Recent advances of ratiometric electrochemiluminescence biosensors

Abstract

Ratiometric electrochemiluminescence (ECL) assays have been widely applied in biosensing because of eliminated outside interferences and improved reliability in detection.

A redox-mediator pathway for enhanced multi-colour electrochemiluminescence in aqueous solution

“…The onset of ECL from both luminophores occurs in the potential region at which both [Ir(sppy) 3 ] 3À and TPrA are oxidised, and as noted above, the TPrAc radical can reduce [Ru(bpy) 3 ] 2+ , but not [Ir(sppy) 3 ] 3À . Of the available species under these conditions, the only possible electron transfer between the ground oxidation states of the Ir and Ru complexes is from [Ru(bpy) 3 ] + to [Ir(sppy) 3 ] 2À , which is sufficiently energetic to attain [Ru(bpy) 3 ] 2+ * (reaction (12); DE 00 z E 0-0 ), but not [Ir(sppy) 3 ] 3À * (DE 00 < E 0-0 ).…”

“…A similar reaction (1) occurs in the mixed annihilation ECL of [Ru(bpy) 3 ] 2+ and Ir(ppy) 3 in acetonitrile, which was isolated from other light-producing pathways by alternating between potentials sufficient to oxidise only Ir(ppy) 3 and reduce only [Ru(bpy) 3 ] 2+ . 23,31,33 The feasibility of generating [Ru(bpy) 3 ] 2+ * via reaction (12) was veried by selectively reducing [Ru(bpy) 3 ] 2+ and oxidising [Ir(sppy) 3 ] 3À under annihilation ECL conditions in 80 : 20 acetonitrile : water solution (Fig. S8 †).…”

“…5 Efforts to enhance the sensitivity of this fundamental ECL detection system have included the development of 'poly-Ru 2+ ' labels, exploiting dendrimers 6 or nanoparticles, 7 but the diminishing increase in ECL intensity with the number of metal centres, and greater background signals due to higher non-specic binding has limited their use in clinical diagnostics. 3 Alternatively, numerous Ir(III) complexes have shown great promise as high quantum yield luminophores for ECL in organic media, 8 and their diverse electrochemical potentials and emission wavelengths have enabled the preliminary development of potential-resolved and multi-colour ECL systems, 2,9 towards the long-held goals of multiplexed [9][10][11] and internally standardised, ratiometric 12 ECL detection. ‡ [13][14][15][16] The poor solubility and/or reduced ECL performance of many Ir(III) complexes in aqueous solution, however, has restricted their analytical application.…”

Design of an electrochemiluminescence detection system through the regulation of charge density in a microchannel

“…4 The ECL intensity was regulated by the concentrations of the luminophore and co-reactant, the luminous efficiency of the luminophore, the parameters of instruments such as electrode materials and areas, cell geometries, applied potentials and so on. [5][6][7][8] Bipolar electrode (BPE) ECL detection systems have attracted extensive attention because the analytes need not participate in the ECL reactions directly. 9,10 Charge balance permitted the ECL reaction occurring at the anode of the BPE to relate to the reduction reaction occurring at the cathode.…”

Novel Ratiometric Electrochemiluminescence Biosensor Based on BP-CdTe QDs with Dual Emission for Detecting MicroRNA-126

“…The shared co-reactant was commonly limited to H 2 O 2 , dissolved O 2 , or S 2 O 8 2 . 14,15 Moreover, the accuracy problems caused by the competitive consumption of the co-reactant and the distance-dependent problem of RET limit the application of the ECL ratio mode. To overcome the limitation of the single co-reactant, dual coreactants have been developed for ECL ratiometric detection, including S 2 O 2− inevitably leads to instability or repeatability problems.…”