A Miniaturized Flow Injection Analysis System for Electrogenerated Chemiluminescence−Based Assays

Single-Electrode Flow Cell for Electrochemiluminescent Flow Analysis

Flow injection analysis and liquid chromatography are frequently combined with electrochemiluminescence (ECL) for flow analysis. Almost all electrochemistry flow analyses employ traditional three-electrode electrochemical flow cells which have working electrode, counter electrode, and reference electrode; however, it is expensive and difficult to fabricate a traditional three-electrode electrochemical flow cell and inconvenient to renew the electrode. In this study, we have developed a single-electrode flow cell using commercially available conductive polyethylene film as the only electrode through potential differences induced by the electrode resistance for the first time. The single-electrode flow cell features a simple structure, easy renewal of the electrode, and low cost compared to the traditional three-electrode electrochemical flow cells. Taking the typical Ru(bpy)32+/oxalate ECL system as the analytical model, flow analysis of clinically important oxalate was achieved using single-electrode flow cell. A regression linear equation was obtained over the oxalate concentration ranges from 1 to 200 μM, with a detection limit of 0.92 μM. The single-electrode flow cell is promising for ECL flow analysis.

Electrochemiluminescence in Microfluidic Channels: Influence of Mass Transport on the Tris(2,2'-bipyridyl)ruthenium(II)/Tripropylamine System at Semitransparent Electrodes

Mass transport in laminar flow can improve the electrochemiluminescence (ECL) performance at the microchannel electrodes, depending on the device geometry and operating regimes. The known Ru(bpy)32+/tripropylamine (TPA) system was selected and studied in continuous microfluidics on semitransparent platinum electrodes. With this electrode material, ECL is mainly generated via a catalytic pathway. This mechanism was characterized under flow conditions by monitoring the ECL emission using linear sweep voltammetry and chronoamperometry. In parallel, ECL imaging of the electrode surface was conducted in order to characterize the ECL profiles above the electrode in the flow direction. Numerical simulations were carried out and then compared to experimental data to both confirm the ECL mechanism and assess the main kinetic parameters. A good agreement was obtained, demonstrating the influence of the operating regimes of the microchannel electrodes on the ECL performances. In the thin-layer regime, due to TPA depletion, ECL is located at the upstream edge of the electrode, while it is homogeneously distributed over the electrode surface in convective regimes. These characteristics will necessarily have to be taken into account in the design of dedicated ECL analytical microfluidic devices operating under continuous flow.

Strategies for Enhancing the Sensitivity of Electrochemiluminescence Biosensors

Electrochemiluminescence (ECL) has received considerable attention as a powerful analytical technique for the sensitive and accurate detection of biological analytes owing to its high sensitivity and selectivity and wide dynamic range. To satisfy the growing demand for ultrasensitive analysis techniques with high efficiency and accuracy in complex real sample matrices, considerable efforts have been dedicated to developing ECL strategies to improve the sensitivity of bioanalysis. As one of the most effective approaches, diverse signal amplification strategies have been integrated with ECL biosensors to achieve desirable analytical performance. This review summarizes the recent advances in ECL biosensing based on various signal amplification strategies, including DNA-assisted amplification strategies, efficient ECL luminophores, surface-enhanced electrochemiluminescence, and ratiometric strategies. Sensitivity-enhancing strategies and bio-related applications are discussed in detail. Moreover, the future trends and challenges of ECL biosensors are discussed.

Screen-Printed Technologies Combined with Flow Analysis Techniques: Moving from Benchtop to Everywhere

Screen-printed electrodes (SPEs) coupled with flow systems have been reported in recent decades for an ever-growing number of applications in modern electroanalysis, aiming for portable methodologies. The information acquired through this combination can be attractive for future users with basic knowledge, especially due to the increased measurement throughput, reduction in reagent consumption and minimal waste generation. The trends and possibilities of this set rely on the synergistic behavior that maximizes both SPE and flow analyses characteristics, allowing mass production and automation. This overview addresses an in-depth update about the scope of samples, target analytes, and analytical throughput (injections per hour, limits of detection, linear range, etc.) obtained by coupling injection techniques (FIA, SIA, and BIA) with SPE-based electrochemical detection.

Electrochemiluminescence as emerging microscopy techniques

The use of electrochemiluminescence (ECL), i.e., chemiluminescence triggered by electrochemical stimulus, as emitting light source for microscopy is an emerging approach with different applications ranging from the visualization of nanomaterials to cell mapping. In this trend article, we give an overview of the state of the art in this new field with the purpose to illustrate all the possible applications so far explored as well as describing the mechanism underlying this transduction technique. The results discussed here would highlight the great potential of the combination between ECL and microscopy and how this marriage can turn into an innovative approach with specific application in analytical sciences. Graphical abstract.