Microwave-assisted synthesis of graphene modified CuO nanoparticles for voltammetric enzyme-free sensing of glucose at biological pH values.

The effect of graphene nanosheets on the glucose sensing performance of CuO powders was investigated. CuO and graphene-modified CuO nanoparticles (NPs) were fabricated by microwave-assisted synthesis and characterized by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The material was placed on a glassy carbon electrode (GCE) which then was characterized by cyclic voltammetry and chronoamperometry with respect to the capability of sensing glucose both at pH 13 and pH 7.

Electrochemical detection of nanomolar dopamine in the presence of neurophysiological concentration of ascorbic acid and uric acid using charge-coated carbon nanotubes via facile and green preparation.

Negatively charged multi-walled carbon nanotubes (MWCNTs) were prepared using simple sonication technique with non-toxic citric acid (CA) for the electrochemical detection of dopamine (DA). CA/MWCNTs were placed on glassy carbon (GC) electrodes by drop-casting method and then electrochemical determinations of DA were performed in the presence of highly concentrated ascorbic acid (AA). For the comparison of the charge effect on MWCNTs surface, positively charged polyethyleneimine (PEI)/MWCNT/GC electrode and pristine MWCNT/GC electrode were also prepared.

Evaluation of electrogenerated chemiluminescence from a neutral Ir(III) complex for quantitative analysis in flowing streams.

Though recently Ir(III) complexes have attracted much interest in electrochemiluminescent (ECL) analysis due to their high emission in various wavelengths, there were a few studies reported on its analytical applications. In this study, we evaluate the ECL from (pq)(2)Ir(acac) (pq = 2-phenylquinolate, acac = acetylacetonate) for the use in flow injection analysis. An aqueous solution of the analyte and (pq)(2)Ir(acac) passes through the reaction/observation cell, and then ECL reaction is generated by electrochemical initiation on the analyte and (pq)(2)Ir(acac).

Electrochemically programmed chemodosimeter on ultrathin platinum films.

We demonstrate electrochemically controlled release of chemodosimeters attached to ultrathin patterned platinum electrodes. Fluorescence and electrochemical methods have been employed for the detection of chemodosimeter modification/desorption and Cu(2+) binding/removal.

Electrogenerated chemiluminescent anion sensing: selective recognition and sensing of pyrophosphate.

Recently, significant advances have been made independently in electrogenerated chemiluminescence (ECL) analysis and supramolecular anion sensing. Herein, we demonstrate a new proof of concept for ECL-based pyrophosphate (PPi) sensing, where the emission intensity is changed by electrochemical turn-on. The ECL PPi sensor (1-2Zn) consists of two orthogonally bonded moieties: boron dipyrromethene (ECL reporter) and a phenoxo-bridged bis(Zn(2+)-dipicolylamine) complex (PPi receptor).

Chiral gold nanoparticle-based electrochemical sensor for enantioselective recognition of 3,4-dihydroxyphenylalanine.

The enantioselective recognition of 3,4-dihydroxyphenylalanine using penicillamine-modified gold nanoparticles has been investigated. Smaller gold nanoparticles with one enantiomeric ligand facilitate the redox reaction of only one enantiomer of 3,4-dihydroxyphenylalanine, with cross inversion for the gold nanoparticles with the other enantiomeric ligand.

Enhanced electrogenerated chemiluminescence of a ruthenium tris(2,2')bipyridyl/tripropylamine system on a boron-doped diamond nanograss array.

Significant enhancement of the ECL signals from the Ru(bpy)(3)(2+)/TPA system was achieved when using a BDD nanograss array, mainly because of the highly facile oxidation of TPA. The facile oxidation of TPA is due to the superior properties of the BDD nanograss array, such as improved electrocatalytic activity and accelerated electron transfer.

Highly sensitive gold nanoparticle-based colorimetric sensing of mercury(II) through simple ligand exchange reaction in aqueous media.

A strategy for the rational design of a novel colorimetric sensor based on dithioerythritol-modified gold nanoparticles for the selective recognition of Hg2+ in aqueous media is presented. This approach relies on the combination of gold nanoparticles with Hg2+ through sulfur-Hg2+-sulfur interaction. The gold nanoparticles showed high selectivity toward Hg2+ with binding-induced red shift in the absorption spectra, with no response to major interfering cations such as Pb2+, Cd2+, and Cu2+ in the presence of ethylenediamine tetraacetic acid.

Electrochemical detection of dopamine in the presence of ascorbic acid using graphene modified electrodes.

Dopamine plays a significant role in the function of human metabolism. It is important to develop sensitive sensor for the determination of dopamine without the interference by ascorbic acid. This paper reports the synthesis of graphene using a modified Hummer's method and its application for the electrochemical detection of dopamine.

Highly sensitive detection of DNA by electrogenerated chemiluminescence amplification using dendritic Ru(bpy)(3)(2+)-doped silica nanoparticles.

This study describes the development and characterization of a novel dendritic signal amplification strategy. It relies on the use of two different Ru(bpy)(3)(2+)-doped silica nanoparticles (Probe(1,2)RSNP and Probe(2c)RSNP) coated with complementary DNAs, which can be simply and conveniently self-assembled to build sandwich-type dendritic architectures on a gold grid. The performance of this dendritic amplification route was demonstrated in conjunction with the electrogenerated chemiluminescent (ECL) detection of the target DNA.

A regenerative electrochemical sensor based on oligonucleotide for the selective determination of mercury(II).

We have developed a selective, sensitive, and re-usable electrochemical sensor for Hg2+ ion detection. This sensor is based on the Hg2+-induced conformational change of a single-stranded DNA (ssDNA) which involves an electroactive, ferrocene-labeled DNA hairpin structure and provides strategically the selective binding of a thymine-thymine mismatch for the Hg2+ ion. The ferrocene-labeled DNA is self-assembled through S-Au bonding on a polycrystalline gold electrode surface and the surface blocked with 3-mercapto-1-propanol to form a mixed monolayer.

Fabrication of nanostructured materials using porous alumina template and their applications for sensing and electrocatalysis.

Ordered porous anodic aluminum oxide templates have been used extensively for the preparation of various functional nanostructures. Researches on these nanostructured materials for various purposes have received a tremendous attention during recent years. A review of the literature on the fabrication of nanostructured materials using ordered porous anodic aluminum oxide templates and their applications is presented.

Enhancement of electrogenerated chemiluminescence and radical stability by peripheral multidonors on alkynylpyrene derivatives.

A very generous donor: The electrochemiluminescence (ECL) efficiency and radical stability of pyrene, a poor ECL luminophore, are markedly improved as the number of peripheral multidonor units increased in a series of compounds (see picture). Photophysical and electrochemical studies and theoretical calculations have contributed to the understanding of the ECL enhancement, which is a step forward in the development of new light-emitting materials.

Cesium ion-selective electrodes based on 1,3-alternate thiacalix[4]biscrown-6,6.

Four thiacalix[4]biscrown ethers with 1,3-alternate conformation were examined for the potentiometric responses in poly(vinyl chloride) membrane electrodes. Their potentiometric selectivities toward potassium and cesium ions over other alkali, alkaline earth, and transition metal ions were measured by the fixed interference method (FIM). Among the ionophores, 1,3-alternate thiacalix[4]biscrown-6,6 showed a high selectivity for cesium over potassium ion and so was optimized as a Cs(+)-selective electrode.

Potassium ion-selective membrane electrodes based on 1,3-alternate calix[4]crown-5-azacrown-5.

A series of 1,3-alternate calix[4]azacrown ethers for which the monoaza and unsymmetrical crowned-azacrown with different side arms were examined as an ionophore for ion-selective polymeric membrane electrode toward potassium ion. Among them, the electrode based on calix[4]crown-5-azacrown-5 with a phenyl group exhibited near Nernstian response for K(+) ions over a wide concentration range (1x10(-5) to 1x10(-1) M) with a limit of detection of 2x10(-6) M. It has a fast response time of approximately 2-3 s and can be used for at least 2 months without observing any major deterioration.

Diazo-coupled calix[4]arenes for qualitative analytical screening of metal ions.

New chromogenic diazophenylcalix[4]arenes 1 and 2 were synthesized in cone conformation. Compound 1 with the ortho-carboxyl groups in CH(3)CN solution preferentially binds with alkaline earth and transition metal ions, whereas no significant changes in absorption spectra are observed in the presence of alkali metal ions. While 2 with the ortho-ester groups shows selective complexation properties towards transition metal ions over alkali and alkaline earth metal ions.

Transition metal ion selective ortho-ester diazophenylcalix[4]arene.

New chromogenic dizophenylcalix[4]arene 1 showing selective color change to transition metal ions over other alkaline and alkaline earth metal ions has been prepared in the cone conformation and tested for its usefulness.

Structure-selective recognition by voltammetry: enantiomeric determination of amines using azophenolic crowns in aprotic solvent.

The enantiomeric recognition of amines by voltammetry using electroactive macrocyclic molecules, nitroazophenolic crown ethers, is reported. The oxidation potential of the nitroazophenol moiety in nitroazophenols with 18-crown-6 sensitively depends on the structure of alkyl amines. Based on this phenomenon, enantiomeric amines and even the quantitative assay of the R/S ratio in enantiomeric mixtures can be selectively recognized by using 18-crown-6 azophenol (3-H) with chiral centers.

Efficient electrogenerated chemiluminescence from cyclometalated iridium(III) complexes.

Very efficient electrogenerated chemiluminescence (ECL) phenomena were realized by deliberately tuning electron-transfer reactions from electrochemically generated electron donor to metal complex radical cations. By controlling the relative positions of HOMO and LUMO levels (oxidation potential and reduction potential) of Ir(III) complexes, we could obtain 77 times higher ECL from iridium(III) complexes in the presence of TPA than that of the Ru(bpy)32+/TPA system. This high ECL efficiency of new Ir(III) complexes can be used in many interesting applications such as sensors and luminescent devices.

Paired cell for the preparation of AgI nanowires using nanoporous alumina membrane templates.

This communication describes a relatively new and simple method for the preparation of AgI nanowires using nanoporous alumina membrane templates which can be easily extended to prepare nanowires of many other materials.