Reduction of Au(III) by a β-cyclodextrin polymer in acid medium. A stated unattainable reaction.

Gold nanoparticles (AuNPs) can be prepared from the reduction of Au(III) with cyclodextrins acting as both, reducing and capping agent. It has been stated that a basic medium (pH=9-12) is a mandatory condition to achieve such reduction. We demonstrated, for the first time, the reduction of Au(III) by a crosslinked β-cyclodextrin-epichlorohydrin polymer (βCDP) in acid medium (pH ∼3).

Conformational Changes of Enzymes and Aptamers Immobilized on Electrodes.

Conformation constitutes a vital property of biomolecules, especially in the cases of enzymes and aptamers, and is essential in defining their molecular recognition ability. When biomolecules are immobilized on electrode surfaces, it is very important to have a control on all the possible conformational changes that may occur, either upon the recognition of their targets or by undesired alterations. Both enzymes and aptamers immobilized on electrodes are susceptible to conformational changes as a response to the nature of the charge of the surface and of the surrounding environment (pH, temperature, ionic strength, etc.

Vertical self-assembly of modified multiwalled carbon nanotubes on gold surfaces induced by chitosan and Tween.

Multiwalled carbon nanotubes modified with 2-aminoethanethiol (MWNT-AET) were vertically self-assembled on gold electrodes with the assistance of chitosan and Tween. According to AFM and cyclic voltammetric determinations the best results were achieved using chitosan.

Chitosan and silver nanoparticles as pudding with raisins with antimicrobial properties.

Chitosan nanoparticles (CS-NP) containing small silver nanoparticles are reported (Ag@CS-NP). CS-NP was synthesized using tripolyphosphate (TPP) as a polyanionic template. TPP also served to electrostatically attract Ag(+) inside CS-NP, where it was reduced by the terminal glucosamine units of the biopolymer.

Gold nanoparticles enhancing dismutation of superoxide radical by its bis(dithiocarbamato)copper(II) shell.

In the past few years three topics in nanoscience have received great attention: catalytic activity of gold nanoparticles (AuNPs), their electron transfer properties, and magnetism. Although these properties could have much in common no report on their synergism has been published. Here we present 10-nm gold nanoparticles conveniently capped with a mixed self-assembled monolayer containing bis(dithiocarbamato)copper(II) complexes, which dismutate superoxide radical with extremely high efficiency (IC(50) = 0.

A copper(II) thiosemicarbazone complex built on gold for the immobilization of lipase and laccase.

A self-assembled monolayer (SAM) of imidazole-2-carbaldehyde thiosemicarbazone (H(2)ImTSC) on gold was formed and characterized by ATR-FTIR, Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and X-ray Photoelectron Spectroscopy (XPS). The self-assembly of the ligand through its thioenolate group was confirmed by ToF-SIMS and the presence of XPS peaks at 161.9 (S(2p1/2)) and 163.

Interaction of nitric oxide with gold nanoparticles capped with a ruthenium(II) complex.

Gold nanoparticles capped with a cis-(4-aminothiophenol)bis(bipyridyl)(chloro)ruthenium(II) complex that are able to coordinate nitric oxide, become fluorescent and then liberate it by photolabilization when irradiated at 430 nm is reported.

Novel enzyme biosensor for hydrogen peroxide via supramolecular associations.

A polythiolated-beta-cyclodextrin polymer was synthesized and used as a coating material for gold electrodes. The functionalized electrodes were employed for immobilizing adamantane-modified horseradish peroxidase via supramolecular associations. The enzyme-containing electrode was used as an amperometric biosensor device with 1mM hydroquinone as electrochemical mediator.

Complexes of 2-acetyl-gamma-butyrolactone and 2-furancarbaldehyde thiosemicarbazones: antibacterial and antifungal activity.

Cobalt, nickel, copper and zinc coordination compounds of two thiosemicarbazones with general composition ML(2) (L: monodeprotonated ligand corresponding to 2-acetyl-gamma-butyrolactone thiosemicarbazone, HL(1), and 2-furancarbaldehyde thiosemicarbazone, HL(2)) and also complexes with general composition MCl(2)(HL(2)) were synthesized (except [NiCl(2)(HL(2))] and [Co(L(2))(2)]). The interaction of CuCl(2) with HL(2) gave [CuCl(HL(2))], a copper(I) complex. The ligands and metal complexes were characterized by IR, (1)H and (13)C NMR spectroscopy, and magnetic susceptibility measurements.

Nitric oxide binding and photodelivery based on ruthenium(II) complexes of 4-arylazo-3,5-dimethylpyrazole.

Two fluorescent ligands, 3,5-dimethyl-4-(6'-sulfonylammonium-1'-azonaphthyl)pyrazole (dmpzn, 1) and 3,5-dimethyl-4-(4'-N,N'-dimethylaminoazophenyl)pyrazole (dmpza, 2) were obtained by condensation of ketoenolic derivatives with hydrazine. 1 and 2 formed the novel dinuclear complexes [(H(2)O)(3)ClRu(micro-L)(2)RuCl(H(2)O)(3)] (3 or 4) and [(H(2)O)(NO)Cl(2)Ru(micro-L)(2)RuCl(2)(NO)(H(2)O)] (6 or 7) (where L 1 = 2 or , respectively) which were characterized by IR, NMR and elemental analysis. The nitrosyl complexes were prepared by bubbling purified nitric oxide through methanol solutions of the corresponding ruthenium(II) chloroderivative or by reaction of the appropriate ligands with Ru(NO)Cl(3).

Hydrogen peroxide biosensor with a supramolecular layer-by-layer design.

A new sensor design is reported for the construction of an amperometric enzyme biosensor toward H (2)O(2). It was based in the supramolecular immobilization of alternating layers of horseradish peroxidase (either modified with 1-adamantane or beta-cyclodextrin-branched carboxymethylcellulose residues) on Au electrodes coated with polythiolated beta-cyclodextrin polymer. The analytical response of the electrodes, using 1 mM hydroquinone as an electrochemical mediator, increases when the number of enzyme layers increases.

Building layer-by-layer a bis(dithiocarbamato)copper(II) complex on Au[111] surfaces.

A bis(dithiocarbamato)copper(II) complex (CuDTC2) was built on Au{111} surfaces (sheets and electrode beads) using different building blocks in a layer-by-layer (LbL) procedure. The process was followed by AFM and cyclic voltammetry. Initially 4-piperidinemethanethiol, which was synthesized here for the first time, was self-assembled on a gold surface and a highly organized array was obtained.

Amperometric biosensor for xanthine with supramolecular architecture.

Xanthine oxidase modified with 1-adamantanyl residues was supramolecularly immobilized on Au electrodes coated with Au nanoparticles coated with a perthiolated beta-cyclodextrin polymer; the analytical response of the electrode toward xanthine was evaluated.

Bienzymatic supramolecular complex of catalase modified with cyclodextrin-branched carboxymethylcellulose and superoxide dismutase: stability and anti-inflammatory properties.

A bienzymatic supramolecular assembly of CAT and SOD is reported. CAT was chemically glycosilated with CD branched CMC and then associated with SOD modified with 1-adamantane carboxylic acid. SOD was remarkably resistant to inactivation by H(2)O(2) and its anti-inflammatory activity was 4.

Supramolecular-mediated immobilization of L-phenylalanine dehydrogenase on cyclodextrin-coated Au electrodes for biosensor applications.

A supramolecular approach was used for adsorbing a monolayer of adamantane-modified phenylalanine dehydrogenase on beta-cyclodextrin-coated Au electrodes. The enzyme electrode (poised at +200 mV vs. Ag/AgCl) showed a linear amperometric response up to 3 mM L-phenylalanine (L-Phe) with a lower detection limit of 15 microM.

Improved pharmacological properties for superoxide dismutase modified with beta-cyclodextrin-carboxymethylcellulose polymer.

Superoxide dismutase was glycosidated with cyclodextrin-branched carboxymethylcellulose. The modified enzyme contained 1.4 mol polymer per mol protein and retained 87% of the initial activity.

Improved anti-inflammatory properties for naproxen with cyclodextrin-grafted polysaccharides.

Mannan and carboxymethylcellulose, previously activated by periodate oxidation, were grafted with mono-6-butylenediamino-6-deoxy-beta-cyclodextrin derivatives by reductive alkylation in the presence of sodium borohydride. The formation of supramolecular complexes between these polymers and Naproxen was confirmed by fluorescence spectroscopy. The solubility of the drug was 3.

Cyclodextrin-grafted polysaccharides as supramolecular carrier systems for naproxen.

Dextran, mannan and carboxymethylcellulose, previously activated by periodate oxidation, were grafted with beta-cyclodextrin moieties by reductive alkylation in the presence of sodium borohydride. These polymers were used as supramolecular carriers for naproxen, improving the "in vivo" anti-inflammatory properties of this drug.

A supramolecular approach to the selective detection of dopamine in the presence of ascorbate.

Dopamine can be detected selectively in the presence of ascorbate at a gold electrode modified by a beta-cyclodextrin/thioctic acid mixed monolayer.

Chemical glycosidation of trypsin with O-carboxymethyl-poly-beta-cyclodextrin: catalytic and stability properties.

The polysaccharide O-carboxymethyl-poly-beta-cyclodextrin was synthesized (molecular mass 13,000 Da, 40% carboxy groups) and attached to the surface of bovine pancreatic trypsin. The resulting neoglycoenzyme retained high proteolytic and esterolytic activity and contained approx. 1.

Electron paramagnetic resonance studies on copper(II)-cyclodextrin systems.

Three copper(II) complexes containing beta-cyclodextrin (betaCD) derivatives as ligands [mono-6-methylamino-6-deoxy-betaCD dithiocarbamate (CDTC), mono-6-histamino-6-deoxy-betaCD (CDHM) and mono-6-Nalpha-arginyl-6-deoxy-betaCD (CDARG)] have been studied by electron paramagnetic resonance. The spectra have been recorded at X- and S-bands and different temperatures and simulated to obtain the best set of magnetic parameters. In particular, the 300 K spectra are typical of the slow motion regime, as expected considering the high molecular weight of the ligands.

Effects of beta-cyclodextrin-dextran polymer on stability properties of trypsin.

Dextran modified with the mono-6-pentylene-diamino-6-deoxy-beta-cyclodextrin derivative was evaluated as a thermoprotectant additive for trypsin. The optimum temperature for trypsin activity was increased by 7 degrees C in the presence of this polymer. The enzyme thermostability was increased from 48.

Interactions of nitric oxide with copper(II) dithiocarbamates in aqueous solution.

This is the first report on the formation of air-stable copper nitrosyl complexes. The interaction of nitric oxide, NO, with Cu(DTC)(2).3H(2)O (DTC: dithiocarbamate) and was studied in aqueous solution at pH 7.

Functional stabilization of trypsin by conjugation with beta-cyclodextrin-modified carboxymethylcellulose.

Bovine pancreatic trypsin was chemically modified by a beta-cyclodextrin-carboxymethylcellulose polymer using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide as coupling agent. The conjugate retained 110% and 95% of the initial esterolytic and proteolytic activity, respectively, and contained about 2 mol of polymer per mol of trypsin. The optimum temperature for trypsin was increased to 8 degrees C after conjugation.