Environmentally Friendly and Highly Sensitive Ruthenium(II) Tris(2,2′‐bipyridyl) Electrochemiluminescent System Using 2‐(Dibutylamino)ethanol as Co‐Reactant

Abstract

Ruthenium(II) tris(2,2'-bipyridyl) ([Ru(bpy) 3 ] 2+ ) has received increasing attention in clinical diagnosis and scientific research because of its high sensitivity, wide dynamic range, stability, simplicity, and versatility as an electrochemiluminescent probe. [1] As the electrochemiluminescence (ECL) results from electrochemical reactions between [Ru(bpy) 3 ] 2+ and co-reactants, extensive research has been focused on exploring effective co-reactants for the sensitive determination of [Ru(bpy) 3 ] 2+ , which has important bioanalytical applications. [2] In 1984, Bard and co-workers first reported the determination of [Ru(bpy) 3 ] 2+ ECL using either oxalate or peroxydisulfate as co-reactants. [3] Later, Leland and Powell suggested tripropylamine (TPA) as a co-reactant, [4] and Blackburn et al. soon developed [Ru(bpy) 3 ] 2+ ECL immunoassays and DNA probe assays using TPA as co-reactant and [Ru(bpy) 3 ] 2+ as the label. [5] [Ru(bpy) 3 ] 2+ /TPA ECL assays have been widely used for over fifteen years now. [2,6] Despite its exclusive popularity, TPA has several important disadvantages. [2] First, TPA is toxic and volatile, but it is used in high concentrations (usually up to 100 mm) to attain good sensitivity. Second, its slow electrochemical oxidation rate limits ECL efficiency. Third, high concentrations of acidic phosphate solutions are needed to prepare concentrated neutral solutions of TPA because TPA is basic. Finally, the ECL intensity of the [Ru(bpy) 3 ] 2+ /TPA system depends strongly on electrode materials. For example, the ECL intensity at Pt electrodes is only about 10 % of that at Au electrodes. Thus, it is desirable to find alternatives to TPA.Several groups have studied the ECL from [Ru(bpy) 3 ] 2+ / amine systems under the condition that the concentrations of [Ru(bpy) 3 ] 2+ are higher than that of amines. [2,7] Generally; tertiary amines are more effective than secondary amines, primary amines, and other kinds of co-reactants. Also, electron-donating groups tend to increase ECL. It seemed impossible to find better co-reactants. Recent studies showed that ECL efficiencies can be improved through increasing the electrochemical oxidation rate of amines when the concentration of [Ru(bpy) 3 ] 2+ is much lower than that of the amines, as in the cases of ECL immunoassays and DNA probe assays. To our knowledge, all methods reported to date use additives to increase the oxidation rate of amines and, thus, ECL efficiencies. [8] Also, there have been only a few reports that attempt to find better co-reactants from easily oxidizable tertiary amines.Herein, we report an investigation of the ECL of a series of tertiary amines with various substituents whilst keeping the concentration of [Ru(bpy) 3 ] 2+ lower than that of the amine. The purpose of the present study is to provide a new way to enhance ECL efficiencies by using easily oxidizable tertiary amines, and develop more efficient and environmentally friendly co-reactants for ECL immunoassays and DNA probe assays. Figure 1 shows the dependence of ECL...

Electrochemiluminescence Detection in Paper‐Based and Other Inexpensive Microfluidic Devices

“…Common co-reactants for ruthenium complex or nanomaterial ECL are aliphatic amines such as tri-npropylamine (TPrA) [18] or 2-(dibutylamino)ethanol (DBAE). [23] Hydrogen peroxide commonly serves as a co-reactant with luminol. [21] Upon oxidation, the co-reactant forms a radical, which transfers an electron to the oxidized luminophore.…”

The Factors Affecting the Electrochemiluminescence of Tris(2,2′‐bipyridyl)Ruthenium(II)/Tertiary Amines

“…ECL based on the excited state of tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy) 3 2þ ) is of great importance for analytical and clinical applications with high sensitivity and wide response ranges for many analytes [4 -9]. But tripropylamine (TPA), extensively used as coreactant to excite Ru(bpy) 3 2þ , is toxic, corrosive, and volatile [10]. Therefore, the search for highly sensitive, safe coreactants and highly efficient exciting conditions is critical for developing new applications of Ru(bpy) 3 2þ ECL.…”

Imaging Analysis Based on Electrogenerated Chemiluminescence

“…/amine co-reactant forms the basis of the biorelated species determination. In 2009, Xu et al [49] reported a more environmentally friendly co-reactant 2-(dibutylamino)ethanol (DBAE) for Ru(bpy) 3 2? ECL assay, which is less toxic and less volatile than TPrA.…”