Self-Assembly Behavior of Bis(terpyridine) and Metallo-bis(terpyridine) Pluronics in Dilute Aqueous Solutions

Bis(terpyridine) and metallo-bis(terpyridine) Pluronics have been synthesized starting from commercially available P105 and P123 hydroxytelechelic Pluronics. The grafting of terpyridine ligands at the extremity of the Pluronic chains results in the further association of the Pluronic micelles in water. Increasing temperature decreases the solubility of the Pluronics, but also increases the solubility of the terpyridine groups. The addition of 0.5 equiv. nickel(II) ions compared to terpyridine groups induces the formation of bis(terpyridine) nickel(II) complexes and disrupts the initial hydrophobic terpyridine aggregates. In that case, formation of flower-like micelles in which the coronal chains form loops due to the terpyridine nickel(II) complexes is observed in the dilute regime

Colloidal stability and thermo-responsive properties of iron oxide nanoparticles coated with polymers: advantages of Pluronic® F68-PEG mixture.

International audienceSuperparamagnetic iron oxide nanoparticles (SPIONs) are recognized to be an attractive platform for developing novel drug delivery approaches and thus several types of functionalized magnetic nanocarriers based on SPIONs have been synthesized and studied. The coating of the metal oxide surface was achieved in a one-pot synthesis with biocompatible polyethylene glycol (PEG) and thermo-responsive modified Pluronic® F68. The resulting thermo-responsive magnetic nanocarriers can incorporate water insoluble drugs into their hydrophobic compartment and later release them in a temperature dependent manner. Here we report novel magnetic nanocarriers with significant improvements regarding the colloidal stability and critical temperature obtained by mixing various molar ratios of hydrophilic PEG with thermo-responsive Pluronic® F68 bearing different end group functionalities. Various methods have been employed to characterize the magnetic nanocarriers, such as photon correlation spectroscopy (DLS), atomic absorption, FT-IR spectroscopy, and surface-enhanced Raman scattering. The transition temperature that determines changes in the conformation of the block copolymer chain was studied by DLS as a function of temperature. Moreover, the drug loading properties of SPION-(F68-OMe)-(F68-FA) and SPION-PEG-F68-FA were analyzed with a hydrophobic fluorescent dye, DID oil. The behavior of the encapsulated DID into the nanocarrier shell was studied as a function of temperature via fluorescence spectroscopy. These results offer original insights into the enhanced colloidal stability and thermo-sensitive properties of the novel synthesized magnetic nanocarriers

Poly(dimethylsiloxane)-substituted 2,2 ': 6,2 ''-Terpyridines: Synthesis and characterization of new amphiphilic supramolecular diblock copolymers

Terpyridine-modified hydrophobic poly(dimethylsiloxane) and hydrophilic poly(ethylene oxide) were combined to new metallo-supramolecular AB-diblock copolymers by utilizing Ru(II) ions. The polymers were synthesized by hydrosilylation of heteroleptic allyloxy-functionalized Ru(II) complexes. The amphiphilic AB-diblock copolymers were used to prepare micelles in an aqueous environment, which were subsequently characterized by dynamic light scattering and cryogenic transmission electron microscopy

Supramolecular self-assembled Ni(II), Fe(II), and Co(II) ABA triblock copolymers

The self-assembly of amphiphilic metallo-supramolecular A-b-B-b-A triblock copolymers containing a B block formed from a bisfunctional terpyridine monomer and an A block based on a monofunctional terpyridine polymer is described. these polymers have been prepared by a polycondensation approach, based on metal-ligand complexation, in which the molecular weight of the central B block has been controlled by the addition of a monofunctional chain-stopper A. Details for the preparation of the A-b-B-b-A triblock copolymers based on the tpy(2)Ni(II), tpy(2)Fe(II), and tpy(2)Co(II) connectivity are given. The influence of the different binding strength of Ni(II), Fe(II), and Co(II) metal ions with terpyridine ligands on the metallo-polycondensation reaction and on the micellization behavior of those materials was studied. Micelles of the obtained block copolymers were prepared and studied by DLS and cryo-TEM

SMART MICELLAR GELS FROM METALLO-SUPRAMOLECULAR COPOLYMERS

International audienceThe advent of supramolecular chemistry in the last decades of the 20 th century has provided chemists with a wealth of new possibilities to synthesize molecular structures and materials that are held together by relatively weak, non-covalent interactions, such as hydrogen bonding, coordinative interactions, electrostatic and van der Waals interactions. 1 The creation of even more complex supramolecular architectures has recently become possible by applying the concept of hierarchical self-assembly, i.e., the non-covalent organization of molecules and macromolecules which takes places over distinct multiple levels, in which the assembly processes gradually decrease in strength. The hierarchical structure of supramolecular assemblies leads to a parallel hierarchy of dynamic processes. Following these principles, the goal of this work is to gain unprecedented control over the structure, self-organization and molecular dynamics of soft-matter systems by exploiting a combination of classical macromolecular architectures and specific supramolecular interactions. This will enable the building of macromolecular assemblies with adaptive structure and stimuli-responsive properties. Our original strategy is to tune the self-assembly of block copolymers via metal-ligand interactions. Firstly, block copolymers bearing a ligand at the chain end will be synthesized. Secondly, systems presenting a hierarchy in both dynamics and structure will be obtained by relying on the interplay between the self-assembling ability of copolymers into micelles and the formation of metal-ligand complexes. Thirdly, the dynamic properties of these structures will be analyzed in solution by rheology

Self-organization of rod–coil tri- and tetra-arm star metallo-supramolecularblock copolymers in selective solvents

Rod–coil tri- and tetra-arm star metallo-supramolecular block copolymers have been synthesized by bis-complex formation between a u-terpyridine ruthenium(II) mono-complex poly(ethylene glycol)(PEG) and either a tris-terpyridine or a tetra-terpyridine functionalized conjugated rigid core. This leads to amphiphilic star copolymers in which the tris-terpyridine or the tetra-terpyridine rigid core can be considered as hydrophobic central block and the complexed PEG blocks as hydrophilic segments. The self-assembly of these two metallo-supramolecular star block copolymers has been investigated by dynamic and static light scattering as well as by cryo-transmission electron microscopy in acetone and acetone/water mixtures

SMART MICELLAR GELS FROM METALLO-SUPRAMOLECULAR COPOLYMERS

International audienceThe advent of supramolecular chemistry in the last decades of the 20 th century has provided chemists with a wealth of new possibilities to synthesize molecular structures and materials that are held together by relatively weak, non-covalent interactions, such as hydrogen bonding, coordinative interactions, electrostatic and van der Waals interactions. 1 The creation of even more complex supramolecular architectures has recently become possible by applying the concept of hierarchical self-assembly, i.e., the non-covalent organization of molecules and macromolecules which takes places over distinct multiple levels, in which the assembly processes gradually decrease in strength. The hierarchical structure of supramolecular assemblies leads to a parallel hierarchy of dynamic processes. Following these principles, the goal of this work is to gain unprecedented control over the structure, self-organization and molecular dynamics of soft-matter systems by exploiting a combination of classical macromolecular architectures and specific supramolecular interactions. This will enable the building of macromolecular assemblies with adaptive structure and stimuli-responsive properties. Our original strategy is to tune the self-assembly of block copolymers via metal-ligand interactions. Firstly, block copolymers bearing a ligand at the chain end will be synthesized. Secondly, systems presenting a hierarchy in both dynamics and structure will be obtained by relying on the interplay between the self-assembling ability of copolymers into micelles and the formation of metal-ligand complexes. Thirdly, the dynamic properties of these structures will be analyzed in solution by rheology