Electrochemiluminescence of Luminol-Tripropylamine System

Qualitative and quantitative electrochemiluminescence evaluation of trace Pt single-atom in MXenes

The analysis of trace Pt single-atom (SA) represents a significant challenge, given the crucial role of single-atom platinum (Pt) in energy storage and electrocatalysis. Here, we present an electrochemiluminescence (ECL) platform that enables the qualitative and quantitative analysis of trace Pt SA using luminol as the ECL luminophore. It is observed that different Pt species in Ti3-xC2Ty MXenes resulted in distinct reactive oxygen species (ROS) potentials for luminol cathodic electrochemiluminescence (ECL), achieved through distinctive oxygen reduction reaction (ORR) pathways, in which oxygen acts as the co-reactant. Furthermore, the cathodic luminol ECL intensity increases in proportion to the Pt atom content, thereby enabling quantitative analysis of trace Pt single atoms. The detection limit is 0.014 wt%, which is comparable to the current mainstream Pt SA quantification techniques. By utilizing this ECL method, it is possible to successfully evaluate both qualitatively and quantitatively the changes in Pt SA during the ORR processes. This ECL platform provides a valuable toolbox for the analysis of Pt SA catalysts and for the evaluation of the mechanisms involved in electrocatalysis applications.

Artemisinin: a novel chiral electrochemiluminescence luminophore-assisted enantiospecific recognition and mechanism identification

Exploring novel electrochemiluminescence (ECL) molecules with high efficiency and good stability in aqueous solutions is crucial for achieving highly sensitive detection of analytes. However, developing chiral luminophores with efficient ECL performance is still a challenge. Herein, we first uncover that artemisinin (ART), a well-known chiral antimalarial drug, features a strong ECL emission at 726 nm with the assistance of a co-reactant potassium persulfate (K2S2O8), and an ECL efficiency of 195.3%, compared to that of standard Ru(bpy)3Cl2/K2S2O8. Mechanistic studies indicate that the strong ECL signal of ART is generated when the excited state formed by the reduction of ART peroxide bonds and combination with persulfate returns to the ground state. Significantly, we found that the ECL sensor based on chiral ART could efficiently identify and detect chiral cysteine (Cys) through ECL signals, with a lower limit of detection of 3.7 nM for l-Cys. Density functional theory calculations and scanning electrochemical microscopy technology further confirm that the disparity in the ECL signals is attributed to the different affinity between chiral ART and d/l-Cys, resulting in distinct electron transfer rates. The study demonstrates a new role of ART in ECL investigation and for the first time, achieves the development of ART for the enantioselective recognition and sensitive detection of chiral substances. This will be of vital significance for ECL and chirality research.

A dry chemistry-based electrochemiluminescence device for point-of-care testing of alanine transaminase

Liver disease causes serious public health problems because of its high prevalence, particularly affecting low- and middle-income countries. Alanine transaminase (ALT) is considered to be one of the most sensitive indicators for diagnosing liver disease. Although many strategies have been reported for ALT detection, few of them have solved the problem of automatic detection. In this work, for the first time, a dry chemistry-based electrochemiluminescence (DC-ECL) device is developed for point-of-care testing (POCT) of ALT, achieving real sample-to-answer detection. The proposed DC-ECL device consists of the following two components: (a) a DC-ECL chip consisting of the outer shell (including the top cap and pedestal) and detection layer (including the baseplate, electrode pad and carrier pad) and (b) an automatic ECL analyzer mainly including the data processing and instrument control unit, imaging detection unit, electrochemical reaction excitation unit, open detection window unit and rechargeable power supply. Under optimized conditions, the device had a wide detection range (0-1000 U/L), the ECL intensity linearly increased with ALT concentration (5-50 U/L) and logarithmic ALT concentration (50-1000 U/L), and the limit of detection was calculated to be 1.702 U/L. In addition, the DC-ECL device had the ability to measure ALT levels in human serum samples and showed acceptable selectivity, stability and repeatability. These results reveal that the DC-ECL device can overcome the disadvantages of traditional methods for ALT detection (such as high cost and requirement of professional technicians) and potentially opens the door to the development of similar POCT analyzers.

A Sensitive Signal-on Supersandwich DNA Biosensor Based on the Enhancement of Poly(aniline-luminol) Nanowires Electrochemiluminescence by Ferrocene

A signal-on supersandwich type of electrochemiluminescence (ECL) DNA biosensor was developed based on the poly(aniline-luminol) nanowires (PALNWs) modified electrode and enhancement of ferrocene (Fc) on ECL of luminol. Aminated capture DNA was covalently linked to the PALNWs on the electrode surface by the crosslinking of glutaraldehyde. In presence of target DNA, its 3' terminus hybridizes with the capture probe and the 5' terminus hybridizes with ferrocene labeled DNA (Fc-DNA) to form a long DNA concatamer supersandwich structure. The ECL intensity of the prepared biosensor was clearly improved by increasing the concentration of target DNA due to the enhancement of ferrocene on luminol ECL. The difference of the ECL intensity in the absence and presence of target DNA was used to monitor the hybridization event. The difference of ECL linearly increased with the logarithm of target DNA concentration in the range from 1.0  ×  10^-16 - 1.0  ×  10^-8 mol L^-1 with a detection limit of 5.8  ×  10^-17 mol L^-1. The sensor had high sensitivity and wide linear relationship for the detection of target DNA.

Bimodal Electrogenerated Chemiluminescence of the Luminol/Dicyclohexylamine (DCHA) System: A Novel and Highly Sensitive Detection of DCHA via ECL-Flow Injection Analysis

Though luminol is one of the most prominent and extensively studied luminophores in ECL studies, only H₂O₂ has been widely used as a co-reactant. This limits the variety of applications because of the short-time radical stability and low quantum efficiency. In the present work, we identified dicyclohexylamine (DCHA) as a new and highly efficient anodic co-reactant in ECL for the luminol molecule. The electrochemical and ECL behavior of the luminol/DCHA system was studied on a simple bare GCE surface, which results in two anodic ECL peaks at the potential region of +0.38 and +0.94 V vs Ag/AgCl. The evidence of (DCHA^•+) and O₂^•- generated in the system was detected via flat-cell electron spin resonance (ESR) spectroscopy experiments at ∼20 °C. Using the bimodal ECL system, the highly sensitive detection of luminol was achieved with the detection limit down to 1.5 pM. Further, a homebuilt electrochemiluminescent detector coupled with a flow injection analysis (ECL-FIA) system was adopted to detect the DCHA contaminant in harvested honey, which achieved higher detection and sensitivity under the optimized experimental conditions. DCHA was detected in the range of 10 nM to 100 μM with the detection limit of 2 nM (S/N = 3). The present findings of new luminol/DCHA ECL signals produced a strong ECL emission, which leads to a greater potential to meet the fast-developing analytical application of a luminol-based ECL system.

An ultra-sensitive electrochemiluminescence probe based on ternary nanocomposite and boron nitride quantum dots for detection of diazinon

A new enzyme-free electrochemiluminescence (ECL) pesticide sensor was fabricated based on ternary nanocomposite of ruthenium nanoparticles/silver nanoparticles/graphene oxide on the surface of glassy carbon electrode for ultratrace determination of diazinon. Due to some drawbacks of enzyme-based sensors such as enzyme instability at elevated temperature, humidity, changes of pH, and high price of the enzyme, the use of enzyme was omitted in the construction of the developed sensor. The silver nanoparticles with good electrocatalytic proficiency as a signal improving agent and tris(2,2bipyridine) ruthenium(II) as a popular luminophore were uniformly deposited on the surface of the prepared graphene oxide/GC electrode at nanoscale. Boron nitride quantum dots as an efficient co-reactant created the superior efficiency in amplifying the ECL intensity of the ruthenium-based ECL system. The prepared electrode was utilized for the detection of diazinon via the robust ECL method. For the present sensor, a wide linear dynamic range and low detection limit were achieved (3.0 × 10^-15 to 6.5 × 10^-9 M and 9.5 × 10^-16 M, respectively). The obtained results confirmed the fabrication of the robust ECL probe, which is characterized by the cooperative effect of silver nanoparticles and the attached luminophore species. The main advantage of the presented sensor was that the samples could be diluted so that the effect of the interference species was negligible. Due to excellent properties toward accurate determination of diazinon, the ECL sensor as a new practical platform was applied for quantitative detection of diazinon in some real samples.

Development of luminol-based chemiluminescence approach for ultrasensitive sensing of Hg(II) using povidone-I2 protected gold nanoparticles as an efficient coreactant

In this work, we fabricated gold nanoparticles (AuNPs) capped with both polyvinyl pyrrolidone (PVP) and iodine (I₂) to act as efficient chemiluminescent coreactants for luminol. AuNPs synthesis was based on the direct chemical reduction of Au³⁺ with NaBH₄ in the presence of PVP-I₂ complex. The successful synthesis of PVP-I₂@AuNPs was confirmed with scanning electron microscopy (SEM) and UV-vis spectrophotometry. Chemiluminescence (CL) intensity of luminol was greatly enhanced, upon its chemical reaction with chemisorbed I₂ on AuNPs surfaces owing to the excellent catalytic activity of AuNPs. The PVP-I₂@AuNPs/luminol CL sensing system was successfully applied for determination of Hg²⁺ ions and the results displayed linearity in a wide range from 0.5 to 2000 nM and an ultrasensitive response to 1.0 nM Hg²⁺. The detection limit of Hg²⁺ ions was 0.1 nM, which was 100 times lower than the limit value (10 nM) defined by the U.S. Environmental Protection Agency in drinkable water. This ultrasensitive luminogenic system for Hg²⁺ detection also exhibited excellent selectivity among 13 types of metals, suggesting that the luminol/PVP-I₂@AuNPs system is a promising sensor for real-time detection of Hg²⁺. Graphical abstract.

A novel ultrasensitive electrochemiluminescence biosensor for glutathione detection based on poly-L-lysine as co-reactant and graphene-based poly(luminol/aniline) as nanoprobes

In this work, an ultrasensitive electrochemiluminescence (ECL) biosensor was constructed using poly-L-lysine (PLL) as a novel co-reactant of luminol and poly(luminol/aniline) nanorods loaded reduced graphene oxide (PLA@rGO) as nanoprobe, which enable highly sensitivity detection of glutathione (GSH). To the best of our knowledge, it is the first time that PLL was used for the co-reactant of luminol. Notably, about a 5-fold enhancement was obtained compared with the individual PLA@rGO using GCE. Due to the remarkable quenching effect between the excited state of PLL and the reduced form of GSH in the ECL system of luminol/PLL, the ECL sensing platform exhibited wide linear ranges of 1.0 × 10^-9-1.0 × 10^-4 M and 1.0 × 10^-4-1.0 × 10^-2 M and a low detection limit of 7.7 × 10^-10 M. Simultaneously, the biosensor was also successfully applied to detect GSH in human serum sample with high recoveries. Hence, this work would open a new platform for the wide application of PLL in immunoassay and various sensors.