Electrochemical detection of high-sensitivity CRP inside a microfluidic device by numerical and experimental studies.

The concentration of C-reactive protein (CRP), a classic acute phase plasma protein, increases rapidly in response to tissue infection or inflammation, especially in cases of cardiovascular disease and stroke. Thus, highly sensitive monitoring of the CRP concentration plays a pivotal role in detecting these diseases. Many researchers have studied methods for the detection of CRP concentrations such as optical, mechanical, and electrochemical techniques inside microfluidic devices.

Highly sensitive potentiometric strip test for detecting high charge density impurities in heparin.

Contamination of heparin with oversulfated chondroitin sulfate (OSCS) became a matter of grave concern in the medical field after many fatal responses to OSCS tainted heparin products occurred during the 2007-2008 period. Even though standard lab-based analytical techniques such as nuclear magnetic resonance (NMR) and strong anion-exchange high performance liquid chromatography (SAX-HPLC) have proven useful for monitoring the OSCS content in heparin products, an easy-to-use, quick, portable, and cost-efficient method is still needed for on-site monitoring during and after the heparin production. In this report, a disposable strip-type electrochemical polyion sensor is described for detection of low levels of OSCS contamination in heparin.

Silver(I) ion selective ionophores containing dithiocarbamoyl moieties on steroid backbone.

Tweezer-type and non-tweezer-type ionophores containing dithiocarbamoyl groups on a 7-deoxycholic amide or cholane derivatives were designed and synthesized. Potentiometric evaluation of the poly(vinyl chloride) (PVC) membranes containing those deoxycholic amides/cholanes linked with tweezer-type dithiocarbamoyl moieties showed excellent affinity and selectivity to silver(I) ion over alkali, alkaline earth and other transition metal cations. On the other hand, deoxycholic amides/cholanes substituted with one dithiocarbamoyl group, i.

Ion-selective electrodes based on molecular tweezer-type neutral carriers.

Potentiometric properties of cholic and deoxycholic acid derivatives substituted with various ion-recognizing moieties, such as dithiocarbamate, bipyridyl, glycolic and malonic diamides, urea and thiourea, and trifluoroacetophenons (TFAP), have been studied using solvent polymeric membranes. The dithiocarbamate and bipyridyl group containing ionophores exhibit high silver ion selectivity. The cholic acid derivatized with glycolic diamides exhibited high calcium selectivity, but its complex formulation constant was 10(5) times smaller than that of ETH 1001.

Synthesis and characterization of 7-deoxycholic amide backbone-based silver(I) ionophores.

Four ionophores containing bipyridyl groups on a 7-deoxycholic amide derivative scaffold were designed and synthesized. Potentiometric evaluation of the Poly(vinyl chloride) (PVC) membranes containing those deoxycholic amides bearing bipyridyl moieties with a short linkage showed good affinity to silver(I) ion over alkali, alkaline earth and other transition metal cations. However, two bipyridyl groups flexibly linked to the deoxycholic frame through a long linkage do not result in appreciable potentiometric responses.

All-solid-state carbonate-selective electrode based on a molecular tweezer-type neutral carrier with solvent-soluble conducting polymer solid contact.

Carbonate-selective membranes were prepared by incorporating a molecular tweezer-type carbonate-selective neutral carrier [N,N-dioctyl-3alpha,12alpha-bis(4-trifluoroacetylbenzyloxy)-5beta-cholan-24-amide] into a room temperature vulcanizing-type silicone rubber (3140 RTV-SR) matrix, and deposited on the planar-type electrodes (Pt containing Ag/AgCl electrodes formed on a ceramic plate) with and without an intermediary conducting polymer layer. Two types of solvent-soluble conducting polymers [poly(1-hexyl-3,4-dimethyl-2,5-pyrrolylene) or poly(3-octylthiophene-2,5-diyl)] have been examined as the solid contact material. Potentiometric properties of the resultant all-solid-state electrodes were evaluated in terms of their carbonate selectivity, response slope, potential stability and reproducibility.

Glass nanopore-based ion-selective electrodes.

Glass nanopore-based all-solid-state ion-selective electrodes (ISEs) have been developed to probe the distribution of ionic species at micro- or submicrometer-length scales, e.g., mapping of ion flux through micrometer-sized pores.

Cation selectivity of ionophores based on tripodal thiazole derivatives on benzene scaffold.

The synthesis and potentiometric evaluation of new 1,3,5-tris(thiazolylcarbethoxy)-2,4,6-trimethylbenzene (3), 1,3,5-tris(thiazolylhydroxy)-2,4,6-trimethylbenzene (4), 1,3,5-tris(thiazolylmethyl)-2,4,6-trimethylbenzene (5), and 1,3,5-tris(thiazolylphenyl)-2,4,6-trimethylbenzene (6), toward mono and divalent cations under various pH conditions are outlined. The ion-selective properties of the newly synthesized compounds were studied by measuring the potentiometric responses of the 3-, 4-, 5-, and 6-based membrane electrodes to alkali metal, alkaline earth metal, ammonium, and transition metal ions, under various pH conditions. The 3-based electrode exhibited a Nernstian response to ammonium and potassium under alkaline pH conditions, while the other three electrodes showed a poor potentiometric performance.

A rapid competitive binding nonseparation electrochemical enzyme immunoassay (NEEIA) test strip for microcystin-LR (MCLR) determination.

A competitive binding nonseparation electrochemical enzyme immunoassay (NEEIA) is described for the determination of microcystin-LR (MCLR) using a double-sided microporous gold electrode in cartridge-type cells. A gold film sputtered on one side of porous nylon membrane constitutes a working electrode, while another gold film formed on the opposite side serves as a pseudo reference electrode. After immobilizing MCLR antibody on working electrode by physical adsorption, the double-sided electrode was placed simply in a diffusion U-type or within a dry strip-type cell with a conjugate pad pre-loaded with a glucose oxidase labeled MCLR (GOx-MCLR) on working electrode side.

Electrochemical characterization of biosensor based on nitrite reductase and methyl viologen co-immobilized glassy carbon electrode.

Nitrite reductase (NiR, nitric-oxide: ferricytochrome c oxidoreductase, EC 1.7.2.

Electrochemical determination of nitrate with nitrate reductase-immobilized electrodes under ambient air.

Nitrate monitoring biosensors were prepared by immobilizing nitrate reductase derived from yeast on a glassy carbon electrode (GCE, d = 3 mm) or screen-printed carbon paste electrode (SPCE, d = 3 mm) using a polymer (poly(vinyl alcohol)) entrapment method. The sensor could directly determine the nitrate in an unpurged aqueous solution with the aid of an appropriate oxygen scavenger: the nitrate reduction reaction driven by the enzyme and an electron-transfer mediator, methyl viologen, at -0.85 V (GCE vs Ag/AgCl) or at -0.

Characterization of epoxy resin-based anion-responsive polymers: applicability to chloride sensing in physiological samples.

The potentiometric properties of an epoxy resin-based anion-responsive polymer and its feasibility as a chloride sensing membrane are described. The response mechanism of the epoxy resin-based membrane is studied by varying the types and contents of epoxy components (e.g.

Molecular recognition of anions through hydrogen bonding stabilization of anion-ionophore adducts: a novel trifluoroacetophenone-based binding motif.

[reaction: see text] A novel trifluoroacetophenone-based binding motif has been developed that recognizes anions such as carboxylates through reversible formation of anion-ionophore adducts that are stabilized by intramolecular H-bonding. The intramolecular H-bonding resulted in more than 10-fold enhancement in the binding affinity and an enthalpy gain (DeltaH degrees ) of 3.0 kcal/mol for the binding of an acetate ion when compared to the case without the intramolecular H-bonding.

Tweezer-type neutral carrier-based calcium-selective membrane electrode with drastically reduced anionic interference.

A new calcium-selective ionophore N,N-dioctyl-3alpha,12alpha-bis(N-heptyl-N-methylcarbamoyl-methoxyacetamidoacetoxy)-5beta-cholan-24-amide (denoted as BACA), was synthesized, and its potentiometric performance has been evaluated in comparison with that of the best known calcium-selective neutral carriers, ETH 129 and ETH 1001. The 1H NMR spectra of BACA titrated with Ca(SCN)2 suggest that BACA forms a 1:1 complex, tweezing a calcium ion between the two parallel diamide groups substituted on a rigid bile acid frame. The calcium-selective membrane based on BACA was less selective to calcium (log K(Ca2+ j)POT = -4.

Determination of oceanic carbon dioxide using a carbonate-selective electrode.

Potentiometric properties of the PVC membrane-based electrodes prepared with molecular tweezer-type neutral carriers, 3,12-bis(TFAB)CA and deoxy-3,12-bis(TFAB)CA, and trifluoroacetyl-p-decylbenzene (TFADB) were measured in buffered electrolytes (0.1 M Tris-H2SO4, pH 8.6 and 8.