Amphiphilic Block Copolymer Poly Research Articles

Polymeric Micelles Based on Poly(citric acid)-b-poly(L-lactide)-b-poly(citric acid) Copolymer: Synthesis and Characterization

Novel amphiphilic block copolymers poly(citric acid)-b-poly(L-lactide)-b-poly(citric acid), (PCA-PLA-PCA), were synthesized by melt polycondensation reaction of citric acid and hydroxyl telechelic poly(L-lactide). The chemical structure of the resulting copolymers was characterized by various analytical techniques. DSC data showed the higher glass transition and melting temperature for copolymer suggesting increased crystallinity confirmed by X-ray diffraction data. The effects of the segment length of both the PLA and the PCA portions on the sizes of the PCA-PLA-PCA polymeric micelles were investigated. The results indicated that the size of the polymeric micelle reflects the chain length of both types of segments in the copolymer.

A mechanistic study on amphiphilic block co-polymer poly(butadiene-b-(ethylene oxide)) vesicles reveals the water permeation mechanism through a polymeric bilayer

The mechanistic study of a diblock copolymer reveals that the osmotic permeation mechanism correlates with chain rigidity, specifically bending rigidity modulus.

Thiol-reactive amphiphilic block copolymer for coating gold nanoparticles with neutral and functionable surfaces.

Nanoparticles designed for biomedical applications are often coated with polymers containing reactive functional groups, such as -COOH and -NH2, to conjugate targeting ligands or drugs. However, introducing highly charged surfaces promotes binding of the nanoparticles to biomolecules in biological systems through ionic interactions, causing the nanoparticles to aggregate in biological environments and consequently undergo strong non-specific binding to off-target cells and tissues. Developing a unique polymer with neutral surfaces that can be further functionalized directly would be critical to develop suitable nanomaterials for nanomedicine. Here, we report a thiol-reactive amphiphilic block copolymer poly(ethylene oxide)-block-poly(pyridyldisulfide ethylmeth acrylate) (PEO-b-PPDSM) for coating gold nanoparticles (AuNPs). The resultant polymer-coated AuNPs have almost neutral surfaces with slightly negative zeta potentials from -10 to 0 mV over a wide pH range from 2 to 12. Although the zeta potential is close to zero we show that the PEO-b-PPDSM copolymer-coated AuNPs have both good stability in various physiological conditions and reduced non-specific adsorption of proteins/biomolecules. Because of the multiple pyridyldisulfide groups on the PPDSM block, these individually dispersed nanocomplexes with an overall hydrodynamic size around 43.8 nm can be directly functionalized via disulfide-thiol exchange chemistry.

SYNTHESIS, THERMAL BEHAVIOR, AND AGGREGATION IN AQUEOUS SOLUTION OF POLY(METHYL METHACRYLATE)-B-POLY(2-HYDROXYETHYL METHACRYLATE)

Amphiphilic block copolymers of poly(methyl methacrylate) PMMA and poly(2-hidroxyethyl methacrylate) PHEMA were synthesized by a two–step atom transfer radical polymerization (ATRP). Copolymers with various degrees of polymerization and different relative block sizes were obtained. The structure of the resulting polymers have been characterized and verified by FT–IR and 1H–NMR, molecular weight were determined by size exclusion chromatography analyses. The thermal properties of these polymers were investigated by differential scanning calorimetry DSC and thermogravimetric analysis TGA. The glass transition temperature of mono halogenated PMMA increases from 116 oC to 123 oC with increasing molecular weight, whereas the glass transition temperature of block copolymers depends slightly on polymer structure. The derivatives of TGA curves indicate that thermal degradation occurs in one stage. The self-assembly of PMMA-b-PHEMA in aqueous solution have been investigated by fluorescence probing methods. The critical micelle concentrations are in the range 10 -6 – 10-7 M. The micropolarity sensed by pyrene is higher than in aggregates formed by block copolymers based on polystyrene.

Amphiphilic block copolymer modified magnetic nanoparticles for microwave-assisted extraction of polycyclic aromatic hydrocarbons in environmental water

In this work, amphiphilic block copolymer poly(tert-butyl methacrylate)-block-poly(glycidyl methacrylate) (PtBMA-b-PGMA) modified Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) were synthesized, and served as an adsorbent for microwave-assisted extraction of polycyclic aromatic hydrocarbons (PAHs). The PtBMA-b-PGMA block copolymers with different block ratios were prepared by two-step atom transfer radical polymerization (ATRP) and the extraction abilities of their corresponding Fe3O4@PtBMA-b-PGMA were investigated. The key factors affecting the extraction efficiency of the adsorbent, including microwave conditions, amount of adsorbent, type and volume of desorption solvent, were studied in detail. In comparison with vortex, which is a conventional method used for assisting extraction, the proposed microwave-assisted method allowed better extraction efficiency and required a shorter extraction time. The calibration curves of PAHs were obtained in the range of 0.05–120μg/L (r>0.9985) and the limits of detection (S/N=3) were in the range of 2.4–6.3ng/L. The recoveries of PAHs spiked in environmental water samples were between 62.5% and 104% with relative standard deviations (RSDs) ranging from 0.84% to 9.02%. The proposed technique combining microwave-assisted extraction and magnetic separation was demonstrated to be a fast, convenient and sensitive pretreating method for PAHs.

Image-guided and tumor-targeted drug delivery with radiolabeled unimolecular micelles

Unimolecular micelles formed by dendritic amphiphilic block copolymers poly(amidoamine)–poly(l-lactide)-b-poly(ethylene glycol) conjugated with anti-CD105 monoclonal antibody (TRC105) and 1,4,7-triazacyclononane-N, N′, N-triacetic acid (NOTA, a macrocyclic chelator for 64Cu) (abbreviated as PAMAM–PLA-b-PEG–TRC105) were synthesized and characterized. Doxorubicin (DOX), a model anti-cancer drug, was loaded into the hydrophobic core of the unimolecular micelles formed by PAMAM and PLA via physical encapsulation. The unimolecular micelles exhibited a uniform size distribution and pH-sensitive drug release behavior. TRC105-conjugated unimolecular micelles showed a CD105-associated cellular uptake in human umbilical vein endothelial cells (HUVEC) compared with non-targeted unimolecular micelles, which was further validated by cellular uptake in CD105-negative MCF-7 cells. In 4T1 murine breast tumor-bearing mice, 64Cu-labeled targeted micelles exhibited a much higher level of tumor accumulation than 64Cu-labeled non-targeted micelles, measured by serial non-invasive positron emission tomography (PET) imaging and confirmed by biodistribution studies. These unimolecular micelles formed by dendritic amphiphilic block copolymers that synergistically integrate passive and active tumor-targeting abilities with pH-controlled drug release and PET imaging capabilities provide the basis for future cancer theranostics.

Charged microcapsules for controlled release of hydrophobic actives Part II: Surface modification by LbL adsorption and lipid bilayer formation on properly anchored dispersant layers

Charge microcapsules with a dodecane core and a poly(methyl methacrylate) (PMMA) shell have been prepared via the internal phase separation method using ionic dispersants. The microcapsules have subsequently been surface modified with polyelectrolyte multilayers and lipid bilayers. Two types of ionic dispersant systems have been investigated: a small set of ionic amphiphilic block copolymers of poly(methyl methacrylate)-block-poly(sodium (meth)acrylate) type and an oil-soluble anionic surfactant, sodium 1,5-dioxo-1,5-bis(3,5,5-trimethylhexyloxy)-3-((3,5,5trimethylhexyloxy)carbonyl)pentane-2-sulfonate, in combination with a water-soluble polycation, poly(diallyldimethylammonium chloride). The Layer-by-Layer adsorption of the polyelectrolyte pair poly(diallydimethylammonium chloride) (350,000g/mol) and poly(sodium methacrylate) (15,000g/mol) was successfully made on both microcapsule systems with the formation of very thin multilayers as indicated with quartz crystal microbalance with dissipation monitoring (QCM-D) measurements on model surfaces. Formation of a lipid bilayer on the surface of the microcapsules from liposomes with a charge opposite that of the capsule surface was also proven to be successful as indicated by the ζ-potential of the microcapsules, the characteristic frequency shift as measured with QCM-D and fluorescence recovery after photobleaching (FRAP) on model systems. However, the proper anchorage of the dispersants in the underlying PMMA surface was key for the successful surface modification.

Photoinduced Charge‐Transfer Interactions on a Graphene/Block Copolymer Electrostatically Bound to Tetracationic Porphyrin in Aqueous Media

Stable dispersions of exfoliated graphene in aqueous media with the aid of the amphiphilic block copolymer poly(isoprene-b-acrylic acid) (PI-b-PAA), in the form of its anion, were used to electrostatically bind cationic 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphine tetra(p-toluenesulfonate) (H2P(4+)). A new graphene/PI-b-PAA(-)-H2P(4+) ensemble was formed and examined by dynamic light scattering, UV/Vis and fluorescence emission spectroscopy. The efficient fluorescence quenching of H2P(4+) in the graphene/PI-b-PAA(-)-H2P(4+) ensemble was probed by using steady-state and time-resolved photoluminescence, suggesting that electron/energy-transfer phenomena occur within the nanoensemble. Blank experiments validated the concept of electrostatic interactions that govern the formation of graphene/PI-b-PAA(-)-H2P(4+) ensemble, which signified the importance of graphene as an electron acceptor toward the preparation of some new donor-acceptor systems. Finally, kinetic analysis of the lifetime profiles of the fluorescence emission gave information regarding the quenching rate constant and quantum yield of the singlet excited state of H2P(4+) in the graphene/PI-b-PAA(-)-H2P(4+) ensemble.

Self-Assembly in Poly(dimethylsiloxane)–Poly(ethylene oxide) Block Copolymer Template Directed Synthesis of Linde Type A Zeolite

We describe the hydrothermal synthesis of zeolite Linde type A (LTA) submicrometer particles using a water-soluble amphiphilic block copolymer of poly(dimethylsiloxane)-b-poly(ethylene oxide) as a template. The formation and growth of the intermediate aggregates in the presence of the diblock copolymer have been monitored by small-angle X-ray scattering (SAXS) above the critical micellar concentration at a constant temperature of 45 °C. The early stage of the growth process was characterized by the incorporation of the zeolite LTA components into the surface of the block copolymer micellar aggregates with the formation of primary units of 4.8 nm with a core-shell morphology. During this period, restricted to an initial time of 1-3 h, the core-shell structure of the particles does not show significant changes, while a subsequent aggregation process among these primary units takes place. A shape transition of the SAXS profile at the late stage of the synthesis has been connected with an aggregation process among primary units that leads to the formation of large clusters with fractal characteristics. The formation of large supramolecular assemblies was finally verified by scanning electron microscopy, which evidenced the presence of submicrometer aggregates with size ranging between 100 and 300 nm, while X-ray diffraction confirmed the presence of crystalline zeolite LTA. The main finding of our results gives novel insight into the mechanism of formation of organic-inorganic mesoporous materials based on the use of a soft interacting nanotemplate as well as stimulates the investigation of alternative protocols for the synthesis of novel hybrid materials with new characteristics and properties.

Synthesis, characterization and self-assembly of amphiphilic block copolymer poly(4-vinyl benzene chloride)-b-poly(N-vinylpyrrolidone) in aqueous solution

The synthesis, characterization and self-assembly of a novel amphiphilic block copolymer containing a poly(N-vinylpyrrolidone) as a segment of hydrophilic and poly(4-vinyl benzene chloride) (PVBC) arms are reported. The copolymer was characterized by FT-IR spectroscopy 1H NMR. The composition and the molecular weights of the block copolymers were established using gel permeation chromatography and 1H NMR. The water-soluble fraction of poly(N-vinyl-2-pyrrolidone) (PVP)/PVBC block copolymers formed micelles which were investigated at 25 °C in water at 5 mg/ml concentration using a tensiometer. The morphology of micelles in aqueous solution was determined by the AFM, SANS, and SAXS methods.

Linear-, Cyclic-, and Multiblock Amphiphilic Polyelectrolytes as Surfactants in Emulsion Polymerization: Role of Topological Structure

Combining atom transfer radical polymerization (ATRP) and “click” chemistry, a set of well-defined amphiphilic block copolymers poly(n-butyl acrylate)-b-poly(acrylic acid) (PnBA20-PAA85) with a similar chemical component, but different topological structures, i.e., linear-, cyclic-, and multiblock structures, were successfully prepared, characterized (size exclusion chromatography (SEC), FT-IR and 1H NMR), and used as surfactants in emulsion polymerization. Our further transmission electron microscopy (TEM) and laser light scattering (LLS) characterization of the resultant latex particles demonstrates all the surfactants with different topologies can effectively stabilize the latex particles but no significant difference among the solids contents was observed. Moreover, we have, for the first time, experimentally established the quantitative relation between the final number of latex particles (Np) and the concentration of polymeric surfactant with different topologies (C), i.e., Np = kCα, and the order of our measured exponent α is as follows: αmulti(1.10) > αlinear(0.81) ≥ αcyclic(0.73), indicating cyclic surfactant molecules behave more like small-molecule surfactants attributed to its strongest unimers extraction and diffusion ability; in contrast, multiblock surfactant molecules can act as seeds to directly nucleate to create latex particles. In addition, Np,multi > Np,linear ≥ Np,cyclic at higher concentration, and Np,linear > Np,cyclic ≥ Np,multi at lower concentration was observed. Similar results (αmulti(1.02) > αlinear(0.65) ≥ αcyclic(0.58)) were also observed when polystyrene-b-poly(acrylic acid) (PS9–PAA60) copolymers were used as surfactants. Further aqueous SEC characterization shows the broad size distribution of our micellar solution has no effect on obtaining narrowly distributed latex particles. Finally, interfacial tension measurement of the micellar solution indicates, compared to multiblock structure, the rate of adsorption at a hydrophobic interface is much faster for linear and cyclic-block structures, agreeing with our observed order of exponent α.

Charged microcapsules for controlled release of hydrophobic actives. Part I: encapsulation methodology and interfacial properties

Highly charged microcapsules have been prepared using the internal phase separation technique. The charges are introduced by using ionic dispersants, which have been characterized with respect to surface activity with a quartz crystal microbalance with dissipation monitoring and with optical tensiometry. The long-term stability of the microcapsule suspension without excess dispersant, as well as the stability at high ionic strength, have been investigated. Three types of ionic dispersants have been evaluated: a weak polyacid (poly(methacrylic acid)), a small set of ionic amphiphilic block copolymers of poly(methyl methacrylate)-block-poly(sodium (meth)acrylate) type and an oil-soluble anionic surfactant, sodium 1,5-dioxo-1,5-bis(3,5,5-trimethylhexyloxy)-3-((3,5,5-trimethylhexyloxy)carbonyl)pentane-2-sulfonate, in combination with a water-soluble polycation, poly(diallyldimethylammonium chloride). The block copolymer based microcapsule suspension is characterized by a long-term stability, even at high ionic strength, provided by electrostatic and steric stabilization. The weak polyacid based microcapsule suspension is stable for a few weeks, after which aggregation starts due to desorption of the dispersant. The surfactant–polycation based microcapsules appear to have a multicore morphology in contrast to the weak polyacid or block copolymer based microcapsules, which are core–shell particles.

Synthesis of multi-responsive polymeric nanocarriers for controlled release of bioactive agents

Polymeric nanocarriers based on the amphiphilic block copolymer poly(2-dimethylamino)ethyl methacrylate-b-poly(2-nireobenzyl acrylate) exhibited multi-responsive to UV, temperature, CO2 and pH, could be used for controlled release of bioactive agents.

Charged microcapsules for controlled release of hydrophobic actives. Part III: the effect of polyelectrolyte brush- and multilayers on sustained release

Poly(methyl methacrylate) microspheres have been prepared by the internal phase separation method using either of the three conventional dispersants poly(vinyl alcohol) (PVA), poly(methacrylic acid) (PMAA), or the amphiphilic block copolymer poly(methyl methacrylate)-block-poly(sodium methacrylate). The block copolymer based microsphere, which has a polyelectrolyte brush on the surface, was surface modified with up to two poly(diallyldimethylammonium chloride)-poly(sodium methacrylate) bilayers. The microspheres were loaded with the hydrophobic dye 2-(4-(2-chloro-4-nitrophenylazo)-N-ethylphenylamino)ethanol (Disperse Red 13) and its release from aqueous dispersions of microspheres with the different surface compositions was measured by spectrophotometry. The burst fraction, burst rate and the diffusion constant were determined from a model combining burst and diffusive release. Out of the three dispersants, the block copolymer gave the slowest release of the dye, with respect to both burst release and diffusive release. A very pronounced further reduction of the diffusion constant was obtained by applying polyelectrolyte multilayers on top of the microspheres. However, the diffusion constant was very weakly dependent on further polyelectrolyte adsorption and one polyelectrolyte bilayer appeared to suffice.

Preparation of Biomimetic Zwitterionic Core Cross-Linked Nanocarriers for Control Release of Bioactive Agents

Biomimetic core cross-linked nanocarriers (CCL-NCs) with zwitterionic shell was constructed from an amphiphilic block copolymer poly(2-(dimethylamino) ethyl methacrylate-co-carboxybetaine)-b-polystyrene ((PDMAEMA-co-PCB)-b-PS) via mini-emulsion RAFT polymerization. CCL-NCs present in this report possess properties of redox-sensitivity, limited unspecific protein adsorptions and low cytotoxicity, which highly enhance their potential application in drug delivery. Morphology of CCL-NCs was characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. The control release process has also been investigated under three different conditions with or without dithiothreitol (DTT) at pH 5.4, 6.5 and 7.4.

Preparation of amphiphilic block copolymer containing triazene moieties and fluorescence study

The present study describes the synthesis via microwave accelerated reversible addition-fragmentation chain transfer (RAFT) polymerization of an amphiphilic block copolymer poly(acrylic acid)-b-poly(dodecylacrylamide-co-1-(phenyl)-3-(2-methacryloyloxyethyl carbamoyloxyethyl)-3-methyltriazene-1) [PAA-b-(PDA-co-PUMA-T)]. The structure and the chemical composition of the block copolymer were confirmed by spectral/thermal analysis. The photoreactivity of the triazene sequences from PAA-b-(PDA-co-PUMA-T) was quantified by UV/vis irradiation in chloroform/dimethylformamide solutions and in thin film, indicating that the solvent polarity modifies with an order of magnitude the rate constant values. The lower rate constant in film state (\(k_{\rm film} = 1.3 \times 10^{-3}\) s − 1), shows that the higher mobility of polymeric chains in solution allow a more rapid orientation, favourable to the triazene bond cleavage. The capability of block copolymer to form micelles in aqueous environment and implicitly, its critical micelle concentration (CMC) was evidenced through fluorescence measurements using pyrene probe (10 − 6 M), the CMC value being of 4.64 ×10 − 3 g L − 1 PAA-b-(PDA-co-PUMA-T) (3.27 ×10 − 7 M). Experiments of fluorescence quenching with various metal cations (UO\(_{2}^{2+}\), Fe2 + , Fe3 + , Ni2 + , Cu2 + , Co2 + , Pb2 + and Hg2 + ) suggested that such a block copolymer could find applications as fluorescence-based chemosensor for the detection of iron cations in homogeneous organic solutions or aqueous environments by thin films. Photosensitive amphiphilic block copolymer bearing triazene sequences was synthesized via microwave accelerated RAFT polymerization. The photolability of triazene units and the formation micelles in aqueous environment were studied, while fluorescence quenching in the presence of various metal cations show that such block copolymer could find applications as fluorescence-based chemosensor.

Dexamethasone-Loaded Block Copolymer Nanoparticles Induce Leukemia Cell Death and Enhance Therapeutic Efficacy: A Novel Application in Pediatric Nanomedicine

Nanotechnology approaches have tremendous potential for enhancing treatment efficacy with lower doses of chemotherapeutics. Nanoparticle (NP)-based drug delivery approaches are poorly developed for childhood leukemia. Dexamethasone (Dex) is one of the most common chemotherapeutic drugs used in the treatment of childhood leukemia. In this study, we encapsulated Dex in polymeric NPs and validated their antileukemic potential in vitro and in vivo. NPs with an average diameter of 110 nm were assembled from an amphiphilic block copolymer of poly(ethylene glycol) (PEG) and poly(ε-caprolactone) (PCL) bearing pendant cyclic ketals (ECT2). The blank NPs were nontoxic to cultured cells in vitro and to mice in vivo. Encapsulation of Dex into the NPs (Dex-NP) did not compromise the bioactivity of the drug. Dex-NPs induced glucocorticoid phosphorylation and showed cytotoxicity similar to the free Dex in leukemic cells. Studies using NPs labeled with fluorescent dyes revealed leukemic cell surface binding and internalization. In vivo biodistribution studies showed NP accumulation in the liver and spleen with subsequent clearance of the particles with time. In a preclinical model of leukemia, Dex-NPs significantly improved the quality of life and survival of mice as compared to the free drug. To our knowledge, this is the first report showing the efficacy of polymeric NPs to deliver Dex to potentially treat childhood leukemia and reveals that low doses of Dex should be sufficient for inducing cell death and improving survival.

Biomimetic synthesis of calcium carbonate bilayers interfaced by a diblock copolymer template

Abstract The synthesis of a new class of hybrid materials with two differently oriented layers of calcite at adjacent sides of an organic template is demonstrated. A Langmuir monolayer of the amphiphilic block copolymer poly(butyl acrylate)-b-poly(hydroxypropyl acrylate) directs the formation of a first CaCO3 phase through interaction with the hydrophilic poly(hydroxypropyl acrylate) blocks. After partial hydrolysis of the hydrophobic poly(butyl acrylate) segments a second CaCO3 phase is formed on the monolayer associated to the first mineral phase. Thus, bilayered CaCO3-based hybrid materials are obtained with two differently oriented calcite phases at opposite sides of the polymer film. By using DNA as an additive the crystal orientation in the second layer can be modified.

Therapeutic Delivery of siRNA Silencing HIF-1 Alpha with Micellar Nanoparticles Inhibits Hypoxic Tumor Growth

The particular characteristics of the tumor microenvironment have the potential to strongly promote tumor growth, metastasis and angiogenesis and induce drug resistance. Therefore, the development of effective, systemic therapeutic approaches specifically based on the tumor microenvironment is highly desirable. Hypoxia-inducible factor-1α (HIF-1α) is an attractive therapeutic target because it is a key transcription factor in tumor development and only accumulates in hypoxic tumors. We report here that a cationic mixed micellar nanoparticle (MNP) consisting of amphiphilic block copolymers poly(ε-caprolactone)-block-poly(2-aminoethylethylene phosphate) (PCL(29)-b-PPEEA(21)) and poly(ε-caprolactone)-block-poly(ethylene glycol) (PCL(40)-b-PEG(45)) was a suitable carrier for HIF-1α siRNA to treat hypoxic tumors, which showed an average diameter of 58.0 ± 3.4 nm. The complex MNP(siRNA), formed by the interaction of MNP and siRNA, was transfected into PC3 prostate cancer cells efficiently, while the inhibition of HIF-1α expression by MNP loaded with HIF-1α siRNA (MNP(siHIF)) blocked PC3 cell proliferation, suppressed cell migration and disturbed angiogenesis under in vitro hypoxic mimicking conditions. It was further demonstrated that systemic delivery of MNP(siHIF) effectively inhibited tumor growth in a PC3 prostate cancer xenograft murine model without activating innate immune responses. Moreover, delivery of MNP(siHIF) sensitized PC3 tumor cells to doxorubicin chemotherapy in vitro and in vivo by downregulating MDR1 gene expression which was induced by hypoxia. The underlying concept of use of MNP(siHIF) to block HIF-1α holds promise as an example of a clinical approach using specific siRNA therapy for cancer treatment aimed at the hypoxic tumor microenvironment.

Hexagonally Arrayed 17 nm Interpenetrating and Continuous Biphasic Structure via Block-Copolymer-Templating Process

Biphasic and interpenetrating continuous membranes with precisely controlled two-dimensional (2D)-hexagonal nanoperiodicity were fabricated using amphiphilic block copolymer poly(ethylene oxide)-b-polymethacrylate with azobenzene mesogen units in the side chain [PEOm-b-PMA(Az)n]. On a silica (SiO2) nanodot array templated from the block copolymer membrane, the next phase, such as titanium dioxide (TiO2), or gold (Au), was coated. Herein, the surface modification of the transferred SiO2 nanodot array was crucial to obtaining the interpenetration of the precursor of TiO2 and its continuous contact. The typical size of the hexagonal array (d) and the center-to-center distance (D) of the SiO2 nanodots were (d, D) = (17 nm, 27 nm) and (d, D) = (22 nm, 51 nm), respectively. The interpenetrating and continuous biphasic structure will provide a promising approach to multiferroic materials, interpenetrative heterojunction for solar cells, new integrated catalysts, and so forth.