Abstract: A sensor system that detects a current representative of a compound in a liquid mixture features a two-electrode strip adapted for releasable attachment to signal readout circuitry. The strip comprises an elongated support (preferably flat) adapted for releasable attachment to the readout circuitry; a first conductor and a second conductor each extend along the support and comprise means for connection to the circuitry. An active electrode, positioned to contact the liquid mixture and the first conductor, comprises a deposit of an enzyme capable of catalyzing a reaction involving the compound and (preferably) an electron mediator, capable of transferring electrons between the enzyme-catalyzed reaction and the first conductor. A reference electrode is positioned to contact the mixture and the second conductor. The system includes circuitry adapted to provide an electrical signal representative of the current. The two-electrode strip is manufactured, e.g.

Abstract: An electrochemical specific binding assay of a ligand (e.g., antigen, hapten or antibody) wherein at least one of the components is enzyme-labelled, and which includes the step of determining the extent to which the transfer of electrons between the enzyme substrate and an electrode, associated with the substrate reaction, is perturbed by complex formation or by displacement of any ligand complex relative to unbound enzyme-labelled component.The electron transfer is aided by electron-transfer mediators which can accept electrons from the enzyme and donate them to the electrode or vice versa (e.g. ferrocene) or by electron-transfer promoters which retain the enzyme in close proximity with the electrode without themselves taking up a formal charge.The electrochemical apparatus will typically comprise two or three electrodes, including one working electrode onto which components may advantageously be immobilized.

Abstract: In its broadest aspect, the present invention provides a method of effecting an electrochemical specific-binding assay of a ligand, either qualitatively or quantitatively, in an apparatus comprising at leasts one electrode, in which method a labelled component of the assay medium is, at least in part, magnetically held in the vicinity of the electrode. The electrochemical assay method may include a separation step, whereby bound label may be separated from free label in the assay medium. Preferably the electrochemical assay method will include the step of determining a perturbation in an electrochemical characteristic of components of the assay medium associated with a ligand complexing reaction.Such an assay method is applicable to, for example, antibodies and antigens and suitable labels include redox centers, enzyme labels in the presence of an electron-transfer mediator and electron-transfer mediator labels in the presence of an electron donor or acceptor.

Abstract: A ligand in a sample can be assayed using electrochemical apparatus containing a working electrode and components comprising:(a) the sample,(b) a specific binding partner to the ligand, or a specific binding partner to the ligand and selected from ligand analogues and specific binding partners, and(c) an electron-source or electron-acceptor; at least one of components (b) being labelled with an electron-transfer mediator capable of aiding the transfer of electrons between the electron-source or electron-acceptor and the working electrode by accepting electrons from the electron-source and donating them to the working electrode, or accepting the electrons from the electrode and donating them to the electron-acceptor.

Abstract: The present invention discloses an assay for nucleic acid which comprises the steps of;(a) providing a probe material comprising;(i) a sequence of nucleic acids complementary to a given target sequence and,(ii) a first ligand chemically linked thereto and capable of a specific binding reaction with an antiligand;(b) contacting the said probe material with an assay system comprising:(i) a suitable mediator, enzyme, substrate system capable of transferring charge to an electrode surface when the enzyme is catalytically active, and;(ii) a second ligand chemically linked to one of said mediator, enzyme or substrate, wherein the second ligand is capable of a competitive binding reaction with the antiligand, and;(iii) the said antiligand, Whereby the said first ligand competes with the said second ligand in a specific binding reaction with the antiligand, and;(c) contacting the above system with a solution suspected of containing the said target sequence whereby the binding of any of the said target sequence presen

Abstract: An electrode has a graphite surface at least part of which is an edge-plane graphite surface to which Cr(III) complexes are attached by surface C--O groups. The graphite can be polished pyrolytic graphite. The complex coverage can be 5-20%. The complex may comprise proteins, enzyme substrates, specific binding agents, intermediate metabolites or the like, e.g. the protein plastocyanin, so that direct unmediated electrochemistry is possible at the electrode.

Abstract: The invention disclosed relates to an electrochemical assay which is particularly concerned with an assay for the presence of, or amount of, glycosylated haemoglobin in a blood sample, but which extends to a general assay for detecting the presence of, monitoring the level of or determining the concentration of compounds containing cis-diol groups, such as glycols, nucleic acid components, sugars, polyols, catechols and glycosylated proteins.When ferrocene boronic acid or a derivative thereof is present free in solution, it can act as a mediator for a wide range of oxido-reductases. However in the presence of, for example, sugars containing the cis-diol structure, the metallocene (such as ferrocene boronic acid) covalently binds to the sugar. When the ferrocene boronic acid is thus bound, it is essentially immobilized and its properties as a mediator and ability to diffuse will be markedly affected.

Abstract: This specification discloses methods of detection or measurement of an enzyme or of its specific substrate, and sensors used in such methods. The present invention is concerned with a multi-enzyme system, and the specification discloses, as one aspect of the invention a method of assay in which an electrode poised at a suitable potential is contacted with a system comprising a first enzyme, a cofactor linked with said enzyme and a mediator compound which transfers charge to the electrode from the first enzyme when its electrical state is changed by reaction of cofactor material.The cofactor may be NAD, NADP (both collectively referred to herein as NAD(P)), cAMP, ATP, GTP, TTP, or CTP.The specification particularly illustrates a method of assay in which an electrode (1) poised at a suitable potential is contacted with a system comprising a first enzyme E.sub.1 a nicotinamide adenine dinucleotide compound N linked with said enzyme E.sub.

Abstract: This invention relates to equipment and methods for detecting the presence of, measuring the amount of, and/or monitoring the level of, one or more selected components in a liquid mixture, employing an electrode sensing system.We have discovered that a class of mediating compounds has extremely useful properties for mediating the transfer of charge between enzyme-catalyzed reactions and electrode surfaces (15) in electrode sensing systems.Specifically, the specification discloses as electrode sensor mediators, organometallic compounds composed of at least two organic rings, each of which has at least two double bonds in a conjugated relationship; a metal atom is in electron-sharing contact with those rings.

Abstract: In a bioelectrochemical process in which the electrons are transferred directly, without use of a mediator, such as a redox dye or cofactor, between an electrode and an electroactive biological material, such as an enzyme or a protein, in either direction, rapid electron transfer has previously been achieved between an electrode and the positively charged protein horse-heart cytochrome c by adding a surface-modifier such as 4,4'-bipyridyl or a derivative thereof.It has now been found possible to promote electron transfer to either a positively or a negatively charged protein using the same surface-modifier for either job, namely a compound of formula ##STR1## wherein: the pyridine ring shown is substituted in the 2-, 3- or 4-position by the (methylene)hydrazinecarbothioamide group shown;R.sup.1 represents hydrogen atom(s) or one or two methyl or ethyl groups in the 2-,3- or 4-position (when the said position is not substituted by the (methylene)hydrazinecarbothioamide group shown);R.sup.

Abstract: A sensor electrode to detect one or more components in a liquid mixture comprises an electrically conductive material having at least an an external surface, the combination of an enzyme catalytic for a reaction of the desired component, and a mediator compound which transfers electrons from the enzyme to the electrode when such catalytic activity takes place. It can be used as an in vivo glucose sensor either with a silver electrode coated with e.g. glucose oxidase and a polyviologen as the mediators, or with a particulate carbon electrode, glucose oxidase and chloranil or fluoranil as mediator. Another system is to use bacterial glucose dehydrogenase or glucose oxidase as the enzyme and/or ferrocene or a ferrocene derivative as the mediators compound to give electrodes with improved linearity, speed of response and insensitivity to oxygen.

Abstract: There are provided processes for carrying out enzymatic reactions, especially processes for the oxidative or reductive transformation of organic compounds catalyzed by enzymes, in which the enzymes require a continuing supply of reducing equivalents to regenerate reduced enzyme species in enzymatically active form, and in which the reducing equivalents are derived electrochemically, including electrochemically from molecular hydrogen, the reducing equivalents preferably being passed directly to the enzyme from the cathode of an electrochemical system.