Electrochemiluminescence Of Ru Research Articles

A dynamic electrochemiluminescence system for continuous on-line measurements based on potential stepping pulse strategy

A dynamic electrochemiluminescence (ECL) detection system combining flow injection analysis with a potential stepping pulse strategy was developed. It contains a flow injection unit that carrying the sample solution flow through a specially designed ECL detection cell continuously, ensuring the valid renew of the test solution and thus is favorable for continuous on-line measurements. This dynamic ECL analytical system based on potential stepping pulse strategy is very efficient and time-saving. Taking the ruthenium(II) tris(bipyridine) (Ru(bpy)32+)-tripropylamine (TPA) system as an example, the ECL responses to step pulse potentials and pulse period, as well as the sample flow rate were examined. Under optimized experimental parameters, the proposed protocol was further successfully applied for the continuous detection of TPA, and malachite green based on its inhibitory effect on the ECL of Ru(bpy)32+-TPA system with a limit of detection of 17.77 nM. The relative standard deviation of 97 cycles measurements was only 0.46 % under ideal conditions. The results indicate that this system could provide reproducible and reliable ECL signals. As a versatile and efficient ECL detection protocol, it has a broad prospect of application.

Plasmon-Enhanced Electrochemiluminescence at the Single-Nanoparticle Level.

Plasmon-enhanced electrochemiluminescence (ECL) at the single-nanoparticle (NP) level was investigated by ECL microscopy. The Au NPs were assembled into an ordered array, providing a high-throughput platform that can easily locate each NP in sequential characterizations. A strong dependence of ECL intensity on Au NP configurations was observed. We demonstrate for the first time that at the single-particle level, the ECL of Ru(bpy)3 2+ -TPrA was majorly quenched by small Au NPs (<40 nm), while enhanced by large Au ones (>80 nm) due to the localized surface plasmon resonance (LSPR). Notably, the ECL intensity was further increased by the coupling effect of neighboring Au NPs. Finite Difference Time Domain (FDTD) simulations conformed well with the experimental results. This plasmon enhanced ECL microscopy for arrayed single NPs provides a reliable tool for screening electrocatalytic activity at a single particle.

Plasmon‐Enhanced Electrochemiluminescence at the Single‐Nanoparticle Level

AbstractPlasmon‐enhanced electrochemiluminescence (ECL) at the single‐nanoparticle (NP) level was investigated by ECL microscopy. The Au NPs were assembled into an ordered array, providing a high‐throughput platform that can easily locate each NP in sequential characterizations. A strong dependence of ECL intensity on Au NP configurations was observed. We demonstrate for the first time that at the single‐particle level, the ECL of Ru(bpy)32+‐TPrA was majorly quenched by small Au NPs (&lt;40 nm), while enhanced by large Au ones (&gt;80 nm) due to the localized surface plasmon resonance (LSPR). Notably, the ECL intensity was further increased by the coupling effect of neighboring Au NPs. Finite Difference Time Domain (FDTD) simulations conformed well with the experimental results. This plasmon enhanced ECL microscopy for arrayed single NPs provides a reliable tool for screening electrocatalytic activity at a single particle.

Electrochemiluminescence of Ru(bpy)3 2+ in 1-ethyl-3-methylimidazolium Tetrafluoroborate Salt and Its Application in the Fabrication of Biosensor for Thrombin

Electrochemiluminescence (ECL) of needle-like structure Ru(bpy)3 2+ (RuND) was investigated in the room temperature ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4) medium. The results revealed that strong anodic ECL and moderate cathodic ECL could be obtained in ionic liquid without the need of additional coreactant, which could simplify the process for biosensor fabrication. Several experimental parameters, such as potential range, potential scan direction, and ECL spectrum were studied and the possible ECL mechanisms were proposed. Ferrence exhibited apparent inhibiting effect on ECL signal, based on which a label-free ECL aptasensor was fabricated for the detection of thrombin in EMImBF4. In the range of 1.0 × 10−12 to 1.0 × 10−9 mol l−1, the ECL intensity varied linearly with the logarithmic of thrombin concentration with a detection limit of 0.74 pM. The fabricated ECL sensor showed high sensitivity and good selectivity in the detection of thrombin. The results suggested that ionic liquids are the potential media for the fabrication of ECL sensors.

Electrochemiluminescence of [Ru(bpy)3]2+/tripropylamine at glassy carbon, platinum, and palladium electrodes

Ru(bpy)32+/TPA system is a tremendously important electrochemiluminescence (ECL) system. Its ECL properties depend significantly on the electrodes used. Although it is well studied at the gold electrode, the ECL of Ru(bpy)32+/TPA system is considerably less studied at other electrodes. In this study, the comparative ECL studies of Ru(bpy)32+/TPA system on glassy carbon, platinum, and palladium electrodes were carried out. Particularly, the ECL of Ru(bpy)32+/TPA system at Pd electrode has been studied for the first time. Our results elucidated that platinum and palladium electrodes could generate strong ECL in slightly alkaline while glassy carbon in neutral pH conditions. An increase in the intensity of the ECL signal was observed in surfactant media. The study promotes a better understanding of Ru(bpy)32+/TPA ECL systems.

Electrochemically induced deposition of hydroxyl‐terminated poly(amidoamine) dendrimers encapsulating Pt nanoparticles on indium tin oxide for enhanced electrochemiluminescence

AbstractWe reported the electrochemically induced deposition of hydroxyl‐terminated poly(amidoamine) dendrimers encapsulating Pt nanoparticles on the surface of indium tin oxide (ITO). The electrochemical deposition led to significantly high surface coverage of Pt nanoparticles encapsulated inside the dendrimers on ITO surfaces, which allowed enhanced (i.e., ca. 212‐fold) electrochemiluminescence of Ru(bpy)32+/tripropylamine on the modified ITOs compared to unmodified ITO.

Electrochemiluminescence of Ru(bpy)32+/thioacetamide and its application for the sensitive determination of hepatotoxic thioacetamide.

Thioacetamide (TAA) is a well-known hepatotoxic substance, so it is important to determine its presence and content in food and environmental samples. Herein, we report a highly sensitive determination method for TAA based on the electrochemiluminescence (ECL) of tris(2,2'-bipyridyl)ruthenium(ii) (Ru(bpy)32+) for the first time by using TAA as a new coreactant for Ru(bpy)32+ ECL via an anodic route. The developed Ru(bpy)32+-TAA ECL system allows the determination of TAA with a good dynamic linear range and low limit of detection (LOD) of 0.1 μM to 1000 μM and 0.035 μM (3σ/m), respectively. In addition, the established ECL system can be applied to detect TAA in fruit juice and waste water samples with outstanding recoveries.

An “on-off” electrochemiluminescence biosensor based on DNA nanotweezer probe coupled with tripod capture DNA for high sensitive detection of Pb2+

In this work, a new DNA nanotweezers-Ag nanoparticle (NP) as signal-switching probe is designed and coupled with tripod-like capture DNA structure to construct an ultrasensitive “ON-OFF” electrochemiluminescence (ECL) biosensor for detecting Pb2+. The unique tweezer nanostructure has two G-base-rich sequences on different arms, and the G4-chain structure is simply constructed by switching tweezer conformation from “open” to “close”, which can be controlled by alternative target released in Pb2+-triggered cyclic amplification process. The activated G4-structure can specifically capture plenty of hemin to the closed state, which has a strong quenching effect on ECL of Ru(phen)32+. After reduced graphene oxide (ERGO) with good electrochemical activity and loading capacity is electrodeposited on the electrode, Ru(phen)32+ as ECL probe is strongly adsorbed on it via π-π conjugation. Then tripod-like DNA structure with spiral extensibility, good capabilities, and no backfilling was linked to the surface to capture G4-structure with hemin, resulting in significant decrease of ECL for sensitive Pb2+ detection. Due to the design flexibility of DNA nanotweezers structure, the strategy provides universal design of ECL biosensors in ingenious assay of a variety of metal ions and other bioassays.

Amplified Anodic Electrogenerated Chemiluminescence of Tris(2,2′‐bipyridyl)ruthenium(II) for the Sensitive Detection of Isatin

AbstractIsatin is an endogenous indole derivative that has been reported to possess various pharmacological and therapeutic activities of clinical importance. To date, isatin has been detected mainly by mass spectrometry. Here, we report for the first time the intense anodic electrochemiluminescence (ECL) of tris(2,2′‐bipyridyl)ruthenium(II) with isatin as an efficient co‐reactant. Interestingly, the ECL response of the Ru(bpy)32+/isatin system in borate buffer solution is about 12 times more intense than in phosphate buffer of the same pH; and approximately 114 times greater than the ECL intensity of the luminophore. Under the optimal conditions, the ECL of Ru(bpy)32+ increases linearly with the concentration of the isatin in the range of 1.0 μM to 1.0 mM (R2=0.998) with a limit of detection (LOD) of 0.28 μM (3σ/m). Moreover, the method has been successfully applied to the detection of isatin in human urine. The developed method has shown excellent recoveries in the range of 99.7–101.3 %. The anodic ECL assay reported in this work is superior in terms of linear range and selectivity than the previously reported methods and can be applied for the detection of isatin in real samples.

Distance-dependent quenching and enhancing of electrochemiluminescence from tris(2, 2′-bipyridine) ruthenium (II)/tripropylamine system by gold nanoparticles and its sensing applications

Understanding the role of gold nanoparticles (AuNPs) in electrochemiluminescence (ECL) processes of the Ru(bpy)32+ (bpy= 2, 2′-bipyridine)/tripropylamine (TPA) system would be beneficial to develop novel ECL sensors for a variety of applications. In this work, we found that the AuNPs on the surface of indium tin oxide (ITO) electrode could catalyze the electrochemical oxidation of TPA, greatly enhancing the ECL signal of Ru(bpy)32+/TPA, present in the solution. If physical separation of AuNPs away from electrode surface after hybridization with target ssDNA, ECL signal decreased dramatically due to the loss of electrochemical activity of AuNPs, based on which a sensitive and specific DNA sensor in a “switch-off” mode was constructed with a detection limit of 0.2 pM. In addition, a suppressing effect of the AuNPs on the ECL of Ru(bpy)32+ was experimentally confirmed by decreasing the electrocatalytic effect to overall ECL emission, including selection of oxalate as a coreactant instead of TPA, or introduction of gold electrode as substrate. Furthermore, when Ru(bpy)32+ and AuNPs were both immobilized on the ITO electrode at close proximity, the ECL quenching induced by energy/electron transfer was predominant. ECL emission of the Ru(bpy)32+/TPA system resulted from a competition between electrocatalytic enhancement and quenching effect. However, the quenched ECL signal would return in case of the AuNPs moving far away from ECL emitters after a hybridization reaction as before, and a separation distance dependent surface enhancement was observed as well. Based on the role change for AuNPs from quenching to enhancing ECL intensity of Ru(bpy)32+/TPA system, a novel ECL DNA sensing strategy in a “turn-on” mode was developed, enabling quantitative analysis of target ssDNA over the range of 0.05 pM to 0.5 nM with a detection limit of 12 fM. Overall, we demonstrated the existence of three effects of AuNPs on the ECL of Ru(bpy)32+/TPA system, and which played the leading role was dependent on the placement of AuNPs, Ru(bpy)32+, and their separation distance. The ECL sensors based on the role change for AuNPs showed both high sensitivity and excellent selectivity.

Determination of Cu2+ in Drinking Water Based on Electrochemiluminescence of Ru(phen)32+ and Cyclam

AbstractA convenient and simple electrochemiluminescence (ECL) method was employed to detect trace amounts of Cu2+ in drinking water. This method is based on the inhibitory effect of Cu2+ on the ECL of Ru(phen)32+ and 1,4,8,11‐tetraazacyclotetradecane (cyclam) system. ECL intensity of Ru(phen)32+ was considerably enhanced by the addition of cyclam because of the ECL reaction between them. The ECL intensity of Ru(phen)32+/cyclam system rapidy decreased with the addition Cu2+ because of the formation of chelate complex [Cu(cyclam)]2+. Good linear response (R2=0.9948) was obtained at Cu2+ concentration of 1.0×10−9−1.0×10−5 mol ⋅ L−1 at glassy carbon electrode in 0.1 mol ⋅ L−1 phosphate buffer (pH 9.0). Observed detection limit of 4.8×10−10 mol ⋅ L−1 satisfied the maximum contaminant level goal (MCLG) for Cu2+ set by the US Environmental Protection Agency (US EPA). Applicability of the proposed method was verified by the good reproducibility and stability of the method when applied to determine Cu2+ in tap water and simulated wastewater. Thus, a novel ECL detection method was developed for Cu2+ detection.

Determination of zinc ion based on electrochemiluminescence of Ru(phen)32+ and phenanthroline

An electrochemiluminescence (ECL) method for determination of zinc ion has been developed based on the enhanced effects of zinc ion on the ECL system of Ru(phen)32+ and phenanthroline (phen). The ECL intensity gradually increased with increasing zinc ion concentration under optimal condition. A linear regression equation (IECL=213.6lg[Zn2+]+7003.6; r=0.99689, n=5) was obtained over 1.0×10−10–1.0×10−6molL−1 zinc ion, and the detection limit was as low as 1.0×10−10molL−1. For detection of 1.0×10−10, 1.0×10−8, and 1.0×10−6molL−1 spiked zinc ion, the recovery ratio ranged from 101% to 103%, and the relative standard deviations were 2.10%, 0.97%, and 3.20%, respectively. These results demonstrated that the proposed method was effective and showed good reproducibility.

Determination of malachite green and leucomalachite green based on electrochemiluminescence of Ru(bpy)32+at graphene oxide modified glassy carbon electrodes

An electrochemiluminescence (ECL) method for the determination of malachite green (MG) and leucomalachite green (LMG) has been established based on ECL of Ru(bpy)32+at the GO-modified GCE.

Omeprazole as a strong coreactant in the electrochemiluminescence of Ru(bpy)32+

Omeprazole (OPZ) as a high-efficiency coreactant in the electrochemiluminescence (ECL) of Ru(bpy)32+ on a bare Pt electrode has been studied in this paper. Based on the strong enhancement effect of OPZ on the ECL of Ru(bpy)32+, a simple, rapid and sensitive method for the determination of omeprazole has been established. Under the optimum conditions, the logarithmic ECL enhancement versus the logarithmic concentration of OPZ is linear over a wide concentration range of 2.0×10−7 to 5.0×10−4M (r=0.9945), with a detection limit of 2.0×10−8M (6.9ng/mL, S/N=3) in a pH=11.5 100mM phosphate buffer solution containing 1.0×10−4M Ru(bpy)32+. To demonstrate its applicability, the proposed method was applied in the determination of OPZ in capsules and the recoveries were ranged from 93.3%-106.7%. These provide a possibility to employ the new ECL method for OPZ detection in pharmaceutical preparations. According to the study of electrochemical behavior, ECL behavior and ECL emission spectrum of Ru(bpy)32+/OPZ system, a possible ECL mechanism was proposed.

A Homogeneous Signal-On Strategy for the Detection of rpoB Genes of Mycobacterium tuberculosis Based on Electrochemiluminescent Graphene Oxide and Ferrocene Quenching

Tuberculosis (TB) remains one of the leading causes of morbidity and mortality all over the world and multidrug resistance TB (MDR-TB) pose a serious threat to the TB control and represent an increasing public health problem. In this work, we report a homogeneous signal-on electrochemiluminescence (ECL) DNA sensor for the sensitive and specific detection of rpoB genes of MDR-TB by using ruthenium(II) complex functionalized graphene oxide (Ru-GO) as suspension sensing interface and ferrocene-labeled ssDNA (Fc-ssDNA) as ECL intensity controller. The ECL of Ru-GO could be effectively quenched by Fc-ssDNA absorbed on the Ru-GO nanosheets. The Ru-GO has good discrimination ability over ssDNA and dsDNA. Mutant ssDNA target responsible for the drug resistant tuberculosis can hybridize with Fc-ssDNA and release Fc-ssDNA from Ru-GO surface, leading to the recovery of ECL. Mutant ssDNA target can be detected in a range from 0.1 to 100 nM with a detection limit of 0.04 nM. The proposed protocol is sensitive, specific, simple, time-saving and polymerase chain reaction free without complicated immobilization, separation and washing steps, which creates a simple but valuable tool for facilitating fast and accurate detection of disease related specific sequences or gene mutations.

Electrochemiluminescence detection of chlorpromazine hydrochloride at bare and graphene oxide modified glassy carbon electrodes

An electrochemiluminescence (ECL) method for the determination of CPZ (chlorpromazine hydrochloride) has been developed based on the ECL of Ru(bpy)32+/Ru(phen)32+.

Determination of hydrazine hydrate based on electrochemiluminescence of Ru(bpy) 3 2+

Considering of the basic properties and also the two nitrogen atoms in the structure, hydrazine hydrate was employed to be an amine additive candidate, to build a Ru(bpy)(3)(2+) /hydrazine electrochemiluminescence (ECL) system, and ECL of Ru(bpy)(3)(2+) has been employed for the determination of hydrazine hydrate in the paper. The result demonstrated that the logarithmic ECL increasing (ΔECL = ECL(after addition of hydrazine) - ECL(before addition of hydrazine)) versus the logarithmic concentration of hydrazine hydrate is linear over a concentration range of 1.0 × 10(-9) to 1.0 × 10(-5) mol/L, on both glassy carbon and Pt electrodes in a pH 9 phosphate buffer. The hydrazine hydrate detection limit was down to 1.0 × 10(-9) mol/L, comparatively lower than other detection methods. To check its applicability, the proposed method was applied to the determination of hydrazine hydrate added into a tap water sample with good reproducibility and stability. All these provide a possibility to develop a novel ECL detection method for hydrazine in water.

Electrogenerated chemiluminescence of [formula omitted]/2-(dibutylamino)ethanol system

2-(Dibutylamino)ethanol (DBAE) is a highly effective coreactant for Ru(bpy)32+ electrochemiluminescence (ECL) and Ru(phen)32+ is a well-known ECL luminophore. In this study, ECL of Ru(phen)32+/DBAE has been investigated for the first time. This study has been carried out using cyclic voltametry and amperometry. The results imply that amperometry is found to be superior to cyclic voltametry as it shows approximately five fold enhancement in ECL emission intensity. Furthermore, compared to Ru(bpy)32+, Ru(phen)32+ provides several fold increase in ECL intensities with DBAE. Sensitive detection of Ru(phen)32+ is achieved with a linear range over approximately four orders of magnitude using very low concentration of DBAE (5mM).

Ultrasensitive electrochemiluminescence method for determination of DNA using Ru(bpy) 32+-coated magnetic submicrobeads wrapped with carbon nanotubes

We developed an ultrasensitive electrochemiluminescence (ECL) method for DNA determination using magnetic submicrobeads (SMBs) as the carrier of Ru(bpy) 3 2+ (bpy = 2,2′-bipyridy) and carbon nanotubes (CNTs) as accessorial electrode material. The SMBs with Ru(bpy) 3 2+ were wrapped with CNTs and then immobilized on an Au electrode. In the presence of tri- n-propylamine, ECL of the Ru(bpy) 3 2+ on the SMBs was detected. Since one target DNA (t-DNA) molecule corresponded to one SMB with a large number of Ru(bpy) 3 2+, the ECL signal was amplified. In addition, the Ru(bpy) 3 2+-loaded SMBs were wrapped with CNTs that contacted the electrode. The ECL of Ru(bpy) 3 2+ was greatly increased. Using this method, t-DNA of 3 × 10 −16 mol/L could be detected. The method could be used to quantify mRNA in cells.

In situ synthesis of gold nanoparticles on porous polyacrylonitrile nanofibers for sensing applications

A simple and cost-effective method was reported to synthesize small size (6 nm) gold nanoparticles (AuNPs) on polyacrylonitrile (PAN) electrospun nanofibers (AuNPs/PAN). The formation of AuNPs is attributed to the in situ reduction of Au(III) to Au(0) by 4-(dimethylamino)benzaldehyde doped in the PAN nanofibers. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) confirmed that the AuNPs/PAN nanofibers showed good conductivity. The AuNPs/PAN nanofibers were used to immobilize tris(2,2'-bipyridyl)ruthenium(II) ions (Ru(bpy)(3)(2+)) to form an electrochemiluminescence (ECL) sensor. The AuNPs on the PAN nanofibers exhibited an excellent catalytic effect on the ECL of Ru(bpy)(3)(2+) which could be employed to detect low concentrations of phenolic compounds. The linear response range of the ECL sensor to hydroquinone is 0.55-37 μM with limit of detection of 80 nM (S/N = 3). This sensor has been successfully applied to determine the hydroquinone content in photographic developer samples. Our work provides a very simple and cost-effective method to synthesize AuNPs on polymer nanofibers which shows great potential in the field of electrocatalysis and chemo/biosensors.