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.

Highly Electroactive Co2+-Based Metal-Organic Frameworks as an Efficient Coreaction Accelerator for Amplifying Near-Infrared Electrochemiluminescence of Gold Nanoclusters in Biomarkers Immunoassay.

Metal nanoclusters (NCs) as a new kind of luminophore have acquired sufficient interest, but their widespread application is restricted on account of their relatively low electrochemiluminescence (ECL) efficiency. Then, aqueous metal NCs with high ECL efficiency were strongly anticipated, especially for the ultrasensitive analysis of biomarkers. Herein, a near-infrared (NIR) ECL biosensing strategy for the test of neuron-specific enolase (NSE) was proposed by utilizing N-acetyl-l-cysteine (NAC)- and cysteamine (Cys)-stabilized gold NCs (NAC/Cys-AuNCs) as ECL emitters with the NIR ECL emission around 860 nm and a metal-organic framework/palladium nanocubes (ZIF-67/PdNCs) hybrid as the coreaction accelerator through their admirable electrocatalytic activity. The NIR emission would reduce photochemical injury to the samples and even realize nondestructive analysis with highly strong susceptibility and suitability. Furthermore, the utilization of ZIF-67/PdNCs could improve the ECL response of NAC/Cys-AuNCs by facilitating the oxidation of the coreactant triethylamine (TEA), leading to the production of a larger quantity of reducing intermediate radical TEA•+. Consequently, NAC/Cys-AuNCs with ZIF-67/PdNCs displayed 2.7 fold enhanced ECL emission compared with the single NAC/Cys-AuNCs using TEA as the coreactant. In addition, HWRGWVC (HWR), a heptapeptide, was introduced to immobilize antibodies for the specially binding Fc fragment of the antibodies, which improved the binding efficiency and sensitivity. As a result, a "signal-on" immunosensor for NSE analysis was obtained with an extensive linear range of 0.1 to 5 ng/mL and a low limit of detection (0.033 fg/mL) (S/N = 3). This study provides a wonderful method for the development of an efficient nondestructive immunoassay.

Multifunctional Supramolecular Hydrogel Modulated Heterojunction Interface Carrier Transport Engineering Facilitates Sensitive Photoelectrochemical Immunosensing.

Highly responsive interface of semiconductor nanophotoelectrochemical materials provides a broad development prospect for the identification of low-abundance cancer marker molecules. This work innovatively proposes an efficient blank WO3/SnIn4S8 heterojunction interface formed by self-assembly on the working electrode for interface regulation and photoregulation. Different from the traditional biomolecular layered interface, a hydrogel layer containing manganese dioxide with a wide light absorption range is formed at the interface after an accurate response to external immune recognition. The formation of the hydrogel layer hinders the effective contact between the heterojunction interface and the electrolyte solution, and manganese dioxide in the hydrogel layer forms a strong competition between the light source and the substrate photoelectric material. The process effectively improves the carrier recombination efficiency at the interface, reduces the interface reaction kinetics and photoelectric conversion efficiency, and thus provides strong support for target identification. Taking advantage of the process, the resulting biosensors are being explored for sensitive detection of human epidermal growth factor receptor 2, with a limit of detection as low as 0.037 pg/mL. Also, this study contributes to the advancement of photoelectrochemical biosensing technology and opens up new avenues for the development of sensitive and accurate analytical tools in the field of bioanalysis.

Electrochemiluminescence quenching effect of Cu2O towards flower-like ferric ion-doped g-C3N4 and its application for Cyfra21-1 immunosensing.

In this article, ferric ion-doped floral graphite carbon nitride (Fe-CN-3, energy donor) was used to construct the substrate of the immunosensor and copper oxide nanocubes (Cu2O, energy acceptor) were taken as an efficient ECL quenching probe. A sandwich quench electrochemiluminescence (ECL) immunosensor for soluble cytokeratin 19 fragment (Cyfra21-1) detection was preliminarily developed based on a novel resonant energy transfer donor-acceptor pair. Fe-CN-3, a carbon nitride that combines the advantages of metal ion doping as well as morphology modulation, is used in ECL luminophores to provide more excellent ECL performance, which makes a significant contribution to the application and development of carbon nitride in the field of ECL biosensors. The regular shape, high specific surface area and excellent biocompatibility of the quencher Cu2O nanocubes facilitate the labeling of secondary antibodies and the construction of sensors. Meanwhile, as an energy acceptor, the UV absorption spectrum of Cu2O can overlap efficiently with the energy donor's ECL emission spectrum, making it prone to the occurrence of ECL-RET and thus obtaining an excellent quenching effect. These merits of the donor-acceptor pair enable the sensor to have a wide detection range of 0.00005-100 ng/mL and a low detection limit of 17.4 fg/mL (S/N = 3), which provides a new approach and theoretical basis for the clinical detection of lung cancer.

Self-powered photoelectrochemical aptasensor for fumonisin B1 detection based on a Z-scheme ZnIn2S4/WO3 photoanode.

The incidence of esophageal cancer is positively associated with fumonisin contamination. It is necessary to develop methods for the rapid detection of fumonisins. In this work, a self-powered photoelectrochemical aptamer sensor based on ZnIn2S4/WO3 photoanode and Au@W-Co3O4 photocathode is proposed for the sensitive detection of fumonisin B1 (FB1). Among them, under visible light irradiation, the Z-type heterostructure of ZnIn2S4/WO3 acts as a photoanode to improve the electron transfer rate, which contributes to the enhancement of the photocathode signal and lays the foundation for a wider detection range. The Au@W-Co3O4 photocathode as a sensing interface reduces the probability of false positives (comparison of anode sensing platforms). The PEC sensor has a good working performance in the detection range (10 pg/mL-1000 ng/mL) with a detection limit of 2.7 pg/mL (S/N = 3). In addition, the sensor offers good selectivity, stability and excellent recoveries in real sample analysis. This work is expected to play a role in the field of analyzing environmental toxins.

FeNi-MIL-88B-based electrochemiluminescence immunosensor for ultra-sensitive detection of CD44 protein via dual-quenching strategy.

BACKGROUND: Cluster of Differentiation 44 (CD44) is considered an important biomarker for various cancers, and achieving highly sensitive detection of CD44 is crucial, which plays a significant role in tumor invasion and metastasis, providing essential information for clinical tumor diagnosis. Commonly used methods for analysis include fluorescence spectroscopy (FL), photoelectrochemical analysis (PEC), electrochemical analysis (EC), and commercial ELISA kits. Although these methods offer high sensitivity, they can be relatively complex to perform experimentally. Electrochemiluminescence (ECL) has gained widespread research attention due to its high sensitivity, ease of operation, effective spatiotemporal control, and close to zero background signal. RESULTS: In this work, a sandwich-type ECL immunosensor for detecting CD44 was constructed using luminol as a luminophore. In this sensing platform, bimetallic MOFs (Pd@FeNi-MIL-88B) loaded with palladium nanoparticles (Pd NPs) were used as a novel enzyme mimic, exhibiting excellent catalytic performance towards the electroreduction of H2O2. The hybrids provided a strong support platform for luminol and antibodies, significantly enhancing the initial ECL signal of luminol. Subsequently, core-shell Au@MnO2 nanocomposites were synthesised by gold nanoparticles (Au NPs) encapsulated in manganese dioxide (MnO2) thin layers, as labels. In the luminol/H2O2 system, Au@MnO2 exhibited strong light absorption in the broad UV-vis spectrum, similar to the black body effect, and the scavenging effect of Mn2+ on O2•-, which achieved the dual-quenching of ECL signal. Under the optimal experimental conditions, the immunosensor demonstrated a detection range of 0.1 pg mL-1 - 100 ng mL-1, with a detection limit of 0.069 pg mL-1. SIGNIFICANCE: Based on Pd@FeNi-MIL-88B nanoenzymes and Au@MnO2 nanocomposites, a dual-quenching sandwich-type ECL immunosensor for the detection of CD44 was constructed. The proposed immunosensor exhibited excellent reproducibility, stability, selectivity, and sensitivity, and provided a valuable analytical strategy and technical platform for the accurate detection of disease biomarkers, and opened up potential application prospects for early clinical treatment.

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.

A Co-Reactive Immunosensor Based on Ti3C2Tx MXene@TiO2-MoS2 Hybrids Promoting luminol@Au@Ni-Co NCs Electrochemiluminescence for CYFRA 21-1 Detection.

The construction of assays is capable of accurately detecting cytokeratin-19 (CYFRA 21-1), which is critical for the rapid diagnosis of nonsmall cell lung cancer. In this work, a novel electrochemiluminescence (ECL) immunosensor based on the co-reaction promotion of luminol@Au@Ni-Co nanocages (NCs) as ECL probe by Ti3C2Tx MXene@TiO2-MoS2 hybrids as co-reaction accelerator was proposed to detect CYFRA 21-1. Ni-Co NCs, as a derivative of Prussian blue analogs, can be loaded with large quantities of Au NPs, luminol, and CYFRA 21-1 secondary antibodies due to their high specific surface area. To further improve the sensitivity of the developed ECL immunosensor, Ti3C2Tx MXene@TiO2-MoS2 hybrids were prepared by in situ growth of TiO2 nanosheets on highly conductive Ti3C2Tx MXene, and MoS2 was homogeneously grown on Ti3C2Tx MXene@TiO2 surfaces by the hydrothermal method. Ti3C2Tx MXene@TiO2-MoS2 hybrids possess excellent catalytic performance on the electro-redox of H2O2 generating more O2·- and obtaining optimal ECL intensity of the luminol/H2O2 system. Under the appropriate experimental conditions, the quantitative detection range of CYFRA 21-1 was from 0.1 pg mL-1 to 100 ng mL-1, and the limit of detection (LOD) was 0.046 pg mL-1. The present sensor has a lower LOD with a wider linear range, which provides a new analytical assay for the early diagnosis of small-cell-type lung cancer labels.

Double-Amplified Electrochemiluminescence Immunoassay Sensor for Highly Sensitive Detection of CA19-9 Using a Ternary Semiconductor CdSSe.

In this paper, an electrochemiluminescence (ECL) immunosensor for ultrasensitive detection of CA19-9 was constructed using ternary compound CdSSe nanoparticles as ECL emitter. The immunosensor employs Cu2S and gold-doped diindium trioxide (Au-In2O3) nanocubes as coreaction accelerators to achieve a double-amplification strategy. In general, a hexagonal maple leaf-shaped Cu2S with a large surface area was selected as the template, and the in situ growth of CdSSe on its surface was achieved using a hydrothermal method. The presence of Cu2S not only inhibited the aggregation of CdSSe nanoparticles to reduce their surface energy but also acted as an ECL cathode coreaction promoter, facilitating the generation of SO4•-. Consequently, the ECL intensity of CdSSe was significantly enhanced, and the reduction potential was significantly lower. In addition, the template method was employed to synthesize Au-In2O3 nanocubes, which offers the advantage of directly connecting materials with antibodies, resulting in a more stable construction of the immunosensor. Furthermore, In2O3 serves as a coreaction promoter, enabling the amplification strategy for ECL intensity of CdSSe, thus contributing to the enhanced sensitivity and performance of the immunosensor. The constructed immunosensor exhibited a wide linear range (100 µU mL-1 to 100 U mL-1) and a low detection limit of 80 µU mL-1, demonstrating its high potential and practical value for sensitive detection of CA19-9.

Ternary electrochemiluminescence quenching effects of CuFe2O4@PDA-MB towards self-enhanced Ru(dcbpy)32+ functionalized 2D metal-organic layer and application in carcinoembryonic antigen immunosensing.

BACKGROUND: Carcinoembryonic antigen (CEA) is a significant glycosylated protein, and the unusual expression of CEA in human serum is used as a tumor marker in the clinical diagnosis of many cancers. Although scientists have reported many ways to detect CEA in recent years, such as electrochemistry, photoelectrochemistry, and fluorescence, their operation is complex and sensitivity is average. Therefore, finding a convenient method to accurately detect CEA is significance for the prevention of malignant tumors. With high sensitivity, quick reaction, and low background, electrochemiluminescence (ECL) has emerged as an essential method for the detection of tumor markers in blood. RESULTS: In this work, a "signal on-off" ECL immunosensor for sensitive analysis of CEA ground on the ternary extinction effects of CuFe2O4@PDA-MB towards a self-enhanced Ru(dcbpy)32+ functionalized metal-organic layer [(Hf)MOL-Ru-PEI-Pd] was prepared. The high ECL efficiency of (Hf)MOL-Ru-PEI-Pd originated from the dual intramolecular self-catalysis, including intramolecular co-reaction between polyethylenimine (PEI) and Ru(dcbpy)32+. At the same time, loading Pd NPs onto (Hf)MOL-Ru-PEI could not only improve the electron transfer ability of (Hf)MOL-Ru-PEI, but also provide more active sites for the reaction of Ru(dcbpy)32+ and PEI. In the presence of CEA, CuFe2O4@PDA-MB-Ab2 efficiently quenches the excited states of (Hf)MOL-Ru-PEI-Pd by PDA, Cu2+, and methylene blue (MB) via energy and electron transfer, leading to an ECL signal decrease. Under optimal conditions, the proposed CEA sensing strategy showed satisfactory properties ranging from 0.1 pg mL-1 to 100 ng mL-1 with a detection limit of 20 fg mL-1. SIGNIFICANCE: The (Hf)MOL-Ru-PEI-Pd and CuFe2O4@PDA-MB were prepared in this work might open up innovative directions to synthesize luminescence-functionalized MOLs and effective quencher. Besides, the ECL quenching mechanism of Ru(dcbpy)32+ by MB was successfully explained by the inner filter effect (ECL-IFE). At last, the proposed immunosensor exhibits excellent repeatability, stability, and selectivity, and may provide an attractive way for CEA and other disease markers determination.

Antioxidant Cascade Modulated Electrochemiluminescence by a Biomimetic Metal-Organic Framework with Dual Enzymatic Activity for Disease Marker Immunoassays.

High-performance electrochemiluminescence is a significant approach for the examination of disease biomarkers, and the utilization of innovative electrochemiluminescence detection systems represents a viable strategy to enhance the efficacy of ECL analysis. In this work, the biomimetic engineering metal-organic framework (MOF-818) has realized the ultrasensitive ECL immunoassay of disease markers based on the guidance of the free radical scavenging strategy provided by the antioxidant cascade. Initially, we synthesized a hydrogen-bonded organic framework (HOF) consisting of luminol and three active ligands based on simple room-temperature self-assembly. The luminol-HOF (L-HOF) showed more stable and brighter ECL luminescence activity than the monomer due to the nano-confinement enhancement of the coordinated luminol units. Subsequently, MOF-818 with biomimetic superoxide dismutase (SOD) and catalase (CAT) activities were recruited for the first time as quenching agents for sandwich immunoassay mode. The enzyme activity leads to the reverse transformation of superoxide anion radicals (O2-) and further antioxidant decomposition, decreasing in the responsiveness of luminol ECL signals. Using carcinoembryonic antigen (CEA) as an analytical model, a detection limit of 0.457 pg/mL was obtained within a detection range of 0.001-50 ng/mL. We believe that this novel sandwich sensing model based on enzyme activity provides a meaningful potential tool for precise detection, expanding the broader application of nanoenzymes in analysis.

DNA Tile and Invading Stacking Primer-Assisted CRISPR-Cas12a Multiple Amplification System for Entropy-Driven Electrochemical Detection of MicroRNA with Tunable Sensitivity.

Conventional electrochemical detection of microRNA (miRNA) encounters issues of poor sensitivity and fixed dynamic range. Here, we report a DNA tile and invading stacking primer-assisted CRISPR-Cas12a multiple amplification strategy to construct an entropy-controlled electrochemical biosensor for the detection of miRNA with tunable sensitivity and dynamic range. To amplify the signal, a cascade amplification of the CRISPR-Cas12a system along with invading stacking primer signal amplification (ISPSA) was designed to detect trace amounts of miRNA-31 (miR-31). The target miR-31 could activate ISPSA and produce numerous DNAs, triggering the cleavage of the single-stranded linker probe (LP) that connects a methylene blue-labeled DNA tile with a DNA tetrahedron to form a Y-shaped DNA scaffold on the electrode. Based on the decrease of current, miR-31 can be accurately and efficiently detected. Impressively, by changing the loop length of the LP, it is possible to finely tune the entropic contribution while keeping the enthalpic contribution constant. This strategy has shown a tunable limit of detection for miRNA from 0.31 fM to 0.56 pM, as well as a dynamic range from ∼2200-fold to ∼270,000-fold. Moreover, it demonstrated satisfactory results in identifying cancer cells with a high expression of miR-31. Our strategy broadens the application of conventional electrochemical biosensing and provides a tunable strategy for detecting miRNAs at varying concentrations.

Long noncoding RNA XLOC_006786 inhibits the proliferation, invasion and metastasis of osteosarcoma cells through NOTCH3 signaling pathway by targeting miR-491-5p.

Recent research has indicated that Long noncoding RNAs (LncRNAs) are crucial in many disorders, especially tumors. However, the exact role of LncRNA XLOC_006786 (LncRNA-SPIDR-2:1) in malignancies, especially in human osteosarcoma, is unclear. The results of RT‒qPCR, western blotting, CCK-8 assays, and Transwell assays showed that LncRNA XLOC_006786 inhibited osteosarcoma cell proliferation, invasion, and migration, indicating that it may be a tumor suppressor gene in osteosarcoma. We found that LncRNA XLOC_006786 negatively regulated NOTCH3, which is an oncogenic gene in osteosarcoma, as we previously reported. Bioinformatics analysis showed that miR-491-5p may be a direct target of LncRNA XLOC_006786, while NOTCH3 is a key target of miR-491-5p. Then, we verified that LncRNA XLOC_006786 could prevent lung metastatic osteosarcoma in vivo. Taken together, our research showed that LncRNA XLOC_006786 suppresses osteosarcoma proliferation, invasion, and metastasis through the NOTCH3 signaling pathway by targeting miR-491-5p.

Electrochemiluminescence Sensor with Controlled-Release Triggering Electrostatic Attraction Elimination Mechanism for Trenbolone Trace Detection.

A controlled-release strategy can meet the needs of sensitive environmental monitoring for pollutants through a self-on/off mode. In this work, an electrochemiluminescence (ECL) biosensor with controlled-release triggering electrostatic attraction elimination and biomolecular stimulated response strategies was constructed to detect environmental steroid hormones sensitively. The blocked pores on the aminated mesoporous silica nanocontainers were opened by specific binding between the trenbolone (TB) antigen and the antibody. The released l-cysteine counteracted the negative charge on the MnO2 NF surface through the redox reaction between -SH and MnO2, making the electrostatic interaction between the MnO2 NFs and the Ru(dcbpy)32+ disappear. Ru(dcbpy)32+ released an ECL signal on the electrode, thus completing the controlled-release triggering electrostatic attraction elimination strategy. In addition, with the TB antibody as the target and the competition strategy between the TB antigen and the standard substance, the constructed controlled-release ECL biosensor was used to detect the TB standard substance. Moreover, MnO2 NFs as the substrate of the ECL biosensor increased the active specific surface area of the electrode, effectively catalyzing the production of OH• and O2•-, thus endowing the ECL biosensor with coreactant-catalytic enhancement characteristic and further improving its ECL performance. This sensitive signal response brought about a low limit of detection of 2.53 fg/mL for the constructed ECL biosensor, which contributed a feasible idea for efficient trace analysis of pollutants in the environment.

Hierarchically Structured and Highly Dispersible MOF Nanozymes Combining Self-Assembly and Biomineralization for Sensitive and Persistent Chemiluminescence Immunoassay.

Metal-organic frameworks (MOF) are promising candidates for the construction of artificial nanozymes and have found applications in many fields. However, the preparation of nanosized MOF materials with high performance and good dispersibility is still a big challenge and is in great demand as signal labels for immunoassays. In this work, hierarchically structured and highly dispersible MOF nanoparticles were facilely prepared in a one-pot method. Self-assembled micelles from PEGylated hematin were used as structured templates to mediate the formation of zeolitic imidazole framework-8 (ZIF-8) nanoparticles in aqueous solution. The encapsulation of micelles in ZIF-8 frameworks produces well-dispersed nanoparticles and generates dual-confinement effects for catalytic hematin. Owing to the hierarchical structures, the formed MOF nanozymes show enhanced peroxidase-like activity and enable persistent chemiluminescence behaviors for the luminol system. Sandwich-type chemiluminescence immunoassays for carcinoembryonic antigen (CEA) were proposed using MOF nanozymes as signal labels, and good analytical performances were achieved. The combination of self-assembly and biomineralization may open new avenues for the development of MOF nanomaterials.

A photoelectrochemical sensor for Hg2+ detection with enhanced cathodic photocurrent via BiOI/Bi2S3 photoanode of self-sacrifice.

Due to the inherent merits of the anodic photoelectrochemical (PEC) sensor, it was widely utilized in the field of analytical chemistry. However, it must be noted that the anodic PEC sensor was susceptible to interference in practical applications. The situation with the cathodic PEC sensor was exactly the opposite. Therefore, this work fabricated a PEC sensor combining photoanode and photocathode that solved the defects of conventional PEC sensors in detecting Hg2+. Specifically, Na2S solution was carefully dropped on the BiOI-modified indium-tin oxide (ITO) to obtain ITO/BiOI/Bi2S3 directly by self-sacrifice method and the resulting electrode was used as photoanode. In addition, a sequential modification process was employed to decorate the ITO substrate with Au nanoparticles (Au NPs), Cu2O, and L-cysteine (L-cys), thereby realizing the fabrication of the photocathode. Moreover, the presence of Au NPs further amplified the photocurrent of the PEC platform. During the detection process, when Hg2+ is present it will bind to the L-cys, resulting in an increase in current, thus enabling sensitive detection of Hg2+. The proposed PEC platform exhibited good stability and reproducibility, providing a new idea for the detection of other heavy metal ions.

Type-I heterojunction destruction by In situ formation of Bi2S3 for split-type photoelectrochemical aptasensor.

Development of new strategies in photoelectrochemical (PEC) sensors is an important way to realize sensitive detection of biomolecule. In this study, mesoporous silica nanospheres (MSNs)-assisted split-type PEC aptasensor with in situ generation of Bi2S3 was proposed to achieve reliable detection of prostate-specific antigen (PSA). To be more specific, this bioresponsive release system will release large amounts of Na2S by the reaction between PSA and aptamer that capped Na2S-loading MSNs. Next, the Na2S reacts with Bi to yield BiOI/BiOBr/Bi2S3 composite, which leads to an alteration in the electron-hole transfer pathway of the photoelectric material and a decrease in the response. As the PSA concentration increases, more Na2S can be released and lower photocurrent is obtained. The linear range under the optimal experimental conditions is 10 pg·mL-1-1 µg⋅mL-1, and the detection limit is 1.23 pg⋅mL-1, which has satisfactory stability and anti-interference.

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.

Controlled Growth of MoS2 on Dendritic Ferric Oxide to Enhance Electrochemiluminescence of Nitrogen-Doped Carbon Quantum Dots for Sensitive Immunoassay.

The essential expansion of electrochemiluminescence (ECL) technology into clinical detection relies on sensitive and stable signal and maintenance of the activity of the immune molecules during the analysis. This poses a critical challenge for an ECL biosensor as a luminophore in general requires high potential excitation resulting in a strong ECL signal; nevertheless, it has an irreversible effect on the activity of the antigen or antibody. Herein, a novel electrochemiluminescence (ECL) biosensor utilizing nitrogen-doped carbon quantum dots (N-CQDs) as emitters and molybdenum sulfide/ferric oxide (MoS2@Fe2O3) nanocomposites as a coreaction accelerator was developed for detection of neuron-specific enolase (NSE), a biomarker of small cell lung cancer. The doping of nitrogen allows the CQDs to exhibit ECL signals with low excitation potential, with a more viable activity possible for immune molecules. MoS2@Fe2O3 nanocomposites exhibit superior coreaction acceleration characteristics in hydrogen peroxide than any single component of them, and the highly branched dendrite microstructure provides a large number of binding sites for immune molecular, which is an inevitable factor for trace detection. In addition, ion beam sputtering gold particle technology is introduced into the sensor fabrication via an Au-N bond, which will provide sufficient density orientation for capturing the antibody load via the Au-N bonds. With excellent repeatability, stability, and specificity, the as-purposed sensing platform showed differentiated ECL responses of NSE range from 10.00 fg/mL to 500 ng/mL, and the limit of detection (LOD) was calculated of 6.30 fg/mL (S/N = 3). The proposed biosensor is prospective to provide a new avenue for the analysis of NSE or other biomarkers.

Polyacrylic acid/polyethylene glycol hybrid antifouling interface for photoelectrochemical immunosensing of NSE based on ZnO/CdSe.

In this paper, a novel photoelectrochemical (PEC) immunosensor based on ZnO/CdSe semiconductor composite material was constructed to detect neuron-specific enolase (NSE) in a super-sensitive and quantitative way. The antifouling interface composed of polyacrylic acid (PAA) and polyethylene glycol (PEG) can prevent non-specific proteins from adhering to the electrode surface. As an electron donor, ascorbic acid (AA) can increase the photocurrent's stability and intensity by clearing away photogenerated holes. Because of the specific recognition between antigen and antibody, the quantitative detection of NSE can be achieved. The PEC antifouling immunosensor based on ZnO/CdSe has a wide linear range (0.10 pg mL-1-100 ng mL-1) and a low detection limit (34 fg mL-1), which has potential application in the clinical diagnosis of small cell lung cancer.