Aggregation-induced Electrochemiluminescence Research Articles

Coreactant-free aggregation-induced electrochemiluminescence system based on the novel zinc-luminol metal-organic gel for ultrasensitive detection of PiRNA-823

Aggregation-induced electrochemiluminescence (AIECL) technology has aroused widespread interest due to the significant improve in ECL response by solving the problems of aggregation-caused quenching and poor water solubility of the luminophore. However, the existing AIECL emitters still suffer from low ECL efficiency, additional coreactants and complex synthesis steps, which greatly limit their applications. Herein, luminol, as a kind of AIE molecule, was assembled with Zn2+ nodes to obtain a novel microflower-like Zinc-luminol metal-organic gel (Zn-MOG) by one-step method. In the light of the strong affinity of N atoms in luminol ligand to Zn2+, Zn-MOG with vigorous viscosity and stability can be formed immediately after vortex oscillation, overcoming the main difficulties of the complicated synthesis steps and poor film-forming performance encountered in current AIECL materials. Impressively, an AIECL resonance energy transfer (RET) biosensor was constructed using Zn-MOG as a donor and Alexa Fluor 430 as an acceptor in combination with DNA-Fuel-driven target recycling amplification for the ultrasensitive detection of PiRNA-823. The fabricated biosensor exhibited a wide linear relationship in the range of 100 aM to 100 pM and a detection limit as low as 60.0 aM. This work is the first to realize the construction of ECL emitters using the AIE effect of luminol, which provides inspiration for the design of AIECL systems without adding coreactants.

Strong aggregation-induced electrochemiluminescence of pyrene-coordination metal-organic frameworks coupled with zero-valent iron as novel accelerator for ultrasensitive immunoassay

Polycyclic aromatic hydrocarbons (PAHs) are excellent alternative luminophores for electrochemiluminescence (ECL) immunoassays. However, they are inevitably limited by the aggregation-caused quenching effect. In this study, aimed at eliminating the aggregation quenching of PAHs, luminescent metal–organic frameworks (MOFs) with 1,3,6,8-tetra(4-carboxybenzene)pyrene (H4TBAPy) as the ligand were exploited as a novel nano-emitter for the construction of ECL immunoassays. The luminophore exhibits efficient aggregation-induced emission enhancement, good acid-base resistance property and unusual ECL reactivity. In addition, the simultaneous use of potassium persulfate and hydrogen peroxide as dual co-reactants resulted in a synergistic enhancement of the cathodic ECL efficiency. The use of magnetic iron-nickel alloys as the multifunctional sensing platform can further enhance the ECL activity, and its enriched zero-valent iron as a co-reactant accelerator effectively drives ECL analytical performance. Profiting from the excellent characteristics, signal-on ECL immunoassays have been constructed. With carcinoembryonic antigen as the model analysis target, a detection limit of 0.63 pg/mL was obtained within the linear range of 1 pg/mL to 50 ng/mL, accompanied by excellent analytical performance. This report opens a new window for the rational design of efficient ECL illuminators, and the proposed ECL immunoassays may find promising applications in the detection of disease markers.

Self-Assembled Tetraphenylethene-Based Nanoaggregates with Tunable Electrochemiluminescence for the Ultrasensitive Detection of E. coli.

As an effective ECL emitter, tetraphenylethene (TPE)-based molecules have recently been reported with aggregation-induced electrochemiluminescence (AIECL) property, while it is still a big challenge to control its aggregation states and obtain uniform aggregates with intense ECL emission. In this study, we develop three TPE derivatives carrying a pyridinium group, an alkyl chain, and a quaternary ammonium group via the Menschutkin reaction. The resulting molecules exhibit significantly red-shifted FL and enhanced ECL emissions due to the tunable reduction of the energy gap between the highest occupied molecular orbitals (HOMOs) and the lowest unoccupied molecular orbitals (LUMOs). More importantly, the amphiphilicity of the as-developed molecules enables their spontaneous self-assembly into well-controlled spherical nanoaggregates, and the ECL intensity of nanoaggregates with 3 -CH2- (named as C3) is 17.0-fold higher compared to that of the original 4-(4-(1,2,2-triphenylvinyl)phenyl)pyridine (TPP) molecule. These cationic nanoaggregates demonstrate a high affinity toward bacteria, and an ECL sensor for the profiling of Escherichia coli (E. coli) was developed with a broad linear range and good selectivity in the presence of an E. coli-specific aptamer. This study provides an effective way to enhance the ECL emission of TPE molecules through their derivatization and a simple way to prepare well-controlled AIECL nanoaggregates for ECL application.

A sensor based on Fe/B/N codoped hierarchical porous carbon spheres that amplify the aggregation-induced electrochemiluminescence of calcein for florfenicol trace detection

Electrochemiluminescence (ECL) signal amplification is an important method for improving sensor sensitivity. In this study, an ECL sensor was developed for florfenicol detection based on the aggregation-induced electrochemiluminescence of calcein and Fe/B/N codoped hierarchical porous carbon spheres (B-N-Fe-HPCs). First, B-N-Fe-HPCs were prepared by a simple high-temperature synthesis method, attached to the gold electrode surface, and used as a signal amplification element. Then, a molecularly imprinted polymer (MIP) was prepared using florfenicol as a template molecule and phthalylenediamine as a functional monomer and doped with calcein on the B-N-Fe-HPC-modified electrode. After the elution of florfenicol, the sensor retains an imprinted site that specifically recognizes florfenicol can readsorb florfenicol in the sample. Because calcein aggregates in the MIP to generate an ECL signal, B-N-Fe-HPCs effectively amplifies this ECL signal. Thus, because the ECL signal of the sensor can be quenched, a new method for detecting florfenicol was established. The sensor used for florfenicol showed very high sensitivity and good selective performance, with a linear range of 1–8000 × 10−12 mol/L and a detection limit of 4.65 × 10−13 mol/L. The sensor was applied to detect actual samples, such as chicken, and the results were satisfactory, with the recovery rate of the spike from 91.2 % to 105.3 %.

Near-infrared II aggregation-induced electrochemiluminescence of organic dots.

For the first time, we report novel aggregation-induced electrochemiluminescence (AIECL) of organic dots in aqueous media, with near-infrared II (NIR-II) luminescence peaked at 906 nm. Furthermore, a hybrid mechanism of ECL generation is revealed by various experiments in conjunction with theoretical calculations. This work opens a window for exploring efficient organic dye-based NIR-II AIECL emitters.

Tetraphenylethene-based platinum (II) complex with aggregation- induced electrochemiluminescence for the detection of glutathione

Aggregation-induced electrochemiluminescence (AIECL) has been attracting great interests in ECL study, while it is still a big challenge to develop AIECL fluorophores with high emission efficiency and fair excitation potential. Herein, we develop a new ECL reagent platinum (II)-1,1,2,2-tetrakis(4-(pyridin-4-yl) phenyl) ethylene (Pt-TPPE) self-assembled via the coordination of pyridine group of TPPE and the metal cation of Pt (II). The resulting Pt-TPPE demonstrates excellent ECL emission properties in terms of high ECL emission efficiency and significant shift of ECL excitation potential from -1.6 V to -1.3 V. The corresponding ECL emission mechanism indicates that the formation of Pt-TPPE greatly limits the movement of TPPE ligand to reduce the non-radiated emission, and the catalytic decomposition of co-reactant K2S2O8 into SO4.− by Pt (II) cation is responsible for the shift of the excitation potential. The competitive coordination of thiol group with the Pt(II) cation effectively dissociate the Pt-TPPE complex, resulting in the quenching of its ECL emission, enabling the sensitive determination of thiol-carrying compound glutathione (GSH) with a low limit of detection (LOD = 0.298 μM) and wide linear range (1 μM-1 mM).

Ultrasensitive aggregation-induced electrochemiluminescence sensor for dopamine detection in polymer hydrogel system

The theory of aggregation-induced electrochemiluminescence (AIECL) provides a new method for preparing novel electrochemiluminescence emitters, but the lack of AIECL-based functional nanomaterials seriously hinder its development and application. In this work, Ti3C2Tx MXene-stabilized iridium bis(1, 2-dipheny1–1 H-benzimidazole)(acetylacetonate) [Ir(pbi)2(acac)] with AIECL in polymer hydrogel was prepared for the first time. Due to the large electroactive surface area of Ti3C2Tx MXene, the stabilized Ir(pbi)2(acac) (Ir@MXene) can amplify the ECL signal of the system. The confinement of Ir@MXene into the polyvinyl alcohol (Ir@MXene-PVA) hydrogel increased the local concentration of Ir(pbi)2(acac), which could not only prevent oxides from entering the Ir(pbi)2(acac) nanodots but also limit the vibration to reduce non-radiative transitions of Ir(pbi)2(acac), leading to a distinct AIECL emission. In addition, dopamine (DA) and H2O2 have been used to explore the ECL quenching behavior of Ir@MXene-PVA systems. Based on ECL quenching of Ir@MXene-PVA system by DA, a sensor has been constructed to detect DA in human serum sensitively. The detection range was 0.01–100 nmol/mL, with a detection limit of 2.0 pmol/mL. This strategy provides an efficient method for the preparation of Ir@MXene-PVA hydrogel with AIECL emission, which may have promising potential in the clinical detection of DA, H2O2, and other biomarkers.

Precise Modulation of Intramolecular Aggregation-induced Electrochemiluminescence by Tetraphenylethylene-based Supramolecular Architectures.

The precisely modulated synthesis of programmable light-emitting materials remains a challenge. To address this challenge, we construct four tetraphenylethylene-based supramolecular architectures (SA, SB, SC, and SD), revealing that they exhibit higher electrochemiluminescence (ECL) intensities and efficiencies than the tetraphenylethylene monomer and can be classified as highly efficient and precisely modulated intramolecular aggregation-induced electrochemiluminescence (PI-AIECL) systems. The best-performing system (SD) shows a high ECL cathodic efficiency exceeding that of the benchmark tris(2,2'-bipyridyl)ruthenium(II) chloride in aqueous solution by nearly six-fold. The electrochemical characterization of these architectures in an organic solvent provides deeper mechanistic insights, revealing that SD features the lowest electrochemical band gap. Density functional theory calculations indicate that the band gap of the guest ligand in the SD structure is the smallest and most closely matched to that of the host scaffold. Finally, the SD system is used to realize ECL-based cysteine detection (detection limit=14.4 nM) in real samples. Thus, this study not only provides a precisely modulated supramolecular strategy allowing chromophores to be controllably regulated on a molecular scale, but also inspires the programmable synthesis of high-performance aggregation-induced electrochemiluminescence emitters.

Aggregation-induced electrochemiluminescence enhancement of Ag-MOG for amyloid β 42 sensing

This study aimed to introduce an immunosensor for measuring amyloid β 42 (Aβ42) levels by aggregation-induced enhanced electrochemiluminescence (ECL). Metal–organic gels (MOGs) are novel soft materials with advantages such as high gel stability, good light-emitting properties, and easy preparation. This study used silver nanoparticle metal–organic gel (Ag-MOG) as a substrate to connect Aβ42-Ab2 and the cathodoluminescent probe. Potassium persulfate was used as a co-reactant that could emit a high ECL signal. CuS@Au had the benefits of a relatively large surface area with excellent carrier function; therefore, it was used as a substrate to load a large amount of Aβ42-Ab1, significantly improving the immunosensor sensitivity. The ECL intensity of Aβ42 was linear in the range of 0.01 pg/mL to 250 ng/mL with a detection limit of 2.2 fg/mL (S/N = 3) under optimized detection conditions. This ECL immunosensor has been successfully applied to detect Aβ42 in human serum with the advantages of excellent stability and high selectivity. This method not only expands the potential applications of ECL immunosensors based on biological testing and clinical diagnosis but also provides a viable approach to basic clinical testing.

Aggregation-induced electrochemiluminescence-active ruthenium(II) complex for selective detection of dopamine

In this paper, we systematically investigated the aggregation-induced electrochemiluminescence (AIECL) of the ruthenium(II) complex ([Ru(phen)2(phen-O2)](PF6)2, phen-O2: 5,6-diketone-1,10-phenanthroline), which was dissolved in solvents with different water/acetonitrile volume ratios. The fluorescence intensity of the system increased 11.5-fold when the proportion of water (a poor solvent) in the solvent mixture was increased to 90%, and the electrochemiluminescence intensity increased 16-fold when the proportion of water in the solvent was increased to 80%. Transmission electron microscopy and dynamic light scattering confirmed the aggregation of [Ru(phen)2(phen-O2)](PF6)2 molecules into nanoclusters. Aggregation-induced electrochemiluminescence properties were observed to increase with an increase in the proportion of water in H2O/CH3CN. Due to the excellent aggregation-induced luminescence performance of [Ru(phen)2(phen-O2)](PF6)2, the quantitative detection of dopamine was achieved with a good linear range of 100 pM–1uM and a limitation of detection of 33.3 pM. This simple and sensitive method based on the AIECL effect can be widely applied to the detection and analysis of other small biological molecules.

High AIECL performance of tetraphenylethene derivatives originated from the linear increasing of benzene ring and solvent regulation for sensitive measurement of melatonin

The efficiency of aggregation-induced electrochemiluminescence (AIECL) in tetraphenylethene (TPE) derivatives were significantly enhanced by combining the regulation of molecular structure and solvent. Firstly, the linear increase of the benzene ring resulted in enhanced molecular aggregation and promoted the electrochemical reaction of the anode, due to increased molecular conjugation and higher lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO). The ECL efficiency of 4,4,4,4-(Ethene-1,1,2,2-tetrayl) tetrakis (([1,1,4,1-terphenyl]-4-carbaldehyde)) (T3) nanoparticles (NPs) with more benzene rings were 5558 times that of 4,4,4,4-(ethene-1,1,2,2-tetrayl) tetrabenzaldehyde (T1) NPs, and its relative ECL efficiency of T3 NPs reached 55.58% compared to the [Ru (bpy)3]2+/tripropylamine (TPrA) system. Furthermore, solvents with different polarities played a crucial role in modulating the degree of molecular aggregation, which also effectively facilitated the AIE process and reduced the aggregation-caused quenching (ACQ) effect caused by excessively dense aggregation. This aspect had often been overlooked in previous AIECL studies. T3 NPs demonstrated optimal ECL performance at fw = 70% (fw was the H2O content in tetrahydrofuran (THF)/H2O), and its ECL efficiency was 232 times greater than fw = 100% and 1853 times greater than fw = 0%. Additionally, it was found that melatonin (MT), one of the hormones widely used to treat insomnia, exhibited antioxidant and free radical scavenging properties, which exerted a significant quenching effect on the ECL of the T3 NPs/TPrA system. Consequently, a sensitive sensing platform was developed for MT with a low detection limit of 8.78 × 10−10 mol L−1, which promoted the application of AIECL in efficient ultra-sensitive biosensing.

The PVDF-HFP/Ag NWs-based wide electrochemical stability window ECL system for miRNA 21 detection in gastric cancer ascites

Due to the limitation of the electrochemical stability window (ESW), the high potential usually led to more side reactions during the electrochemical reaction. Therefore, a novel electrochemiluminescence (ECL) sensor with wide ESW was constructed in this study. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/silver nanowires (Ag NWs) composite was used as the substrate of the ECL biosensor. PVDF-HFP was good mechanical strength, high temperature stability and electrochemical stability. Meanwhile, Ag NWs with excellent electrical conductivity, light transmission and flexibility were employed to improve the charge transfer efficiency in the PVDF-HFP and provide binding sites for biomolecules. The optimized ESW of PVDF-HFP/Ag NWs/GCE was up to 3.717 V. Furthermore, titanium nanoclusters (Ti NCs) were synthesized and used as the aggregation-induced ECL (AIECL) probe. In addition, the biosensor achieved the good quantitative detection of miRNA 21 in ascites of gastric cancer patients within the linear range of 1 fM − 1 nM.

Ultrasensitive analysis of miRNA-141 based on coordination-mediated lamellar nanostructures of [-TPE-(COOH)4-Al-]nLNs with highly efficient aggregation-induced electrochemiluminescence

In this work, [-TPE-(COOH)4-Al-]nLNs with lamellar nanostructures (LNs) were conveniently synthesized through the high affinity coordination between Al3+ and carboxyl groups of 1,1,2,2-tetra(4-carboxylphenyl)ethylene (TPE-(COOH)4). As there was a strong chelate effect and π-π stacking, the [-TPE-(COOH)4-Al-]nLNs could extend not only on a flat surface, but also in a spatial stack. The obtained [-TPE-(COOH)4-Al-]nLNs exhibited excellent aggregation-induced electrochemiluminescence (AIECL) which was much stronger than that of the TPE-(COOH)4 monomer. Furthermore, through stacking and adjustment of Al3+, they also possessed higher electrochemiluminescence (ECL) efficiency compared to the crystal structure based on TPE-(COOH)4, which has a denser aggregation structure that causes aggregation-caused quenching (ACQ) phenomenon. Meanwhile, the [-TPE-(COOH)4-Al-]nLNs with Al3+ as the coordination center were superior to the coordination aggregation structures with heavy metal or rare metal ions as the coordination centers in terms of cost and biocompatibility. Using [-TPE-(COOH)4-Al-]nLNs as a luminescent material, an ultrasensitive ECL biosensor was fabricated for miRNA-141 detection combined with the cascaded strand displacement amplification (CSDA) strategy. Compared to traditional strand displacement amplification (SDA) reaction, the output DNA usually obtained in the first cycle could further return to attend multiple cycle amplification, resulting in the generation of more output DNA and an obvious signal amplification. The constructed biosensor showed excellent detection performance with a linear range from 1 × 10-18 M to 1 × 10-9 M and a detection limit of 1.2 × 10-19 M. This study provided a more convenient and effective AIECL strategy for tetraphenylethylene (TPE) derivatives and broadened the application of ECL technology in ultra-sensitive biochemical detection.

Encapsulation of Tetraphenylethylene Derivative in Liposome Vesicles as Promising Aggregation-Induced Electrochemiluminescence Emitter for Detection of Human Epidermal Growth Factor Receptor 2.

In this work, a sensitive signal-on electrochemiluminescence biosensor using liposome-encapsuled 1,1,2,2-tetra(4-carboxylphenyl)ethylene (TPE) as a promising aggregation-induced electrochemiluminescence (AIECL) emitter for detection of biomarkers was developed. Aggregation-induced enhancement occurs internally through the spatial confinement effect and intramolecular self-encapsulation of encapsulating TPE and triethylamine (TEA) molecules in liposome cavities. Peptide sequence WTGWCLNPEESTWGFCTGSF (WF-20) was used to replace the antibody for reducing the steric hindrance of the sensing surface while taking into account the affinity. The proposed sensing strategies showed satisfactory properties for detection of human epidermal growth factor receptor 2 (HER2) ranging from 0.01 to 500 ng/mL with a limit of detection of 6.65 pg/mL. The results confirmed that encapsulation of luminescent molecules in the vesicle structure for triggering the AIECL phenomenon is a promising method to prepare a signal label for a trace detection biomarker.

Porphyrins-mediated interfacial charge modulation to enhance aggregation-induced electrochemiluminescence of iridium complex for ultrasensitive bioassay

Iridium (III) complexes have attracted much attention as electrochemiluminescence (ECL) luminophores, but their inferior ECL efficiency (ΦECL) in the aqueous solutions has impeded further applications. Herein, meso-tetra (4-carboxyphenyl) porphine (TCPP) was developed as interfacial charge mediator to dramatically enhance aggregation-induced electrochemiluminescence (AIECL) of tris (2-phenylpyridine) iridium(Ⅲ) (Ir(ppy)3), thus improving its ΦECL. As an interfacial charge mediator, TCPP can efficiently accelerate the electrooxidation of Ir(ppy)3 through higher hole transport kinetics. Meanwhile, it is found that its rigid structure can suppress the motions of Ir(ppy)3 to elevate radiative transition efficiency in emission process. Thus, a significantly enhanced AIECL was achieved for aggregation-induced emission luminogens (AIEgens) Ir(ppy)3 @TCPP. Compared to monomer Ir(ppy)3, Ir(ppy)3 @TCPP increased ECL efficiency by 18 times. Ir(ppy)3 @TCPP served as AIEgens to construct ECL biosensor for detecting miRNA-126. Strand-displacement amplification (SDA) coupled with rolling-circle amplification (RCA) for improving the conversion efficiency of target miRNA-126. The integration of excellent AIECL characteristics of Ir(ppy)3 @TCPP and outstanding amplification efficiency of SDA-RCA endowed sensing system with high sensitivity. The limit of detection (LOD) was as low as 17 aM. This work creatively exploited interfacial charge modulation as an effective way to enhance AIECL efficiency. The prepared Ir(ppy)3 @TCPP provided much attractive ECL system for bioanalysis.

Tetraphenylethylene-doped covalent organic frameworks as a highly efficient aggregation-induced electrochemiluminescence emitter for ultrasensitive miRNA-21 analysis

MicroRNAs (miRNAs) as a well-known kind of cancer marker are closely associated with the formation and metastasis of tumors. Here, a novel tetraphenylethylene (TPE)-doped covalent organic frameworks (TPE-COFs) with strong aggregation-induced electrochemiluminescence (AIECL) response was synthesized and introduced to construct an ultrasensitive biosensor for the detection of miRNA-21. The strong aggregation-induced emission (AIE) response was obtained because the molecular motion of TPE was restricted by COFs which had the porosity and highly ordered topological structure. Meanwhile, the porous structure of COFs allowed TPE to react with electrochemiluminescence (ECL) coreactants more effectively. Furthermore, COFs significantly improved the electron transport efficiency of the entire ECL system. All of these endowed the TPE-COFs with superior AIECL performance. Then, a TPE-COFs based ECL resonance energy transfer (ECL-RET) system was constructed for ultrasensitive miRNA-21 biosensing with differential signal readout. The proposed assays exhibited excellent sensitivity with a wide dynamic range from 10 aM to 1 pM and a low detection limit of 2.18 aM. Therefore, these indicated that doping TPE in COFs was a creative way to develop functional COFs and provided an effective way for enhancing AIECL. Furthermore, this work boarded the application of AIECL in analytical chemistry.

Tetraphenylethene‐Based Multicomponent Platinum (II) Metallacages with Tunable Luminescence and Aggregation‐Induced Electrochemiluminescence Properties

AbstractMetallacages (MCs) are one kind of functional 3D supramolecular complexes with controllable structures, their special cage structures lead to diverse photophysical properties, enabling their wide application in catalysis, bio‐imaging, and organic light‐emitting devices. Herein, a series of tetraphenylene (TPE)‐based MCs with tunable structures is reported via the coordination‐driven self‐assembly strategy. The resulting MCs demonstrate tunable fluorescence (FL) and electrochemiluminescence (ECL) due to their size‐dependent energy gaps. More importantly, their aggregation‐induced ECL (AIECL) property is observed, and the corresponding self‐catalytic ECL enhancement mechanism is proposed. In addition, a sensitive ECL sensor toward iodide ions (I−) is developed based on the competitive coordination of I− with the pyridine group of ligands. This study may promote the design of MCs materials and broaden their applications in the ECL study.

Aggregation-Induced Electrochemiluminescence Based on a Zinc-Based Metal-Organic Framework and a Double Quencher Au@UiO-66-NH2 for the Sensitive Detection of Amyloid β 42 via Resonance Energy Transfer.

A novel sandwich electrochemiluminescence (ECL) biosensor based on aggregation-induced electrochemiluminescence resonance energy transfer (AIECL-RET) was designed for the sensitive detection of amyloid β42 (Aβ42). The synthesized silver nanoparticle-functionalized zinc metal-organic framework (Ag@ZnPTC) and gold nanoparticle-functionalized zirconium organic framework (Au@UiO-66-NH2) were used as the ECL donor and acceptor, respectively. AgNPs were generated in situ on the surface of ZnPTC, which further improved the ECL intensity and the loading of antibody 1 (Ab1). Under the optimized experimental conditions, the linear detection range of Aβ42 concentration was 10 fg/mL to 100 ng/mL, and the detection limit was 2.4 fg/mL (S/N = 3). The recoveries of Aβ42 were 99.5-104%. The method has good stability, repeatability, and specificity. Ag@ZnPTC/Au@UiO-66-NH2 provides an assay for the sensitive detection of disease biomarkers.

Aggregation-Induced Electrochemiluminescence Frame of Silica-Confined Tetraphenylethylene Derivative Matrixes for CD44 Detection via Peptide Recognition.

The theory of aggregation-induced electrochemiluminescence (AIECL) has introduced new vitality into preparing new electrochemiluminescence (ECL) emitters. However, the progress in the application of biosensing analysis has been slow owing to the lack of AIECL-based functional nanomaterials. Herein, a biosensor was fabricated using mesoporous silica nanosphere (MSN) matrix-confined 1,1,2,2-tetra(4-carboxylphenyl)ethylene (TPE) as a well-ordered ECL emitter and self-designed WHPWSYC (WC-7) heptapeptide as the target capturer for CD44 detection. TPE and its co-reactant, triethylamine (TEA), were encapsulated in the MSN nanomatrix to enhance the radiation transition by limiting the intramolecular rotation of TPE molecule benefit from the spatial confinement effect, and the ECL intensity is self-enhanced by replacing electron free diffusion in the conventional ECL system. MSN-TPE-TEA can act as satisfactory sensing substrates that improve the reproducibility and batch-to-batch consistency of biosensors and functions as a stable signal label for trace analysis of biomarkers. As a substitute for antibody and hyaluronic acid, the WC-7 heptapeptide significantly reduced the steric hindrance of the sensing interface in CD44 affinity tests. Combined with the DNA strand displacement reaction, this strategy shows a good ECL response to standard CD44 antigen and MCF-7 cells with different concentrations, which is another feasible method for detecting CD44 in body fluids or living cells.

A cellular NO sensor based on aggregation-induced electrochemiluminescence and photoelectron transfer of a novel ruthenium(II) complex

Here, we present a dual amplification strategy of electrochemiluminescence (ECL) based on aggregation-induced and photoelectron transfer (PET) inhibition using a designed ruthenium-based complex for the highly sensitive detection of nitric oxide (NO). A novel ruthenium(II) complex ([Ru(phen)2(DA-phen)]2+, DA-phen: 5,6-diamino-1,10-phenanthroline) was synthesized that uses the O-diaminophenyl group for specific recognition of NO and the ruthenium metal center with 1,10-phenanthroline as the luminophore. In the first step, the 1,10-phenanthroline groups function as the aggregation part. Increasing the volume fraction of a poor solution (H2O: fw, v%) in the DMSO mixture system from 0% to 80% yielded an increase in the fluorescence (FL) and electrochemiluminescence (ECL) intensities by 3- and 42-fold when compared with the FL and ECL intensities in pure DMSO, respectively. The second step involves a PET process. Reacting the complex with NO in physiological pH aqueous media under aerobic conditions to afford its triazole derivative, [Ru(phen)2(TA-phen)]2+ (TA-phen: 5,6-triazole-1,10-phenanthroline), inhibited the electron transfer process, yielding a remarkable further increase in the FL and ECL efficiencies of the Ru(II) complex. The ECL intensities was 86-fold higher in the presence of NO. This dual amplification strategy enabled the sensitive detection of NO from 1.8 × 10–10 to 1.8 × 10–5 M with a detection limit of 60 pM (S/N = 3) and offered excellent specificity with no detectable interference by RNS and metal ions. Furthermore, selective NO detection in cells was achieved using this complex. Thus, this assay should be suitable for applications in environmental toxicology research and early clinical diagnosis.