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

Abstract

A new miniaturized flow injection analysis (FIA) system for developing electrochemiluminescence (ECL)-based assays is presented. Novel thin-layer flowÀcell (TLFCL) screen-printed carbon electrodes integrated in one-channel flow cells were used as the electrode surface. These TLFCL electrodes, combined with miniaturized electrochemical and optical instrumentation, allowed a high degree of automation and simplicity of the assay. The performance of this high-throughput flow system was corroborated with a proof-of-concept centered on H 2 O 2 detection. For that purpose, an ECL transduction chemistry mechanism based on a electrochemiluminescence resonance energy transfer (ECL-RET) donorÀacceptor strategy, between an electro-oxidized luminophore (luminol) to a fluorophore (fluorescein), in the presence of the analyte of interest, was carried out. The results showed that fluorescein ECL-RET luminescent response increases the sensitivity of H 2 O 2 detection by up to one order of magnitude, in comparison with a luminolÀH 2 O 2 fluorescein-free assay. All experiments were performed in a decentralized, small-sized, easy-to-use FIA system coupled to ECL detection instrumentation.The light emitted from electrogenerated chemiluminescence (ECL) is a process in which electrochemically generated species combine to undergo electron-transfer reactions to form excited, light-emitting species, giving place to the development of high sensitive and selective assays. [1][2][3][4][5][6][7][8][9][10][11] In order to increase the automation of luminescent analytical procedures, the detection of ECL response by flow injection analysis system (FIA) is an interesting option. [12,13] Flow analysis is characterized by highly reproducible and throughput sampling. In addition, sequential injection analysis allows a considerable reduction in the consumption of the sample and reagents. [14] Bearing in mind that ECL based advances are moving towards the development of portable, high-throughput and point-of-care testing systems, [8,15] disposable screen-printed electrodes coupled to a small-sized, non-conventional, FIA system appears as an attractive possibility.For that purpose, in this work, screen-printed electrodes integrated in one channel flow-cell (TLFCL, Thin layer flow-cell) were used as the electrode surface. In these electrodes a transparent slide, that usefully allows the detection of air bubbles inside the cell, is attached over the screen-printed electrodes platform delimiting a flow channel. The injection of sample volume is done through an "in-line luer" injection port, placed closest to the electrochemical cell, where the injection can be easily controlled by operator through a precise syringe. This configuration brings important advantages since it simplifies operability and effectiveness of working in FIA systems. A similar format was already reported in two previous works [16,17] where enzymatic amperometric based sensors were developed. However, this is the first time that these electrodes, integrated in the necessary accessori...

An Overview of Recent Electroanalytical Applications Utilizing Screen‐Printed Electrodes Within Flow Systems

“…In 2017, nine new FIA-SPE methods for the determination of the following analytes were developed: isoniazid drug, [51] serotonin, [52] uric acid, [53] nitrite, [54] proton activity, [55] H 2 O 2 , [56] lactose, [57] 2-nitro-p-phenylenediamine, [58] and the electroactivity of nanoparticles. [59] During this year, two new flow cells were proposed for coupling with SPEs.…”

“…The first one was a thin-layer flow-cell that combined CSPE as the electrode surface and optical instrumentation (electrogenerated chemiluminescence). [56] The performance of the miniaturized cell was evaluated through the detection of H 2 O 2 in the presence and absence of fluorescein. A threefold increase in the sensitivity was observed in the presence of a fluorescein luminescent signal.…”

“…Platinized AuSPE NR NR [55] Hydrogen peroxide NR SPCE 1.0 18 [56] Lactose Milk Different types of SPEs modified with corynascus thermophilus 180 12 [57]…”

“…During this year, two new flow cells were proposed for coupling with SPEs. The first one was a thin‐layer flow‐cell that combined CSPE as the electrode surface and optical instrumentation (electrogenerated chemiluminescence) . The performance of the miniaturized cell was evaluated through the detection of H 2 O 2 in the presence and absence of fluorescein.…”

Strategies for Enhancing the Sensitivity of Electrochemiluminescence Biosensors

“…Electrogenerated chemiluminescence (ECL) is the phenomenon resulting from electrogenerated species undergoing an electron-transfer reaction at the electrode surface, resulting in the emission of light [ 1 , 2 , 3 ]. ECL has received a large amount of attention due to its advantages of high sensitivity, low background noise, spatial and temporal control, and no required light source [ 4 , 5 , 6 , 7 ]. The first detailed ECL studies were reported in the 1960s by Hercules and Bard [ 8 , 9 ].…”