F127 Block Copolymer Research Articles

3D cubic mesoporous silica microsphere as a carrier for poorly soluble drug carvedilol

The present work was proposed not only to exploit the potential of 3D cage-like mesoporous silica SBA-16 with a well-defined spherical morphology as a carrier for poorly soluble drugs, but also to compare the drug loading and release properties of 3D cubic SBA-16 with that of classic 2D hexagonal MCM-41. SBA-16 microsphere with highly ordered mesostructures was synthesized by a facile method using block co-polymer F127 as template, cetyltrimethylammonium bromide (CTAB) as co-template and tetraethyl orthosilicate (TEOS) as silica source. Carvedilol (CAR), an antihypertensive agent, was used as a model drug and loaded into mesoporous silica via solvent deposition method at drug–silica ratio of 1:3. In vitro dissolution was performed in both simulated intestinal fluid (SIF, pH 6.8) and simulated gastric fluid (SGF, pH 1.2). Of particular interest was that in SIF both MCM-41 and SBA-16 samples exhibited promoted dissolution profile for CAR as compared to its corresponding crystalline form which exhibited poor dissolution behavior. This dissolution-enhancing effect might be due to the non-crystalline state and increased surface area of confined CAR as well as the hydrophilic nature of silica. In comparison with MCM-41, SBA-16 displayed a more rapid release profile in both SIF and SGF, which may be ascribed to the 3D interconnected pore networks and the highly accessible surface areas. The suitability of the utilization of SBA-16 microsphere as carriers will open new avenues for the formulation of poorly soluble drugs.

Adsorption and structural properties of ordered mesoporous alumina synthesized in the presence of F127 block copolymer

A facile one-pot evaporation induced self-assembly synthesis of ordered mesoporous alumina (OMA) was explored by using Pluronic ® F127 nonionic triblock copolymer (structure directing agent), aluminum alkoxide (alumina precursor), nitric acid (pH adjustor) and ethanol (solvent). A series of OMA samples with highly ordered cage-like structures, large spherical mesopores, high specific surface area and large pore volume were obtained and studied by nitrogen adsorption, small angle X-ray scattering, and transmission electron microscopy.

The potential of Pluronic polymeric micelles encapsulated with paclitaxel for the treatment of melanoma using subcutaneous and pulmonary metastatic mice models

The increasing global incidence of malignant melanoma combined with the poor prognosis and low survival rates of patients necessitates the development of new chemotherapeutic strategies. Thus, the objective of this present study was to investigate the therapeutic efficacy of Pluronic polymeric micelles encapsulating paclitaxel (PTX) in both B16F10 melanoma subcutaneous mice model and pulmonary metastatic mice model. Herein, we developed a PTX-loaded polymeric micelles (PF-PTX) consisting of Pluronic P 123 and F127 block copolymers with small particle size (∼25 nm), high encapsulation efficiency (>90%), good stability in lyophilized form and pH-dependent in vitro release. Furthermore, influence of PF-PTX on in vitro cytotoxicity was determined by MTT assay using B16F10 melanoma cell line, while cellular distribution of PF-PTX was detected by confocal microscopy. Additionally, C57BL/6 mice bearing subcutaneous or pulmonary B16F10 melanoma tumors were treated with Taxol or PF-PTX, and antitumor effect was compared. It was found that antitumor efficacy of PF-PTX in both tumor models showed significant tumor growth delay and increased survival. In summary, the simple Pluronic-based nanocarrier could be harnessed for the delivery of anticancer drug to melanoma, with increased therapeutic index.

MnO/C core–shell nanorods as high capacity anode materials for lithium-ion batteries

MnO/C core–shell nanorods were synthesized by an in situ reduction method using MnO2 nanowires as precursor and block copolymer F127 as carbon source. Field emission scanning electron microscopy and transmission electron microscopy analysis indicated that a thin carbon layer was coated on the surfaces of the individual MnO nanorods. The electrochemical properties were evaluated by cyclic voltammetry and galvanostatic charge–discharge techniques. The as-prepared MnO/C core–shell nanorods exhibit a higher specific capacity than MnO microparticles as anode material for lithium ion batteries.

Water-dispersible carbon nanotubes from a mixture of an ethoxy-modified trisiloxane and pluronic block copolymer F127

The ability of a mixture of an ethoxy-modified trisiloxane (a silicone surfactant, named Ag-64) and a block copolymer F127 to disperse carbon nanotubes (CNTs) was investigated by experimental investigation and molecular dynamics simulation. Dispersions with large amounts of individual CNTs were obtained. The quantity of dispersed CNTs was obviously larger than each quantity of the dispersions with individual surfactants at the same concentration, even exceeded the sum of them. The mechanism of dispersing CNTs was also discussed. It can be inferred that Ag-64 and few F127 could wrap onto the surface of CNTs to dispart clusters to individuals, and the other F127 interact with adsorbed Ag-64 and F127 to generate stronger steric stabilization. Thus, a synergistic effect on dispersing CNTs by the mixture of Ag-64 and F127 was observed.

Controlled Aqueous Solution Synthesis of Platinum–Palladium Alloy Nanodendrites with Various Compositions Using Amphiphilic Triblock Copolymers

In a recent study, we demonstrated that Pluronic F127 triblock copolymer plays a critical role in the formation of dendritic Pt nanostructures (L. Wang, Y. Yamauchi, J. Am. Chem. Soc. 2009, 131, 9152-9153). Herein, we expand this concept to produce novel dendritic Pt-Pd alloy nanoparticles. In this paper, a very simple, one-step and efficient route is proposed to directly produce dendritic Pt-Pd alloy nanoparticles with high surface area in high yield, which is carried out simply by stirring an aqueous solution that contains K(2)PtCl(4) and Na(2)PdCl(4) binary precursors in the presence of Pluronic F127 block copolymer and ascorbic acid at room temperature within 30 min without the need for any template, seed-mediated growth, or additive. By simply changing the compositional ratios of the Pt and Pd sources in the precursor solutions, Pt-Pd nanodendrites with various compositions can be easily produced. Because of its unique simplicity, the proposed approach can be considered as a powerful strategy for producing Pt-Pd alloy nanoparticles with unique nanoarchitectures for commercial devices.

Niobium-Doped Titania Nanoparticles: Synthesis and Assembly into Mesoporous Films and Electrical Conductivity

Crystalline niobium-doped titania nanoparticles were synthesized via solvothermal procedures using tert-butyl alcohol as a novel reaction medium, and their assembly into mesoporous films was investigated. The solvothermal procedure enables the preparation of crystalline doped and undoped nonagglomerated titania nanoparticles, whose size can be controlled from 4 to 15 nm by changing the reaction temperature and time. The anatase lattice of these particles can incorporate more than 20 mol % of Nb ions. The nanoparticles can be easily dispersed at high concentrations in THF to form stable colloidal suspensions and can be assembled into uniform porous mesostructures directed by the commercial Pluronic block copolymer F127. The resulting mesoporous films show a regular mesostructure with a d spacing of about 17 nm, a uniform pore size of about 10 nm with crystalline walls, a high porosity of 43%, and a large surface area of 190 m(2) cm(-3). Substitutional doping with niobium ions drastically increases the electrical conductivity of the titania particles. The electrical conductivity of as-prepared nanoparticles containing 20 mol % of Nb is 2 x 10(-5) S cm(-1); it increases to 0.25 S cm(-1) after treatment at 600 °C in nitrogen.

Electroless Growth of Silver Nanoparticles into Mesostructured Silica Block Copolymer Films

Silver nanoparticles and silver nanowires have been grown inside mesostructured silica films obtained from block copolymers using two successive reduction steps: the first one involves a sodium borohydride reduction or a photoreduction of silver nitrate contained in the film, and the second one consists of a silver deposit on the primary nanoparticles, carried out by silver ion solution reduction with hydroxylamine chloride. We have demonstrated that the F127 block copolymer ((PEO)(106)(PPO)(70)(PEO)(106)), "F type", mesostructured silica film is a suitable "soft" template for the fabrication of spherical silver nanoparticles arrays. Silver spheres grow from 7 to 11 nm upon the second reduction step. As a consequence, a red shift of the surface plasmon resonance associated with metallic silver has been observed and attributed to plasmonic coupling between particles. Using a P123 block copolymer ((PEO)(20)(PPO)(70)(PEO)(20)), "P type", mesostructured silica film, we have obtained silver nanowires with typical dimension of 10 nm x 100 nm. The corresponding surface plasmon resonance is blue-shifted. The hydroxylamine chloride treatment appears to be efficient only when a previous chemical reduction is performed, assuming that the first sodium borohydride reduction induces a high concentration of silver nuclei in the first layer of the porous silica (film/air interface), which explains their reactivity for further growth.

Block copolymer assisted synthesis of bimetallic colloids with Au core and nanodendritic Pt shell

We report block copolymer assisted synthesis of a Au metal core coated with a nanodendritic Pt shell (Au@Pt). Herein, a rapid, one-step and efficient wet-chemical route is proposed to straightforwardly synthesize Au@Pt with high yield (approximately 100%), which was mediated by Pluronic F127 block copolymer from the reduction of Pt and Au complexes by ascorbic acid (AA).

Synthesis of mesoporous aluminophosphates impregnated with metals and their application in gas oil desulphurization by adsorption

Mesoporous materials based on aluminophosphates and silicates have been synthesised and impregnated with different loadings of transition metals such as Ag, Cu and Ni. These materials have been characterised and tested as selective adsorbents for the desulphurization of light cycle oil (LCO) by liquid adsorption. The polarity of the adsorbent matrix showed a positive effect on desulphurization, leading the impregnated aluminophosphates to higher adsorption capacities than the silicates. Among the transition metals tested, Ag-impregnated materials showed the best results followed by Cu and Ni. The aluminophosphate synthesised using pluronic F-127 block copolymer impregnated with a 5% of Ag (MFAP-5Ag) presented the best adsorption results with a maximum adsorption capacity of 11.36 mg S/g of adsorbent (equilibrium experiments), and breakthrough and saturation capacities of 4.25 mgS/g and 7.06 mgS/g, respectively (dynamic experiments).

Block Copolymer Mediated Synthesis of Dendritic Platinum Nanoparticles

Dendritic platinum nanoparticles are straightforwardly synthesized in high yield via a one-step aqueous-phase reaction mediated by Pluronic F127 block copolymer from the reduction of a platinum complex by ascorbic acid without the need for organic solvents, templates, or ion replacements. The proposed method is unique in its simplicity. The as-prepared dendritic platinum nanoparticles possess the highest surface area (56 m(2) g(-1)) of all reported unsupported platinum materials.

Controlled synthesis of core/shell magnetic iron oxide/carbon systems via a self-template method

A sol-gel assembly process was developed for the synthesis of magnetic core/carbon shell materials with porous networks. Fe(CO)5 was assembled into the pore channels of mesoporous silicavia a sol-gel method at 18 °C, by using the block copolymer F127 as the template and Fe(CO)5 as an additional precursor. At this temperature, the magnetic precursor Fe(CO)5 was pre-organized into hydrophobic cores of micelles by self-assembly of F127. In the subsequent carbonization of the assembly under an Ar atmosphere, Fe(CO)5 transformed into magnetic nanoparticles and surfactant F127 transferred into carbon shells enveloping the magnetic nanoparticles, forming magnetic iron oxide core/carbon shell structures. The removal of the silica with 5% HF acid resulted in the core/shell nanoporous composite. The obtained system demonstrates a saturation magnetic value of 3 emu g−1 as well as a high surface area (98 cm2 g−1) and pore volume (0.21 m3 g−1), which would benefit its potential applications as adsorbents and catalysts, or applications in targeted drug delivery systems. This facile strategy would provide an efficient approach for tailoring core/shell porous materials with desired functionalities and structures by adjusting precursors and structure-directing agents.

Control of internal (2D and 3D hexagonal) mesostructure and particle morphology of spherical mesoporous silica particles using the emulsion and solvent evaporation (ESE) method

In this study we demonstrate the opportunities controlling internal structure as well as exterior morphology of surfactant templated mesostructured materials through the newly developed emulsion and solvent evaporation (ESE) method. In particular, we consider the control of synthesis temperature and map the influence upon both internal structure and surface morphology of particles templated by the temperature sensitive Pluronic block copolymer F127. Furthermore, we vary compositions, by adding poly(propylene glycol) acting as a swelling agent, as well as by controlling the moisture content. Both of these are having an impact on the internal mesostructure as well as the pore size. Apart from probing internal structure by scattering techniques, the accessibility of the mesoscopic pores of these materials are investigated by measuring the adsorption of a cationic dye, Janus Green B, into the materials. This method shows that accessibility varies dramatically with internal structure. Further, by carefully controlling the moisture content when using the cationic surfactant C 16TAB as template, a well ordered 3D hexagonal closed packed ( P6 3/mmc ) material with large surface area as well as pore volume was prepared. This further indicates the versatility of the new preparation technique.

Small angle neutron scattering study on the aggregation behaviour of PEO-PPO-PEO copolymers in the presence of a hydrophobic diol

Small angle neutron scattering (SANS) measurements on aqueous solutions of four polyethylene oxide-polypropylene oxide-polyethylene oxide block copolymers (commercially known as Pluronic®)F88, P85, F127 and P123 in the presence of hydrophobic C14Diol (also known as Surfynol® 104) reveal information on micellization, micellar size and micellar transitions. While most hydrophilic F88 (with least PPO/PEO ratio) remained unimers in water at 30°C, other copolymers formed micellar solutions. Surfynol® 104 is sparingly soluble in water to only about ∼0.1 wt%, but on addition to pluronic solution, it gets incorporated in the micellar region of block copolymer which leads to increase in aggregation number and transformation of spherical to ellipsoidal micelles. The added diol-induced micellization in F88, though hydrophilic copolymers F88 and F127 did not show any appreciable micellar growth or shape changes as observed for P85 and P123 (which are comparatively more hydrophobic). The SANS results on copolymer pairs with same molecular weight PPO but different % PEO (viz. F88 and P85, F127 and P123) and with same molecular weight PEO but different PPO (F88 and F127) reveal that the copolymer with large PPO/PEO ratio facilitate micellar transition in the presence of diol. An increase in temperature and presence of added electrolyte (sodium chloride) in the solution further enhances these effects. The micellar parameters for these systems were found out using available software and are reported.

Cage-like ordered mesoporous organosilicas with isocyanurate bridging groups: Synthesis, template removal and structural properties

The removal of triblock copolymer template from SBA-16 cage-like ordered mesoporous organosilicas (OMOs) functionalized with bulky isocyanurate (ICS) heterocyclic bridging groups is examined. These isocyanurate-containing OMOs (ICS–OMOs) were prepared by co-condensation synthesis of tris[3-(trimethoxysilyl)propyl]isocyanurate and tetraethyl orthosilicate in the presence of poly(ethylene oxide)- block-poly(propylene oxide)- block-poly(ethylene oxide) (EO 106PO 70EO 106) triblock copolymer F127 used as a template and sodium chloride additive under low acidic conditions. Initial studies revealed that the extracted ICS–OMOs materials have a cubic structure ( Im3m symmetry), high contents of isocyanurate bridging groups (0.76 and 1.08 mmol/g) as well as pore diameters ranging from 6.6 to 7.2 nm. The effect of the heating temperature on the structural ordering, specific surface area, pore volume and cage pore diameter of the as-synthesized and extracted ICS–OMOs was investigated. In addition, the synthesis, characterization and template removal of a bifunctional cage-like periodic mesoporous organosilica (PMO) containing ethane (E) and isocyanurate bridging groups is discussed. The E–ICS–PMO samples were fabricated via one-pot synthesis using 1,2-bis(triethoxysilyl)ethane, tris[3-(trimethoxysilyl)propyl]isocyanurate and F127 block copolymer. The resulting ICS–OMOs and E–ICS–PMOs were characterized by nitrogen adsorption–desorption isotherms at −196 °C, small-angle X-ray scattering (SAXS) or low-angle powder X-ray diffraction (XRD), high-resolution thermogravimetry (TG), Fourier-transform infrared spectroscopy (FT-IR) and CHNS elemental analysis. The SAXS/XRD and nitrogen adsorption show that the use of a short extraction and temperature-controlled heating at 315 °C in flowing nitrogen is an effective way to remove the remaining polymeric template from cubic mesostructures without decomposition of isocyanurate bridging groups, as evidenced by FT-IR, TGA and CHNS analysis. Moreover, a complete thermal degradation of isocyanurate groups at 550 °C in air has led to a significant shrinkage of the mesostructure, however its ordered nature was retained.

Self-assembled nanoscale architecture of TiO<sub>2</sub> and application for dye-sensitized solar cells

A single-crystal-like titania nanowire network was successfully synthesized by a surfactant assisted "oriented attachment" mechanism. Highly crystallized titania nanorods have been synthesized by hydrothermal process using block-copolymer F127 with ethylenediamine. It was observed from high resolution TEM image that titanium atoms aligned perfectly in titania anatase structure with no defect. A high light-to-electricity conversion yield (9.3%) was attained by applying these titania nanoscale materials for making an electrode of dye-sensitized solar cells.

Microporous and mesoporous 8YSZ materials derived from polymeric acetylacetone-modified precursors for inorganic membrane applications

Both microporous and mesoporous 8% mol-yttria-stabilized zirconia (8YSZ) material can be prepared from the same 8YSZ sols. Stable 8YSZ sols with particle sizes smaller than 10 nm were prepared by using acetylacetone as a precursor modifier in combination with carboxylic acids. Nonanic and caproic acids are preferred due to their higher stability in combinations of highly concentrated sols. Cubic 8YSZ microporous material can be prepared by using acetylacetone as a precursor modifier with caproic acid as the catalyst. These materials can be transformed into mesoporous material composed of crystalline primary cubic YSZ nanoparticles by simply mixing with structure-directing agents. Use of the block copolymer F127 resulted in the largest specific surface area of 100 m 2/g. Thin 8YSZ layers of these sols can be prepared on glass slips and on graded porous alumina supports with thicknesses between 20 and 100 nm.

Pluronic ® F127 enhances the effect as an adjuvant of chitosan microspheres in the intranasal delivery of Bordetella bronchiseptica antigens containing dermonecrotoxin

We have studied a vaccine delivery system in vitro and in vivo based on chitosan microspheres (CMs) prepared in the presence of selected immunomodulators, Pluronic ® block copolymer F127 (F127). The Bordetella bronchiseptica multiple antigens containing dermonecrotoxin (BBD), a virulent factor leading to atrophic rhinitis (AR) in swine was loaded in CMs/F127 or CMs alone. The microspheres, prepared using an ionic gelation process with tripolyphosphate, demonstrated release profiles that showed a greater amount of BBD being released from BBD-loaded CMs/F127 (BBD-CMs/F127). In vitro experiments using mouse alveolar macrophage cells (RAW 264.7) demonstrated that BBD-CMs/F127 have significantly higher immune-stimulating activities than controls. The highest immune-stimulating activities by the BBD-CMs/F127 using RAW 264.7 cells were mirrored in the in vivo studies following nasal administration to mice. The mice immunized with BBD-CMs/F127 showed higher BBD specific IgA antibody responses in nasal wash, saliva and serum than mice immunized with BBD-CMs alone. Protective immunity was measured by survival rate after challenge with B. bronchiseptica via the nasal cavity. The survival rate of the group treated with BBD-CMs/F127 was higher than those of other groups. These results suggested that CMs/F127 represents a novel mucosal delivery system and that F127 could enhance the delivery of BBD-CMs in the vaccination scheme.

Enhanced permeation performance of cellulose acetate ultrafiltration membrane by incorporation of Pluronic F127

Modified cellulose acetate (CA) ultrafiltration membranes were prepared using Pluronic F127 block copolymer as both pore-forming agent and surface modification agent. The water content of modified CA membranes increased with an increase of Pluronic F127 content in the casting solutions. The scanning electron microscopy (SEM) photographs showed that the modified CA membranes had thinner top layer and bigger pore volume in the porous sub-layer compared to the CA control membrane. The decrease of static water contact angle with an increase in Pluronic F127 content indicated an increase of surface hydrophilicity. The results of Fourier transform infrared spectrometer (FT-IR) analysis confirmed that most of Pluronic F127 has been leached out from the modified CA membranes. The ultrafiltration experiments revealed that the addition of Pluronic F127 influenced the permeation performance of the membranes, all the modified CA membranes exhibited higher water flux and higher bovine serum albumin (BSA) rejection ratios than those of the CA control membrane.

Adsorption and structural properties of channel-like and cage-like organosilicas

Channel-like and cage-like mesoporous silicas, SBA-15 (P6mm symmetry group) and SBA-16 (Im3m symmetry group), were modified by introducing single ureidopropyl surface groups, mixed ureidopropyl and mercaptopropyl surface groups, and single bis(propyl)disulfide bridging groups. These hexagonal and cubic organosilicas were prepared under acidic conditions via co-condensation of tetraethyl orthosilicate (TEOS) and proper organosilanes using poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) amphiphilic block copolymer templates, P123 (EO20PO70EO20) and F127 (EO106PO70EO106). The modified SBA-15 and SBA-16 materials were synthesized by varying the molar ratio of organosilane to TEOS in the initial synthesis gel. The removal of polymeric templates, P123 and F127, was performed with ethanol/hydrochloric acid solution. In the case of SBA-15 the P123 template was fully extracted, whereas this extraction process was less efficient for the removal of F127 template from the SBA-16-type organosilicas; in the latter case a small residue of F127 was retained. The adsorption and structural properties of the resulting materials were studied by nitrogen adsorption-desorption isotherms at −196∘C (surface area, pore size distribution, pore volumes), powder X-Ray diffraction, CHNS elemental analysis and high-resolution thermogravimetry. The structural ordering, the BET specific surface area, pore volume and pore size decreased for both channel-like and cage-like mesoporous organosilicas with increasing concentration of incorporated organic groups.