Aggregation-induced Electrochemiluminescence Research Articles

Analysis of okadaic acid using electrochemiluminescence imaging on microfluidic biosensing chip

The sensitivity and specificity of electrochemiluminescence (ECL)-based biosensor directly rely on the property of luminophor, the type of sensing carriers and the effectiveness of signal amplification used in the sensor design, which poses a major challenge to manage these elements simultaneously. In this work, an aggregation-induced electrochemiluminescence (AIECL) microfluidic sensing chip using 4′,4″,4‴,4‴'-(ethene-1,1,2,2-tetrayl)tetrabiphenyl-4-carboxylic acid (TPE)-derived hafnium-based metal-organic framework (Hf-MOF) as emitter was developed. An easily overlooked marine pollutant, okadaic acid (OA) with different concentrations ranging from 5.00 ng/mL to 1.50 × 104 ng/mL at the electrode is visualized imaging benefit from high luminescence efficiency of Hf-MOF coupled the rolling circle amplification strategy assisted by trans-cleavage activity of CRISPR/Cas12a. These highlights will solve the long-lasting task in the accurate analysis of small molecule pollutants, which can be able to provide more worthy reference solution about construction of novel ECL luminophor and signal extraction of low-abundance disease-related biomarkers.

Multiquenching-Based Aggregation-Induced Electrochemiluminescence Sensing for Highly Sensitive Detection of the SARS-CoV-2 N Protein.

The rapid epidemic around the world of coronavirus disease 2019 (COVID-19), caused by the SARS-CoV-2 virus, proves the need and stimulates efforts to explore efficient diagnostic tests for the sensitive detection of the SARS-CoV-2 virus. An aggregation-induced electrochemiluminescence (AIECL) sensor was developed for the ultrasensitive detection of the SARS-CoV-2 nucleocapsid (N) protein in this work. Tetraphenylethylene doped in zeolite imidazole backbone-90 (TPE-ZIF-90) showed highly efficient aggregation-induced emission (AIE) to endow TPE-ZIF-90 with high ECL intensity. Upon the capture of the SARS-CoV-2 N protein by immune recognition, an alkaline phosphatase (ALP)-modified gold nanoparticle (AuNP)-decorated zinc oxide (ZnO) nanoflower (ALP/Au-ZnO) composite was introduced on the sensing platform, which catalyzed L-ascorbate-2-phosphate trisodium salt (AA2P) to produce PO43- and ascorbic acid (AA). Based on a multiquenching of the ECL signal strategy, including resonance energy transfer (RET) between TPE-ZIF-90 and Au-ZnO, disassembly of TPE-ZIF-90 triggered by the strong coordination between PO43- and Zn2+, and RET between TPE-ZIF-90 and AuNPs produced in situ by the AA reductive reaction, the constructed AIECL sensor achieved highly sensitive detection of the SARS-CoV-2 N protein with a low limit of detection of 0.52 fg/mL. With the merits of high specificity, good stability, and proven application ability, the present RET- and enzyme-triggered multiquenching AIECL sensor may become a powerful tool in the field of SARS-CoV-2 virus diagnosis.

1,1,2,2-Tetra(4-carboxylphenyl)ethylene-Based Metal-Organic Gel as Aggregation-Induced Electrochemiluminescence Emitter for the Detection of Aflatoxin B1 Based on Nanosurface Energy Transfer.

In this Letter, a sensitive DNA sensing platform was developed using an indium-ion-coordinated 1,1,2,2-tetra(4-carboxylphenyl)ethylene (TPE) metal-organic gel (In-MOG) as an aggregation-induced electrochemiluminescence (AIECL) emitter and nanosurface energy transfer (NSET) as an efficient quenching strategy for detecting aflatoxin B1 (AFB1), the most dangerous food toxin. The coordination occurred in indium ions, and carboxyl groups restricted the internal rotation and vibration of TPE molecules, forcing them to release photons via radiative transitions. The quenchers of microfluidic-produced gold nanoparticles were embedded in a long-tailed triangular DNA structure, where the quenching phenomenon aligned with the theory of ECL-NSET under the overlap of spectra and appropriate donor-acceptor spacing. The proposed analytical method showed a sensitive ECL response to AFB1 in the wide concentration range of 0.50-200.00 ng/mL with a limit of detection of 0.17 ng/mL. Experimental results confirmed that constraining luminescent molecules using coordination and bonding to trigger the AIECL phenomenon was a promising method to prepare signal labels for the trace detection of food toxins.

Aggregation-induced electrochemiluminescence based on intramolecular charge transfer and twisted molecular conformation for label-free Immunoassay

Organic emitters with exceptional properties exhibit significant potential in the field of aggregation-induced electrochemiluminescence (AIECL); however, their practicality is impeded by limited ECL efficiency (ΦECL). This paper investigates a novel type of AIECL emitter (BDPPA NPs), where an efficient intramolecular charge transfer (ICT) effect and highly twisted conformation contribute to a remarkable enhancement of ECL. The ICT effect reduces the electron transfer path, while the twisted conformation effectively restricts π-π stacking and intramolecular motions. Intriguingly, compared to the standard system of [Ru(bpy)32+]/TPrA, bright emissions with up to 54 % ΦECL were achieved, enabling direct visual observation of ECL through the co-reactant route. The label-free immunosensor exhibited distinguished performance in detecting SARS-CoV-2 N protein across an exceptionally wide linear range of 0.001–500 ng mL−1, with a remarkably low detection limit of 0.28 pg mL−1. Furthermore, this developed ECL platform exhibited excellent sensitivity, specificity, and stability characteristics, providing an efficient avenue for constructing platforms for bioanalysis and clinical diagnosis analysis.

Conjugated polymer-encapsulation-manipulated aggregation-induced electrochemiluminescence of tetraphenylethylene for sensitive malathion analysis

Tetraphenylethylene (TPE) and its derivatives with tunable structure and excellent photoelectric performance have aroused great concern in the field of electrochemiluminescence (ECL), but improving their ECL efficiency remains an enormous challenge in ECL bioanalysis. Herein, an encapsulation-manipulated aggregation-induced ECL (EM-AIECL) strategy was explored to effectively boost the ECL efficiency of TPE. Large π-conjugated polymer poly[2,5-dioctyl-1,4-phenylene] (PDP) was creatively developed as encapsulation matrix to envelop TPE molecules via hydrophobic interactions. The resulting complex TPE@PDP nanoparticles (NPs) not only restricted the molecule motion of TPE due to space limitation, but also inhibited the aggregation-caused quenching effect caused by TPE crystals featuring dense aggregation structure. Furthermore, the robust electronic coupling between PDP and TPE aggregates enabled superior charge transport within TPE@PDP NPs, thus yielding strong AIECL. As compared to TPE crystals, TPE@PDP NPs showcased 3.87-fold enhancement of ECL intensity. Impressively, TPE@PDP NPs coupled a three-dimensional DNA walker-assisted multiple rolling circle amplification strategy to construct an ECL sensing platform for malathion analysis, and a wide linear range of 5.0 fM ∼ 0.5 μM and low limit of detection of 0.9 fM were obtained. EM-AIECL strategy provides a new idea for designing organic AIECL luminophors, and opens an avenue for detecting pesticides specifically and sensitively.

Dual emitting aggregation-induced electrochemiluminescence from tetrastyrene derivative for chloramphenicol detection

Chloramphenicol (CAP) poses a threat to human health due to its toxicity and bioaccumulation, and it is very important to measure it accurately and sensitively. This work explored a host-guest recognition strategy to mediate dual aggregation-induced electrochemiluminescence (AIECL) of 1,1,2,2-tetrakis(4-(pyridin-4-yl) phenyl)-ethene (TPPE) for ratio detection of CAP, in which, cucurbit[8]uril (CB[8]) served as host to assemble guest TPPE. The resulting supramolecular complex CB[8]-TPPE exhibited excellent dual-AIECL-emission with signal strength approximately four times that of TPPE aggregates and black hole quencher-1 (BHQ1) could efficiently quench dual-AIECL signal. CB[8]-TPPE coupled dual-function quencher BHQ1 and high-efficiency DNA reactor to achieve ultra-sensitive detection of CAP, exhibiting a linearity range of 10 fmol·L−1–100 nmol·L−1 and limit of detection of 1.81 fmol·L−1. CB[8]-TPPE provides a novel way to improve the dual-emission of TPE derivatives and sets up a promising platform for CAP detection, demonstrating a good practical application potential.

Nanobody-Based Microfluidic Immunosensor Chip Using Tetraphenylethylene-Derived Covalent Organic Frameworks as Aggregation-Induced Electrochemiluminescence Emitters for the Detection of Thymic Stromal Lymphopoietin.

In this letter, a sensitive microfluidic immunosensor chip was developed using tetrakis(4-aminophenyl)ethene (TPE)-derived covalent organic frameworks (T-COF) as aggregation-induced electrochemiluminescence (AIECL) emitters and nanobodies as efficient immune recognition units for the detection of thymic stromal lymphopoietin (TSLP), a novel target of asthma. The internal rotation and vibration of TPE molecules were constrained within the framework structure, forcing nonradiative relaxation to convert into pronounced radiative transitions. A camel-derived nanobody exhibited superior specificity, higher residual activity and epitope recognition postcuring compared to monoclonal antibodies. Benefiting from the affinity between silver ions (Ag+) and cytosine (C), a double-stranded DNA (dsDNA) embedded with Ag+ was modified onto the surface of TSLP. A positive correlation was obtained between the TSLP concentration (1.00 pg/mL to 4.00 ng/mL) and ECL intensity, as Ag+ was confirmed to be an excellent accelerator of the generation of free radical species. We propose that utilizing COF to constrain luminescent molecules and trigger the AIECL phenomenon is another promising method for preparing signal tags to detect low-abundance disease-related markers.

Solvent Regulation Induced Cathode Aggregation-Induced Electrochemiluminescence of Tetraphenylethylene Nanoaggregates for Ultrasensitive Zearalenone Analysis.

Zearalenone (ZEN) is an extremely hazardous chemical widely existing in cereals, and its high-sensitivity detection possesses significant significance to human health. Here, the cathodic aggregation-induced electrochemiluminescence (AIECL) performance of tetraphenylethylene nanoaggregates (TPE NAs) was modulated by solvent regulation, based on which an electrochemiluminescence (ECL) aptasensor was constructed for sensitive detection of ZEN. The aggregation state and AIECL of TPE NAs were directly and simply controlled by adjusting the type of organic solvent and the fraction of water, which solved the current shortcomings of low strength and weak stability of the cathode ECL signal for TPE. Impressively, in a tetrahydrofuran-water mixed solution (volume ratio, 6:4), the relative ECL efficiency of TPE NAs reached 16.03%, which was 9.2 times that in pure water conditions, and the maximum ECL spectral wavelength was obviously red-shifted to 617 nm. In addition, "H"-shape DNA structure-mediated dual-catalyzed hairpin self-assembly (H-D-CHA) with higher efficiency by the synergistic effect between the two CHA reactions was utilized to construct a sensitive ECL aptasensor for ZEN analysis with a low detection limit of 0.362 fg/mL. In conclusion, solvent regulation was a simple and efficient method for improving the performance of AIECL materials, and the proposed ECL aptasensor had great potential for ZEN monitoring in food safety.

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.