionally similar surfactants with linear alkyl chains, yielding information about the effects of the Guerbet alkyl chain on micellization. Isothermal titration calorimetry was also used to characterize the CMC and enthalpy of micellization which generally compare well with the dye solubilization results. Cloud point data reveal nonmonotonic relationships for the Lutensol® surfactants with respect to composition, unlike linear alkyl chain surfactants. Finally, dilute solution viscosity measurements performed on some Lutensol® surfactants show a change in the slope, suggesting a structural change that tends to be more pronounced for surfactants with longer PEO blocks. The data presented herein enhance the understanding of surfactant structure–property relationships required for industrial formulation.

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Glucose-induced sphere to ellipsoid transition of polyoxyethylene–polyoxypropylene block copolymer micelles in aqueous solutions

Cited by 22 publications

References 61 publications

Formulation of Poloxamers for Drug Delivery

Formulation of Poloxamers for Drug Delivery

Micellization Thermodynamics of Pluronic P123 (EO20PO70EO20) Amphiphilic Block Copolymer in Aqueous Ethylammonium Nitrate (EAN) Solutions

Self‐Assembly of Polyethylene Glycol Ether Surfactants in Aqueous Solutions: The Effect of Linker between Alkyl and Ethoxylate

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