Microtube Electrodes for Imaging the Electrochemiluminescence Layer and Deciphering the Reaction Mechanism

Abstract

Electrochemiluminescence (ECL) is a powerful transduction technique in biosensing and diagnostics, while mechanistic studies are still scarce. Herein we report the combined use of microtube electrode (MTE) and microscopy to measure the thickness of ECL layer (TEL) to decipher reaction mechanisms. For the classical system involving tris(2,2'-bipyridyl)ruthenium and tri-n-propylamine, the ECL pattern generated at the MTE tends to change from ring to spot upon increasing the luminophore concentration, with the TEL varying from ca. 3.1 mm to > 4.5 mm. This variation is rationalized to arise from the contribution of the so-called catalytic route. While using 2-(dibutylamino)ethanol as the coreactant, the ECL pattern remains ring-shaped and independent on the luminophore concentration. The TEL in this case is ca. 2.1 mm, implying that ECL generation is always surfaceconfined. MTEs can thus act as optical rulers for measuring the TEL and providing insightful mechanistic information.

Spatially Selective Imaging of Cell–Matrix and Cell–Cell Junctions by Electrochemiluminescence

“…It has been reported previously that ECL generation can be extended away from the electrode surface at a high concentration of Ru(bpy) 3 2+ , [28] because in this case the so‐called catalytic route dominates the ECL generation. Figure 2 a–c displays ECL images of photoresist spots obtained in PBS containing 500 μM Ru(bpy) 3 2+ and different concentrations of TPrA.…”

Confined Electrochemiluminescence Generation at Ultra-High-Density Gold Microwell Electrodes

“…While in the case of the high concentration of Ru(bpy) 3 2+ (500 μM), the ECL patterns generated at gold-coated UMEA change from ring to spot upon increasing the exposure time (see Supplementary Figure S5), which can be ascribed to the so-called "catalytic route" (Guo et al, 2020). In this case, TPrA +• can be produced from the homogeneous chemical oxidation between TPrA and electrochemically generated Ru(bpy) 3…”

“…While those concerning the ECL reaction mechanisms are scarce (Chovin et al, 2004). Very recently, we have reported the measurement of the thickness of ECL-emitting layer using microtube electrode ensembles, showing that the combined use of microelectrode ensembles and ECL imaging technique is indeed a powerful tool for deciphering ECL reaction mechanisms (Guo et al, 2020).…”

Electrogenerated chemiluminescence detection of single entities

“…Lately, Su's group reported the measurement of an ECL layer to decipher reaction mechanisms by imaging microtube electrodes using ECLM. 82 They fabricated microtubes of three sizes with outer/inner diameters as ca. 2.3/1.4 mm, 5.4/4.5 mm, and 10.4/9.0 mm, respectively.…”

“…Microelectrodes and nanochannels have been applied to conne the species generated in ECL reactions. 71,81,82 Recently, Jiang and co-workers reported a nanopipette for intracellular analysis of single cells (Fig. 11a).…”