Amplification Strategy Research Articles

Step Pulse-Mediated Low-Triggering Potential Electrochemiluminescence of Polyfluorene Nanoparticles for Bioassay.

When the electrochemiluminescence (ECL) reaction occurs at a triggering potential beyond ±1.0 V, the interference from the adverse oxidation-reduction reaction cannot be ignored. However, currently reported anode ECL usually occurs above +1.0 V. This study innovatively developed a convenient and simple step pulse (SP) method to modulate the low ECL triggering potential of poly [(9,9-dioctyl-fluorenyl-2,7-diacyl)-alt-co-(9-hexyl-3,6-carbazole)] (PFA) nanoparticles (NPs). Compared to cyclic voltammetry with a triggering potential exceeding +1.25 V for PFA NPs, SP scanning enabled PFA NPs to exhibit a strong and stable ECL emission with a triggering potential as low as +0.75 V and tripropylamine (TPrA) as a coreactant. PFA NPs coupled an efficient aptameric recognition-driven cascade nucleic acid amplification strategy to construct a sensitive biosensing platform for measuring phosphorylated Tau (p-Tau) protein as an Alzheimer's disease biomarker. p-Tau could release the secondary target (ST) chain through the aptameric recognition reaction with the aptamer, and the released ST could further trigger cascade catalytic hairpin assembly (CHA) and rolling circle amplification (RCA) at the PFA NP-modified electrode, producing a large number of long chains. The large amount of G-quadruplex/hemin formed by long chains and hemin will consume the ECL quencher H2O2 added in detection solution, thereby restoring the ECL signal and enabling the low potential quantitative analysis of p-Tau with a limit of detection of 4.15 fg/mL. SP technique provides a new way to reduce ECL triggering potential, and PFA NPs create a promising low-triggering potential ECL-sensing platform for bioanalysis.

Dual quenching ECL strategy based on AgInZnS quantum dots and a new co-reaction promoter oxygen vacancy-modified P5AIn/TiO2 for sensitive CEA detection

A novel electrochemiluminescence (ECL) biosensor for the sensitive detection of carcinoembryonic antigen (CEA) was constructed, utilizing environmentally friendly AgInZnS quantum dots (AgInZnS QDs) and a new co-reaction promoter enriched with oxygen vacancies, namely titanium dioxide/poly(5-aminoindole) (Ov-TiO2/P5AIn). The composite of P5AIn and TiO2 significantly enhanced the reaction rate of AgInZnS QDs with tripropylamine (TPrA). In addition, the presence of oxygen vacancies significantly enhances the electron migration rate of the electrode material, leading to more efficient catalysis of TPrA+ generation and a significant enhancement of ECL signals. Furthermore, a dual-quenching sensing strategy was employed using cuprous oxide-triaminophenol (Cu2O@APF) as the quencher, enabling the biosensor to switch. Through dual quenching of the ECL emission from AgInZnS QDs by Cu2O and APF, the biosensor achieves an extremely low “off” state of the ECL signal. Furthermore, a signal amplification strategy driven by the synergistic action of exonuclease III (ExoIII) and restriction endonuclease (Nt.BbvCI) was designed for a dual-site DNA walker, achieving cyclic amplification of the target signal and ECL signal, thereby turning the signal “on” again. The above mechanism significantly improved the specificity and sensitivity of the biosensor for CEA detection. The prepared biosensor exhibits good stability, selectivity, and sensitivity. The linear range for CEA detection is 5 × 10−14 to 10−8 M, with a detection limit of 16 fM. Additionally, the biosensor demonstrates satisfactory analytical capability for CEA in real blood samples. This strategy provides a reliable new approach for the sensitive detection of CEA and other tumor markers.

Strain Amplification Strategy for the Regulation of 2D and 3D Optical Micro/Nanostructures

Strain Amplification Strategy for the Regulation of 2D and 3D Optical Micro/Nanostructures

Dynamic Nanostructure-Based DNA Logic Gates for Cancer Diagnosis and Therapy.

DNA logic gates with dynamic nanostructures have made a profound impact on cancer diagnosis and treatment. Through programming the dynamic structure changes of DNA nanodevices, precise molecular recognition with signal amplification and smart therapeutic strategies have been reported. This enhances the specificity and sensitivity of cancer theranostics, and improves diagnosis precision and treatment outcomes. This review explores the basic components of dynamic DNA nanostructures and corresponding DNA logic gates, as well as their applications for cancer diagnosis and therapies. The dynamic DNA nanostructures would contribute to cancer early detection and personalized treatment.

A colorimetric platform using highly active Prussian blue composite nanocubes for the rapid determination of ascorbic acid and acid phosphatase.

Cobalt-doped Prussian blue composite nanocubes (Co-PB NCs) were synthesized, which can quickly convert O2 to O2•- and 1O2. Due to the presence of cobalt and iron transition metal redox electron pairs, Co-PB NCs with high oxidase mimetic activity can rapidly oxidize the substrate 3,3',5,5'-tetramethylbenzidine (TMB) to produce blue products (ox-TMB) without the assistance of unstable H2O2. Using ascorbic acid-2-phosphate trisodium salt (AAP) as a substrate, it can be converted to reduced ascorbic acid (AA) under acid phosphatase (ACP) hydrolysis, resulting in suppression of TMB oxidation. Therefore, an enzyme cascade signal amplification strategy for rapid colorimetric detection of AA/ACP was developed based on the high-efficiency oxidase-like activity of Co-PB NCs combined with the hydrolysis effect of ACP. The color changes at low concentrations of AA and ACP could be observed by the naked eye, and the detection limits of AA and ACP were 1.67μM and 0.0266 U/L, respectively. The developed colorimetric method was applied to the determination of AA in beverages and ACP in human serum, and the RSDs were less than 3%, showing good reproducibility. This work provides a promising strategy for the use of metal-doped Prussian blue composite material for the construction of rapid colorimetric sensing platforms that avoid the use of unstable hydrogen peroxide.

Enhanced bipolar electrode electrochemiluminescence biosensor for ultrasensitive monitoring of alkaline phosphatase activity during osteoblast differentiation by integrating electrocatalytic and enzymatic strategies

Alkaline phosphatase (ALP) is an important biomarker that reflects osteoblast activity and bone growth. Accurately detecting ALP activity is of pivotal clinical significance for the diagnosis and differentiation of bone system diseases. In this work, an enhanced bipolar electrode electrochemiluminescence (BPE-ECL) biosensor based on enzyme catalysis and electrocatalysis was proposed for ultrasensitive detection of ALP in osteoblasts. Carbon nitride nanosheets (CNNS) were utilized as electrocatalysts to facilitate the electrochemical reaction of bipyridine ruthenium (Ru(bpy)32+) and tripropylamine (TPrA) in the reporting cell. Meanwhile, in the sensing cell, the target ALP catalyzed the conversion of p-aminophenyl phosphate monohydrate into p-aminophenol (p-AP). The p-AP was subsequently oxidized at the anode of the driving electrode, producing electrons and increasing the Faradaic current of BPE. The dual-signal amplification strategy, combining electrocatalysis and enzyme catalysis, resulted in a 10-fold enhancement of the ECL intensity of Ru(bpy)32+/TPrA. The BPE-ECL biosensor achieved ultrasensitive detection of ALP with a detection limit as low as 1.9×10−6 U/L, and was successfully applied to monitor ALP activity in osteoblast cells. Additionally, a portable smartphone imaging was developed for the visual detection of ALP. This research introduces an innovative BPE-ECL biosensor for the monitoring of ALP activity and point-of-care testing (POCT) in osteoblasts in clinical settings.

Directional Characteristic Enhancement of an Omnidirectional Detection Sensor Enabled by Strain Partitioning Effects in a Periodic Composite Hole Substrate.

An omnidirectional stretchable strain sensor with high resolution is a critical component for motion detection and human-machine interaction. It is the current dominant solution to integrate several consistent units into the omnidirectional sensor based on a certain geometric structure. However, the excessive similarity in orientation characteristics among sensing units restricts orientation recognition due to their closely matched strain sensitivity. In this study, based on strain partition modulation (SPM), a sensitivity anisotropic amplification strategy is proposed for resistive strain sensors. The stress distribution of a sensitive conductive network is modulated by structural parameters of the customized periodic hole array introduced underneath the elastomer substrate. Meanwhile, the strain isolation structures are designed on both sides of the sensing unit for stress interference immune. The optimized sensors exhibit excellent sensitivity (19 for 0-80%; 109 for 80%-140%; 368 for 140%-200%), with nearly a 7-fold improvement in the 140%-200% interval compared to bare elastomer sensors. More importantly, a sensing array composed of multiple units with different hole configurations can highlight orientation characteristics with amplitude difference between channels reaching up to 29 times. For the 48-class strain-orientation decoupling task, the recognition rate of the sensitivity-differentiated layout sensor with the lightweight deep learning network is as high as 96.01%, superior to that of 85.7% for the sensitivity-consistent layout. Furthermore, the application of the sensor to the fitness field demonstrates an accurate recognition of the wrist flexion direction (98.4%) and spinal bending angle (83.4%). Looking forward, this methodology provides unique prospects for broader applications such as tactile sensors, soft robotics, and health monitoring technologies.

Proteins sensing of plasma-derived extracellular vesicles in Alzheimer’s disease based on primer exchange reaction amplification strategy

Neuron-derived extracellular vesicles (EVs) in blood offer unique cellular and molecular information related to the onset and progression of Alzheimer’s disease (AD), and they are increasingly being investigated as sources of biomarkers. However, sensitively detecting AD-related EVs markers in blood remains a challenge. In this study, we employed a magnetic separation-assisted primer exchange reaction (MSPER) amplification strategy to achieve highly sensitive and convenient detection of CD63 and Aβ42 proteins on EVs (CD63+/Aβ42+ EVs). Specifically, CD63-expressing EVs are enriched using CD63 antibody-functionalized immune-magnetic beads (anti-CD63@IMBs). Subsequently, Aβ42 and CD63 aptamer are introduced to efficiently recognize CD63 and Aβ42 proteins on the EVs. Iterative primer exchange reaction (PER) concatemers, which create additional binding sites for fluorescence imagers, are then used to produce an amplified fluorescence signal. With this method, we achieved a limit of detection (LOD) of 7.2 × 103 particles/mL for sensitive detection of CD63+/Aβ42+ EVs. More importantly, this MSPER amplification strategy allows us to distinguish AD model mice from healthy controls with high accuracy. This method may provide an alternative for the early diagnosis and monitoring of AD through the detection of CD63+/Aβ42+ EVs.

Recent Advances in DNA-Based Nanoprobes for In vivo MiRNA Imaging.

As a post transcriptional regulator of gene expression, microRNAs (miRNA) is closely related to many major human diseases, especially cancer. Therefore, its precise detection is very important for disease diagnosis and treatment. With the advancement of fluorescent dye and imaging technology, the focus has shifted from in vitro miRNA detection to in vivo miRNA imaging. This concept review summarizes signal amplification strategies including DNAzyme catalytic reaction, hybrid chain reaction (HCR), catalytic hairpin assembly (CHA) to enhance detection signal of lowly expressed miRNAs; external stimuli of ultraviolet (UV) light or near-infrared region (NIR) light, and internal stimuli such as adenosine triphosphate (ATP), glutathione (GSH), protease and cell membrane protein to prevent nonspecific activation for the avoidance of false positive signal; and the development of fluorescent probes with emission in NIR for in vivo miRNA imaging; as well as rare earth nanoparticle based the second near-infrared window (NIR-II) nanoprobes with excellent tissue penetration and depth for in vivo miRNA imaging. The concept review also indicated current challenges for in vivo miRNA imaging including the dynamic monitoring of miRNA expression change and simultaneous in vivo imaging of multiple miRNAs.

Simultaneous Multi-miRNA Detection in Urinary Small Extracellular Vesicles Using Target-Triggered Locked Hairpin DNA-Functionalized Au Nanoprobes for Systemic Lupus Erythematosus Diagnosis.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by multiorgan involvement and complex clinical manifestations, leading to cumbersome diagnostic processes. MicroRNAs (miRNAs) in small extracellular vesicles (sEVs) have emerged as promising biomarkers for liquid biopsy. Herein, we constructed a simple multi-miRNA detection platform based on target-triggered locked hairpin DNA-functionalized Au nanoprobes (AuNP@LH) as a simple and noninvasive tool for the diagnosis and classification of SLE. The nanoprobes were prepared by modifying locked hairpin DNA designed for target miRNAs on gold nanoparticles. In the presence of target miRNAs, target-triggered hairpin assembly amplification was induced, and then fluorophore-labeled bolt DNA was released, resulting in a fluorescence signal responsive to miRNA concentration. Benefiting from the enzyme-free amplification strategy, the limits of detection (LOD) of three miRNA biomarkers for SLE were 19 pM for microRNA-146a, 66 pM for microRNA-29c, and 19 pM for microRNA-150. The proposed probes have been successfully applied to simultaneously detect multiple miRNAs in urinary sEVs from patients diagnosed with SLE and healthy controls, which exhibited good practicability in SLE diagnosis with the area under curve (AUC) of the receiver characteristic curve reaching 1.00. Furthermore, SLE patients with different disease severity can be differentiated with 81.2% accuracy. Predictably, with the advantages of low cost, rapidity, high sensitivity, and noninvasiveness, our multi-miRNA detection platform is a potential tool for multiple miRNA analysis and related clinical applications.

Controlling the Depth of Hybridization Chain Reaction by Extended Dangling Ends and Its Analytical Applications.

Hybridization chain reaction (HCR) is a powerful enzyme-free nucleic acid amplification strategy. Triggered by an initiator strand, it yields nicked double helices analogous to alternating copolymers. However, there is no effective way to regulate the HCR reaction, and the most apparent phenomenon is the uncontrollable polymerization of product after introducing an initiator. Here we explore controlling the depth of the HCR reaction by extended dangling ends on hairpin monomers and report that sequence length, nucleotide composition, and secondary structure can alter HCR polymerization and can be utilized for the desired regulation. Interaction dynamics between initiator and hairpin monomers simulated by oxDNA are in good accordance with experimental results. Such a controlling effect can be utilized for new analytical applications that HCR cannot previously achieve, such as analyzing strand-extension enzymes and identifying short-sequence structures. The finding provides a concise but effective way for controlling the depth of HCR reaction and opens the application scope of HCR to more fields.

Microfluidic-SERS sensing system based on dual signal amplification and aptamer for gastric cancer detection.

Studies have found that matrix metalloproteinase-9 (MMP-9) and interleukin-6 (IL-6) play an important role in tumorigenesis. In order to detect MMP-9 and IL-6 concentrations with high sensitivity and specificity, an efficient microfluidic-SERS sensing system was prepared based on surface-enhanced Raman scattering (SERS). The aptamer recognition-release mechanism and the dual signal amplification strategy were applied in the sensing system. The sensor system was developed using two kinds of nanomaterials with excellent SERS properties, namely gold-coated iron tetroxide particles (Fe3O4@AuNPs) and gold nanocages (AuNCs). In addition, Fe3O4@AuNPs also has magnetic adsorption properties. In the sensing system, single-stranded DNA1 (ssDNA1) and aptamer were modified on Fe3O4@AuNPs. Single-stranded DNA2 (ssDNA2) and Raman tags were modified on AuNCs. When the target was present, the aptamer bound to the target and detached from the Fe3O4@AuNPs, andssDNA2 bound to the exposed ssDNA1. At this time, the Fe3O4@AuNPs@AuNCs@SERS tag complex was formed, and the SERS signal was enhanced for the first time. Under the action of an external magnet on the microfluidic chip, the complex was magnetized and enriched. The SERS signal was enhanced for the second time. Due to the high affinity between the aptamer and the target object, the sensing system has a strong specificity. The double amplification of the SERS signal gave the system excellent sensitivity. The limit of detection (LOD) relative to MMP-9 and IL-6 were as low as 0.178pg/mL and 0.165pg/mL, respectively. The microfluidic-SERS sensing system has a feasible prospect in the early screening of gastric cancer.

Photoelectrochemical Immunoassay of Alpha‐Fetoprotein Based on Au Nanoparticles‐Decorated ZnO Microrods

AbstractHerein a split‐type photoelectrochemical (PEC) immunosensor based on in situ grown gold nanoparticles (Au NPs) on the surface of ZnO microrods (ZnO MRs) was devised for the detection of alpha‐fetoprotein (AFP) by employing dopamine (DA)‐loaded liposomes as the signal amplification strategy. Specifically, as the level of AFP rises, a proportional number of sandwich‐type immunocomplexes form in the well of the microplate, which can introduce a corresponding amount of DA‐encapsulated liposomes at the same time. Encapsulated DA molecules will be released with the stimulation of Triton X‐100, thereby resulting in the marked enhancement of the PEC signal. Under optimized conditions, the proposed PEC immunosensing platform displays specific photocurrent responses toward AFP in a broad dynamic working range of 0.05 −50 ng mL−1, achieving an impressively low limit of detection (LOD) of 18.7 pg mL−1. Furthermore, this methodology not only displays high specificity, and satisfactory storage stability but also ensures acceptable accuracy and practicality for the analytical applications of human serum samples.

Dual signal amplification strategy-based electrochemical aptasensor utilizing redox molecule/MOF composites for multi-pesticide detection

Electrochemical aptasensor is a great tool for simultaneously assessing harmful pesticide residues in agricultural products and foods. This study ingeniously designed an electrochemical aptasensor based on dual signal amplification strategies for concurrent detection of various pesticide residues. Firstly, poly(diallyldimethylammonium chloride)-functionalized reduced graphene oxide (PR) and Au-Pt-Pd trimetallic nanoflowers supported on HP-UiO66-NH2 were creatively employed together as substrates to load more aptamers, ascribed to the improved conductivity, abundant sites and a large electrochemical effective surface area. Secondly, ferrocene-cysteine gold nanoparticles supported on CeMOF(Ⅲ, Ⅳ) and methylene blue-loaded MOF235 were innovatively engineered to build two distinctive signal labels, which displayed comparable large and stable signal currents among other redox molecule/MOF composites. Additionally, PR contributed further signal amplification. Consequently, the constructed aptasensor showed superior performance for simultaneous detection of acetamiprid (AD) and malathion (ML), with linear ranges from 10 pM to 0.1 μM and detection limits of 4.8 pM for AD and 0.51 pM for ML. Moreover, the aptasensor performed well in the assay of AD and ML in Chinese cabbage samples with high accuracy compared with a high-performance liquid chromatography-tandem mass spectrometry method. Overall, the strategies proposed herein provided a useful and potential route for general development of electrochemical aptasensors to simultaneously detect multiple pesticide residues.

Enhancing Sensitivity and Selectivity: Current Trends in Electrochemical Immunosensors for Organophosphate Analysis.

This review examines recent advancements in electrochemical immunosensors for the detection of organophosphate pesticides, focusing on strategies to enhance sensitivity and selectivity. The widespread use of these pesticides has necessitated the development of rapid, accurate, and field-deployable detection methods. We discuss the fundamental principles of electrochemical immunosensors and explore innovative approaches to improve their performance. These include the utilization of nanomaterials such as metal nanoparticles, carbon nanotubes, and graphene for signal amplification; enzyme-based amplification strategies; and the design of three-dimensional electrode architectures. The integration of these sensors into microfluidic and lab-on-a-chip devices has enabled miniaturization and automation, while screen-printed and disposable electrodes have facilitated on-site testing. We analyze the challenges faced in real sample analysis, including matrix effects and the stability of biological recognition elements. Emerging trends such as the application of artificial intelligence for data interpretation and the development of aptamer-based sensors are highlighted. The review also considers the potential for commercialization and the hurdles that must be overcome for widespread adoption. Future research directions are identified, including the development of multi-analyte detection platforms and the integration of sensors with emerging technologies like the Internet of Things. This comprehensive overview provides insights into the current state of the field and outlines promising avenues for future development in organophosphate pesticide detection.

Ultrasensitive detection of cancer-associated nucleic acids and mutations by primer exchange reaction-based signal amplification and flow cytometry

The detection of cancer-associated nucleic acids and mutations through liquid biopsy has emerged as a highly promising non-invasive approach for early cancer detection and monitoring. In this study, we report the development of primer exchange reaction (PER) based signal amplification strategy that enables the rapid, sensitive and specific detection of nucleic acids bearing cancer specific single nucleotide mutations using flow cytometry. Using micrometer size beads as support for immobilizing oligonucleotides and programmable PER assembly for target oligonucleotide recognition and fluorescence signal amplification, we demonstrated the versatile detection of target nucleic acids including KRAS oligonucleotide, fragmented mRNAs, and miR-21. Moreover, our detection system can discriminate single base mutations frequently occurred in cancer-associated genes including KRAS, PIK3CA and P53 from cell extracts and circulating tumor DNAs (ctDNAs). The detection is highly sensitive, with a limit of detection down to 27 fM without pre-amplification. In view of a clinical application, we demonstrate the detection of single mutations after extraction and pre-amplification of ctDNAs from the plasma of breast cancer patients. Importantly, our detection strategy enabled the detection of single KRAS mutation even in the presence of 1000-fold excess of wild type (WT) DNA using multi-color flow cytometry detection approach. Overall, our strategy holds immense potential for clinical applications, offering significant improvements for early cancer detection and monitoring.

Activating Two-Photon Silica Nanoamplifier-Based CHA and FRET for Accurate Ratiometric Bioimaging of Intracellular MicroRNA.

In situ visualization of microRNA (miRNA) in cancer cells and diseased tissues is essential for advancing our comprehension of the onset and progression of associated diseases. Two-photon (TP) imaging, as an imaging technology with high spatiotemporal resolution, deep tissue penetration, and accurate target quantification, has distinctive advantages over single-photon imaging and has attracted increasing attention. Extensive research has been conducted on two-photon dye-doped silica nanoparticles, which exhibit a large two-photon absorption (TPA) cross-section, high fluorescence quantum yield, and excellent biocompatibility. However, the low abundance of RNA in tumor cells leads to insufficient signal output. Based on functional nucleic acid, a catalyzed hairpin self-assembly (CHA) signal amplification strategy, which has simplicity, robustness, and nonenzymatic characteristics, can achieve the amplification of DNA or RNA signals. Here, a two-photon silica nanoamplifier (TP-SNA) utilizing TP dye-doped silica nanoparticles (SiNPs) and functional nucleic acid was constructed, employing triggering catalyzed hairpin self-assembly and fluorescence resonance energy transfer (FRET) for highly sensitive detection and precise TP imaging of endogenous miRNAs in tumor cells and tissues at varying depths. The TP-SNA demonstrated the capability to detect miR-203 with a detection limit of 33 pM. The maximum two-photon tissue penetration depth of the two-photon nanoamplifier was 210 μm. The two-photon nanoamplifier developed in this study makes full use of the advantages of accurate TP ratiometric bioimaging and the CHA signal amplification strategy, which shows good application value for future transformation into clinical diagnosis.

Self-Matching Assembly of Chiral Gold Nanoparticles Leads to High Optical Asymmetry and Sensitive Detection of Adenosine Triphosphate.

To achieve chiral amplification, life uses small chiral molecules as building blocks to construct hierarchical chiral architectures that can realize advanced physiological functions. Inspired by the chiral amplification strategy of nature, we herein demonstrate that the chiral assembly of chiral gold nanorods (GNRs) leads to enhanced optical asymmetry factors (g-factors), up to 0.24. The assembly of chiral GNRs, dictated by structural self-matching, leads to g-factors with over 100-fold higher values than those of individual chiral GNRs, as confirmed by numerical simulations. Moreover, the efficient optical asymmetry of chiral GNR assemblies enables their application as highly sensitive sensors of adenosine triphosphate (ATP detection limit of 1.0 μM), with selectivity against adenosine diphosphate and adenosine monophosphate.

Silver amplified immunosensor via effective fluorogenic Ag+-imidazole aggregation for detection of AFB1

BackgroundCereals are susceptible to aflatoxin contamination during storage and transportation, which is highly carcinogenic and teratogenic, and seriously threaten human health. The accurate and rapid detection of total aflatoxin (including aflatoxin B1, B2, G1, and G2) is of great importance for food safety. Conventional fluorescence immunoassays have the advantage of being sensitive and fast; however, these methods can be affected by strong background and matrix interference. Therefore, the development of ultrasensitive, cost-effective, and interference rejection sensors for detecting aflatoxins in moldy grains is vital for food safety and human health. ResultsIn this paper, a broad-spectrum aflatoxin monoclonal antibody was prepared by using hybridoma cell fusion technology. An aggregation-induced emission (AIE) based immunosensor via silver amplification coupled with a fluorogenic Ag+ probe was established for AFB1 analysis. Silver nanoparticles are decomposed into numerous Ag+ by H2O2, and then Ag+ further specifically binds with imidazole-modified AIE molecules, improving the sensitivity and anti-interference ability of the method. The IC50 and IC15 of AIE-based immunosensor for AFB1 were 0.019 and 0.0014 μg/L, respectively, 2.3-fold and 5.8-fold higher than those of icELISA. The AIE-based immunosensor was also used to analyze AFB1 from actual cereal samples, with spiked recoveries ranging from 72.91 to 115.92 %. In addition, the method was used to detect total aflatoxins in moldy grains. SignificanceBased on the advantages of broad-spectrum aflatoxin monoclonal antibody, high-efficiency metal signal amplification, and functional AIE molecule, a sensitive, accurate, cost-effective, and time-saving method was developed for the analysis of total aflatoxins in cereals. Moreover, the proposed signal amplification strategy shows great potential for analyzing other trace-level small molecular pollutants.

AIEgens-based luminescent metal-organic frameworks as novel electrochemiluminescence emitters Integrated with co-reaction amplification strategy for CA15-3 detection

A current research focus in the field of electrochemiluminescence (ECL) is the development of novel high-performance emitters. Herein, we reported the synthesis of a zirconium-based metal–organic framework (Zr-TBAPy-MOF) using the aggregation-induced emission luminogens (AIEgens) 1,3,6,8-tetra(4-carboxyphenyl)pyrene (H4TBAPy) as ligands and Zr6-clusters as nodes. The resulting AIE-active luminescent MOF (AIE-LMOF) exhibited superior ECL properties and was used as an ECL emitter to construct a high-sensitivity ECL immunosensor. Conceptual experiments demonstrated that Zr-TBAPy-MOF showed significantly stronger ECL emission compared to both the monomers and aggregates of H4TBAPy, attributed to the effective restriction of intramolecular motion (RIM). On the sensor substrate, we designed an Au@ZnO/Cu2O nanocomposite as a co-reactant accelerator. This significantly promoted the generation of sulfate radicals (SO4•−) from persulfate (S2O82−) through the sustainable switching of Cu+/Cu2+ oxidation states in copper oxide (Cu2O). Additionally, zinc oxide (ZnO), which had excellent electrochemical properties, further enhanced the catalytic activity of the materials. Leveraging these advantages, we developed a sandwich-type ECL immunosensor for the ultrasensitive detection of carbohydrate antigen 15–3 (CA15-3), demonstrating a wide sensitive range (0.001 − 100 U/mL) and a low detection limit (0.0007 U/mL). Overall, this work paves the way for the development of efficient ECL luminophores with significant potential in the field of immunoassays for the early diagnosis of disease.