Long-lasting Chemiluminescence Research Articles

Hemin/G-quadruplex functionalized porphyrin-based MOF nanozymes and their application in mediating long-lasting chemiluminescence optical fiber aptasensor for sensitive and accurate detection of ricin

A novel hemin/G-quadruplex functionalized porphyrin-based MOF nanozyme (HGP-PCN) was firstly synthesized and employed to fabricate a chemiluminescence (CL) assay strategy for ricin detection. Porphyrin-based MOFs with large specific area could fully expose their catalytic centers, provide functional interface to load hemin/G-quadruplex, and then generate “double catalytic activity amplification”. The catalytic mechanism of HGP-PCN was thoroughly illustrated by chemical characterizations and theoretical calculations. The continuous generation of •OH, O2•−, and 1O2 from H2O2 catalyzed by Fe-N4 active sites on the HGP-PCN nanozyme could induce long-lasting and stable CL signals, which is helpful to fabricate sensitive and accurate CL sensing platform. The HGP-PCN nanozymes mediated long-lasting CL optical fiber aptasensor (CN-LCOFA) was fabricated to quantify ricin. The ricin toxic B (RTB) chain aptamers labelled HGP-PCN (Apt-HGP-PCN) was used for signaling while functionalized optical fiber probe was used as biorecognition interface. The CN-LCOFA could ultra-sensitively detect ricin within 23 min, the dynamic linear range was 4.1–185.0 ng/mL, and the LOD was 1.28 ng/mL. The analytical performance of CN-LCOFA including detection time, detection range and LOD was significantly superior to the ricin detection methods that reported in currently literatures. The detection accuracy of CN-LCOFA for ricin spiked in human serum was comparable with that of HPLC-MS. This novel nanozyme-catalyzed long-lasting CL system and ultrasensitive assay strategy could provide effective methods for food safety and environmental monitoring.

Long-lasting chemiluminescence of lucigenin/p-aminophenol system for detection of p-aminophenol in environmental water

Long-lasting chemiluminescence of lucigenin/p-aminophenol (4-AP) system is explored for the first time and possible chemiluminescence enhancement mechanism is also proposed in this work. 4-AP can enhance chemiluminescence of lucigenin nearly 150 times and is stable for nearly 5 min, which overcomes the need of flow syringe pump. While o-aminophenol (2-AP) slightly enhances chemiluminescence of lucigenin and m-aminophenol (3-AP) does not. Thus, it can be applied in discrimination of three aminophenol isomers. More importantly, cyclic voltammetry proves the lowest oxidation peak for 4-AP at 115 mV, which is speculated to be the main reason for 4-AP induced chemiluminescence enhancement. It has been applied in chemiluminescence enhancement detection of 4-AP and p-nitrophenol (4-NP) from 80 nM to 60 μM, from 0.5 μM to 60 μM with limit of detection (LOD) of 26 nM and 0.17 μM, respectively. It shows high selectivity and anti-interference in chemiluminescence enhancment detection of 4-AP and 4-NP towards other organic compounds and metal ions. It also exhibits high accuracy in chemiluminescence enhancment detection of 4-AP and 4-NP in lake water with recoveries from 98.7% to 101.5% for and recoveries from 98.7% to 102.2%, respectively. It expands the study of long-lasting lucigenin chemiluminescence system and chemiluminescence method utilized in discrimination of aminophenols isomers.

Construction of Magnetic Core-Large Mesoporous Satellite Immunosensor for Long-Lasting Chemiluminescence and Highly Sensitive Tumor Marker Determination.

Chemiluminescence immunoassay exhibits high sensitivity and signal-to-noise ratio, thus attracting great attention in the early diagnosis and dynamic monitoring of diseases. However, the collection of conventional flash-type chemiluminescence signal (<5s) relies heavily on automatic sampling and reading instrument. Herein, a novel core-satellite multifunctional chemiluminescence immunosensor is designed for the efficient enrichment and highly sensitive determination of cancer biomarker carcinoembryonic antigen (CEA) with enhanced and long-lasting output signal that can be conveniently recorded by a simple microplate plate reading instrument. Anti-CEA monoclonal antibody 2 (Ab2) modified Fe3 O4 @SiO2 microspheres (Fe3 O4 @SiO2 -Ab2, 370nm in diameter) are synthesized as the core for selectively capturing and enriching target CEA in solution, and anti-human CEA monoclonal antibody 1 (Ab1) and horseradish peroxidase (HRP) co-immobilized dendritic large-mesoporous silica nanospheres (MSNs-HRP/Ab1, 80nm in diameter, pore size: 17nm) are synthesized as the satellite for efficient immunological recognition and signal amplification. The as-designed core-satellite magnetic chemiluminescence immunosensors exhibit a broad linear range of 0.01-20ngmL-1 and a low detection limit of 3.0pgmL-1 for the convenient, highly specific, and sensitive determination of CEA in human serum. Such core-satellite chemiluminescence immunosensors are expected to act as a powerful tool for in vitro detection of various biomarkers, overcome the defect of conventional chemiluminescence relying heavily on expensive and bulky automatic instruments and popularize chemiluminescence analysis to primary medical institutions and remote areas.

Novel chemiluminescent nanosystem for highly sensitive detection of hydrogen peroxide in vivo

The overproduction of hydrogen peroxide (H2O2) is closely associated with the progression of various diseases, and thus, it is an important diagnostic marker for in vivo molecular imaging. Although chemiluminescence (CL) imaging with L-012 as a CL agent has been employed to detect H2O2, the low reactivity of H2O2 with L-012 and the short CL emission time of L-012 limit its in vivo H2O2 detection applications. Herein, a novel Co2+-doped L-012/magnesium peroxide-based CL nanosystem (L-012/Co@MgO2) is designed. L-012/Co@MgO2 decomposes in aqueous solutions and releases L-012 and Co2+, and the highly reactive hydroxyl radicals produced by the Co2+-catalysed H2O2 decomposition under an inflammatory environment react with L-012 and yield strong and long-lasting CL emissions. In addition to visually detecting and quantitatively analysing H2O2, the biocompatible L-012/Co@MgO2 CL system against blood cells and major organs can successfully realise H2O2 detection in lipopolysaccharides-induced inflammatory disease models and in vitro screening of the H2O2 scavenging activity of antioxidants. The proposed CL nanosystem has potential applications for the biosensing and bioimaging of H2O2, which is highly produced in various diseases.

Highly intensive and long-lasting chemiluminescence “Three-in-One” Hemin/Fe3O4@MoS2 hybrid nanozyme powered lab-on-fiber device for Ochratoxin A immunoassay

A novel long-lasting chemiluminescent (CL) “Three-in-One” Hemin/Fe3O4 @MoS2 hybrid nanozyme powered lab-on-fiber (CN-LOF) device was developed for Ochratoxin A (OTA) detection. The “Three-in-One” nanozymes could catalyze luminol-H2O2 system to produce robust and long-lasting CL under pH range of 6.5–9.0 and temperature range of 0–70 ℃, such excellent catalytic activity was mainly originated from the synergistic effect of MoS2, Fe3O4 and hemin and the nanozyme’s elegant 2D/3D structure. In the reaction system, the nanozymes could continuously catalyze H2O2 to generate O2•− and 1O2 species, which was the main reason for the production of persistent CL. Using OTA antibodies labeled nanozyme for CL signal amplification while a reusable functionalized optical fiber as a biorecognition and separation element and also as a CL transducer, the CN-LOF could quantify OTA with high sensitivity and stability within 20 min. The obtained linear detection range for OTA was 0.69–65.85 ng/mL and the LOD was 0.16 ng/mL under optimal conditions. The proposed CN-LOF method had been successfully applied to the detection of OTA in underground water and milk samples, and the detection results were highly consistent with those of LC-MS, demonstrated the CN-LOF method had great application potential in the analysis of environmental samples and the detection of foodborne biotoxins.

Highly Stable Fe/Co-TPY-MIL-88(NH2) Metal-Organic Framework (MOF) in Enzymatic Cascade Reactions for Chemiluminescence-Based Detection of Extracellular Vesicles.

Metal-Organic Frameworks (MOFs) can deliver many advantages when acting as enzyme mimics to assist with signal amplification in molecular detection: they have abundant active catalytic sites per unit volume of the material; their structures and elemental compositions are highly tunable, and their high specific surface area and porous property can assist with target separation and enrichment. In the present work, we have demonstrated that, by adding the pore partition agent, 2,4,6-tris(4-pyridyl)pyridine (TPY) during synthesis of the bimetallic Fe/Co-MIL-88(NH2) MOF to block the open metal sites, a highly porous MOF of Fe/Co-TPY-MIL-88(NH2) can be produced. This material also exhibits high stability in basic solutions and biofluids and possesses high peroxidase-mimicking activity, which can be utilized to produce long-lasting chemiluminescence (CL) from luminol and H2O2. Moreover, acting as the peroxidase-mimic, the Fe/Co-TPY-MIL-88(NH2) MOF can form the enzymatic cascade with glucose oxidase (GOx) for biomarker detection. When applied to detect extracellular vesicles (EVs), the MOF material and GOx are brought to the proximity on the EVs through two surface proteins, which triggers the enzyme cascade to produce high CL from glucose and luminol. EVs within the concentration range of 5 × 105 to 4 × 107 particles/mL can be detected with an LOD of 1 × 105 particles/mL, and the method can be used to analyze EV contents in human serum without sample preparation and EV purification. Overall, our work demonstrates that the high versatility and tunability of the MOF structures could bring in significant benefits to biosensing and enable ultrasensitive detection of biomarkers with judicious material designs.

Mesoporous silica-encapsulated Co-doped ceria nanodots with enhanced peroxidase-like activity enable intensive and long-lasting chemiluminescence for glutathione detection

Chemiluminescence (CL) assay has been considered as a sensitive method for quantitative detection of glutathione (GSH), a significant regulatory metabolite in cells. However, most reported CL assays present flash-type CL emission with limited detection accuracy and repeatability. Herein, an intensive and long-lasting glow-type CL system was proposed based on a novel bimetallic Co-doped ceria mesoporous nanocomposite (Co-ceria@MSN), which was prepared by in-situ growth of sub-3 nm ultrasmall Co-ceria nanodots within the pore channels of mesoporous silica nanospheres (MSN). Attributing to the confinement effect of MSN and the superior peroxidase-like catalytic activity of Co-ceria nanodots, this nanocomposite could function as a nanozyme to catalyze luminol/H2O2 CL reaction, producing a robust and long-lasting CL emission with a long plateau for over 1.2 h at physiological pH. Surprisingly, both the CL intensity and duration time were found to exist a strong dependence on GSH concentration. Accordingly, the proposed glow-type CL platform was further applied for GSH determination with a limit of detection down to 10 nM. This strategy was successfully utilized for quantitative evaluation of cellular GSH levels, indicating its broad prospects in clinical diagnosis.

Strong chemiluminescence intensities of bis-acridinium esters under neutral and alkaline conditions

Four novel bis-acridinium esters were synthesized using common methods, and their chemiluminescence properties were investigated at pH 7−10. In the chemiluminescence of bis-acridinium esters, the introduction of fluorine at the 2-position of the phenyl ring and methyl groups at the 2,7-positions of the acridine ring changed greatly the chemiluminescence intensities. Pentane-1,5-diyl bis(2-fluoro-4-(2,7,10-trimethylacridinium-9-carbonyloxy)benzoate) bis(trifluoromethanesulfonate) showed strong chemiluminescence and long-lasting chemiluminescence under both neutral and alkaline conditions. Pentane-1,5-diyl bis(2-fluoro-4-(10-methylacridinium-9-carbonyloxy)benzoate) bis(trifluoromethanesulfonate) was applied for highly sensitive chemiluminescence determination of hydrogen peroxide and catalase activity. The linear calibration ranges of hydrogen peroxide and catalase activity were 5–1000 μM (R = 0.999) and 0.05−1 U/mL (R = 0.998), respectively.

A novel enzyme-free long-lasting chemiluminescence system based on a luminol functionalized β-cyclodextrin hydrogel for sensitive detection of H2O2 in urine and cells.

A novel long-lasting chemiluminescent (CL) hydrogel (β-CD@luminol-Co2+) was synthesized by embedding luminol and cobalt ions (Co2+) into β-cyclodextrin (β-CD) through non-covalent interactions. Due to its porous structure and viscosity, the synthesized β-CD@luminol-Co2+ hydrogel exhibited long-lasting CL properties and can emit light for 12 h under both alkaline and neutral conditions. In addition, the CL intensities of β-CD@luminol-Co2+ were linear with the logarithm of the hydrogen peroxide (H2O2) concentration in the range of 1.0 × 10-11-1.0 × 10-7 M, and the limit of detection (LOD) was 0.63 × 10-11 M and 0.85 × 10-11 M under alkaline and neutral conditions, respectively. On this basis, an enzyme-free CL sensor based on β-CD@luminol-Co2+ was fabricated for the sensitive detection of H2O2 in human urine samples under alkaline conditions, and showed good accuracy and recovery. Since β-CD@luminol-Co2+ showed good CL properties under neutral conditions, it can be applied to detect H2O2 in cells. In order to prolong the emission wavelength of β-CD@luminol-Co2+ for better cell imaging, β-CD@luminol-FL-Co2+ was prepared by adding fluorescein (FL) to β-CD@luminol-Co2+. The as-prepared β-CD@luminol-FL-Co2+ also displayed long-lasting CL properties and showed a linear relationship with H2O2 concentrations. In addition, the maximum emission wavelength of β-CD@luminol-FL-Co2+ was 520 nm, which was red-shifted by 95 nm compared with β-CD@luminol-Co2+. The methyl thiazolyl tetrazolium (MTT) assay results and confocal microscopy images illustrated that β-CD@luminol-FL-Co2+ had low toxicity and can be taken up by A549 cells. Finally, β-CD@luminol-FL-Co2+ was successfully applied for CL imaging and detection of intracellular H2O2 in A549 cells under neutral conditions. This enzyme-free long-lasting CL system with high sensitivity can also be extended to real-time monitoring of H2O2in vivo.

An ultrasensitive and long-lasting chemiluminescence immunoassay for IP-10 detection based on a 4-bromophenol-reinforced bienzymatic system

The 10-kDa chemokine interferon-gamma-inducible protein 10 (IP-10) is considered one of the most promising biomarkers for diagnosing both tuberculosis and COVID-19 infections. The blood samples of patients at different disease states contain different levels of IP-10, which need to be detected in a rapid, specific and ultrasensitive manner. Here, we report a bienzymatic chemiluminescence sandwich immunoassay (BCSI) assay for the ultrasensitive and stable detection of IP-10. In this assay, IP-10 is first efficiently captured using a double-antibody sandwich strategy. The detection antibody is linked to catalase (CAT) via a streptavidin–biotin signal amplification system to achieve highly efficient conversion of hydrogen peroxide (H2O2) to oxygen and water. In the chemiluminescence (CL) reaction, horseradish peroxidase (HRP) acts as an efficient catalyst, and 4-bromophenol acts as an enhancer for the cyclic transition of HRP, which results in a strong and durable CL signal. The bienzymatic catalysis with CAT and HRP and the potentiation of 4-bromophenol enables the assay to be ultrasensitive and stable. The CL intensity was found to be well correlated with the detection of IP-10 at levels in the range of 0.71 to 125,000 pg/mL, which covers more than 6 orders of magnitude, with a detection limit of 0.63 pg/mL. The coefficient of variation was 1.49%, and the recovery range of IP-10 in serum was 86.21%-104.57%. This assay provides a wide linear range and high sensitivity and may be a promising method for the high-throughput detection of IP-10 in the diagnosis of tuberculosis and COVID-19.

Nano-channel confined biomimetic nanozyme/bioenzyme cascade reaction for long-lasting and intensive chemiluminescence

We present here a novel nano-channel confined biomimetic nanozyme/bioenzyme system, which is prepared by co-immobilizing polyoxometalates (vanadomolybdophosphoric heteropoly acid, PMoV2) and glucose oxidase (GOx) in the nano-scale channel of core-shell mesoporous silica (CSMS) microspheres. The biomimetic dual-enzyme nanoreactors (CSMS@PMoV2@GOx) is used for producing long-lasting chemiluminescence (CL) emission. With glucose and luminol in the reaction mixture, hydrogen peroxide (H2O2) is formed in mesoporous channels by GOx catalysis and then is consumed immediately by PMoV2 to induce CL emission. Confined in nano-size channels of CSMS materials, the biomimetic cascade reactions can induce a long-lasting CL emission with a flat period over 12 h. The proposed CSMS@PMoV2@GOx system has excellent reproducibility and storage stability, and has been applied for glucose sensing in human serum samples with satisfactory accuracy. Our study provides a new glow-type CL system based on nanozyme/bioenzyme cascade reactions confined in nano-scale channels of CSMS microspheres, and will also shed a light on potential application of functional polyoxometalates immobilized in mesoporous materials, which would be of great value in various fields including bioassays and heterogeneous catalysis.

Long-Lasting Luminol Chemiluminescence Emission with 1,10-Phenanthroline-2,9-dicarboxylic Acid Copper(II) Complex on Paper

As most of the known systems are flashtype, long-lasting chemiluminescence (CL) emissions are extremely needed for the application of cold light sources, accurate CL quantitative analysis, and biological mapping. In this work, the flashtype system of luminol was altered to a long lasting CL system just because of the paper substrate. The Cu(II)-based organic complex was loaded on the paper surface, which can trigger luminol-H2O2 to produce a long lasting CL emission for over 30 min. By using 1,10-phenanthroline-2,9-dicarboxylic acid (PDA) as the ligand, a hexacoordinated Cu(II)-based organic complex was synthesized by the simple freeze-drying method. It is interesting that the complex morphology can be controlled by adding different amounts of water in the synthesizing procedure. The complex with a certain size can be definitely trapped in the pores of the cellulose. Then, slow diffusion, which can be attributed to the long lasting CL emission, was produced. With the high catalytic activity of the complex, reactive oxygen species from H2O2 was generated and was responsible for the high CL intensity. By using the paper substrate, the flash-type luminol system can be easily transferred to the long-duration CL system without any extra reagent. This long-lasting emission system was used for hydrogen sulfide detection by the CL imaging method. This paper-based sensor has great potential for CL imaging in the clinical field in the future.

Acridinium Ester Chemiluminescence: Methyl Substitution on the Acridine Moiety.

Methyl groups were introduced on the acridine moiety in chemiluminescent acridinium esters that have electron-withdrawing groups (trifluoromethyl, cyano, nitro, ethoxycarbonyl) at the 4-position on the phenyl ester. The introduction of methyl groups at the 2-, 2,7-, and 2,3,6,7-positions on the acridine moiety shifted the optimal pH that gave relatively strong chemiluminescence intensity from neutral conditions to alkaline conditions. 4-(Ethoxycarbonyl)phenyl 2,3,6,7,10-pentamethyl-10λ4-acridine-9-carboxylate, trifluoromethanesulfonate salt showed long-lasting chemiluminescence under alkaline conditions. Acridinium esters to determine hydrogen peroxide concentration at pH 7-10 were newly developed.

Novel Protease-Free Long-Lasting Chemiluminescence System Based on the Dox-ABEI Chimeric Magnetic DNA Hydrogel for Ultrasensitive Immunoassay.

Most of chemiluminescence (CL) substrates exhibit the flash-type light emission. Therefore, the long-lasting CL system is always the crown in the field of CL-based analysis methodology. In this work, we constructed a Dox-ABEI chimeric magnetic DNA hydrogel (MDH) as a novel protease-free long-lasting CL reaction system. The functional MDH can transform flash-type ABEI/H2O2/CO2+ reaction into a glow-type CL system because of its block effect on delaying the diffusion rate of co-reactants, making the CL reaction gradually occur. More importantly, the functional MDH possessed the advantages of biocompatibility and controllability and could be well-designed to incorporate different biosensing strategies. Subsequently, we established a functional MDH-based long-lasting CL immunoassay system for ultrasensitive and highly specific detection of d-dimer and fibrin degradation products (FDPs). The designed CL immunoassay can detect d-dimer and FDP down to 53.7 and 31.6 fg/mL, respectively, with a wide line ranging from 100 fg/mL to 100 ng/mL, which was superior to the previously reported CL biosensing strategies. Moreover, benefiting from the magnetic separation of MDH and excellent CL performance, the developed immunoassaying method was successfully applied in the detection of clinical samples, which showed a close correlation with clinical reference technology. Thus, this functional MDH proved to be an excellent long-lasting CL system and a potential technical platform for clinical bioanalysis applications.

Long-Lasting and Intense Chemiluminescence of Luminol Triggered by Oxidized g-C3N4 Nanosheets.

Most of the known chemiluminescence (CL) systems are flash-type, whereas a CL system with long-lasting and strong emission is very favorable for accurate CL quantitative analysis and imaging assays. In this work, we found that the oxidized g-C3N4 (g-CNOX) could trigger luminol-H2O2 to produce a long-lasting and intense CL emission. The CL emission lasted for over 10 min and could be observed by the naked eye in a dark room. By means of a CL spectrum, X-ray photoelectron spectra, and electron spin resonance spectra, the possible mechanism of this CL reaction was proposed. This strong and long-duration CL emission was attributed to the high catalytic activity of g-CNOX nanosheets and continuous generation of reactive oxygen species from H2O2 on g-CNOX surface. Taking full advantage of the long-lasting CL property of this system, we proposed one "non-in-situ mixing" mode of CL measurement. Compared with the traditional "in-situ mixing" CL measurement mode, this measurement mode was convenient to operate and had good reproducibility. This work not only provides a long-lasting CL reaction but also deepens the understanding of the structure and properties of g-C3N4 material.

A Smart Advanced Chemiluminescence-Sensing Platform for Determination and Imaging of the Tissue Distribution of Natural Antioxidants.

Antioxidants have gained marked attention owing to their ability to prevent the oxidation of biological components and to protect the body from reactive oxygen species, thereby maintaining human health. Thus, antioxidant-rich dietary supplements and natural foods can be effective against oxidative stress and can even act as chemopreventive agents. Therefore, a simple and rapid assay for evaluation of antioxidant capacity and assessment of their distribution profile in natural sources is vital. Herein, we report a rapid, innovative chemiluminescence (CL) platform for evaluation and visualization of antioxidant capacity. We found that intense and long-lasting CL was formed upon the redox reaction of quinones, e.g., menadione, with antioxidants, e.g., l-ascorbic acid, in the presence of luminol. The produced CL intensities were proportional to the antioxidants' concentrations with a detection limit of 0.18 μM for the model antioxidant, l-ascorbic acid. As the formed CL was long-lasting, it could be easily captured and detected with a charge-coupled device (CCD) camera. To evaluate the quantification ability of the CCD camera, we developed a smart and fast microplate-based assay based on photographing the generated CL with a cooled CCD camera. The photographed CL intensities were linearly proportional with the antioxidant concentrations, and then the method was applied for photographing multiple food sample extracts. Ultimately, we utilized our method for the distribution profiling of antioxidant capacity in food cut sections. Samples were dipped in luminol and then in quinone, followed by CCD camera photography, without the need for any pulverization/extraction procedure, giving precise antioxidant distribution information.

Quinone-based antibody labeling reagent for enzyme-free chemiluminescent immunoassays. Application to avidin and biotinylated anti-rabbit IgG labeling

Chemiluminescence-enzyme immunoassays make it possible to measure trace components with high sensitivity and selectivity due to the high specificity of the antigen-antibody reaction and the high sensitivity of chemiluminescence assays. However, using an enzyme-labeled antibody suffers from many problems such as low reproducibility due to the instability of the enzyme and inhibition of antigen-antibody reaction due to its steric effect. Therefore, herein we report an innovative non-enzymatic chemiluminescence immunoassays labeling reagent through using quinone as a signal-generating tag coupled with biotin as a binder, to overcome enzymatic labeling problems. Biotinylated-1,4-naphthoquinone (biotin-NQ) was synthesized and characterized and it could produce long-lasting chemiluminescence upon mixing with dithiothreitol and luminol based on the redox cycle of quinone. Biotin-NQ showed exceptional stability towards different stress factors that may be encountered during performing the immunoassay such as high temperatures, highly acidic and alkaline conditions, and repeated freeze-thaw cycles. On the other hand, all these conditions lead to decreased labeling enzyme reactivity due to possible denaturation of its protein structure. Finally, the measurement of the biotin-labeled antibody was successfully performed using biotin-NQ and avidin. As a result, the antibody could be detected down to 25.7 nM which is 2.5 times sensitive than biotin-HRP chemiluminescence-enzyme immunoassays. Moreover, our method was applied successfully for determination of avidin using immobilized biotinylated antibody and biotin-NQ, which simulates immunoassays. Avidin could be detected down to 23.4 nM with excellent linearity (r = 0.996). Accordingly, our developed reagent, biotin-NQ, could be used as a universal highly stable, cost-effective, and steric free non-enzymatic label for immunoassays.

Intensive and Persistent Chemiluminescence System Based on Nano-/Bioenzymes with Local Tandem Catalysis and Surface Diffusion.

A chemiluminescence (CL) system with long persistent and intensive emission is essential for accurate CL quantitative analysis and imaging assay. However, with most known CL systems being flash-type, it is still a great challenge to develop long-lasting CL systems. Here, by combining an iron porphyrin metal-organic frameworks (FePorMOFs) based peroxidase mimic with natural glucose oxidase (GOx), an intensive and persistent CL system is presented on the basis of local tandem catalysis and surface diffusion of the nano-/bioenzymes (FePorMOF/GOx). FePorMOF synthesized by iron porphyrin linker and zirconium ion node possesses high peroxidase catalytic activity and stability. Using luminol and glucose as substrate, the FePorMOF/GOx CL system can produce intensive CL emission containing a plateau period of 7.5 h. The strong CL signal is due to the local tandem generation and reaction of H2O2 by GOx and FePorMOF, which avoids the diffusion-limited kinetics and leads to a high catalytic efficiency of the nano-/bioenzymes. On the other hand, the long persistent CL emission is attributed mainly to the enzymatic reaction-controlled H2O2 supply and surface diffusion-controlled CL reaction. The proposed CL system is explored for CL imaging sensing of glucose and homogeneous immunoassay of α-fetoprotein. The nano-/bioenzymes CL system exhibits intensive and long constant CL emission in physiological condition, showing promising applications in real-time bioassay and bioimaging.

Enhancing hydrogel-based long-lasting chemiluminescence by a platinum-metal organic framework and its application in array detection of pesticides and d-amino acids.

Organophosphorus pesticides (OPs) are harmful to people's health and d-amino acids (d-AAs) in the human body are closely related to various diseases. So, detection of OPs in foods and d-AAs in serum is important for food safety and clinical diagnosis. Herein, a long-lasting chemiluminescence (CL) imaging sensor was constructed for the detection of OPs and d-AAs. The method was based on N-(4-aminobutyl)-N-ethylisoluminol/Co2+/chitosan (ABEI/Co2+/CS) hydrogels, where metal organic framework materials (MOF-Pt) were selected as catalysts to improve the sensitivity greatly. Under the catalysis of acetylcholinesterase (AChE) and choline oxidase (CHO), H2O2 was produced by using acetylcholine chloride (ACh) as a substrate, which was sensitive to the proposed CL system. OPs inhibited the activity of AChE and decreased the production of H2O2, reducing CL intensity. The linear range of the method for chlorpyrifos was 0.5 ng mL-1-1.0 μg mL-1, with a limit of detection (LOD) of 0.21 ng mL-1. Seventeen kinds of OPs can be visually and simultaneously discerned by the CL imager. On the other hand, d-AAs were catalyzed and oxidized by d-α-amino oxidase (DAAO) to produce H2O2. Thus, d-Ala in serum was used as a model to be detected by the proposed method. The linear range for d-Ala was 1.0 μM-10 mM, with an LOD of 0.12 μM.

P-Bromophenol-Enhanced Bienzymatic Chemiluminescence Competitive Immunoassay for Ultrasensitive Determination of Aflatoxin B1.

Aflatoxin B1 (AFB1) contamination is one of the most critical global issues in food safety. The high carcinogenic nature necessitates rapid and specific methods for the determination of AFB1 in foodstuffs at ultratrace levels. Here, we report an enhanced bienzymatic chemiluminescence competitive immunoassay for ultrasensitive and high-throughput determination of AFB1. In this assay, protein G was first coated on the wells of a microplate for recognizing the Fc fragment of anti-AFB1 mAbs to reduce the antibody dosage and guarantee high immunological reaction efficiency. The target AFB1 competed with glucose oxidase labeled AFB1 for the limited anti-AFB1 mAbs in the wells of the microplate. p-Bromophenol was employed as an enhancer to obtain intense and long-lasting chemiluminescence. The utilization of an enhancer and bienzymatic catalysts effectively improved the detection sensitivity. The developed method offered a good linearity over 5 orders of magnitude, a detection limit of 5 pg L-1, and a relative standard deviation of 1.9% for AFB1. The application of the developed method to the analysis of grain samples gave quantitative recoveries from 94.0% to 97.0%. The developed method provides a universal platform for high-throughput, ultrasensitive, and high specific detection of pollutants or nutrients in foods.