Coreactant-free and Near-Infrared Electrochemiluminescence Immunoassay with n-Type Au Nanocrystals as Luminophores

Abstract

The electrochemiluminescence (ECL) bioassay is prominently carried out with the involvement of the coreactant. To remove the detrimental effects of the coreactant on the ECL of luminophores, herein, a promising ECL immunoassay strategy with biocompatible nanoparticles as the luminophore is proposed, which involves directly and electrochemically oxidizing the luminophore methionine-capped Au (Met@Au) nanocrystals (NCs) without the participation of any coreactant. Met@Au NCs are a kind of n-type nanoparticles, and they can be electrochemically injected with valence band (VB) holes around +0.80 and +1.10 V (vs Ag/AgCl). The electrochemically injected exogenous VB hole can recombine with the endogenous conduction band electron of Met@Au NCs and eventually bring out two coreactant-free and near-infrared ECL processes around 0.80 V (ECL-1) and 1.10 V (ECL-2). The intensity of coreactant-free ECL is primarily determined by the electrochemical oxidation-induced hole-injection process. ECL-2 is considerably stronger than ECL-1 and can be exploited for determining the carcinoembryonic antigen (CEA) in a sandwich immunoassay procedure with a linear range from 0.1 to 50 pg/mL as well as a limit of detection of 0.03 pg/mL (S/N = 3).

Self-Enhanced Electrochemiluminescence Imaging System Based on the Accelerated Generation of ROS under Ultrasound

“…Electrochemiluminescence (ECL) is a luminescence process in which luminophores undergo high-energy electron transfer and emit photons in the electrochemical reaction. − It has the advantages of no external light source, high sensitivity, and controllable potential. With the high spatiotemporal resolution from microscopy, ECL imaging has been widely applied in immunoassays − and single-particle or cell imaging behavior research. − Most of these cases heavily rely on co-reactants because they can significantly promote the generation of light-emitting excited species. ,, For example, the most famous tris­(bipyridyl)ruthenium (Ru­(bpy) 3 2+ )/tri- n -propylamine (TPrA) ECL system, which has been extensively applied in the commercial ECL immunoassay. , However, TPrA is poorly water-soluble and highly toxic, and a large dose of TPrA (typically 100 mM) is required to gain enough light emission. Thus, the presence of high-concentration co-reactants in solution blocks practical bioanalytical applications.…”

“…3,16,17 For example, the most famous tris(bipyridyl)ruthenium (Ru(bpy) 3 2+ )/tri-n-propylamine (TPrA) ECL system, which has been extensively applied in the commercial ECL immunoassay. 18,19 However, TPrA is poorly water-soluble and highly toxic, and a large dose of TPrA (typically 100 mM) is required to gain enough light emission. Thus, the presence of high-concentration co-reactants in solution blocks practical bioanalytical applications.…”

Electrochemiluminescence biosensor for cardiac troponin I with signal amplification based on a MoS2@Cu2O–Ag-modified electrode and Ce:ZnO-NGQDs

“…9,10 So far, it has been widely used in immunoassays. [11][12][13][14] Our work focuses on building a sandwiched ECL sensor to detect cTnI at ultrasensitive levels.…”

Viscosity-Responsive Electrochemiluminescence of Diphenylbenzofulvene Derivatives

“…Electrochemiluminescence (ECL) is a unique luminescent phenomenon generated by electrically stimulating substances to produce a species in an excited state and finally returning them to the ground state. − Since it integrates the characteristics of both luminescence and electricity, ECL features many advantages like high sensitivity, simple operation, low inherent background, and strong controllability. Over the past decade, ECL has acted as a powerful analytical tool in numerous fields including bioimaging, immunoassays, pharmaceutical detection, clinical diagnosis, and environment and food analysis. − In particular, ECL has advanced rapidly in recent years. For example, the intriguing concept of “aggregation-induced emission” , was introduced in the ECL field, known as “AIE-ECL”, which achieved the water-insoluble organic probes for ultrasensitive aqueous-phase detection. − Furthermore, the intensity of the AIE-ECL system gives rise to a clearly distinguishable change with the aggregation degree of the emitter.…”