Fe-MOF/AuNP-based ratiometric electrochemical immunosensor for the detection of deoxynivalenol in grain products.

A ratiometric assay was designed to improve the sensitivity and reliability of electrochemical immunosensors for deoxynivalenol (DON) detection. The indicator signal caused by the Fe-based metal-organic framework nanocomposites loaded with gold nanoparticles and the internal reference signal from the [Fe(CN)6]3-/4- in the electrolyte came together at the immunosensor. When immunoreactivity occurred, the indicator signals decreased as the concentration of DON increased, while the internal reference signals increased slightly. The ratio of the indicator signal to the internal reference signal was available for reproducible and sensitive monitoring of DON. The prepared immunosensor showed excellent performance in the range from 0.5 to 5000 pg mL-1, and the detection limit was 0.0166 pg mL-1. The immunosensor achieved satisfactory detection toward DON in spiked and actual samples and has a promising application in the control of DON in grain products.

The component of the Chamaecyparis obtusa essential oil and insecticidal activity against Tribolium castaneum (Herbst).

Tribolium castaneum (Herbst) is a worldwide grain storage pest controlled by chemical control methods of phosphine fumigation, which results in many hazards, damages human health, makes pests resistant to pesticides, and pollutes the environment. In recent years, the popularity of botanical insecticides has continued to rise, and plant essential oils (EO) are considered potential alternatives for developing insecticides. In the current study, we selected the Chamaecyparis obtusa EO to determine its insecticidal effects and component analysis on T. castaneum. Through gas chromatography-ion mobility spectrometry (GC-IMS) technology, cedrol was the most obvious compound in the signal peak of the volatile components detected in the C. obtusa EO. The results of the bioassay showed that the C. obtusa EO had certain contact activity against T. castaneum, and the LD50 was 52.54 µg/adult. At three concentrations (0.41,1.62, 2.83 uL/cm2), the repellent rates of C. obtusa EO against T. castaneum were all above 80% at 15, 30, 60, and 120 min, respectively, indicating that the repellent effect was strong. Meanwhile, the C. obtusa EO exhibited fumigant toxicity against T. castaneum with LC50 values of 7.09 µg/L air. In addition, C. obtusa EO significantly increased the activity of AChE, CarE, POD, CAT, T-SOD, and chitinase in T. castaneum. Finally, the mechanism of C. obtusa EO on T. castaneum adults was explored based on transcriptome sequencing. We found that the DEGs focused on the chitin metabolic process and some aging genes in T. castaneum. Therefore, C. obtusa EO could be used as potential eco-friendly candidates for stored grain pest management.

Characterizing the Internal Structure of Chinese Steamed Bread during Storage for Quality Evaluation Using X-ray Computer Tomography.

Chinese steamed bread (CSB) is a traditional food of the Chinese nation, and the preservation of its quality and freshness during storage is very important for its industrial production. Therefore, it is necessary to study the storage characteristics of CSB. Non-destructive CT technology was utilized to characterize and visualize the microstructure of CSB during storage, and also to further study of quality changes. Two-dimensional and three-dimensional images of CSBs were obtained through X-ray scanning and 3D reconstruction. Morphological parameters of the microstructure of CSBs were acquired based on CT image using image processing methods. Additionally, commonly used physicochemical indexes (hardness, flexibility, moisture content) for the quality evaluation of CSBs were analyzed. Moreover, a correlation analysis was conducted based on the three-dimensional morphological parameters and physicochemical indexes of CSBs. The results showed that three-dimensional morphological parameters of CSBs were negatively correlated with moisture content (Pearson correlation coefficient range-0.86~-0.97) and positively correlated with hardness (Pearson correlation coefficient range-0.87~0.99). The results indicate the inspiring capability of CT in the storage quality evaluation of CSB, providing a potential analytical method for the detection of quality and freshness in the industrial production of CSB.

Single-cell transcriptomic analysis reveals differential cell subpopulations and distinct phenotype transition in normal and dissected ascending aorta.

BACKGROUND: Acute thoracic aortic dissection (ATAD) is a fatal condition characterized by tear of intima, formation of false lumen and rupture of aorta. However, the subpopulations of normal and dissected aorta remain less studied. METHODS: Single-cell RNA sequencing was performed including 5 patients with ATAD and 4 healthy controls. Immunohistochemistry and immunofluorescence were used to verify the findings. RESULTS: We got 8 cell types from human ascending aorta and identified 50 subpopulations including vascular smooth muscle cells (VSMCs), endothelial cells, fibroblasts, neutrophils, monocytes and macrophages. Six transmembrane epithelial antigen of prostate 4 metalloreductase (STEAP4) was identified as a new marker of synthetic VSMCs. CytoTRACE identified subpopulations with higher differentiation potential in specified cell types including synthetic VSMCs, enolase 1+ fibroblasts and myeloid-derived neutrophils. Synthetic VSMCs-derived C-X-C motif chemokine ligand 12 (CXCL12) might interact with neutrophils and fibroblasts via C-X-C motif chemokine receptor 4 (CXCR4) and atypical chemokine receptor 3 (ACKR3), respectively, which might recruit neutrophils and induce transdifferentitation of fibroblasts into synthetic VSMCs. CONCLUSION: We characterized signatures of different cell types in normal and dissected human ascending aorta and identified a new marker for isolation of synthetic VSMCs. Moreover, we proposed a potential mechanism that synthetic VSMCs might interact with neutrophils and fibroblasts via CXCL12-CXCR4/ACKR3 axis whereby deteriorating the progression of ATAD, which might provide new insights to better understand the development and progression of ATAD.

The effect of emotional uncertainty on attentional bias toward neutral infant faces in adults.

Recent studies have found that adults have stronger attentional bias toward neutral infant faces than emotional (positive or negative) infant faces. This phenomenon may derive from uncertainty over neutral expressions. To test this hypothesis, we recruited 176 participants to examine the relationship between their attentional bias toward neutral infant faces (with neutral adult faces as a comparison baseline) and their level of certainty in their appraisal of emotional valence through eye-tracking indices. The results showed that participants had a longer dwell time and higher fixation counts for infant faces than for adult faces and that a more uncertain appraisal of facial expressions positively predicted attentional bias toward neutral infant faces. Therefore, this study preliminarily demonstrates that emotional uncertainty heightens adults' attentional bias toward infant faces with neutral expressions.

Irisin alleviates obesity-related spermatogenesis dysfunction via the regulation of the AMPKα signalling pathway.

BACKGROUND: Infertility is a common complication in obese men. Oxidative stress and testicular apoptosis play critical roles in obesity-induced spermatogenesis dysfunction. It has been reported that irisin, an exercise-induced myokine, may attenuate oxidative damage and testicular apoptosis in several diseases; however, its role in obesity-induced spermatogenesis dysfunction remains unclear. The purpose of this study was to investigate the role and underlying mechanism of irisin in obesity-induced dysfunction of spermatogenesis. METHODS: Male mice were fed a high-fat diet (HFD) for 24 weeks to establish a model of obesity-induced spermatogenesis dysfunction. To explore the effects of irisin, mice were subcutaneously infused with recombinant irisin for 8 weeks beginning at 16 weeks after starting a HFD. To confirm the role of AMP-activated protein kinase α (AMPKα), AMPKα-deficient mice were used. RESULTS: The data showed decreased serum irisin levels in obese patients, which was negatively correlated with sperm count and progressive motility. Irisin was downregulated in the plasma and testes of obese mice. Supplementation with irisin protected against HFD-induced spermatogenesis dysfunction and increased testosterone levels in mice. HFD-induced oxidative stress, endoplasmic reticulum (ER) stress and testicular apoptosis were largely attenuated by irisin treatment. Mechanistically, we identified that irisin activated the AMPKα signalling pathway. With AMPKα depletion, we found that the protective effects of irisin on spermatogenesis dysfunction were abolished in vivo and in vitro. CONCLUSIONS: In conclusion, we found that irisin alleviated obesity-related spermatogenesis dysfunction via activation of the AMPKα signalling pathway. Based on these findings, we hypothesized that irisin is a potential therapeutic agent against obesity-related spermatogenesis dysfunction.

[miR-155/BACH1 Signaling Pathway in Human Lung Adenocarcinoma Cell Death Induced by Arsenic Trioxide].

OBJECTIVE: To explore the changes of micro RNA 155 (miR-155),BTB and CNC homologous protein 1 (BACH1),quinone oxidoreductase 1 (NQO1) and heme-oxygenase-1 (HO-1) in the process of arsenic trioxide-induced cell death,and to clarify the relationship between miR-155 and BACH1,providing experimental basis for the sensitivity of arsenic trioxide (ATO) treatment. METHODS: Human lung adenocarcinoma cell line A549 cells were treated with different concentrations of ATO. MTT assay and total antioxidant capacity detection kit were used to determine cell viability and total antioxidant capacity,respectively. BACH1,NQO1 and HO-1 protein expression were probed by Western blot and real-time fluorescence quantitative (qRT-PCR) was utilized to test the miR-155 level. A549 cells were transfected with miR-155 mimic and its negative control,then the expression level of miR-155 was detected by qRT-PCR,and these cells were treated with 20 µmol/L for 24 h followed by MTT and Western blot detection. RESULTS: 10 µmol/L ATO significantly reduced the cell viability in A549 cells. 10 µmol/L and 20 µmol/L ATO treatment activated BACH1 expression and inhibited miR-155,NQO1 and HO-1 expression,leading to decreased total antioxidant capacity. Importantly,the cell death induced by 20 µmol/L ATO was significantly decreased in miR-155 mimic transfection cells in comparison with non-transfected cells and miR-155 mimic negative control transfected cells. Moreover,high expression of miR-155 reduced BACH1 activation and increased NQO1 and HO-1 expression in cells treated with 20 µmol/L ATO ( P<0.05). CONCLUSION: Restraining total antioxidant capacity contributes to ATO induced cell death,the underlying mechanisms may be that ATO can activate BACH1 expression through inhibition of the miR-155 level,leading to subsequent inhibition of NQO1 and HO-1 expression. Taken together,these data suggest that miR-155 and BACH1 could be used as sensitivity targets for ATO treatment in lung cancer.

Colorimetric Sensor Array for Thiols Discrimination Based on Urease-Metal Ion Pairs.

Thiols play a crucial role in various physiological functions, and the discrimination of thiols is a significant but difficult issue. Herein, we presented a new strategy for strengthening the discrimination of thiols by a facile colorimetric sensor array composed of a series of urease-metal ion pairs. The proposed sensor array was fabricated based on the interactions between thiols and metal ions and the effective activation of urease by thiols. Different thiols exhibited different affinities toward the metal ions, producing differential retentions of urease activity and generating distinct colorimetric response patterns. These response patterns are characteristic for each thiol and can be quantitatively differentiated by linear discriminant analysis (LDA). Cysteine (Cys), glutathione (GSH), and four other kinds of thiols have been well distinguished on the basis of this sensor array at a low concentration (1.0 µM). Remarkably, the practicability of the proposed sensor array was further validated by high accuracy (96.67%) identification of 30 unknown thiol samples. In this strategy, urease and its metal ion inhibitors were adapted to fabricate the sensor array, offering a facile way to develop sensitive array sensing systems based on inexpensive and commercially available enzymes and their inhibitors.

Chemical Constituents from the Fruiting Bodies of Hexagonia apiaria and Their Anti-inflammatory Activity.

A chemical investigation of the fruiting bodies of Hexagonia apiaria resulted in the identification of nine compounds including five new triterpenoids, hexagonins A-E (1-5), along with four known compounds. The purified constituents were examined for their anti-inflammatory activity. Among the tested compounds, hexatenuin A displayed the most significant inhibition of superoxide anion generation and elastase release. These triterpenoids may have potentials as anti-inflammatory agents.

[A long-term follow-up of the correlation between obstructive sleep apnea hypopnea syndrome and multiple organ diseases].

OBJECTIVE: To explore the correlation between obstructive sleep apnea hypopnea syndrome (OSAHS) and multiple organ diseases. METHODS: Home-visit questionnaires were performed in 1 868 subjects (956 male, 912 female) with an average age of (79 ± 5) years, and a prospective follow-up was performed for a period of 20 years with annual medical examinations. Multiple organ diseases included hypertension, coronary heart disease, stroke, diabetes, pulmonary heart disease, renal insufficiency and erythrocytosis. The subjects were grouped by the diagnosis of OSAHS. RESULTS: Among the 1 868 subjects, 598 (32.0%) were diagnosed with OSAHS, and 1 270 (68.0%) of non-OSAHS as the control group. By the end of follow-up, in the OSAHS group there were 477 (79.8%) cases with hypertension, 337 (56.4%) cases with coronary heart disease, 167 (27.9%) cases with stroke, 76 (12.7%) cases with diabetes, 37 (6.2%) cases with pulmonary heart disease, 73 (12.2%) cases with renal insufficiency and 211(35.3%) cases with erythrocytosis, all of which were significantly higher than those of the control group [323(25.4%), 315 (24.8%), 95 (7.5%), 69 (5.4%), 40 (3.2%), 58 (4.6%), 30 (2.4%), P < 0.01]. The number of diseases in the OSAHS group was also higher than that in the control group (P < 0.05) . CONCLUSION: The incidence of multiple organ diseases was remarkably higher in the OSAHS group than that in the control group, which indicated that OSAHS was a risk factor for multiple organ diseases. These diseases in OSAHS patients may be related to hypoxia caused by OSAHS, endocrine and metabolic disorders, unhealthy lifestyles and arteriosclerosis.

Reducing microplastics in tea infusions released from filter bags by pre-washing method: Quantitative evidences based on Raman imaging and Py-GC/MS.

Microplastics released from plastic-based filter bags during tea brewing have attracted widespread attention. Laser confocal micro-Raman and direct classical least squares were used to identify and estimate micron-sized microplastics. Characteristic peaks from pyrolysis-gas chromatography/mass spectrometry of polyethylene terephthalate, polypropylene, and nylon 6 were selected to construct curves for quantification submicron-sized microplastics. The results showed that microplastics released from tea bags in the tea infusions ranged from 80 to 1288 pieces (micron-sized) and 0 to 63.755 µg (submicron-sized) per filter bag. Nylon 6 woven tea bags released far fewer microplastics than nonwoven filter bags. In particular, a simple strategy of three pre-washes with room temperature water significantly reduced microplastic residues with removal rates of 76 %-94 % (micron-sized) and 80 %-87 % (submicron-sized), respectively. The developed assay can be used for the quantitative evaluation of microplastics in tea infusions, and the pre-washing reduced the risk of human exposure to microplastics during tea consumption.

Zeolitic Imidazolate Framework-8 Composite-Based Enzyme-Linked Aptamer Assay for the Sensitive Detection of Deoxynivalenol.

The mycotoxin deoxynivalenol (DON) is a prevalent contaminant in cereals that threatens the health of both humans and animals and causes economic losses due to crop contamination. The rapid and sensitive detection of DON is essential for food safety. Herein, a colorimetric biosensor based on horseradish peroxidase- and gold nanoparticle-encapsulated zeolitic imidazolate framework-8 (HRP&Au@ZIF-8) was developed for the sensitive screening of DON. The synthesized HRP&Au@ZIF-8 probes not only held great potential for signal amplification but also exhibited stable catalytic activity even under extreme conditions, which endowed the biosensor with both good sensitivity and stability. Under the optimized conditions, qualitative measurement of DON can be achieved through visual inspection, and quantitative evaluation can be performed via absorbance measurements at a characteristic wavelength of 450 nm. The proposed method has demonstrated high sensitivity with a linear detection range of 1-200 ng/mL and a detection limit of 0.5068 ng/mL. It also presented good selectivity and reliability. Furthermore, DON in spiked cereal samples has been quantified successfully using this method. This novel approach demonstrates significant potential for the facile and expeditious detection of DON in cereal products and brings us one step closer to enhancing food safety.

An electrochemical immunosensor based on prussian blue@zeolitic imidazolate framework-8 nanocomposites probe for the detection of deoxynivalenol in grain products.

The presence of deoxynivalenol (DON) in grains poses a threat to human health, which is critical for sensitive detection of DON. In this electrochemical immunosensor, zeolitic imidazolate framework-8 (ZIF-8) loaded with Prussian blue (PB) nanoparticles was coated by polydopamine (PDA) as a redox probe. The high porosity of ZIF-8, the unique electrochemical activity of PB and the outstanding electrical conductivity of PDA improved the sensitivity of the immunosensor. Under the optimized conditions, the peak current in differential pulse voltammetry displayed a good linear relationship over DON concentrations in a range of 0.1-5000 pg mL-1 with a detection limit of 0.0186 pg mL-1. In addition, the immunosensor also had good selectivity and stability. Good recoveries of 85.67 to 118.00 % have been achieved for the detection of DON in spiked grain products. This new strategy exhibits great potential for simple and rapid detection of DON in grain and feed products.

NH2-MIL-125(Ti)/Reduced Graphene Oxide Enhanced Electrochemical Detection of Fenitrothion in Agricultural Products.

The abuse of organophosphate pesticides causes serious threats to human health, which threatens approximately 3 million people and leads to more than 2000 deaths each year. Therefore, it is necessary to determine the residue of fenitrothion (FT) in environmental and food samples. Herein, we developed a non-enzymatic electrochemical sensor with differential pulse voltammetry signal output to determine FT in model solutions and spiked samples. Delicately, the sensor was designed based on the fabrication of hydrothermally synthesized titanium-based metal-organic frameworks (MOFs) material (NH2-MIL-125(Ti))/reduced graphene oxide (RGO) (NH2-MIL-125(Ti)/RGO) nanocomposites for better target enrichment and electron transfer. The peak response of differential pulse voltammetry for FT under optimized conditions was linear in the range of 0.072-18 µM with the logarithm of concentrations, and the detection limit was 0.0338 µM. The fabricated sensor also demonstrated high stability and reproducibility. Moreover, it exhibited excellent sensing performances for FT in spiked agricultural products. The convenient fabrication method of NH2-MIL-125(Ti)/RGO opens up a new approach for the rational design of non-enzymatic detection methods for pesticides.

Spectroscopic studies on thermal degradation and quantitative prediction on acid value of edible oil during frying by Raman spectroscopy.

The health risks posed by harmful substances resulting from the thermal degradation of frying oils are of great concern. Characteristic peak intensity ratios (PIRs) screened from Raman spectra were used to characterize the thermal degradation. High correlation coefficients between PIRs and acid values (AVs) of 0.972 (linear fitting), 0.984 (logarithmic function fitting), and 0.954 (linear fitting) for fried soybean oil, canola oil, and palm oil, were obtained at the PIRs of I1267/I1749, I1267/I1659, and I1267/I1749, respectively. The highly correlated PIRs common to the three oils were determined by Pearson's correlation coefficient combined with heat maps. To accommodate both linear and nonlinear features, a global model for predicting AVs of multi-varieties frying oils was constructed using a least-squares support vector machine algorithm, and the results performed well with a root mean square error of prediction of 0.016 and a ratio of prediction to deviation of 11.351. The whole results demonstrate that Raman spectroscopy could characterize the thermal degradation and has excellent quantitative analysis ability for food control based on AV in frying oils, thus providing a new approach to quality control of frying oils.

Off-label use versus formal recommendations of conventional and novel antibiotics for the treatment of infections caused by multidrug-resistant bacteria.

The infections caused by multidrug- and extensively drug-resistant (MDR, XDR) bacteria, including Gram-positive cocci (GPC, including methicillin-resistant Staphylococcus aureus, MDR-Streptococcus pneumoniae and vancomycin-resistant enterococci) and Gram-negative bacilli (GNB, including carbapenem-resistant [CR] Enterobacterales, CR-Pseudomonas aeruginosa and XDR/CR-Acinetobacter baumannii complex) can be quite challenging for physicians with respect to treatment decisions. Apart from complicated urinary tract and intra-abdominal infections (cUTIs, cIAIs), bloodstream infections and pneumonia, these difficult-to-treat bacteria also cause infections at miscellaneous sites (bones, joints, native/prosthetic valves and skin structures, etc.). Antibiotics like dalbavancin, oritavancin, telavancin and daptomycin are currently approved for the treatment of acute bacterial skin and skin structural infections (ABSSSIs) caused by GPC. Additionally, ceftaroline, linezolid and tigecycline have been formally approved for the treatment of community-acquired pneumonia and ABSSSI. Cefiderocol and meropenem-vaborbactam are currently approved for the treatment of cUTIs caused by XDR-GNB. The spectra of ceftazidime-avibactam and imipenem/cilastatin-relebactam are broader than that of ceftolozane-tazobactam, but these three antibiotics are currently approved for the treatment of hospital-acquired pneumonia, cIAIs and cUTIs caused by MDR-GNB. Clinical investigations of other novel antibiotics (including cefepime-zidebactam, aztreonam-avibactam and sulbactam-durlobactam) for the treatment of various infections are ongoing. Nevertheless, evidence for adequate antibiotic regimens against osteomyelitis, arthritis and infective endocarditis due to several GPC and MDR-GNB is still mostly lacking. A comprehensive review of PubMed publications was undertaken and the formal indications and off-label use of important conventional and novel antibiotics against MDR/XDR-GPC and GNB isolates cultured from miscellaneous sites are presented in this paper.

Identification and Evaluation of Microplastics from Tea Filter Bags Based on Raman Imaging.

Microplastic (MP) contamination is a public issue for the environment and for human health. Plastic-based food filter bags, including polyethylene terephthalate, polypropylene, nylon 6 (NY6), and polyethylene, are widely used for soft drink sub-packaging, increasing the risk of MPs in foods and the environment. Three types of commercially available filter bags, including non-woven and woven bags, were collected, and MPs released after soaking were mapped using Raman imaging combined with chemometrics. Compared with peak area imaging at a single characteristic peak, Raman imaging combined with direct classical least squares calculation was more efficient and reliable for identifying MP features. Up to 94% of the bags released MPs after soaking, and there was no significant correlation with soaking conditions. Most MPs were tiny fragments and particles, and a few were fibrous MPs 620-840 µm in size. Woven NY6 filter bags had the lowest risk of releasing MPs. Source exploration revealed that most MPs originated from fragments and particles adsorbed on the surface of bags and strings. The results of this study are applicable to filter bag risk assessment and provide scientific guidance for regulating MPs in food.

Estimation of contamination level in microplastic-exposed crayfish by laser confocal micro-Raman imaging.

Crayfish is one of the most important freshwater aquaculture species in China. The potential risks of crayfish consumption caused by environmental microplastic pollution have attracted much attention. In this study, a total of 72 crayfish samples were exposed to the microplastic concentrations of 1 mg/L, 3 mg/L, and 9 mg/L for 7, 14, and 28 days, and microplastic contamination levels in crayfish were then explored by laser confocal micro-Raman (LCM-Raman) imaging and scanning electron microscope (SEM). LCM-Raman imaging showed better performance in microplastics identification. Besides, the average percentage of the contaminated area in visualized LCM-Raman images was used to quantitatively assess contamination levels. Following 28 days of exposure to 9 mg/L microplastics, microplastic accumulation reached about 13,000 particles per crayfish. The results confirmed that LCM-Raman imaging combined with image processing technology could be used to construct a high-performance analytical strategy for the assessment of microplastic contamination in crayfish.

Ozone reduces lifespan and alters gene expression profiles in Rhyzopertha dominica (Fabricius).

Rhyzopertha dominica is one of the most important stored grain pests that seriously damage rice and wheat. At present, the method of controlling stored grain pests mainly relies on insecticide fumigation. However, the excessive use of pesticides not only leaves pesticide residues, with harmful effects on human health and the environment, but also induces insect resistance. Ozone is a strong oxidant with the characteristics of easy decomposition and without residue. Although ozone has been widely used in the food industry in recent years, research on the control of stored grain pests is limited. In this research, we used ozone treatment to control R. dominica adults and explore the molecular mechanisms that affect them. Here, we found that ozone treatment on R. dominica adults could decrease life span and increase malondialdehyde (MDA) content, as well as reduce activity of total superoxide dismutase (SOD) and catalase (CAT). Using RNA-seq technology, we identified 641 genes that were differentially expressed between ozone-treated and control R. dominica adults [fold-change of ≥ 2 (q-value < 5%)]. When comparing ozone treatment with control R. dominica adults, 330 genes were significantly upregulated and 311 were downregulated. RT-qPCR confirmed that 11 genes were differentially expressed in ozone-treated and control R. dominica adults. These genes were involved in insect cuticle protein and antioxidant system. This research showed that ozone treatment could reduce the lifespan of R. dominica through antioxidant system. It is an environmentally benign method for the control of stored grain pests and has great development potential.

Colorimetric ELISA based on urease catalysis curcumin as a ratiometric indicator for the sensitive determination of aflatoxin B1 in grain products.

There is an urgent need to measure aflatoxin B1 (AFB1) in food to prevent contaminated food consumption. In this work, a novel colorimetric enzyme-linked immunosorbent assay (ELISA) was developed for the detection of AFB1 using curcumin as a colorimetric indicator. An indirect competitive enzyme-label immunoassay was developed using urease and rabbit anti-mouse immunoglobulin G labeled with gold nanoparticles as the signal-transduction tag. Urease catalyzed the hydrolysis of urea to produce ammonia, which increased the pH of the solution. The phenolic hydroxyl group of curcumin ionized into phenolic oxygen anions under alkaline conditions, which strengthened the synergistic effect of electron supply and absorption in curcumin. As a result, the color of curcumin changed from yellow to reddish-brown, producing a visible color change. Under optimal conditions, AFB1 could be qualitatively determined with the naked eye, and quantitatively assessed by measuring the ratio of absorbance at wavelengths of 550 and 428 nm. The change in the ratio of absorbance Δ550/Δ428 decreased linearly in a range of 0.01-5 ng mL-1, and the limit of detection was 67 pg mL-1. Therefore, the selectivity and reliability of this proposed method were well validated. This method was also successfully used for the quantitation of AFB1 in spiked rice flour and wheat flour samples. This approach may broaden the application field of colorimetric ELISA for aflatoxin, providing a promising platform for the rapid screening of aflatoxin in food.