Onion-like Multifunctional Microtrap Vehicles for Attraction–Trapping–Destruction of Biological Threats

A multifunctional motile microtrap is developed that is capable of autonomously attracting, trapping, and destroying pathogens by controlled chemoattractant and therapeutic agent release. The onion-inspired multi-layer structure contains a magnesium engine core and inner chemoattractant and therapeutic layers. Upon chemical propulsion, the magnesium core is depleted, resulting in a hollow structure that exposes the inner layers and serves as structural trap. The sequential dissolution and autonomous release of the chemoattractant and killing agents result in long-range chemotactic attraction, trapping, and destruction of motile pathogens. The dissolved chemoattractant (l -serine) significantly increases the accumulation and capture of motile pathogens (E. coli) within the microtrap structure, while the internal release of silver ions (Ag⁺) leads to lysis of the pathogen accumulated within the microtrap cavity.     

An anisaldehyde sodium bisulfite derivative: poly[[μ4‐(hydroxy)(4‐methoxyphenyl)methanesulfonato]sodium]

The title complex, [Na(C₈H₉O₅S)]_n, is polymeric and consists of broad layers parallel to (100) made up of an inner hydrophilic core of Na⁺ cations and polar SO₃C(OH)– groups, padded on both sides by two hydrophobic layers of pendant methoxyphenyl groups. The Na⁺ cations in the inner core are six‐coordinated into highly distorted NaO₆ octahedra by four symmetry‐related (hydroxy)(4‐methoxyphenyl)methanesulfonate anions, leading to a tightly woven two‐dimensional structure. While there are some hydrogen bonds providing interplanar cohesion, interactions between adjacent layers are weak hydrophobic ones. The present compound appears to be the first reported structure containing the (hydroxy)(4‐methoxyphenyl)methanesulfonate ligand.     

pH‐responsive polymer core–shell nanospheres for drug delivery

Stimuli‐responsive polymer nanoparticles are playing an increasingly more important role in drug delivery applications. However, limited knowledge has been accumulated about processes which use stimuli‐responsive polymer nanospheres (matrix nanoparticles whose entire mass is solid) to carry and deliver hydrophobic therapeutics in aqueous solution. In this research, pyrene was selected as a model hydrophobic drug and a pyrene‐loaded core‐shell structured nanosphere named poly(DEAEMA)‐poly(PEGMA) was designed as a drug carrier where DEAEMA and PEGMA represent 2‐(diethylamino)ethyl methacrylate and poly(ethylene glycol) methacrylate, respectively. The pyrene‐loaded core‐shell nanospheres were prepared via an in situ two‐step semibatch emulsion polymerization method. The particle size of the core‐shell nanosphere can be well controlled through adjusting the level of surfactant used in the polymerization where an average particle diameter of below 100 nm was readily achieved. The surfactant was removed via a dialysis operation after polymerization. Egg lecithin vesicles (liposome) were prepared to mimic the membrane of a cell and to receive the released pyrene from the nanosphere carriers. The in vitro release profiles of pyrene toward different pH liposome vesicles were recorded as a function of time at 37 °C. It was found that release of pyrene from the core‐shell polymer matrix can be triggered by a change in the environmental pH. In particular the pyrene‐loaded nanospheres are capable of responding to a narrow window of pH change from pH = 5, 6, to 7 and can achieve a significant pyrene release of above 80% within 90 h. The rate of release increased with a decrease in pH. A first‐order kinetic model was proposed to describe the rate of release with respect to the concentration of pyrene in the polymer matrix. The first‐order rate constant of release k was thus determined as 0.049 h^?1 for pH = 5; 0.043 h^?1 for pH = 6; and 0.035 h^?1 for pH = 7 at 37 °C. The release of pyrene was considered to follow a diffusion‐controlled mechanism. The synthesis and encapsulation process developed herein provides a new approach to prepare smart nanoparticles for efficient delivery of hydrophobic drugs. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4440–4450     

Synthesis and characterization of core–shell‐type polymeric micelles from diblock copolymers via reversible addition–fragmentation chain transfer

A method was developed to enable the formation of nanoparticles by reversible addition–fragmentation chain transfer polymerization. The thermoresponsive behavior of polymeric micelles was modified by means of micellar inner cores and an outer shell. Polymeric micelles comprising AB block copolymers of poly(N‐isopropylacrylamide) (PIPAAm) and poly(2‐hydroxyethylacrylate) (PHEA) or polystyrene (PSt) were prepared. PIPAAm‐b‐PHEA and PIPAAm‐b‐PSt block copolymers formed a core–shell micellar structure after the dialysis of the block copolymer solutions in organic solvents against water at 20 °C. Upon heating above the lower critical solution temperature (LCST), PIPAAm‐b‐PHEA micelles exhibited an abrupt increase in polarity and an abrupt decrease in rigidity sensed by pyrene. In contrast, PIPAAm‐b‐PSt micelles maintained constant values with lower polarity and higher rigidity than those of PIPAAm‐b‐PHEA micelles over the temperature range of 20–40 °C. Structural deformations produced by the change in the outer polymer shell with temperature cycles through the LCST were proposed for the PHEA core, which possessed a lower glass‐transition temperature (ca. 20 °C) than the LCST of the PIPAAm outer shell (ca. 32.5 °C), whereas the PSt core with a much higher glass‐transition temperature (ca. 100 °C) retained its structure. The nature of the hydrophobic segments composing the micelle inner core offered an important control point for thermoresponsive drug release and the drug activity of the thermoresponsive polymeric micelles. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3312–3320, 2006     

Fabrication of novel core–shell PLGA and alginate fiber for dual‐drug delivery system

Biodegradable fibers for the controlled delivery of anti‐inflammatory agent dexamethasone were developed and studied. Mono and core–shell structure fiber are prepared by wet‐spinning solutions of hydrophobic poly (lactide‐co‐glycolide) and hydrophilic alginic acid shell. The two model drugs, dexamethasone and dexamethasone‐21‐phosphate, were entrapped in core and shell, respectively. These fibers were characterized in terms of morphology, diameters, mechanical properties, in vitro degradation, and drug release. The optical microscopy and scanning electron microscopy photos revealed directly that fibers possessed core–shell structure. The release of dexamethasone and dexamethasone‐21‐phosphate was investigated, and the results showed that alginate shell retarded dexamethasone release significantly in both early and late stages. The core–shell structure fiber release shows a two stage release of dexamethasone and dexamethasone‐21‐phosphate with distinctly different release rates, and minimal initial burst release is observed. The results indicated that the prepared fibers are efficient carrier for both types of dexamethasone. Copyright © 2016 John Wiley & Sons, Ltd.     

Preparation and characterization of cellulose acetate‐coated compound fertilizer with controlled‐release and water‐retention

A novel cellulose acetate‐coated compound fertilizer with controlled‐release and water‐retention (CAFCW) was prepared, which possessed the three‐layer structure. Its core was water‐soluble compound fertilizer granular, the inner coating was cellulose acetate (CA), and the outer coating was poly(acrylic acid‐co‐acrylamide)/unexpanded vermiculite (P(AA‐co‐AM)/UVMT) superabsorbent composite. The effects of the amount of acrylamide, crosslinker, initiator, degree of neutralization of acrylic acid (AA), and unexpanded vermiculite concentration on water absorbency were investigated and optimized. The water absorbency of CAFCW was 72 times its own weight if it was allowed to swell in tap water at room temperature for 90 min. Element analysis and atomic absorption spectrophotometer results showed that the product contained 11% nitrogen, 6% phosphorus (shown by P₂O₅), 9% potassium (shown by K₂O), 1% calcium (shown by CaO), and 0.4% magnesium (shown by MgO). Swelling rate, slow‐release, and water‐retention properties of CAFCW were also investigated. This product with good controlled‐release and water‐retention capacity, being degradable in soil and environmentally friendly, could be especially useful in agricultural and horticultural applications. Copyright © 2008 John Wiley & Sons, Ltd.     

Electron‐pair density decomposition for core–valence separable systems

The electron pair density of a core‐valence separable system can be decomposed into three parts: core‐core, core‐valence, and valence‐valence. The core‐core part has a Hartree‐Fock like structure. The core‐valence part can be written as Γ_cv (1,2) = γ_c (1,1)γ_v (2,2) ? γ_c (1,2)γ_v (2,1) + γ_c (2,2)γ_v (1,1) ? γ_c (2,1)γ_v (1,2), where only the 1‐matrices from the core and valence orbitals contribute. The valence‐valence part is left to be determined from the reduced frozen‐core type wave function, which often contains the essential information on the electron correlation and the chemical bond. We demonstrate the analysis to the ground state of negative ion Li^? and 2¹Σ_u⁺ excited state of the Li₂ molecule. © 2012 Wiley Periodicals, Inc.     

Polymeric sodium 3,5‐di­carboxy­benzene­sulfonate–urea–water (1/1/1)

In the title compound, poly­[sodium‐μ₄‐3,5‐di­carboxy­benzene­sulfonato‐κ⁴O:O′:O′′:O′′′‐μ₂‐urea‐κ²O:N] monohydrate], {[Na(C₈H₅O₇S)(CH₄N₂O)]·H₂O}_n, the organic anions are arranged almost vertically within (001) monolayers, with the sulfonate and carboxylic acid groups pointing into the interlayer region. The inversion‐related aromatic rings of the anions inside the layers are arrayed via offset face‐to‐face interactions into molecular stacks along the crystallographic a axis. The `up' and `down' arrangement of the aromatic portions makes both faces of the layers ionic and hydro­philic, whereas the interiors of the layers are primarily hydro­phobic. The interleaving of the anions is such that the carboxylic acid groups are oriented more toward the interior than are the sulfonate groups. The aromatic rings in neighbouring layers are arranged in a herring‐bone fashion. The coordination sphere of the Na⁺ ions contains two sulfonate and two carboxylic acid O atoms, from a total of four different acid anions belonging to two neighbouring anionic monolayers. The urea mol­ecules are positioned between translation‐related anionic stacks inside the (001) layers, serving a triple function, viz. they fill in the large meshes (empty cavities) formed within the anionic–cationic network, and they provide additional Na⁺ coordination and hydrogen‐bond sites.     

Regioselective synthesis of symmetrical pyridyl selenium compounds by bromine–magnesium exchange of bromopyridines using isopropyl magnesium chloride: X‐ray crystal structure of 2,2′,5,5′‐tetrabromo‐3,3′‐dipyridyldiselenide

2,2′‐Dipyridyl‐3,3′‐dipyridyl,5,5′‐dipyridyl‐diselenides have been synthesized by a convenient method employing non‐cryogenic conditions. Various bromopyridines (2‐Bromopyridine, 2,5‐dibromopyridines and 2,3,5‐Tribromopyridines) undergo selective monobromine–magnesium exchange to yield the corresponding pyridyl magnesium chlorides at room temperature upon treatment with ⁱPrMgCl. The resulting pyridyl magnesium chloride is quenched with elemental selenium, which upon further oxidation affords the above diselenides in good yields. The compounds prepared using this methodology have been characterized by elemental analysis, IR, NMR (¹H, ¹³C, ⁷⁷Se) and mass spectral analysis. The molecular structure of 2,2′,5,5′‐Tetrabromo‐3,3′‐dipyridyldiselenide has been established by single‐crystal X‐ray diffraction analysis. It exists as a dimeric form due to the non‐bonding interactions between the selenium of one pyridine moiety and the hydrogen of the other. Copyright © 2004 John Wiley & Sons, Ltd.     

A Biomimetic Coordination Nanoplatform for Controlled Encapsulation and Delivery of Drug–Gene Combinations

Inspired by natural biomineralization processes, a simple and universal strategy is introduced to construct a biomimetic nanoplatform for systemic codelivery of a nucleic acid therapeutic (G3139) and a chemotherapeutic drug doxorubicin (DOX). This codelivery system was synthesized through one‐pot supramolecular self‐assembly of G3139, DOX, and Fe^II ions through multiple coordination interactions, followed by an adapted surface mineralization with metal–organic frameworks. The resulting core–shell nanoparticles have uniform size, well‐defined nanosphere structure, robust colloidal stability, ultrahigh drug loading efficiency and capacity, and precisely adjustable ratios of two therapeutic agents. The system can efficiently accumulate in the tumor, allowing for sensitive MRI detection and synergistical inhibition of tumor growth without apparent systemic toxicity.     

Strong Lithium Polysulfide Chemisorption on Electroactive Sites of Nitrogen‐Doped Carbon Composites For High‐Performance Lithium–Sulfur Battery Cathodes

Despite the high theoretical capacity of lithium–sulfur batteries, their practical applications are severely hindered by a fast capacity decay, stemming from the dissolution and diffusion of lithium polysulfides in the electrolyte. A novel functional carbon composite (carbon‐nanotube‐interpenetrated mesoporous nitrogen‐doped carbon spheres, MNCS/CNT), which can strongly adsorb lithium polysulfides, is now reported to act as a sulfur host. The nitrogen functional groups of this composite enable the effective trapping of lithium polysulfides on electroactive sites within the cathode, leading to a much improved electrochemical performance (1200 mAh g^?1 after 200 cycles). The enhancement in adsorption can be attributed to the chemical bonding of lithium ions by nitrogen functional groups in the MNCS/CNT framework. Furthermore, the micrometer‐sized spherical structure of the material yields a high areal capacity (ca. 6 mAh cm^?2) with a high sulfur loading of approximately 5 mg cm^?2, which is ideal for practical applications of the lithium–sulfur batteries.     

Magnetic Nanohybrids Loaded with Bimetal Core–Shell–Shell Nanorods for Bacteria Capture,Separation, and Near‐Infrared Photothermal Treatment

A novel antimicrobial nanohybrid based on near‐infrared (NIR) photothermal conversion is designed for bacteria capture, separation, and sterilization (killing). Positively charged magnetic reduced graphene oxide with modification by polyethylenimine (rGO–Fe₃O₄–PEI) is prepared and then loaded with core–shell–shell Au–Ag–Au nanorods to construct the nanohybrid rGO–Fe₃O₄–Au–Ag–Au. NIR laser irradiation melts the outer Au shell and exposes the inner Ag shell, which facilitates controlled release of the silver shell. The nanohybrids combine physical photothermal sterilization as a result of the outer Au shell with the antibacterial effect of the inner Ag shell. In addition, the nanohybrid exhibits high heat conductivity because of the rGO and rapid magnetic‐separation capability that is attributable to Fe₃O₄. The nanohybrid provides a significant improvement of bactericidal efficiency with respect to bare Au–Ag–Au nanorods and facilitates the isolation of bacteria from sample matrixes. A concentration of 25 μg mL^?1 of nanohybrid causes 100 % capture and separation of Escherichia coli O157:H7 (1×10⁸ cfu mL^?1) from an aqueous medium in 10 min. In addition, it causes a 22 °C temperature rise for the surrounding solution under NIR irradiation (785 nm, 50 mW cm^?2) for 10 min. With magnetic separation, 30 μg mL^?1 of nanohybrid results in a 100 % killing rate for E. coli O157:H7 cells. The facile bacteria separation and photothermal sterilization is potentially feasible for environmental and/or clinical treatment.     

Coordination behaviour and two‐dimensional‐network formation in poly[[μ‐aqua‐diaqua(μ5‐propane‐1,3‐diyldinitrilotetraacetato)dilithium(I)cobalt(II)] dihydrate]: the first example of an MII–1,3‐pdta complex with a monovalent metal counter‐ion

The title compound, {[CoLi₂(C₁₁H₁₄N₂O₈)(H₂O)₃]·2H₂O}_n, constitutes the first example of a salt of the [M^II(1,3‐pdta)]²⁻ complex (1,3‐pdta is propane‐1,3‐diyldinitrilotetraacetate) with a monopositive cation as counter‐ion. Insertion of the Li⁺ cation could only be achieved through application of the ion‐exchange column technique which, however, appeared unsuccessful with other alkali metals and the ammonium cation. The structure contains two tetrahedrally coordinated Li⁺ cations, an octahedral [Co(1,3‐pdta)]²⁻ anion and five water molecules, two of which are uncoordinated, and is built of two‐dimensional layers extending parallel to the (010) lattice plane, the constituents of which are connected by the coordinate bonds. O—H_water...O hydrogen bonds operate both within and between these layers. The crystal investigated belongs to the enantiomeric space group P2₁ with only one (Λ) of two possible optical isomers of the [Co(1,3‐pdta)]²⁻ complex. A possible cause of enantiomer separation during crystallization might be the rigidification and polarization of the [M(1,3‐pdta)]²⁻ core, resulting from direct coordination of Li⁺ cations to three out of four carboxylate groups constituting the 1,3‐pdta ligand. The structure of (I) differs considerably from those of the other [M^II(1,3‐pdta)]²⁻ complexes, in which the charge compensation is realized by means of divalent hexaaqua complex cations. This finding demonstrates a significant structure‐determining role of the counter‐ions.     

A heterotrimetallic Cu–Co–Zn complex with the 2,2′‐iminodiethanol ligand

The crystal structure of the title compound, triacetato‐1κO;3κ⁴O,O′‐(2,2′‐imino­diethanol)‐1κ³O,N,O′‐bis­(μ‐2,2′‐iminodi­ethanol­ato)‐1κ²O:2κ⁶O,N,O′:3κ²O′‐cobalt(III)copper(II)zinc(II), [CoCuZn(C₄H₉NO₂)₂(C₂H₃O₂)₃(C₄H₁₁NO₂)], shows a mol­ecule with a triangular three‐metal core. The metal sites were refined with full occupancies, but the possibility that the Zn and Cu positions are actually mixed Cu/Zn sites cannot be excluded. The inter­metallic Cu⋯Co and Co⋯Zn distances are 2.924 (3) and 2.906 (3) Å, respectively. The neutral mol­ecules are held together by N—H⋯O hydrogen bonds involving amine groups from the 2,2′‐iminodiethanol ligands and acetate groups to build two‐dimensional layers.     

Amphiphilic Organic–Inorganic Hybrid Zeotype Aluminosilicate like a Nanoporous Crystallized Langmuir–Blodgett Film

A new organic–inorganic hybrid zeotype compound with amphiphilic one‐dimensional nanopore and aluminosilicate composition was developed. The framework structure is composed of double aluminosilicate layers and 12‐ring nanopores; a hydrophilic layer pillared by Q² silicon atom species and a lipophilic layer pillared by phenylene groups are alternately stacked, and 12‐ring nanopores perpendicularly penetrate the layers. The framework topology looks similar to that of an AFI‐type zeolite but possesses a quasi‐multidimensional pore structure consisting of a 12‐ring channel and intersecting small pores equivalent to 8‐rings. The hybrid material with alternately laminated lipophilic and hydrophilic nanospaces can be assumed as a crystallized Langmuir–Blodgett film. It demonstrates microporous adsorption for both hydrophilic and lipophilic adsorptives, and its outer surface tightly adsorbs lysozyme whose molecular size is much larger than its micropore opening. Our results suggest the possibility of designing porous adsorbent with high amphipathicity.     

Template‐Engaged Solid‐State Synthesis of Barium Magnesium Silicate Yolk@Shell Particles and Their High Photoluminescence Efficiency

This study presents a new synthetic method for fabricating yolk@shell‐structured barium magnesium silicate (BMS) particles through a template‐engaged solid‐state reaction. First, as the core template, (BaMg)CO₃ spherical particles were prepared based on the coprecipitation of Ba²⁺ and Mg²⁺. These core particles were then uniformly shelled with silica (SiO₂) by using CTAB as the structure‐directing template to form (BaMg)CO₃@SiO₂ particles with a core@shell structure. The (BaMg)CO₃@SiO₂ particles were then converted to yolk@shell barium magnesium silicate (BMS) particles by an interfacial solid‐state reaction between the (BaMg)CO₃ (core) and the SiO₂ (shell) at 750 °C. During this interfacial solid‐state reaction, Kirkendall diffusion contributed to the formation of yolk@shell BMS particles. Thus, the synthetic temperature for the (BaMg)SiO₄:Eu³⁺ phosphor is significantly reduced from 1200 °C with the conventional method to 750 °C with the proposed method. In addition, the photoluminescence intensity of the yolk@shell (BaMg)SiO₄:Eu³⁺phosphor was found to be 9.8 times higher than that of the conventional (BaMg)SiO₄:Eu³⁺ phosphor. The higher absorption of excitation light by the structure of the yolk@shell phosphor is induced by multiple light‐reflection and ‐scattering events in the interstitial void between the yolk and the shell. When preparing the yolk@shell (BaMg)SiO₄:Eu³⁺ phosphor, a hydrogen environment for the solid‐state reaction results in higher photoluminescence efficiency than nitrogen and air environments. The proposed synthetic method can be easily extended to the synthesis of other yolk@shell multicomponent metal silicates.     

Cadaverinium dichloride: a case of centro–non‐centrosymmetric ambiguity

In the title salt, also known as pentane‐1,5‐diammonium dichloride, C₅H₁₆N₂²⁺·2Cl⁻, the cation exists in an ideal fully extended conformation and lies on a mirror plane in the space group Pbam. In the crystal structure, layers of cations are hydrogen bonded with Cl⁻ anions, which occupy the space between the layers. This kind of packing leads to a short unit‐cell parameter of 4.463 (1) Å. This structure is another case of centro–non‐centrosymmetric ambiguity; the best results were obtained in a centrosymmetric space group, with the disordered NH₃ groups accounting for the non‐centrosymmetric `component'.     

High‐efficiency doped polymeric organic light‐emitting diodes

Fabrication of polymer light‐emitting diodes based on emission from the phosphorescent molecule fac‐tris(2‐phenylpyridine) iridium doped into a poly(N‐vinyl carbazole) host are reported. For single‐layered devices with magnesium‐silver cathodes, the luminance efficiency at 20 mA/cm² was measured as 8.7 cd/A. This efficiency could be increased by over a factor of two by incorporation of evaporated small‐molecule layers into the device structure. Significant increases in device efficiency were also obtained without these evaporated layers by modification of the electrodes. Incorporation of 3,4‐poly(ethylene dioxythiophene):poly(styrene sulfonate) at the anode improved the device efficiency but had little impact on drive voltage. Insertion of lithium fluoride at the cathode resulted in no improvement in performance for magnesium‐silver and aluminum cathodes, but a significant improvement was realized in efficiency and drive voltage for calcium‐aluminum cathodes. Excellent device performance was observed for all three cathode metals used in conjunction with cesium fluoride. Through optimization of the electrodes and emitter‐layer thickness, devices exhibiting efficiencies as high as 37.3 cd/A are realized. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2715–2725, 2003     

Atom‐Precise Polyoxometalate–Ag2S Core–Shell Nanoparticles

Atomically precise polyoxometalate–Ag₂S core–shell nanoparticles were generated in a top‐down approach under solvothermal conditions and structurally confirmed by X‐ray single‐crystal diffraction as an interesting core–shell structure comprising an in situ generated Mo₆O₂₂^8? polyoxometalate core and a mango‐like Ag₅₈S₃₈ shell. This result demonstrates the possibility to integrate polyoxometalate and Ag₂S nanoparticles into a core–shell heteronanostructure with precisely controlled atomical compositions of both core and shell.     

Stabilization of Palladium Nanoparticles on Nanodiamond–Graphene Core–Shell Supports for CO Oxidation

Nanodiamond–graphene core–shell materials have several unique properties compared with purely sp²‐bonded nanocarbons and perform remarkably well as metal‐free catalysts. In this work, we report that palladium nanoparticles supported on nanodiamond–graphene core–shell materials (Pd/ND@G) exhibit superior catalytic activity in CO oxidation compared to Pd NPs supported on an sp²‐bonded onion‐like carbon (Pd/OLC) material. Characterization revealed that the Pd NPs in Pd/ND@G have a special morphology with reduced crystallinity and are more stable towards sintering at high temperature than the Pd NPs in Pd/OLC. The electronic structure of Pd is changed in Pd/ND@G, resulting in weak CO chemisorption on the Pd NPs. Our work indicates that strong metal–support interactions can be achieved on a non‐reducible support, as exemplified for nanocarbon, by carefully tuning the surface structure of the support, thus providing a good example for designing a high‐performance nanostructured catalyst.