Journal articles

The methoxylated p-sulphonate isomer of the triazine dye C.I. Reactive Blue 2, selectively precipitates L-lactate dehydrogenase from crude rabbit muscle extracts. At mildly alkaline pH values and a 7-fold molar excess of the dye analogue to enzyme subunits, 106 mg of homogeneous lactate dehydrogenase essentially free of soluble ligands and the principal contaminating enzyme activities, may be obtained in 60% overall yield from 100 g tissue in less than 3 h. © 1989.

A bis-substituted conjugate of the dichlorotriazinyl dye C.I. Reactive Blue 4 (Procion Blue MX-R) with 1H,1H-pentadecafluorooctylamine was synthesised and characterised. This novel conjugate showed strong surface activity on aqueous-fluorocarbon interfaces and was used to prepare dyed liquid and solid perfluorocarbon supports for affinity chromatography. Rabbit muscle lactate dehydrogenase was purified up to 8.4-fold from a crude extract by chromatography on the surface active dye adsorbed on perfluorodecalin emulsion droplets and on a powdered microparticulate fluoropolymer.

Biosensors are analytical devices that respond selectively to analytes in an appropriate sample and convert their concentration into an electrical signal via a combination of a biological recognition system and an electrochemical, optical or other transducer. Such devices will find application in medicine, agriculture, environmental monitoring and the bioprocessing industries.

This paper describes the use of monolithic silicon technology for the fabrication of multi-analyte miniature biosensors for clinical applications. Electrochemically generated conducting polymers were used to entrap enzyme at the sensing microelectrode surfaces. This enzyme immobilisation procedure allows precise control of the spatial distribution of the enzyme and can, therefore, be applied to the fabrication of multi-electrode multi-analyte biosensors.

Non-specific adsorption of serum protein components to a direct immunosensor constructed from a silvered diffraction grating coated with goat immunoglobulin G has been determined. Non-specific adsorption to a 'simplistic' sensor interface was found to be significant and would be expected to limit the sensitivity of reported immunosensors when used for the estimation of specific analytes in serum. This work highlights the need for complex sensor interfaces comprised of suitable chemical modifications and controlled, oriented, immobilisation of immunological components. © 1990.

The fabrication and operation of a multi-analyte miniature conductance biosensor is described. The device responds to changes in the electrode double layer capacitance as the ionic strength is increased by the enzyme-catalysed generation of charged reaction products. Enzymes such as urease and l-asparaginase and a three-enzyme system consisting of urease, creatinase and creatininase were used to determine urea, l-asparagine and creatinine, respectively.

The design, synthesis and chromatographic operation of a new range of stable and selective immobilized dye affinity adsorbents for potential application in the purification of pharmaceutical proteins is described. Computer aided molecular design has been exploited to design novel dye ligands which show a predictable selectivity for the target protein and which, when coupled to stable perfluoropolymer supports, yield high capacity, low leakage adsorbents for affinity chromatography.

C.I. Reactive Blue 2 analogues were bonded onto an agarose support matrix by a novel method which entailed immobilisation by the anthraquinone ring 1-amino group as opposed to the usual triazine ring coupling methods. Dyes with spacer arms attached to the anthraquinone ring 1-amino group were synthesised by reacting methoxytriazine analogues of C.I. Reactive Blue 2 with chloroacetyl chloride and ethylenediamine. Unlike the blue parent dyes, all C.I. Reactive Blue 2 analogues with derivatised anthraquinone ring 1-amino groups were of a characteristic red colour.

This review introduces biosensors as analytical devices that respond selectively to analytes in appropriate samples and convert their concentrations into electrical signals via a combination of a biological recognition system and a suitable transducer. The last decade has seen dramatic advances in the design of sensor configurations, the marriage of biologial systems with modern monolithic silicon and optical technologies, the development of effective electron-exchange systems and the introduction of direct immunosensors.

The triazine dye C.I. Reactive Blue 2 has been immobilised on a particulate perfluorocarbon support by preparation of a hydrophilic polymeric coating comprising polyvinyl alcohol (average molecular weight, Mr 14 000) esterified with perfluorooctanolyl chloride and securely adsorbed ont he perfluorocarbon support by multiple Van der Waals interactions. This polyvinyl alcohol-based coating wets the perfluorocarbon support and provides a neutral barrier to non-specific adsorption of proteins. Reaction with the triazine dye C.I.