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Abstract: Immobilisation of a luminescent material on an electrode surface is well known to substantially modulate its photophysical and electrochemical properties. Here a positively charged ruthenium metal complex ([Ru(bpy)3]2+) is immobilised on all electrode surface by ion paring with a sulfonated conducting polymer poly(2-methoxyaniline-5-sulfonic acid), (PMAS). Significantly, our study reveals that the electron transport between the ruthenium metal centres can be greatly enhanced due to the interaction with the conducting polymer when both are surface confined. Charge transfer diffusion rates in the present system are an order of magnitude faster than those found where the metal centre is immobilised within a non-conducting polymeric matrix. Electron transport appears to be mediated through the PMAS conjugated structure, contrasting with the electron hopping process typically observed in non-conducting metallopolymers. This increased regeneration rate causes the ruthenium-based electrochemiluminescence (ECL) efficiency to be increased. The impact of these observations on the ECL detection of low concentrations of disease biomarkers is discussed. [Copyright &y& Elsevier]

Abstract: The electrochemical and photochemical properties of [Ru(bpy)2dcb]Cl2 monolayers and their subsequent use for the detection of amino acids, e.g., proline, is reported; dcb is 4,4′-dicarboxy-2,2′-bipyridine and bpy is 2,2′-bipyridine. The ability of such a complex to form stable monolayers enables its utilization for the detection of oxalate and several amino acids, producing significant ECL. The electrochemical response of the Ru2+/3+ couple is electrochemically reversible and the monolayers show excellent stability with the response decreasing by less than 8% after continuous scanning over 4h. The ECL and current responses increase linearly with increasing analyte concentration 0.2⩽[Proline]⩽1nM while for hydroxy-proline the dynamic range is from 1 to 10nM. The ECL signal was monitored at ∼644nm, representing the λ max for the [Ru(bpy)2dcb]Cl2 monolayers. This wavelength is shifted by approximately 28nm compared to the photoexcited λ max for the same system. This technique is simple, rapid, selective and sensitive, and shows potential for the high-throughput quantitation of amino acids if adapted with other techniques such as FIA or LC systems. [Copyright &y& Elsevier]

Invited for this month′s cover is the group of Prof. Francesco Paolucci and the group of Prof. Robert Forster and Prof. Tia E. Keyes. The cover picture shows release of the luminescent rhenium coordination complex in solution. [ABSTRACT FROM AUTHOR]