Attapulgite clay combined with tris(2,2'bipyridyl)ruthenium(ii) for the enhancement of the electrogenerated chemiluminescence sensing

This paper reports on the application of attapulgite for the immobilization of tris(2,2'-bipyridyl)ruthenium(II) ([Ru(bpy) ₃] ²⁺) to improve its electrochemiluminescence (ECL) sensing. The attapulgite clay is a kind of natural nanomaterial and belongs to a family of fibrous hydrous magnesium silicates. The immobilized [Ru(bpy) ₃] ²⁺ displayed a pair of well-defined redox peaks with an electron-transfer rate constant of 9.27 s ^-?1 and a fast ECL response to oxalate and tripropylamine (TPA) in 0.1 M pH 7.0 phosphate buffer. The immobilized [Ru(bpy) ₃] ²⁺ could maintain its ECL behavior in response to the co-reactants oxalate and TPA with high sensitivity. The ECL intensity was found to be linearly related to the concentration of oxalate over the range from 1.2 to 1080 μM, and the detection limit was 0.4 μM (S/N = 3). The linear concentration range for TPA extended from 1 nM to 5.4 μM and the detection limit (S/N = 3) was 0.5 nM, which is two orders of magnitude lower than that obtained at a {clay/[Ru(bpy) ₃] ²⁺}n multilayer film modified electrode. Our study demonstrated that the low-cost and natural attapulgite is superior to previous nanomaterial for the enhancement of ECL detection and may provide a better approach for the practical application of ECL determination.