Encapsulation of zinc phthalocyanine into bovine serum albumin aggregates

Artificial hybridization of molecules with proteins is beneficial for biomedical applications. Herein, we describe a novel method for encapsulation of zinc phthalocyanine (ZnPc) aggregates into bovine serum albumin (BSA) aggregates, but not monomeric BSA. This property is potentially useful for not only photodynamic or photothermal therapy but also development of a novel delivery system for hydrophobic drug molecules.     

Insight into the chiral induction in supramolecular stacks through preferential chiral solvation

Preferred handedness in the supramolecular chirality of self-assembled achiral oligo(p-phenylenevinylene) (OPV) derivatives is induced by chiral solvents and spectroscopic probing provides insight into the mechanistic aspects of this chiral induction through chiral solvation.     

Encapsulation of transition metal atoms into carbon nanotubes: a supramolecular approach

A functionalised fullerene incorporating a double-chelating group binds transition metal cations and acts as an effective vehicle for delivering metals into carbon nanotubes.     

Towards tobacco mosaic virus-like self-assembled supramolecular architectures

This paper discusses the molecular design of selected examples of structural units containing taper shaped exo-receptors and various crown ether, oligooxyethylenic, and H-bonding based endo-receptors, which self-assemble into cylindrical channel-like architectures via principles resembling those of tobacco mosaic virus (TMV). The ability of these structural units to self- assemble via a delicate combination of exo-and endo-recognition processes will be presented. A comparison between various supramolecular (generated via H-bonding, ionic, and electrostatic interactions) and molecular “polymer backbones” will be made. The present limitations concerning the ability to engineer the structural parameters of these supramolecular channel-like architectures and some possible novel material functions derived from them will be briefly mentioned.     

Pyrazine control of the solid-state supramolecular chemistry of zinc phthalocyanine

Crystals of monoaxially coordinated T-shaped and H-shaped supramolecular zinc(II) phthalocyaninato complexes with pyrazine are obtained. In both types of molecules the central Zn atom of ZnPc complexes with pyrazine exhibits 4 + 1 coordination. The Zn atom is equatorially coordinated by four isoindole N atoms of Pc macrocycle and axially by N atom of pyrazine molecule. The interaction of the central Zn atom of ZnPc with the axial N atom of pyrazine leads to a deviation of Zn from the centre of cavity by 0.371(2) Å in the T-shaped complex and by 0.296(2) Å in the H-shaped complex. Thermogravimetric analysis of the crystals exhibits three slopes down, corresponding to the loss in succession of solvated pyrazine molecules, than the loss of ligated pyrazine molecules from the T-shaped complex and the finally the loss of the bridged pyrazine molecule from the H-shaped complex. Finally the thermal processing leads to the β-ZnPc as residue. The UV–Vis spectrum taken in solution shows the batochromic shift in the polar solvent like α-chloronaphthalene in relation to the spectrum in non-polar solvent like benzene.     

Encapsulation of cobalt phthalocyanine in zeolite-y: evidence for nonplanar geometry

Cobalt (II) phthalocyanine (CoPc) molecules have been encapsulated within the supercage of zeolite-Y. The square-planar complex, being larger than the almost spherical cage, is forced to adopt a distorted geometry on encapsulation. A comparative spectroscopic and magnetic investigation of CoPc encapsulated in zeolite-Y and in the unencapsulated state is reported. These results supported by molecular modeling have been used to understand the nature and extent of the loss of planarity of CoPc on encapsulation. The encapsulated molecule is shown to be the trans-diprotonated species in which the center of inversion is lost due to distortions required to accommodate the square complex within the zeolite. Encapsulation also leads to an enhancement of the magnetic moment of the CoPc. This is shown to be a consequence of the nonplanar geometry of the encapsulated molecule resulting in an excited high-spin state being thermally accessible.     

Photophysical and theoretical investigations on fullerene/phthalocyanine supramolecular complexes

The present paper reports the photophysical aspects of a very interesting and unique host-guest interaction between fullerene and phthalocyanines, viz., free base phthalocyanine (H2-Pc) and zinc-phthalocyanine (Zn-Pc), in toluene medium. Ground state electronic interaction between these two supramolecules has been evidenced from the observation of well-defined charge transfer (CT) absorption bands in the visible region. Vertical ionization potentials of the phthalocyanines have been determined utilizing CT transition energy. Magnitude of degrees of CT reveals that, in the ground state, 2-4% CT takes place. Binding constants (K) for the fullerene/phthalocyanine complexes were determined from the fluorescence quenching experiment. Large K values in the ranges approximately 4.7 x 10(4) to 7.3 x 10(4) and 2.3 x 10(4) to 2.5 x 10(4) dm(3) x mol(-1) were obtained for the 1:1 fullerene complexes of Zn and H 2-Pc, respectively. Values of K suggest that both H 2- and Zn-Pc could not serve as an efficient discriminators between C60 and C70. Theoretical calculations as well as (13)C NMR studies establish that the orientation of C 70 toward phthalocyanine is favored in end-on orientation, which proves that interaction between fullerenes and phthalocyanines were governed by the electrostatic mechanism rather than dispersive forces associated with pi-pi interaction.     

Encapsulation of inorganic particles via miniemulsion polymerization

The encapsulation of TiO₂ particles via miniemulsion polymerization is strongly dependent on the size and stability of the inorganic particles in the monomer medium in which they are initially dispersed. It was found from XPS and FT‐IR studies that both the hydrophilic and hydrophobic TiO₂ particles, which were studied, have hydroxyl groups present on their surfaces, which can strongly interact with the amine end‐groups of the polymeric stabilizer, OLOA370 (polybutene‐succinimide diethyl triamine). It was found from the dispersion and adsorption studies that the amount of OLOA370 retained on the TiO₂ particles is strongly dependent on the area exposed by the sonification that is applied to break up the aggregates in the dispersion process. The TiO₂ dispersions in styrene monomer were themselves dispersed as miniemulsion droplets and subsequently polymerized. It was concluded from the density gradient column (DGC) analysis of the latexes obtained from the encapsulation polymerizations, that the stability of the inorganic particles in the monomer, as well as their particle size, significantly influence the encapsulation efficiencies. The use of the hydrophilic titanium dioxide particles in combination with the stabilizer, OLOA370, resulted in a good dispersibility, dispersion stability, and small TiO₂ particle size. This lead to better encapsulation efficiencies compared to the hydrophobic particles. The poorer results obtained with the hydrophobic TiO₂ particles were attributed to their larger particle size, which resulted from the reduced adsorption of the OLOA370. Fewer hydroxyls and the presence of the trimethoxy octyl silane (TMOS) groups, which themselves are unable to provide sufficient steric stability, are proposed to explain these findings.     

Site-directed coordination chemistry with P22 virus-like particles

Protein cage nanoparticles (PCNs) are attractive platforms for developing functional nanomaterials using biomimetic approaches for functionalization and cargo encapsulation. Many strategies have been employed to direct the loading of molecular cargos inside a wide range of PCN architectures. Here we demonstrate the exploitation of a metal-ligand coordination bond with respect to the direct packing of guest molecules on the interior interface of a virus-like PCN derived from Salmonella typhimurium bacteriophage P22. The incorporation of these guest species was assessed using mass spectrometry, multiangle laser light scattering, and analytical ultracentrifugation. In addition to small-molecule encapsulation, this approach was also effective for the directed synthesis of a large macromolecular coordination polymer packed inside of the P22 capsid and initiated on the interior surface. A wide range of metals and ligands with different thermodynamic affinities and kinetic stabilities are potentially available for this approach, highlighting the potential for metal-ligand coordination chemistry to direct the site-specific incorporation of cargo molecules for a variety of applications.     

Encapsulation of polyanilines into graphite oxide

Herein we report on the intercalation of polyaniline, poly(2-ethylaniline), and poly(2-propylaniline) into graphite oxide. This was achieved by taking advantage of the exfoliation/reconstruction properties of the layered host. The resulting intercalates were characterized by powder X-ray diffraction and thermogravimetric analysis.     

Cuprophilic and pi-stacking interactions in the formation of supramolecular stacks from dicoordinate organocopper complexes

The unsupported organocopper pyridine complexes C6F5Cu(py) (2) and [C6F5Cu]2(4,4'-bipy) (3) form supramolecular structures that are unprecedented in organocopper chemistry; one-dimensional chains of copper atoms with Cu...Cu distances of 2.8924(3) angstroms in the blue-luminescent complex are likely associated with cuprophilic interactions, whereas multiple perfluoroarene-arene interactions dominate in the supramolecular assembly of 3.     

Encapsulation of small metal particles in solid organic matrices

The methods of synthesis of macroscopic amounts of size-selected clusters with desired properties, and most importantly, the possibility of their controlled assembly into new materials with novel properties are currently of great interest. The interaction of metal atoms and small clusters with solid organic matrices may lead to the stabilization of reactive particles up to room temperatures. Thus obtained nanoscale heterogeneous materials offer an area of intriguing technological promise. In this review, we discuss recent developments in the encapsulation of small metallic particles in different organic solid matrices: organic monomeric compounds, polymers and carbon derivatives.     

Encapsulation of quantum dots in supramolecular systems based on amphiphilic compounds and polyelectrolytes

Supramolecular nanocontainers based on monocationic and gemini surfactants and oppositely charged polyelectrolytes (polyacrylic acid, polyethyleneimine) for the stabilization and enhancement of solubility of hydrophobic quantum dots CdSe/ZnS were formed. The size (from 2 to 70 nm depending on the type of nanocontainers) and shape of aggregates containing quantum dots were determined by transmission electron microscopy. It was shown that the nature of the stabilizing agent influences the morphology of aggregates. The increase in photostability of quantum dots in micellar solutions of gemini surfactants and the possibility of their preservation in the polyelectrolyte capsules are identified.     

Self-assembled supramolecular array of polymeric phthalocyanine on gold for the determination of hydrogen peroxide

This Article describes for the first time the formation of a supramolecular self-assembled monolayer of polymeric phthalocyanine (poly(CuPc)) onto a gold substrate. The latter is established through the interaction of the cyano group, belonging to the poly(CuPc), with the metal substrate. The functionalized gold substrate was characterized using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and electrochemical methods. Results clearly demonstrated the interaction between gold and the nitrogen atom of cyano group and showed at the same time the formation of a completely covered polymeric monolayer on the gold surface. In addition, the modified gold surface seems to exhibit a reversible redox behavior and is found to act as an electronic conductor, which allows rapid electron transfer. Electrochemical impedance spectroscopy (EIS) analyses in the presence of [Fe(CN)(6)](3-/4-) as a redox couple revealed that the modified electrode showed a much lower electron transfer resistance compared with bare gold. In addition, the modified electrode is found to catalyze the H(2)O(2) reduction very effectively, showing a catalytic current that varies linearly with the peroxide concentration in the range of 0.35 to 70 μM with a detection limit of 0.25 μM.     

Encapsulation of Microbial Cells into Silica Gel

This work deals with changes in microbial phenol degradation and cell proliferation caused by immobilization into silica gel. Mixed microbial culture and the yeast Candida tropicalis were immobilized in silica layers and pieces prepared by mixing of prepolymerized tetraethoxysilane with cell suspension. The phenol degradation rate of cells entrapped in silica gel was compared with those immobilized into an organic polymer-polyurethane. The phenol degradation efficiency decreased in the following order: free cell suspension > cells entrapped into polyurethane foam > cells entrapped into prepolymerized TEOS. Inside the silica there was no growth observed by optical microscope. The immobilization of bacterium Pseudomonas species 2 into silica gel, cells which co-metabolize PCBs with biphenyl, did not result in substantial change of intermediate concentration.     

Encapsulation of three different hydrophobic dyes in functionalized silica particles

This paper describes a method to prepare silica particles able to encapsulate 3 different hydrophobic dyes: Disperse Red, Solvent Red and 2-{4-[4-(Benzyl-ethyl-amino)-phenylazo]-benzenesulfonyl}-ethanol (HESA). Dye doped silica particles were prepared by the sol–gel process in aqueous medium, with a base catalyst, using various concentrations of a “home made” surfactant (named NP₉-Si). The surfactant is the addition byproduct of –OH groups of polyethylene glycol nonylphenyl ether Tergitol^® NP-9 with -NCO groups from (3-isocyanatopropyl) triethoxysilane and was added to increase both the stabilization of the silica particles and the compatibility of the inorganic network versus the dopant (the aromatic dye). It was shown that there is an optimum range of the amount of surfactant which should be added in the sol–gel reaction system. If a higher amount of surfactant is used, it forms probably micelles which entrap the dye and prevent its encapsulation in the formed silica particles. Because the silica particles are designed to encapsulate systems containing aromatic derivatives (aromatic dyes) we used phenyltriethoxy silane and tetraethylorthosilicate as silica precursors. As coupling agent for the silica network we used a bis (trialkoxysilane) derivative—1,2-bis (triethoxy silyl) ethane.     

Encapsulation of inorganic particles by dispersion polymerization through ultrasonic irradiation

1 Introduction In recent literature, several processes have been de-scribed to synthesize particles that consist of an inor-ganic core surrounded by a polymer shell. The tech-nique of polymer encapsulation is becoming more and more popular since polymer-e…