Nanoemulsions for synthesis of biomedical nanocarriers
Nanoemulsions are kinetically stabilized emulsions with droplet sizes in the nanometer scale. These nanodroplets are able to confine spaces in which reactions of polymerization or precipitation can take place, leading to the formation of particles and capsules that can act as nanocarriers for biomedical applications. This review discusses the different possibilities of using nanoemulsions for preparing biomedical nanocarriers. According to the chemical nature, nanocarriers prepared in nanoemulsions are classified in polymeric, inorganic, or hybrid. The main synthetic strategies for each type are revised, including miniemulsion polymerization, nanoemulsion-solvent evaporation, spontaneous em…
Synthesis and Properties of Amine-Cured Epoxy/Organophilic Layered Silicate Nanocomposites
Epoxy-layered silicate composites have been prepared by dispersing an organically modified montmorillonite (Nanofil 919) in an epoxy resin and curing in the presence of an aromatic hardener. Dispersion of the layered silicate within the epoxy matrix was verified using X-ray diffraction and transmission electron microscopy revealing that interaction improves upon organic silicate modification. Flexural properties and toughness increase with the organic silicate loading whereas glass transition temperature decreases and thermal stability remains practically unmodified.
Synergy of Miniemulsion and Solvothermal Conditions for the Low-Temperature Crystallization of Magnetic Nanostructured Transition-Metal Ferrites
Crystalline first-row transition-metal (Mn, Fe, Co, Ni, Cu, and Zn) ferrites were prepared by an unprecedented synergetic combination of miniemulsion synthesis and solvothermal route, pursuing unconventional conditions in terms of space confinement, temperature, and pressure. This synergy allowed for obtaining six different crystalline ferrites at much lower temperature (i.e., 80 °C) than usually required and without any postsynthesis thermal treatment. X-ray diffraction (XRD) revealed that analogous ferrites synthesized by miniemulsion at ambient pressure or in bulk (i.e., from an aqueous bulk solution and not in the confined space of the miniemulsion droplets) either at ambient pressure o…
Controlling dielectrical properties of polymer blends through defined PEDOT nanostructures
[EN] The paper reports the crucial role of the morphology of poly(3,4-ethylenedioxythiophene) (PEDOT) nanostructures on the thermal and dielectric properties of polymer blends prepared thereof. PEDOT nanostructures with two different morphologies (nanoparticles and nanowires) were synthesized. The size for the nanoparticles was in the range 10 40 nm and the diameter of the nanowires was of ca. 200 nm. These nanostructures were blended with an insulating polymer matrix, poly(methyl methacrylate) (PMMA), to evaluate the dielectrical properties of the materials. The results of broadband dielèctric spectroscopy showed a strong correlation between the morphology of the nanostructure and the impr…
Ceria/polymer nanocontainers for high-performance encapsulation of fluorophores
We report the synthesis of high-performance organic–inorganic hybrid fluorescent nanocapsules comprising a polymer shell armored with an inorganic layer and a liquid core containing a fluorophore. The polymeric capsules are synthesized by free radical miniemulsion polymerization and contain covalently bound carboxylate surface functionalities that allow for the binding of metal ions through electrostatic interaction. A cerium(IV) oxide nanoparticle layer, formed in situ at the surface of the hybrid nanocapsules, acts as oxygen scavenger and keeps external reactive molecular oxygen from entering into the capsules, eventually resulting in a reduction of the photooxidation of encapsulated fluo…
Highly Loaded Semipermeable Nanocapsules for Magnetic Resonance Imaging.
Magnetic resonance imaging has become an essential tool in medicine for the investigation of physiological processes. The key issues related to contrast agents, i.e., substances that are injected in the body for imaging, are the efficient enhancement of contrast, their low toxicity, and their defined biodistribution. Polyurea nanocapsules containing the gadolinium complex Gadobutrol as a contrast agent in high local concentration and high relaxivity up to 40 s-1 mmol-1 L are described. A high concentration of the contrast agent inside the nanocapsules can be ensured by increasing the crystallinity in the shell of the nanocapsules. Nanocapsules from aliphatic polyurea are found to display hi…
A new approach for crystallization of copper(II) oxide hollow nanostructures with superior catalytic and magnetic response.
We report the synthesis of copper(II) oxide hollow nanostructures at ambient pressure and close to room temperature by applying the soft templating effect provided by the confinement of droplets in miniemulsion systems. Particle growth can be explained by considering a mechanism that involves both diffusion and reaction control. The catalytic reduction of p-nitrophenol in aqueous media is used as a model reaction to prove the catalytic activity of the materials: the synthesized hollow structures show nearly 100 times higher rate constants than solid CuO microspheres. The kinetic behavior and the order of the reduction reaction change due to the increase of the surface area of the hollow str…
Exploring wet chemistry approaches to ZnFe2O4 spinel ferrite nanoparticles with different inversion degrees: A comparative study
Zinc ferrite (ZnFe2O4) spinel nanocrystals were synthesised through three different low-temperature routes, namely hydrothermal, combined miniemulsion/hydrothermal, and microwave-assisted non-aqueous sol–gel synthesis. With the aim of studying the influence of the respective approach on the structural evolution of the compounds during the synthetic process, the samples were prepared with different processing times. The resulting nanoparticles were inspected with a wide range of analytical techniques, both with regards to the local (X-ray absorption spectroscopy – XAS) and the long-range (Raman spectroscopy, X-ray diffraction – XRD) order.
Colloidally Confined Crystallization of Highly Efficient Ammonium Phosphomolybdate Catalysts
Nanodroplets in inverse miniemulsions provide a colloidal confinement for the crystallization of ammonium phosphomolybdate (APM), influencing the resulting particle size. The effects of the space confinement are investigated by comparing the crystallization of analogous materials both in miniemulsion and in bulk solution. Both routes result in particles with a rhombododecahedral morphology, but the ones produced in miniemulsion have sizes between 40 and 90 nm, 3 orders of magnitude smaller than the ones obtained in bulk solution. The catalytic activity of the materials is studied by taking the epoxidation of cis-cyclooctene as a model reaction. The miniemulsion route yields APM particles ca…
Nonenzymatic Transformation of Amorphous CaCO3 into Calcium Phosphate Mineral after Exposure to Sodium Phosphate in Vitro: Implications for in Vivo Hydroxyapatite Bone Formation.
Studies indicate that mammalian bone formation is initiated at calcium carbonate bioseeds, a process that is driven enzymatically by carbonic anhydrase (CA). We show that amorphous calcium carbonate (ACC) and bicarbonate (HCO3 (-) ) cause induction of expression of the CA in human osteogenic SaOS-2 cells. The mineral deposits formed on the surface of the cells are rich in C, Ca and P. FTIR analysis revealed that ACC, vaterite, and aragonite, after exposure to phosphate, undergo transformation into calcium phosphate. This exchange was not seen for calcite. The changes to ACC, vaterite, and aragonite depended on the concentration of phosphate. The rate of incorporation of phosphate into ACC, …
Viscoelastic behavior of epoxy prepolymer/organophilic montmorillonite dispersions
Dispersions of a bisphenol A-based epoxy resin with an organophilic montmorillonite (Nanofil 919) were studied by X-ray diffraction and oscillatory shear rheometry. X-ray studies reveal that the clay is intercalated by the epoxy and forms stable dispersions. The viscoelastic behavior of the nanodispersions was measured as a function of the Nanofil concentration and temperature. An increase in both G′ and G″ moduli was detected as the concentration increases. Furthermore, a transition from a liquid-like behavior, at low temperatures, to a solid-like behavior, at higher temperatures, was observed for all the samples. This transition is accounted for the formation of a percolated structure of …
Metal Oxide/Polymer Hybrid Nanoparticles with Versatile Functionality Prepared by Controlled Surface Crystallization
Metal oxide/polymer hybrids are prepared from polystyrene nanoparticles functionalized at the surface with phosphonate and phosphate groups. The polymer particles are synthesized with specifically designed surface-active monomers (surfmers) and used as nucleation surfaces for the controlled in situ crystallization of cerium, iron, and zinc oxide nanocrystals. The formation of the metal oxide is driven by the addition of a base to suspensions of the polymer particles containing the corresponding precursor. The crystal formation at the particle surface is studied for the different hybrid systems by X-ray diffraction and transmission electron microscopy (TEM). The potential catalytic activity …
Luminescent and Magnetoresponsive Multifunctional Chalcogenide/Polymer Hybrid Nanoparticles
Cadmium sulfide/magnetite/polymer multifunctional hybrid nanoparticles are prepared by crystallizing CdS in a controlled manner on the surface of phosphonate-functionalized polystyrene particles with a magnetic core. The supporting polymer magnetoresponsive nanoparticles are produced by a modified miniemulsion polymerization process: a first miniemulsion containing the core monomer (styrene) and a phosphonate-functionalized surface-active monomer is mixed with a second miniemulsion containing magnetite nanoparticles capped with oleic acid and the same surface-active monomer. The chalcogenide formation occurs in situ at the surface of the polymer particles by adding a precipitating agent (so…
Macromol. Rapid Commun. 17/2016
Anàlisi de l?especificitat morfològica i semàntica de la neologia andorrana
L’estudi de la neologia és important no sols des d’un punt de vista metalingüístic, sinó també des de la perspectiva de la planificació lingüística, ja que mitjançant la monitorització de la creació lèxica és possible fer noves propostes lexicogràfiques i terminològiques. Donada la singularitat d’Andorra dins del domini lingüístic català, tant en termes demogràfics i geogràfics com polítics i culturals, la llengua pot tenir necessitats lèxiques i terminològiques diferents de la d’altres territoris. En aquest treball s’han analitzat els patrons de morfologia i dels processos de formació de la neologia andorrana, tot comparant-los amb els de la resta del domini lingúístic. A més, s’han classi…
A new polyphosphate calcium material with morphogenetic activity
Abstract Polyphosphate [polyP] has been proven to elicit morphogenetic activity on bone cells. By applying mild reaction conditions, a Ca-polyP material that displays a hardness of ≈1.3 GPa has been fabricated. The Ca-polyP granules are prone to hydrolytic degradation during in vitro incubation of the cells, suggesting that this property is associated with the observed bioactivity.
Low-Temperature Miniemulsion-Based Routes for Synthesis of Metal Oxides.
Abstract The use of miniemulsions containing chemical precursors in the disperse phase is a versatile method to produce nanoparticles and nanostructures of different chemical nature, including not only polymers, but also a variety of inorganic materials. This Minireview focuses on materials in which nanostructures of metal oxides are synthesized in processes that involve the miniemulsion technique in any of the steps. This includes in the first place those approaches in which the spaces provided by nanodroplets are directly used to confine precipitation reactions that lead eventually to oxides. On the other hand, miniemulsions can also be used to form functionalized polymer nanoparticles th…
In Situ Polyphosphate Nanoparticle Formation in Hybrid Poly(vinyl alcohol)/Karaya Gum Hydrogels: A Porous Scaffold Inducing Infiltration of Mesenchymal Stem Cells
Abstract The preparation and characterization of a porous hybrid cryogel based on the two organic polymers, poly(vinyl alcohol) (PVA) and karaya gum (KG), into which polyphosphate (polyP) nanoparticles have been incorporated, are described. The PVA/KG cryogel is prepared by intermolecular cross‐linking of PVA via freeze‐thawing and Ca2+‐mediated ionic gelation of KG to form stable salt bridges. The incorporation of polyP as amorphous nanoparticles with Ca2+ ions (Ca‐polyP‐NP) is achieved using an in situ approach. The polyP constituent does not significantly affect the viscoelastic properties of the PVA/KG cryogel that are comparable to natural soft tissue. The exposure of the Ca‐polyP‐NP w…
Application of Nanoemulsions in the Synthesis of Nanoparticles
Abstract Nanodroplets of a liquid in another immiscible liquid provide confined spaces in which chemical reactions can take place. If these reactions lead to the formation of nanoparticles, as it is the case for polymerization or precipitation reactions, nanodroplets can be used as templates for particle synthesis. The most common example of application of nanoemulsions for particle synthesis is the preparation of polymer nanoparticles by miniemulsion polymerization, but also inorganic materials can be produced in this way. Nanoemulsions are as well an excellent platform for preparing polymer/inorganic hybrid nanoparticles, either by using directly the templating effect of droplets during t…
A chitosan/silica hybrid 3D scaffold for simultaneous entrapment of two different hydrophilic substances
We report the preparation of a hybrid chitosan/silica three-dimensional (3D) scaffold loaded simultaneously with two model hydrophilic substances, ibuprofen sodium salt and erioglaucine disodium salt. The first substance is entrapped in situ during the preparation of chitosan submillimetric beads by ionotropic gelation with sodium triphosphate, while the latter is post-loaded during the scaffold formation. Controlled release experiments carried out under neutral conditions demonstrate that the presence of nanostructured silica within the polymer matrix retards the release of both hydrophilic substances and increases the structure stability of the scaffold. Release profiles can be fitted to …
Amorphous polyphosphate–hydroxyapatite: A morphogenetically active substrate for bone-related SaOS-2 cells in vitro
There is increasing evidence that inorganic calcium-polyphosphates (polyP) are involved in human bone hydroxyapatite (HA) formation. Here we investigated the morphology of the particles, containing calcium phosphate (CaP) with different concentrations of various Na-polyP concentrations, as well as their effects in cell culture. We used both SaOS-2 cells and human mesenchymal stem cells. The polymeric phosphate readily binds calcium ions under formation of insoluble precipitates. We found that addition of low concentrations of polyP (10wt.%, referred to the CaP deposits) results in an increased size of the HA crystals. Surprisingly, at higher polyP concentrations (10wt.%) the formation of cr…
Amplified morphogenetic and bone forming activity of amorphous versus crystalline calcium phosphate/polyphosphate.
Amorphous Ca-phosphate (ACP) particles stabilized by inorganic polyphosphate (polyP) were prepared by co-precipitation of calcium and phosphate in the presence of polyP (15% [w/w]). These hybrid nanoparticles showed no signs of crystallinity according to X-ray diffraction analysis, in contrast to the particles obtained at a lower (5% [w/w]) polyP concentration or to hydroxyapatite. The ACP/15% polyP particles proved to be a suitable matrix for cell growth and attachment and showed pronounced osteoblastic and vasculogenic activity in vitro. They strongly stimulated mineralization of the human osteosarcoma cell line SaOS-2, as well as cell migration/microvascularization, as demonstrated in th…
ZnO-latex hybrids obtained by polymer-controlled crystallization: a spectroscopic investigation.
Micro- and submicrosized ZnO-polymer hybrid materials were synthesized by precipitating zinc oxide from an aqueous medium in the presence of poly(styrene-acrylic acid) latex nanoparticles, prepared by miniemulsion polymerization. Up to 10 wt % of the latex becomes incorporated into the crystals. Although the long-range order of the inorganic material is essentially not altered by the polymer, studies by photoluminescence (PL) spectroscopy and electron paramagnetic resonance (EPR) show that the latex particles influence the optical and paramagnetic properties of the hybrids, which can be correlated with changes in the defect structure. Typical PL emission spectra showed a narrow UV peak and …
Amino-Acid-Based Polymerizable Surfactants for the Synthesis of Chiral Nanoparticles
Amino-acid-based chiral surfactants with polymerizable moieties are synthesized, and a versatile approach to prepare particles thereof with a chiral surface functionality is presented. As an example of an application, the synthesized particles are tested for their ability as nucleating agents in the enantioselective crystallization of amino acid conglomerate systems, taking rac-asparagine as a model system. Particles resulting from chiral surfactants with different tail groups are compared and the results demonstrate that only the chiral nanoparticles made of the polymerizable surfactant are able to act efficiently as nucleation agent in enantioselective crystallization.
Rebalancing β-Amyloid-Induced Decrease of ATP Level by Amorphous Nano/Micro Polyphosphate: Suppression of the Neurotoxic Effect of Amyloid β-Protein Fragment 25-35
Morbus Alzheimer neuropathology is characterized by an impaired energy homeostasis of brain tissue. We present an approach towards a potential therapy of Alzheimer disease based on the high-energy polymer inorganic polyphosphate (polyP), which physiologically occurs both in the extracellular and in the intracellular space. Rat pheochromocytoma (PC) 12 cells, as well as rat primary cortical neurons were exposed to the Alzheimer peptide Aβ25-35. They were incubated in vitro with polyphosphate (polyP); ortho-phosphate was used as a control. The polymer remained as Na+ salt; or complexed in a stoichiometric ratio to Ca2+ (Na-polyP[Ca2+]); or was processed as amorphous Ca-polyP microparticles (C…
ALTMET Polymerization of Amino Acid-Based Monomers Targeting Controlled Drug Release
Giving the imminent necessity of a new generation of biodegradable and biocompatible polymers prepared from feedstock, the synthesis of a potentially biodegradable amino acid-based copolymer by the alternating diene metathesis (ALTMET) strategy is herein presented. The reaction was tailored to minimize isomerization and deactivation of ruthenium catalysts by intramolecular coordination with the amide carbonyl group of the amino-acid-based monomer. Alternated l-lysine–phosphoester copolymers with molar masses higher than 18 000 g/mol were obtained using Hoveyda–Grubbs second-generation and Umicore M2 catalysts. The copolymer was further used to prepare nanoparticles loaded with rifampicin (u…
Poly(3,4-Ethylenedioxythiophene) nanoparticles as building blocks for hybrid thermoelectric flexible films
Hybrid thermoelectric flexible films based on poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles and carbon nanotubes were prepared by using layer-by-layer (LbL) assembly. The employed PEDOT nanoparticles were synthesized by oxidative miniemulsion polymerization by using iron(III) p-toluenesulfonate hexahydrate (FeTos) as an oxidant and poly(diallyldimethylammonium chloride) (PDADMAC) as stabilizer. Sodium deoxycholate (DOC) was used as a stabilizer to prepare the aqueous dispersions of the carbon nanotubes. Hybrid thermoelectric films were finally prepared with different monomer/oxidant molar ratios and different types of carbon nanotubes, aiming to maximize the power factor (PF). The …
Silanization as a versatile functionalization method for the synthesis of polymer/magnetite hybrid nanoparticles with controlled structure
We compare the use of different trimethoxysilane compounds for the surface functionalization of magnetite nanoparticles and their subsequent incorporation in hybrid particles formed by in situ polymerization. For the encapsulation of inorganic nanoparticles via miniemulsion polymerization, surface functionalization of the inorganic material is necessary to hydrophobize the otherwise hydrophilic inorganic material and to compatibilize it with the polymer. Hydrophobic magnetite nanoparticles are usually prepared by surface functionalization with oleic acid, which leads to effective hydrophobization, but offers only limited control over the structure of the hybrid particles. As an alternative,…
Transformation of Amorphous Polyphosphate Nanoparticles into Coacervate Complexes: An Approach for the Encapsulation of Mesenchymal Stem Cells.
Inorganic polyphosphate [polyP] has proven to be a promising physiological biopolymer for potential use in regenerative medicine because of its morphogenetic activity and function as an extracellular energy-donating system. Amorphous Ca2+ -polyP nanoparticles [Ca-polyP-NPs] are characterized by a high zeta potential with -34 mV (at pH 7.4). This should contribute to the stability of suspensions of the spherical nanoparticles (radius 94 nm), but make them less biocompatible. The zeta potential decreases to near zero after exposure of the Ca-polyP-NPs to protein/peptide-containing serum or medium plus serum. Electron microscopy analysis reveals that the particles rapidly change into a coacerv…
Nanofibrous photocatalysts from electrospun nanocapsules
We present the design of multicompartment metal oxide/silica nanofibrous photocatalysts by colloid-electrospinning and subsequent calcination. During the calcination process, silica nanomaterials are cemented to form the fibrous framework and metal oxide precursors are crystallized inside and onto the fibers. This multicompartment nanofibrous structure, constructed with nanoparticles and core-shell nanocapsules, is therefore beneficial for the separation of the materials and the light utilization due to the multiple reflections and scattering of incident light in the cavities. The photocatalytic activity of the fibers was verified by the successful degradation of a model dye rhodamine B. Th…
Triple-target stimuli-responsive anti-COVID-19 face mask with physiological virus-inactivating agents
Conventional face masks to prevent SARS-CoV-2 transmission are mostly based on a passive filtration principle. Ideally, anti-COVID-19 masks should protect the carrier not only by size exclusion of virus aerosol particles, but also be able to capture and destroy or inactivate the virus. Here we present the proof-of-concept of a filter mat for such a mask, which actively attracts aerosol droplets and kills the virus. The electrospun mats are made of polycaprolactone (PCL) a hydrophilic, functionalizable and biodegradable polyester, into which inorganic polyphosphate (polyP) a physiological biocompatible, biodegradable and antivirally active polymer (chain length, ∼40 Pi units) has been integr…
Inorganic Protection of Polymer Nanocapsules: A Strategy to Improve the Efficiency of Encapsulated Optically Active Molecules
Cerium-Doped Copper(II) Oxide Hollow Nanostructures as Efficient and Tunable Sensors for Volatile Organic Compounds
Tuning sensing capabilities of simple to complex oxides for achieving enhanced sensitivity and selectivity toward the detection of toxic volatile organic compounds (VOCs) is extremely important and remains a challenge. In the present work, we report the synthesis of pristine and Ce-doped CuO hollow nanostructures, which have much higher VOC sensing and response characteristics than their solid analogues. Undoped CuO hollow nanostructures exhibit high response for sensing of acetone as compared to commercial CuO nanoparticles. As a result of doping with cerium, the material starts showing selectivity. CuO hollow structures doped with 5 at. % of Ce return highest response toward methanol sens…
Amorphous, Smart, and Bioinspired Polyphosphate Nano/Microparticles: A Biomaterial for Regeneration and Repair of Osteo-Articular Impairments In-Situ
Using femur explants from mice as an in vitro model, we investigated the effect of the physiological polymer, inorganic polyphosphate (polyP), on differentiation of the cells of the bone marrow in their natural microenvironment into the osteogenic and chondrogenic lineages. In the form of amorphous Ca-polyP nano/microparticles, polyP retains its function to act as both an intra- and extracellular metabolic fuel and a stimulus eliciting morphogenetic signals. The method for synthesis of the nano/microparticles with the polyanionic polyP also allowed the fabrication of hybrid particles with the bisphosphonate zoledronic acid, a drug used in therapy of bone metastases in cancer patients. The r…
Multifunctional clickable and protein-repellent magnetic silica nanoparticles
Silica nanoparticles are versatile materials whose physicochemical surface properties can be precisely adjusted. Because it is possible to combine several functionalities in a single carrier, silica-based materials are excellent candidates for biomedical applications. However, the functionality of the nanoparticles can get lost upon exposure to biological media due to uncontrolled biomolecule adsorption. Therefore, it is important to develop strategies that reduce non-specific protein-particle interactions without losing the introduced surface functionality. Herein, organosilane chemistry is employed to produce magnetic silica nanoparticles bearing differing amounts of amino and alkene func…
Sepiolite-reinforced epoxy nanocomposites: Thermal, mechanical, and morphological behavior
A bisphenol A-based epoxy resin was modified with pristine sepiolite and an organically surface-modified sepiolite and thermally cured using two different curing agents: an aliphatic and a cycloaromatic diamine. The nanocomposites were characterized by dynamic mechanical analysis (DMA), rheology, thermogravimetric analysis (TGA), and electron microscopy. The initial sepiolite–epoxy mixtures show a better dispersion for the sepiolite-modified system that forms a percolation network structure. Mechanical properties have also been determined. The flexural modulus of the epoxy matrix slightly increases by the incorporation of the organophilic sepiolite. The flexural strength of the sepiolite-mo…
Self-Healing Properties of Bioinspired Amorphous CaCO3/Polyphosphate-Supplemented Cement
There is a strong interest in cement additives that are able to prevent or mitigate the adverse effects of cracks in concrete that cause corrosion of the reinforcement. Inorganic polyphosphate (polyP), a natural polymer that is synthesized by bacteria, even those on cement/concrete, can increase the resistance of concrete to progressive damage from micro-cracking. Here we use a novel bioinspired strategy based on polyP-stabilized amorphous calcium carbonate (ACC) to give this material self-healing properties. Portland cement was supplemented with ACC nanoparticles which were stabilized with 10% (w/w) Na&ndash
Zirconium oxocluster/polymer hybrid nanoparticles prepared by photoactivated miniemulsion copolymerization
The photoactivated free radical miniemulsion copolymerization of methyl methacrylate (MMA) and the zirconium oxocluster Zr4O2(methacrylate) 12 is used as an effective and fast preparation method for polymer/inorganic hybrid nanoparticles. The oxoclusters, covalently anchored to the polymer network, act as metal-organic cross-linkers, thus improving the thermomechanical properties of the resulting hybrid nanoparticles. Benzoin carbonyl organic compounds were used as photoinitiators. The obtained materials are compared in terms of cross-linking, effectiveness of cluster incorporation, and size distribution with the analogous nanoparticles produced by using conventional thermally induced free …
PEDOT thin films with n-type thermopower
peer-reviewed Synthesis of n-type organic semiconductors is challenging as reduced states are difficult to obtain due to their instability in air. Here, we report tailoring of semiconducting behavior through control of surfactant concentration during synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles. Nanoparticles were synthesized by mini-emulsion polymerization, where stable suspensions were used to produce polymer films by a simple casting technique on polyethylene terephthalate (PET) substrates. Electrical conductivity and Seebeck coefficients were measured as a function of surfactant concentration. It was found that conductivity decreases three orders of magnitude as s…
Organic-Inorganic Hybrids: Metal Oxide/Polymer Hybrid Nanoparticles with Versatile Functionality Prepared by Controlled Surface Crystallization (Adv. Funct. Mater. 4/2013)
Peptide-Controlled Assembly of Macroscopic Calcium Oxalate Nanosheets
The fabrication of two-dimensional (2D) biomineral nanosheets is of high interest owing to their promise for applications in electronics, filtration, catalysis, and chemical sensing. Using a facile approach inspired by biomineralization in nature, we fabricate laterally macroscopic calcium oxalate nanosheets using β-folded peptides. The template peptides are composed of repetitive glutamic acid and leucine amino acids, self-organized at the air-water interface. Surface-specific sum frequency generation spectroscopy and molecular dynamics simulations reveal that the formation of oxalate nanosheets relies on the peptide-Ca 2+ ion interaction at the interface, which not only restructures the …
Electrochemical Synthesis of an Organic Thermoelectric Power Generator.
[EN] Energy harvesting through residual heat is considered one of the most promising ways to power wearable devices. In this work, thermoelectric textiles were prepared by coating the fabrics, first with multiple-wall carbon nanotubes (MWCNTs) by using the layer-by-layer technique and second with poly(3,4-ethylenedioxythiophene) (PEDOT) deposited by electrochemical polymerization. Sodium deoxycholate and poly(diallyldimethylammonium chloride) were used as stabilizers to prepare the aqueous dispersions of MWCNTs. The electrochemical deposition of PEDOT on the MWCNT-coated fabric was carried out in a three-electrode electrochemical cell. The polymerization of PEDOT on the fabric increased the…
Surface-Functionalized Latex Particles as Controlling Agents for the Mineralization of Zinc Oxide in Aqueous Medium
Polystyrene latex particles modified at the surface with different hydrophilic functional groups were prepared by miniemulsion polymerization and used as controlling agents in the crystallization of zinc oxide from aqueous medium. The effects of the chemical nature of the surface functionalization and the latex concentration on the crystal growth, morphology, and crystalline structure of the resulting zinc oxide were analyzed. Micro- and submicrosized crystals with a broad variety of morphologies depending on the functionalization were obtained. Among the different latexes studied, the acrylic-acid-derived particles were shown to be a convenient system for further quantitative investigation…
A physiologically active interpenetrating collagen network that supports growth and migration of epidermal keratinocytes: zinc-polyP nanoparticles integrated into compressed collagen.
The distinguished property of the physiological polymer, inorganic polyphosphate (polyP), is to act as a bio-intelligent material which releases stimulus-dependent metabolic energy to accelerate wound healing. This characteristic is based on the bio-imitating feature of polyP to be converted, upon exposure to peptide-containing body fluids, from stable amorphous nanoparticles to a physiologically active and energy-delivering coacervate phase. This property of polyP has been utilized to fabricate a wound mat consisting of compressed collagen supplemented with amorphous polyP particles, formed from the inorganic polyanion with an over-stoichiometric ratio of zinc ions. The proliferation and t…
Magnetic Polyurethane Microcarriers from Nanoparticle-Stabilized Emulsions for Thermal Energy Storage
Hydrated inorganic salts are phase change materials (PCMs) with promising thermal energy storage capacity. However, their application is commonly restricted because of problems of phase segregation...
Frontispiece: Low‐Temperature Miniemulsion‐Based Routes for Synthesis of Metal Oxides
Transformation of Construction Cement to a Self-Healing Hybrid Binder
A new biomimetic strategy to im prove the self-healing properties of Portland cement is presented that is based on the application of the biogenic inorganic polymer polyphosphate (polyP), which is used as a cement admixture. The data show that synthetic linear polyp, with an average chain length of 40, as well as natural long-chain polyP isolated from soil bacteria, has the ability to support self-healing of this construction material. Furthermore, polyP, used as a water-soluble Na-salt, is subject to Na+/Ca2+ exchange by the Ca2+ from the cement, resulting in the formation of a water-rich coacervate when added to the cement surface, especially to the surface of bacteria-containing cement/c…
pH-responsive physically and chemically cross-linked glutamic-acid-based hydrogels and nanogels
Abstract Given the great demand for polymers prepared from renewable materials, the synthesis of a glutamic-acid-based hydrogel by solution and inverse miniemulsion polymerization is herein presented. Free radical initiated homopolymerizations of N-acryloyl- l -glutamic acid (l- AGA) resulted in either a readily water-soluble polymer or a physically cross-linked hydrogel, being the formation of physical cross-linking junctions closely related to monomer concentration and mixture viscosity. Chemically cross-linked poly( l -AGA-co-BIS) hydrogels were also synthesized by copolymerization of l -AGA and N,N′-methylenebis(acrylamide) (BIS). Both poly (l- AGA) and poly( l -AGA-co-BIS) swelling beh…
Increased Stability of Polysaccharide/Silica Hybrid Sub‐Millicarriers for Retarded Release of Hydrophilic Substances
Magnetically enhanced polymer-supported ceria nanocatalysts for the hydration of nitriles.
The heterogeneous catalysis of the hydration of nitriles to amides is a process of great industrial relevance in which cerium(IV) oxide (also referred to as ceria) has shown an outstanding catalytic performance. The use of non-supported ceria nanoparticles is related to difficulties in the purification of the product and the recovery and recyclability of the catalyst. Therefore, in this work, ceria nanoparticles are supported on a polymer matrix either by synthesizing polymer particles by so-called Pickering miniemulsions while using ceria nanoparticles as emulsion stabilizers or, as a comparison, by in-situ crystallization on preformed polymer particles. The former strategy presents signif…