Novel Potentiometric Membrane Sensor for the Determination of Trace Amounts of Chromium(III) Ions

A plasticized Cr3+ ion sensor by incorporating 2,3,8,9-tetraphenyl-1,4,7,10-tetraazacyclododeca-1,3,7,9-tetraene (TTCT) ionophore exhibits a good potentiometric response for Cr3+ over a wide concentration range (1.0×10-6-1.0×10-1 M) with a slope of 19.5 mV per decade. The sensor response is stable for at least three months. Good selectivity for Cr3+ in comparison with alkali, alkaline earth, transition and heavy metal ions, and minimal interference are caused by Li+, Na+, K+, Co2+, Hg2+, Ca2+, Pb2+ and Zn2+ ions, which are known to interfere with other chromium membrane sensors. The TTCT-based electrode shows a fast response time (15 s), and can be used in aqueous solutions of pH 3 - 5.5. The proposed sensor was used for the potentiometric titration of Cr3+ with EDTA and for a direct potentiometric determination of Cr3+ content in environmental samples.

Mercury selective electrochemical sensor based on a double armed crown ether as ionophore

PVC based membranes of a double armed crown ether, N, N'-dibenzyl, 1,4,10,13-tetraoxa-7, 16-diaza cyclooctadecane (I) as ionophore with sodium tetra phenyl borate (NaTPB) as anion excluder and with many plasticizing solvent mediators have been prepared and used for Hg(II) ion determination. The membrane with DBBP (dibutyl butyl phosphonate ) as plasticizer with various ingredients in the ratio PVC: I: NaTPB: DBBP (150: 12: 2: 100) shows the best results in terms of working concentration range (3.1x10-5-1.0x10-tM) with a Nernstian slope (29.0′0.5 mV/decade of activity). The electrode works in the pH range 2.1-4.5. The response time of the sensor is 15s and it can be used for about 4 months in aqueous as well as in non-aqueous medium. It has good stability and reproducibility. The potentiometric selectivity coefficient values for mono-, di-, and trivalent cations are tabulated. The sensor is highly selective for Hg2+ in the presence of normal interferents like cadmium, silver, sodium and iron.

Gold Nanoparticle-based Colorimetric Sensor for pH Sensing

We present a newly designed colormetric sensor sensitive to pH value based on a gold nanocomposite composed of gold nanoparticles and pH-sensitive polymer{dodecylthioether end functionalized poly[2-(diethlamino) ethyl methacrylate], poly(DEAEMA)-DDT}. We have shown that this design can produce stable GNP precipitate under weakly basic condition(pH=7.5) and this precipitate can be dispersed in acidic solution(pH=4.0), due to the 2-(diethylamino) ethyl methacrylate protonated by H+.

Preparation of nanoparticles of bipyridineruthenium and silicotungstate and application as electrochemiluminescence sensor

The novel nanoparticles, [Ru(bPY)(3)](2)SiW12O40 center dot 2H(2)O(2) were firstly synthesized and characterized by elemental analysis, IR, and TEM. The nanoparticles were used to fabricate a chemically modified carbon paste electrode (CPE) by dispersing nanoparticles and graphite powder in silicone grease. Thus-prepared CPE shows bifunctional electrocatalytic activities towards the reduction of nitrite and the oxidation of oxalate, and exhibits sensitive electrochemiluminescence (ECL).

Layer-by-layer assembly of functional silica and Au nanoparticles for fabricating electrogenerated chemiluminescence sensor

We described the use of silica nanoparticles as building blocks for the immobilization of electrogenerated chemiluminescence (ECL) reagent Ru(bpy)3" and the fabrication of layer-by-layer assembly film by alternating the deposition of the Ru(bpy)3 2'-doped silica nanoparticles and Au nanoparticles.

Quantitative electrochemiluminescence detection of proteins: Avidin-based sensor and tris(2,2 '-bipyridine) ruthenium(II) label

Quantitative electrochemilumineseence (ECL) detection of a model protein, bovine serum albumin (BSA) was achieved via biotin-avidin interaction using an avidin-based sensor and a well-developed ECL system of tris(2,2'-bipyridine) ruthenium(II) derivative as label and tri-n-propylamine (TPA) as coreactant. To detect the protein, avidin was linked to the glassy carbon electrode through passive adsorptions and covalent interaction with carboxylate-terminated carbon nanotubes that was used as binder to immobilize avidin onto the electrode. Then, biotinylated BSA tagged with tris(2,2'-bipyridine) ruthenium(II) label was attached to the prepared avidin surface.

Ionic liquids Supported Growth of Highly Ordered Microdroplets Induced by Fluidic Leakage at Poly(dimethylsiloxane) Interfaces

"Fluidic leakage" caused by vacuum force at the reversible sealing poly(dimethylsiloxane) (PDMS) interfaces was converted to one useable avenue, which led to formation of highly ordered surfactant microdroplets functionalized with ionic liquids (ILs). Vacuum force is the prerequisite to lead constant microsolutions to diffuse to the PDMS interfaces. Imidazolium ions of ILs rendered structural rearrangement of the surfactant aggregates and the ordered droplets formation.

Effects of divalent metal ions on electrochemiluminescence sensor with Ru(bPY)(3)(2+) immobilized in Eastman-AQ membrane

Different effects of divalent metal ions on electrochemiluminescence (ECL) sensor with Ru(bPY)(3)(2+) immobilized in Eastman-AQ membrane were investigated. Mg2+,Ca2+ and Fe2+ can elevate the ECL of Ru(bpY)(3)(2+)/proline; while metal ions that underwent redox reactions on the electrode such as Mn2+ and Co2+ presented intensive quenching effects on Ru(bpy)(3)(2+) ECL. Also, the quenching effect of Mn2+ on the ECL sensor with Ru(bpY)(3)(2+) immobilized in Eastman-AQ membrane enhanced to about 30-folds compared with the case that Ru(bpy)(3)(2+) was dissolved in phosphate buffer, and the enhanced quenching effects of Mn2+ were studied.

Glucose biosensor based on gold nanoparticle-catalyzed luminol electrochemiluminescence on a three-dimensional sol-gel network

An electrochemiluminescent glucose biosensor was proposed based on gold nanoparticle-catalyzed luminol electrochemiluminescence (ECL). Gold nanoparticles were self-assembled onto silica sol-gel network, and then glucose oxidase was adsorbed on the surface of gold nanoparticles. The surface assembly process and the electrochemistry and ECL behaviors of the biosensor were investigated. The assembled gold nanoparticles could efficiently electrocatalyze luminol ECL ECL intensity of the biosensor depended on scan rate, luminol concentration, and size of gold nanoparticles.

Directing single-walled carbon nanotubes to self-assemble at water/oil interfaces and facilitate electron transfer

Both the behavior and the general key factors for assembling flexible SWNT films at the water/oil interface were investigated; the electron transfer, one of the most fundamental chemical processes, at the SWNT-sandwiched water/oil interface was also firstly illustrated using scanning electrochemical microscopy.