Quantitative Detection Of Aflatoxin B1 Research Articles

Crescent-shaped Janus nanoassemblies of gold nanoparticles and AIEgens: Enhancing plasmonic and fluorescent activities for colorimetric and ratiometric fluorescence lateral flow immunoassay

Herein, crescent-shaped Janus nanoassemblies (Au-AIENPs) with high plasmonic and fluorescent activities are prepared by co-assembling oleylamine-coated gold nanoparticles (OA-AuNPs) and red-emitting aggregation-induced emission luminogens (AIEgens) in separate compartments of polymer nanoparticles. The obtained Au-AIENPs show typical Janus heterostructures, where AIEgens preferentially aggregate to form fluorescent core and OA-AuNPs are distributed in the polymer matrix to form a crescent-shaped plasmonic shell, thus resulting in effective spatial separation of OA-AuNPs and AIEgens to achieve the balance between plasmonic and fluorescent signals and reduce the mutual interference between signals. Taking advantage of the excellent plasmonic and fluorescent activities of Au-AIENPs, we successfully established a colorimetric and ratiometric fluorescence dual-mode lateral flow immunoassay (Au-AIENPs-RLFIA) for the visual and quantitative detection of aflatoxin B1 (AFB1) in corn sample. Under the developed conditions, the visual detection limit (vLOD) of the Au-AIENPs-RLFIA for colorimetric and ratiomentic fluorescence detection was 0.62 ng/mL and 0.02 ng/mL, respectively, while the quantitative LOD (qLOD) for ratiomentic fluorescence mode was as low as 0.0076 ng/mL. The above results indicate that the designed Janus Au-AIENPs are promising as dual-signal output probes and hold great potential for improving flexible dual-mode detection of various targets on the LFIA platform.

Fe-N-C single-atom nanozyme-linked immunosorbent assay for quantitative detection of aflatoxin B1

Aflatoxin B1 (AFB1) is a prominent food contaminant known for its high toxicity. Rapid, low-cost, and sensitive detection of AFB1 is an urgent demand for food safety risk control. In the traditional enzyme-linked immunosorbent assay (ELISA) method for AFB1 detection, horseradish peroxide (HRP) is high-cost and possesses poor environmental stability. In this study, a direct competitive single-atom nanozymes (SAzymes) -linked immunosorbent assay was developed based on Fe-N-C SAzymes. The proposed methods exhibited excellent sensitivity, rapid detection, fabrication, and low cost. Under the optimal conditions, the limit of detection of the new assay was 3.3 pg mL−1, with a quantitative relationship between 0.0084 and 0.358 ng mL−1. In addition, the developed method presented good recoveries in spiked samples, ranging from 84.50% and 103.75%, with coefficients of variation below 10%. Furthermore, the developed detection method showed good consistency (R2 = 0.9852) with the reference method, liquid chromatography/mass spectrometry (LC-MS/MS). To our knowledge, this is the first report about single-atom nanozymes-based ELISA for AFB1 determination. This work provides a feasible strategy for the rapid and sensitive detection of food contaminants using SAzymes.

Spatio-temporal distribution patterns and quantitative detection of aflatoxin B1 and total aflatoxin in peanut kernels explored by short-wave infrared hyperspectral imaging.

Aflatoxin contamination in peanut kernels seriously harms the health of humans and causes significant economic losses. Rapid and accurate detection of aflatoxin is necessary to minimize its contamination. However, current detection methods are time-consuming, expensive and destructive to samples. Therefore, short-wave infrared (SWIR) hyperspectral imaging coupled with multivariate statistical analysis was used to investigate the spatio-temporal distribution patterns of aflatoxin, and quantitatively detect the aflatoxin B1 (AFB1) and total aflatoxin in peanut kernels. In addition, Aspergillus flavus contamination was identified to prevent the production of aflatoxin. The result of validation set demonstrated that SWIR hyperspectral imaging could predict the contents of the AFB1 and total aflatoxin accurately, with residual prediction deviation values of 2.7959 and 2.7274, and limits of detection of 29.3722 and 45.7429μg/kg, respectively. This study presents a novel method for the quantitative detection of aflatoxin and offers an early warning system for its potential application.

Nafion-based label-free immunosensor as a reliable warning system: The case of AFB1 detection in cattle feed

This study presents a simple method for the rapid and versatile fabrication of label-free immunosensors on Nafion-modified screen-printed platforms. Herein, Nafion is exploited both as an immobilization matrix and as a weak (unexpectedly) electrochemical enhancer for the first time. The electrochemical characteristics in terms of diffusivity and conductivity of thin cation-exchange polymer membrane-modified screen-printed electrodes were investigated using cyclic voltammetry and electrochemical impedance spectroscopy. The free electrode surface area, the diffusion coefficient, the peak-to-peak separation, the heterogeneous electron transfer constant, and the charge transfer resistance for Nafion-modified and bare SPE have been calculated and compared. Then, Nafion-SPEs were employed to develop a competitive label-free immunoassay for the quantitative detection of Aflatoxin B1. Morphological characterization of the proposed immunosensor was performed using Scanning Electron Microscopy, and its analytical performance was evaluated using square wave voltammetry as a detection technique and [Fe(CN)6]3−/4− as a redox probe. The immunosensor showed satisfactory results in spiked cattle feed in terms of limit of detection (3.8 ngmL−1), linear range (LR 10–100 ngmL−1), sensitivity (33.0 ngmL−1) and reproducibility (RSD%<10%). The comparison of performance to that of a labelled immunosensor and a conventional chromatographic technique revealed a strong correlation between the respective results, but with shorter analysis time for the proposed tool. Furthermore, The present study achieved evidence of the dependability of the proposed method, proving that its use as an early warning system for the detection of AFB1 in cattle feed is something doable and not an abstract idea.

An electrochemiluminescence biosensor based on Graphitic carbon nitride luminescence quenching for detection of AFB1

Based on graphite-like carbon nitride (g-CN) nanocomposites coupled with aptamer, a regenerable electrochemiluminescence (ECL) biosensor is developed for the quantitative detection of aflatoxin B1 (AFB1). In the existence of AFB1, the structure of the aptamer changed into a loop, and the original ECL intensity was reduced owing to the enhancement of luminescence quenching between the ferrocene modified at the end of the aptamer and the luminescent substrate g-CN. Moreover, AFB1 with oxidation state could also react with high energy state g-CN, leading to further reduction of the electrochemiluminescence signal. At optimum conditions, ECL intensity was decreased in linearity with an AFB1 concentration range from 0.005 ng/mL to 10 ng/mL, and the minimum detectable concentration was down to 0.005 ng/mL, which realized trace detection demand with high sensitivity. It was selective for AFB1 and its performance had been verified on rice samples, which indicated a promising applying prospect of non-enzymatic electrochemiluminescence AFB1 detection.

A highly sensitive photothermal immunochromatographic sensor for detection of aflatoxin B1 based on Cu2-xSe-Au nanoparticles

In the study, Cu2-xSe-Au nanoparticles (CSA) with a photothermal conversion efficiency of 60.78 % at 808 nm were applied to the construction of thermal analysis immunochromatographic test strips for the highly sensitive quantitative detection of aflatoxin B1 (AFB1) in grain. The CSA was coupled with the AFB1 antibody to form a photothermal sensor probe by physical adsorption. The constructed immunosensor exhibited high sensitivity and a wide linear range from 0.01 to 10 μg/L in PBS. The detection limits of 0.00842 μg/L based on the thermal analysis was significantly improved by 11.88-fold compared with colorimetric results. No cross-reaction with the other mycotoxins was found except for aflatoxin B2, aflatoxin M1, aflatoxin G1 and aflatoxin G2. Applied to analysize grain sample, the method achieved the detection of AFB1 ranging from 0.16 to 160 μg/kg.

Target-responsive aptamer-cross-linked hydrogel sensors for the visual quantitative detection of aflatoxin B1 using exonuclease I-Triggered target cyclic amplification.

For the on-site detection of aflatoxin B1 (AFB1), a DNA hydrogel was prepared as a biosensor substrate, while an AFB1 aptamer was used as the recognition element. An AFB1-responsive aptamer-cross-linked hydrogel sensor was constructed using an enzyme-linked signal amplification strategy; AFB1 binds competitively to the aptamer, causing the hydrogel to undergo cleavage and release horseradish peroxidase (HRP). The addition of exonuclease I (ExoI) to the hydrogel causes the release of AFB1 from the aptamer, promoting additional hydrogel cleavage to release more HRP, ultimately catalysing the reaction between 3,3',5,5'-tetramethylbenzidine and H2O2. The hydrogel sensor exhibited an outstanding sensitivity (limit of detection, 4.93nM; dynamic range, 0-500nM), and its selectivity towards seven other mycotoxins was confirmed. The feasibility and reliability were verified by measuring the AFB1 levels in peanut oil (recoveries, 89.59-95.66%; relative standard deviation, <7%); the obtained results were comparable to those obtained by UPLC-HRMS.

Integrating magnetic metal-organic frameworks-based sample preparation with microchannel resistance biosensor for rapid and quantitative detection of aflatoxin B1

Aflatoxin B1, a secondary metabolite produced by fungi, is one of the most toxic mycotoxins that poses a major food security and public health threat worldwide. Effective sample pretreatment and high sensitivity detection techniques are urgently needed due to its trace amount in complex samples. Herein, an integrated detection strategy was developed by combining Mg/Zn-metal organic framework-74 modified Fe3O4 magnetic nanoparticles (Mg/Zn-MOF-74 @Fe3O4 MNPs)-based sample preparation and microchannel resistance biosensor for rapid and highly sensitive detection of aflatoxin B1 in food samples. The synthesis and characterization of Mg/Zn-MOF-74 @Fe3O4 MNPs was reported, which exhibited efficient separation and enrichment capacity when exposed to complex grain samples. The competitive immunoassay-based microchannel resistance biosensor enabled specific and high-sensitive analysis of aflatoxin B1 by using current as a readout, which caused by the blocking effect between the functionalized-polystyrene microspheres and microchannel. Under optimized conditions, this biosensor was capable to quantitatively analysis aflatoxin B1 from 10 pg/mL to 20 ng/mL, and with a limit of detection of 4.75 pg/mL. This integrated detection strategy has been tested for the quantitative detection of aflatoxin B1 in grain samples that is a potential protocol for food safety control and environmental monitoring.

Determination of aflatoxin B1 value in corn based on Fourier transform near-infrared spectroscopy: Comparison of optimization effect of characteristic wavelengths

Aflatoxin B1 (AFB1) is an important cause of human liver cancer. This study proposes a quantitative detection method for the AFB1 in corn based on Fourier transform near-infrared (FT-NIR) spectroscopy technology. First, we acquired spectral data of corn samples with different degrees of mildew using FT-NIR spectrometer; then, we used the ant colony optimization (ACO) and the NSGA-Ⅱ algorithms to optimize the characteristic wavelengths of the spectra after SNV treatment respectively; Finally, the back propagation neural network (BPNN) models were established using the optimized characteristic wavelengths to realize the accurate detection of the AFB1 in corn. The results obtained showed that the prediction performance of the BPNN model established using the four characteristic wavelength variables optimized by NSGA-Ⅱ algorithm is the best, and the best NSGA-Ⅱ-BPNN model's correlation coefficient of prediction (RP) is 0.9951, the root mean square error of prediction (RMSEP) is 1.5606 μg ⋅ kg−1. The overall results demonstrate that the quantitative detection of AFB1 in corn by FT-NIR technique is feasible; in addition, the NSGA-Ⅱ algorithm has its unique advantages in the optimization of spectral characteristics, and it can obtain characteristic wavelength variables with strong pertinence and a small number.

Input features and parameters optimization improved the prediction accuracy of support vector regression models based on colorimetric sensor data for detection of aflatoxin B1 in corn

A new method for quantitative detection of aflatoxin B1 (AFB1) in corn based on colorimetric sensor technology was proposed in this study. First, we chose 12 kinds of color sensitive materials to make the colorimetric sensor array. The prepared colorimetric sensor array was used to collect the olfactory sensory information of corn samples with different degrees of mildew, and the information was characterized in the form of images, and using a new unsupervised feature selection with multi-subspace randomization and collaboration (SRCFS) algorithm combined with support vector machine regression (SVR) to optimize the image features of the colorimetric sensor to determine the best color components combination. The SVR model was established by using the best color components combination to achieve rapid quantitative analysis of the AFB1 in corn; in the process of SVR model calibration, optimization of SVR parameters C and g using particle swarm optimization (PSO). The research results showed that compared with the PSO-SVR model, the mean of correlation coefficient of prediction (RP) of the SRCFS-PSO-SVR model has increased from 0.97 to 0.98, and the mean of root mean square error of prediction (RMSEP) has decreased from 4.8 μg·kg−1 to 3.5 μg·kg−1; the RP of the best SRCFS-PSO-SVR model was 0.99 and the RMSEP was 2.8 μg·kg−1. The results reveal that the quantitative detection of the AFB1 in corn can be achieved by using colorimetric sensor technology combined with chemometric methods. Moreover, the SRCFS algorithm can efficiently find the feature combination of colorimetric sensor.

Integrating Magnetic Metal-Organic Frameworks-Based Sample Preparation with Microchannel Resistance Biosensor for Rapid and Quantitative Detection of Aflatoxin B1

Integrating Magnetic Metal-Organic Frameworks-Based Sample Preparation with Microchannel Resistance Biosensor for Rapid and Quantitative Detection of Aflatoxin B1

Quantitative detection of Aflatoxin B1 by subpixel CNN regression

Aflatoxin is a highly toxic substance dispersed in peanuts, which seriously harms the health of humans and animals. In this paper, we propose a new method for aflatoxin B1(AFB1) detection inspired by quantitative remote sensing. Firstly, we obtained the relative content of AFB1 at the sub-pixel level by subpixel decomposition (endmember extraction, nonnegative matrix decomposition). Then we modified the transfer learning models (LeNet5, AlexNet, VGG16, and ResNet18) to construct a deep learning regression network for quantitative detection of AFB1. There are 67,178 pixels used for training and 67,164 pixels used for testing. After subpixel decomposition, each aflatoxin pixel was determined to contain content, and each pixel had 400 hyperspectral values (415–799 nm). The experimental results showed that, among the four models, the modified ResNet18 model achieved the best effect, with R2 of 0.8898, RMSE of 0.0138, and RPD of 2.8851. Here, we implemented a sub-pixel model for quantitative AFB1 detection and proposed a regression method based on deep learning. Meanwhile, the modified convolution classification model has high predictive ability and robustness. This method provides a new scheme in designing the sorting machine and has practical value.

Polystyrene Microsphere-Based Immunochromatographic Assay for Detection of Aflatoxin B1 in Maize.

Aflatoxin B1 (AFB1), a mycotoxin, is hepatotoxic, carcinogenic, and nephrotoxic in humans and animals, and contaminate a wide range of maize. In this study, an immunochromatographic assay (ICA) based on polystyrene microspheres (PMs) was developed for sensitive and quantitative detection of AFB1 in maize. The amounts of PMs, the condition for activating carboxyl groups of PMs, the amount of monoclonal antibody (mAb), and the volume of the immune probe were optimized to enhance the performance PMs-ICA for point-of-care testing of AFB1 in maize. The PMs-ICA showed the cut-off value of 1 ng/mL in phosphate buffer (PB) and 6 µg/kg in maize samples, respectively. The quantitative limit of detection (qLOD) was 0.27 and 1.43 µg/kg in PB and maize samples, respectively. The accuracy and precision of the PMs-ICA were evaluated by analysis of spiked maize samples with recoveries of 96.0% to 107.6% with coefficients of variation below 10%. In addition, the reliability of PMs-ICA was confirmed by the liquid chromatography-tandem mass spectrometry method. The results indicated that the PMs-ICA could be used as a sensitive, simple, rapid point-of-care testing of AFB1 in maize.

Quantitative detection of aflatoxin B1 using quantum dots-based immunoassay in a recyclable gravity-driven microfluidic chip

To achieve rapid and sensitive detection of aflatoxin B1 (AFB1), we developed a polydimethylsiloxane gravity-driven cyclic microfluidic chip using the two-signal mode strategy. The structural design of the chip, together with the two-wavelength quantum dot ratio fluorescence, effectively eliminates the influence of environmental factors, improves the signal stability, and ensures that the final detection result positively correlates with the target concentration. Moreover, the theoretical analysis performed for the established physical model of the three-dimensional reaction interface inside the chip confirmed the improved reaction rate of immune adsorption in the microfluidic strategy. Overall, the method exhibited a wide analytic range (0.2–500 ng mL−1), low detection limit (0.06 ng mL−1), high specificity, good precision (coefficient of variation < 5%), excellent reusability (20 times, 89.1%) and satisfactory practical sample analysis capacity. Furthermore, the reusability and designability of this chip provide a reliable scheme for field detection of AFB1, analysis of other small molecules, and establishment of high-throughput detection systems under different conditions.

Development of Aflatoxin B1 Aptamer Sensor Based on Iron Porphyrin Organic Porous Material

In this paper, using molybdenum disulfide doped with gold nanoclusters (Au NCs@MoS2) as the substrate, an aflatoxin aptamer sensor was constructed utilizing iron porphyrin organic porous material modified with streptavidin and loaded with gold nano-bipyramids (SA-Au NBPs@ porous aromatic framework (PAF)-40-Fe) as a label. The catalyzed reduction current of hydrogen peroxide (H2O2) by Au NBPs@PAF-40-Fe was detected which is proportional to the concentration of aflatoxin B1. Thereby, quantitative detection of aflatoxin B1 (AFB1) is achieved. Under the optimal conditions, the linear range of the sensor is 0.05 ~ 85 ng/mL with detection limit of 0.017 ng/mL and the linear correlation coefficient (R2) of 0.9825. The average recovery is 99.28 %. This aflatoxin aptamer sensor has good selectivity and provides a highly sensitive method for the detection of aflatoxin.

Detection of Aflatoxin B1 Based on a Porous Anodized Aluminum Membrane Combined with Surface-Enhanced Raman Scattering Spectroscopy.

An Aflatoxin B1 (AFB1) biosensor was fabricated via an Ag nanoparticles assembly on the surface of a porous anodized aluminum (PAA) membrane. First, the Raman reporter 4-Aminothiophenol (4-ATP) and DNA (partially complementary to AFB1 aptamer) were attached to the surface of Ag nanoparticles (AgNPs) by chemical bonding to form a 4-ATP-AgNPs-DNA complex. Similarly, the surface of a PAA membrane was functionalized with an AFB1 aptamer. Then, the PAA surface was functionalized with 4-ATP-AgNPs-DNA through base complementary pairing to form AgNPs-PAA sensor with a strong Raman signal. When AFB1 was added, AgNPs would be detached from the PAA surface because of the specific binding between AFB1 and the aptamer, resulting in a reduction in Raman signals. The detection limit of the proposed biosensor is 0.009 ng/mL in actual walnut and the linear range is 0.01–10 ng/mL. The sensor has good selectivity and repeatability; it can be applied to the rapid qualitative and quantitative detection of AFB1.

Time-resolved fluorescent immunochromatographic assay-based on three antibody labels for the simultaneous detection of aflatoxin B1 and zearalenone in Chinese herbal medicines

ABSTRACTA time-resolved fluorescent immunochromatographic assay (TRFICA) was successfully developed for the sensitive, simultaneous, and quantitative detection of aflatoxin B1 (AFB1) and zearalenone (ZEN) in Chinese herbal medicines. Eu-nanospheres (EuNPs) with unique optical properties increased the stability and sensitivity of the immunochromatographic assay. To obtain stable quantitative results, we applied a three-label system in which monoclonal antibodies for AFB1 and ZEN were conjugated to the EuNPs as detection probes on the test line (T line), and EuNP-labelled chicken IgY conjugates acted as the reference on the control line (C line). The fluorescence intensities of the T and C lines were recorded, and the T/C ratio was employed as the quantitative signal for the elimination of strip variation and matrix effects. The parameters that affected the TRFICA were optimised. Under optimal conditions, the established TRFICA gave good linear ranges from 0.60 μg/kg to 3.92 μg/kg for AFB1 and from 0.40 μg/kg to 1.28 μg/kg for ZEN. The limits of detection for AFB1 and ZEN were as low as 0.60 and 0.40 μg/kg, respectively, in Chinese herbal medicines Semen coicis, Rhizoma dioscoreae, and Platycodon grandiflorus, respectively. The average recoveries of the spiked samples were 73%–95% for AFB1 and 75.83%–90% for ZEN, both with a relative standard deviation of < 9.08%. The results of 15 actual samples detected by the developed TRFICA showed a satisfactory correlation with those of ultra-performance liquid chromatography tandem mass spectrometry. Therefore, the TRFICA is a simple, rapid, and sensitive approach to quantitatively detect mycotoxins in Chinese herbal medicines.

Lateral flow aptamer assay for detection of aflatoxin B1 in tea using upconversion nanoparticles

Aflatoxin, extensively existing in peanuts, corn, rice, soybeans, wheat and tea, is a type of mycotoxins with the highest toxicity and carcinogenicity and thus poses a serious threat to human health. In this article, upconversion nanoparticles modified with aptamers specific to aflatoxin B1 were used as fluorescence markers. By this way, we constructed a paper-based lateral flow assays detection technology for rapid detection of aflatoxin B1 with good linearity in the concentration range of 0.1–100 ng/mL and detection limit of 0.03 ng/mL. This method can realize quantitative detection of aflatoxin B1 in real tea sample with high sensitivity and specificity. Hence it is suitable for rapid on - site detection of aflatoxin B1 by utilizing this method, which shows good economic value and application prospects.

A competitive-type photoelectrochemical immunosensor for aflatoxin B1 detection based on flower-like WO3 as matrix and Ag2S-enhanced BiVO4 for signal amplification

A competitive photoelectrochemical (PEC) immunosensor was successfully utilized for quantitative detection of aflatoxin B1 (AFB1). The flower-like tungsten oxide (WO3) hierarchical architectures with large specific surface areas and porous nanostructure was prepared as a matrix material for immobilizing of BSA-AFB1. The Ag ions-modified bismuth vanadate nano-polyhedron (BiVO4@Ag+) was utilized as labels for immobilization anti-AFB1 through affinity specific binding. The Ag2S was prepared in-situ growth by immediately deposition the S2− onto the BiVO4@Ag+. The high photocurrent intensity was generated by the obtained BiVO4@Ag2S under visible-light irradiation. Moreover, excellent sensitivity was achieved by using the WO3 as the matrix and BiVO4@Ag2S as labels to enhance photocurrent response and improve the photocurrent conversion efficiency. Under optimal conditions, the competitive PEC immunosensor showed wide linear range from 1.0 pg mL−1 to 120 ng mL−1 with limit detection of 0.28 pg mL−1 for AFB1. The biosensor was performed with good reproducibility, acceptable stability, and high specificity, which indicated potential application in the detection of other toxic small molecules.

Quantum dot nanobead-based multiplexed immunochromatographic assay for simultaneous detection of aflatoxin B1 and zearalenone

Immunochromatographic assay (ICA) is a promising technology for on-site detection. Nonetheless, the wide-scale application of ICA is hindered by several disadvantages, such as poor reproducibility, low sensitivity, and single-target detection. Thus, a novel quantum dot nanobead (QB)-based multiplexed ICA (QB-ICA) with multiple test lines was developed in this study for the simultaneous quantitative detection of aflatoxin B1 (AFB1) and zearalenone (ZEN), where QBs with high luminescence were used as labels to enhance the analytical sensitivity of the ICA. Moreover, a streptavidin (SA)-biotin system, which was undisturbed by the target mycotoxins, was introduced as the signal output for the control line. Consequently, stable and reliable T/C values (ratios of signals on the test line to that of the control line) were obtained as quantitative signals. The proposed QB-ICA demonstrated high sensitivity for the simultaneous detection of AFB1 and ZEN, of which the half-maximal inhibitory concentrations reached as low as 38.98 pg mL−1 and 1.23 ng mL−1, respectively. At 10% competitive inhibition concentration, the limit detections (LOD) were 1.65 and 59.15 pg mL−1 for AFB1 and ZEN, respectively. The average recoveries of the intra- and inter-assays ranged from 81.77% to 119.70% and from 94.18% to 111.4% for AFB1 and ZEN quantification, respectively, and the variation coefficients were less than 12%, thereby indicating that the proposed method is highly accurate and robust. These findings suggest that QB-ICA using SA-biotin system as the signal output of control line is an excellent point-of-care platform for the rapid screening of mycotoxins.