Polymeric Micelle Assembly Research Articles

Lanthanide‐Containing Heteropolyoxomolybdate as Precursor to Porous Complex Oxides via Polymeric Micelle Assembly and Its Heterostructure with Carbon Dots for Anticounterfeiting Application

AbstractThe fabrication of porous complex oxides with intriguing opto‐functional properties remains a challenge that requires innovative synthetic strategies. In this work, a facile soft template method is developed based on stable micellar solutions formed with lanthanide‐containing heteropolyoxomolybdate and alkaline earth citrates as metal salt precursors and block copolymer as templates. The resulting structures exhibit an effective interfacial Förster resonance energy transfer (IFRET) between the porous CaMoO4:Eu3+ (CEMO) host and the embedded surface‐active carbon dots through the conjugated bonds between Ca2+/Mo6+ cations and the C═O functional groups. Such IFRET process extends of Eu3+ absorption band toward the UV and blue regions, enabling the proof‐of‐concept demonstration of multiresponsive anticounterfeiting codes. The study not only presents a new strategy to prepare porous lanthanide‐doped complex oxides but also provides a feasible way to achieve spectral regulation through interfacial interaction for multifunctional luminescent materials.

Tunable Polymeric Mixed Micellar Nanoassemblies of Lutrol F127/Gelucire 44/14 for Oral Delivery of Praziquantel: A Promising Nanovector against Hymenolepis nana in Experimentally-Infected Rats.

Hymenolepiasis represents a parasitic infection of common prevalence in pediatrics with intimidating impacts, particularly amongst immunocompromised patients. The present work aimed to snowball the curative outcomes of the current mainstay of hymenolepiasis chemotherapy, praziquantel (PRZ), through assembly of polymeric mixed micelles (PMMs). Such innovative nano-cargo could consolidate PRZ hydrosolubility, extend its circulation time and eventually upraise its bioavailability, thus accomplishing a nanoparadigm for hymenolepiasis tackling at lower dose levels. For consummating this goal, PRZ-PMMs were tailored via thin-film hydration technique integrating a binary system of Lutrol F127 and Gelucire 44/14. Box-Behnken design was planned for optimizing the nanoformulation variables employing Design-Expert® software. Also, in Hymenolepis nana-infected rats, the pharmacodynamics of the optimal micellar formulation versus the analogous crude PRZ suspension were scrutinized on the 1st and 3rd days after administration of a single oral dose (12.5 or 25 mg/kg). Moreover, in vitro ovicidal activity of the monitored formulations was estimated utilizing Fuchsin vital stain. Furthermore, the in vivo pharmacokinetics were assessed in rats. The optimum PRZ-PMMs disclosed conciliation between thermodynamic and kinetic stability, high entrapment efficiency (86.29%), spherical nanosized morphology (15.18 nm), and controlled-release characteristics over 24 h (78.22%). 1H NMR studies verified PRZ assimilation within the micellar core. Additionally, the in vivo results highlighted a significant boosted efficacy of PRZ-PMMs manifested by fecal eggs output and worm burden reduction, which was clearly evident at the lesser PRZ dose, besides a reversed effect for the intestinal histological disruptions. At 50 µg/mL, PRZ-PMMs increased the percent of non-viable eggs to 100% versus 47% for crude PRZ, whilst shell destruction and loss of embryo were only clear with the applied nano-cargo. Moreover, superior bioavailability by 3.43-fold with elongated residence time was measured for PRZ-PMMs compared to PRZ suspension. Practically, our results unravel the potential of PRZ-PMMs as an oral promising tolerable lower dose nanoplatform for more competent PRZ mass chemotherapy.

Facile synthesis of a mesoporous TiO2 film templated by a block copolymer for photocatalytic applications

Large-sized mesoporous TiO2 through a polymeric micelle assembly approach for photocatalysts.

Tunable Concave Surface Features of Mesoporous Palladium Nanocrystals Prepared from Supramolecular Micellar Templates.

Concave metallic nanocrystals with a high density of low-coordinated atoms on the surface are essential for the realization of unique catalytic properties. Herein, mesoporous palladium nanocrystals (MPNs) that possess various degrees of curvature are successfully synthesized following an approach that relies on a facile polymeric micelle assembly approach. The as-prepared MPNs exhibit larger surface areas compared to conventional Pd nanocrystals and their nonporous counterparts. The MPNs display enhanced electrocatalytic activity for ethanol oxidation when compared to state-of-the-art commercial palladium black and conventional palladium nanocubes used as catalysts. Interestingly, as the degree of curvature increases, the surface-area-normalized activity also increases, demonstrating that the curvature of MPNs and the presence of high-index facets are crucial considerations for the design of electrocatalysts.

Trimetallic Mesoporous AuCuNi Electrocatalysts with Controlled Compositions Using Block Copolymer Micelles as Templates

AbstractNanostructure engineering is important in the development of metal‐based catalysts to improve material utilization efficiency and catalytic activity. Among the available nanoscale architectures, mesoporous structures have raised much attention due to their large surface area and their highly accessible inner sites for guest species, suitable for a wide range of applications. Gold (Au)‐based materials are promising catalysts thanks to their stability, nontoxicity, and good resistance to poisoning effects. Modifying the composition by introducing inexpensive metals to prepare multicomponent Au‐based catalysts is an effective route to both reduce the cost and improve the catalytic activity. Herein, a polymeric micelle assembly approach to synthesize mesoporous AuCuNi ternary alloy films by electrochemical deposition is reported. This simple method involves the co‐electrodeposition process of Au, Cu, and Ni precursors at fixed applied potential in the presence of polymeric micelles acting as a sacrificial template. The compositional ratio can be easily adjusted to optimize the catalytic performance of the mesoporous AuCuNi films, which show promising results for glucose oxidation and methanol oxidation reactions. It is believed that mesoporous AuCuNi films can be desirable to satisfy the needs for the next generation of multifunctional catalyst.

FRET-enabled monitoring of the thermosensitive nanoscale assembly of polymeric micelles into macroscale hydrogel and sequential cognate micelles release.

Thermosensitive "micellar hydrogel" is prepared based on poly(ε-caprolactone-co- 1,4,8-trioxa[4.6]spiro-9-undecanone)-b-poly(ethylene glycol)- b-poly(ε-caprolactone- co-1,4,8-trioxa[4.6]spiro-9-undecanone) (PECT) triblock copolymer. Fluorescence resonance energy transfer (FRET) is adopted to explore its assembly (formation) and disassembly (degradation) mechanism within the range of 10nm. Results prove that the thermosensitive non-covalent aggregation of micelles facilitates the hydrogel formation and the sustained shedding of cognate micelles induces the hydrogel degradation, during which polymers are steadily incorporated in micelles without any micelle disassembly or reassembly. It is confirmed that using multiple-tags based imaging technology, such as FRET imaging, the fate of macro biodegradable materials invitro and invivo can be followed at a precise nano even molecular level. Such an unique hydrogel composed of nothing more than PECT micelles can act as not only an injectable nanomedicine reservoir by subcutaneous or peri-tissue administration, but also an advanced "combo" macroscale platform for co-delivery of multi-modal therapeutic agents. Our findings also indicate that biological stimuli (e.g., temperature, enzymes)-induced non-covalent micelle self-assembly may provide us an effective strategy to prepare a macroscale device from nanoscale subunits.

Chemical and mechanical modulation of polymeric micelle assembly.

Recently, polymeric micelles self-assembled from amphiphilic polymers have been studied for various industrial and biomedical applications. This nanoparticle self-assembly typically occurs in a solvent-exchange process. In this process, the quality of the resulting particles is uncontrollably mediated by polymeric solubility and mixing conditions. Here, we hypothesized that improving the solubility of an amphiphilic polymer in an organic solvent via chemical modification while controlling the mixing rate of organic and aqueous phases would enhance control over particle morphology and size. We examined this hypothesis by synthesizing a poly(2-hydroxyethyl)aspartamide (PHEA) grafted with controlled numbers of octadecyl (C18) chains and oligovaline groups (termed "oligovaline-PHEA-C18"). The mixing rate of DMF and water was controlled either by microfluidic mixing of laminar DMF and water flows or through turbulent bulk mixing. Interestingly, oligovaline-PHEA-C18 exhibited an increased solubility in DMF compared with PHEA-C18, as demonstrated by an increase of mixing energy. In addition, increasing the mixing rate between water and DMF using the microfluidic mixer resulted in a decrease of the diameter of the resulting polymeric micelles, as compared with the particles formed from a bulk mixing process. Overall, these findings will expand the parameter space available to control particle self-assembly while also serving to improve existing nanoparticle processing techniques.

Rational construction of probes rendering ratiometric response to the cancer-specific enzyme NQO1

Pursuit of fluorescent probes for identification of cancer biomarkers benefits reliable predictions of early cancer detection. Here, a strategy employing polymeric micelle assembly for encapsulation of a new enzyme (NQO1)-responsive small molecule was established for facile access to nanoprobes with favorable features in bioimaging, such as good aqueous solubility, enhanced photo-stability and biocompatibility. In the presence of the enzyme NQO1, these nanoprobes underwent ratiometric fluorescence changes from yellow-green fluorescence signals to red fluorescence signals. By exploiting this favorable ratiometric response to NQO1, we explored these nanoprobes for evaluation of enzyme activity in living cells, which showed distinct differentiation between NQO1-positive cancer cells and NQO1-negative cells.

Mesoporous TiO2Thin Film Formed From a Bioinspired Supramolecular Assembly

In this study we synthesize a novel mesoporous titanium oxide (TiO2) through calcination of a bioinspired supramolecular assembly of polymeric micelles, based on the thymine-functionalized homopolymer, poly(4-vinylbenzyl triazolylmethyl-methylthymine), complexed with Ti(OH)(2)(2+) ions. We characterize thin films of these structures using wide-angle X-ray diffraction, small-angle X-ray scattering, nitrogen adsorption/desorption isotherms, transmission electron microscope, and scanning electron microscope. This approach is simple, effective, and inexpensive when compared with the synthesis of diblock or triblock copolymers typically required to prepare soft templates. This new mesoporous material exhibits superior photocatalytic activity for the degradation of the organic dye methylene blue almost three times higher than that of bulk TiO2.

Synthesis of Mesoporous Transition-Metal Phosphates by Polymeric Micelle Assembly.

Mesoporous iron phosphate (FePO4 ) was synthesized through assembly of polymeric micelles made of asymmetric triblock co-polymer (polystyrene-b-poly-2-vinylpyridine-b-ethylene oxide; PS-PVP-PEO). The phosphoric acid solution stimulates the formation of micelles with core-shell-corona architecture. The negatively charged PO4 (3-) ions dissolved in the solution strongly interact with the positively charged PVP(+) units through an electrostatic attraction. Also, the presence of PO4 (3-) ions realizes a bridge between the micelle surface and the metal ions. The removal of polymeric template forms the robust framework of iron phosphate with 30 nm pore diameter and 15 nm wall thickness. Our method is applicable to other mesoporous metal phosphates by changing metal sources. The obtained materials were fully characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), N2 adsorption-desorption, Raman spectroscope, and other techniques.

Back Cover: Polymeric Micelle Assembly for the Smart Synthesis of Mesoporous Platinum Nanospheres with Tunable Pore Sizes (Angew. Chem. Int. Ed. 38/2015)

A polymeric micelle assembly is used for the fabrication of well-dispersed mesoporous Pt nanospheres by Y. Yamauchi, B. P. Bastakoti et al. in their Communication on page 11073 ff. A core–shell–corona triblock copolymer [poly(styrene-b-2-vinylpyridine-b-ethylene oxide), PS-b-P2VP-b-PEO], is employed as the pore-directing agent. The negatively charged Pt species preferably interact with the protonated P2VP blocks, while the free PEO chains prevent the aggregation of the Pt nanospheres.

Polymeric Micelle Assembly for the Smart Synthesis of Mesoporous Platinum Nanospheres with Tunable Pore Sizes

AbstractA facile method for the fabrication of well‐dispersed mesoporous Pt nanospheres involves the use of a polymeric micelle assembly. A core–shell–corona type triblock copolymer [poly(styrene‐b‐2‐vinylpyridine‐b‐ethylene oxide), PS‐b‐P2VP‐b‐PEO] is employed as the pore‐directing agent. Negatively charged PtCl42− ions preferably interact with the protonated P2VP+ blocks while the free PEO chains prevent the aggregation of the Pt nanospheres. The size of the mesopores can be finely tuned by varying the length of the PS chain. Furthermore, it is demonstrated that the metallic mesoporous nanospheres thus obtained are promising candidates for applications in electrochemistry.

Polymeric micelle assembly for the smart synthesis of mesoporous platinum nanospheres with tunable pore sizes.

A facile method for the fabrication of well-dispersed mesoporous Pt nanospheres involves the use of a polymeric micelle assembly. A core-shell-corona type triblock copolymer [poly(styrene-b-2-vinylpyridine-b-ethylene oxide), PS-b-P2VP-b-PEO] is employed as the pore-directing agent. Negatively charged PtCl4 (2-) ions preferably interact with the protonated P2VP(+) blocks while the free PEO chains prevent the aggregation of the Pt nanospheres. The size of the mesopores can be finely tuned by varying the length of the PS chain. Furthermore, it is demonstrated that the metallic mesoporous nanospheres thus obtained are promising candidates for applications in electrochemistry.

Polymeric Micelle Assembly with Inorganic Nanosheets for Construction of Mesoporous Architectures with Crystallized Walls

AbstractHere we propose a novel way to construct mesoporous architectures through evaporation‐induced assembly of polymeric micelles with crystalline nanosheets. As a model study, we used niobate nanosheets exfoliated by the direct reaction of K4Nb6O17⋅3 H2O crystals with an aqueous solution of propylamine. The electrostatic interaction between negatively charged nanosheets and positively charged polymeric micelles enable us to form composite micelles with the nanosheets. Removal of the micelles by calcination results in robust mesoporous oxides with the original crystalline structure.

Back Cover: Polymeric Micelle Assembly with Inorganic Nanosheets for Construction of Mesoporous Architectures with Crystallized Walls (Angew. Chem. Int. Ed. 14/2015)

Back Cover: Polymeric Micelle Assembly with Inorganic Nanosheets for Construction of Mesoporous Architectures with Crystallized Walls (Angew. Chem. Int. Ed. 14/2015)

Polymeric micelle assembly with inorganic nanosheets for construction of mesoporous architectures with crystallized walls.

Here we propose a novel way to construct mesoporous architectures through evaporation-induced assembly of polymeric micelles with crystalline nanosheets. As a model study, we used niobate nanosheets exfoliated by the direct reaction of K4Nb6O17⋅3 H2O crystals with an aqueous solution of propylamine. The electrostatic interaction between negatively charged nanosheets and positively charged polymeric micelles enable us to form composite micelles with the nanosheets. Removal of the micelles by calcination results in robust mesoporous oxides with the original crystalline structure.

Mesoporous TiO2/Zn2Ti3O8 hybrid films synthesized by polymeric micelle assembly.

A hybrid mesoporous TiO2/Zn2Ti3O8 film with a pore size of around 40 nm is successfully synthesized by the polymeric micelle assembly approach. The chemically distinct units of polymeric micelles of the poly(styrene-2-vinylpyridine-ethylene oxide) triblock copolymer simultaneously contribute to the formation of mesoporous TiO2/Zn2Ti3O8 films with enhanced photocatalytic activity during H2 evolution reaction.

Liquid marbles prepared from pH-responsive self-assembled micelles.

In this study, we report the assembly of amphiphilic polymeric micelles at the liquid/air interface to prepare liquid marbles for the first time. The polymeric micelles were synthesized from the self-assembly of a fluoropolymer, poly(styrene-co-acrylic acid-co-2,2,3,4,4,4-hexafluorobutyl methacrylate), in a selective solvent. The particle size, morphology and chemical composition of the micelles were determined by dynamic light scattering (DLS), transmission electron microscopy, scanning electron microscopy and X-ray photoelectron spectroscopy. DLS and aqueous electrophoresis revealed the pH-responsiveness of the micelles in aqueous dispersion. Liquid marbles with water volumes varying from 10 μL to 1 mL were formed by rolling water droplets on the micelle powder bed. The increase in water volume led to the shape transition of the liquid marbles from quasi-spherical to a puddle-like shape because of gravity. Fluorescence microscopy was used to observe the morphology of the formed liquid marbles, which confirmed that the micelles were adsorbed at the interface of water and air. The effective surface tension of the liquid marbles decreased with the increasing concentration of NaOH, which was added to the interior water phase. This agreed with the results of droplet roller experiments: the mechanical integrity of the liquid marbles prepared from alkaline solution (pH 10) was relatively poorer than those prepared from acidic solution (pH 2). Moreover, these liquid marbles coated with micelles showed pH-responsiveness when transferred onto the surfaces of aqueous solutions with different pH values. The liquid marbles were relatively stable on the acidic solution, whereas they burst immediately on the alkaline solution with a pH of 10. In addition, apart from water, Gellan gum solution and glycerol could be also successfully encapsulated by the fluorinated micelles to form stable liquid marbles.

Synthesis of a large-sized mesoporous phosphosilicate thin film through evaporation-induced polymeric micelle assembly.

A triblock copolymer, poly(styrene-b-2-vinyl pyridine-b-ethylene oxide) (PS-b-P2VP-b-PEO) was used as a soft template to synthesize large-sized mesoporous phosphosilicate thin films. The kinetically frozen PS core stabilizes the micelles. The strong interaction of the inorganic precursors with the P2VP shell enables the fabrication of highly robust walls of phosphosilicate and the PEO helps orderly packing of the micelles during solvent evaporation. The molar ratio of phosphoric acid and tetraethyl orthosilicate is crucial to achieve the final mesostructure. The insertion of phosphorus species into the siloxane network is studied by (29) Si and (31) P MAS NMR spectra. The mesoporous phosphosilicate films exhibit steady cell adhesion properties and show great promise as excellent materials in bone-growth engineering applications.

Synthesis of Mesoporous TiO2/SiO2 Hybrid Films as an Efficient Photocatalyst by Polymeric Micelle Assembly

Thermally stable mesoporous TiO2/SiO2 hybrid films with pore size of 50 nm have been synthesized by adopting the polymeric micelle-assembly method. A triblock copolymer, poly(styrene-b-2-vinyl pyridine-b-ethylene oxide), which serves as a template for the mesopores, was utilized to form polymeric micelles. The effective interaction of titanium tetraisopropoxide (TTIP) and tetraethyl orthosilicate (TEOS) with the polymeric micelles enabled us to fabricate stable mesoporous films. By changing the molar ratio of TEOS and TTIP, several mesoporous TiO2/SiO2 hybrid films with different compositions can be synthesized. The presence of amorphous SiO2 phase effectively retards the growth of anatase TiO2 crystal in the pore walls and retains the original mesoporous structure, even at higher temperature (650 °C). These TiO2/SiO2 hybrid films are of very high quality, without any cracks or voids. The addition of SiO2 phase to mesoporous TiO2 films not only adsorbs more organic dyes, but also significantly enhances the photocatalytic activity compared to mesoporous pure TiO2 film without SiO2 phase.