For Fumonisin B1 Research Articles

Assessment of Mycotoxin Exposure and Associated Risk in Pregnant Dutch Women: The Human Biomonitoring Approach.

Mycotoxins are toxic secondary metabolites produced by various fungi that can contaminate food crops, which, in turn, may lead to human exposure. Chronic exposure to mycotoxins can cause adverse health effects including reproductive and developmental toxicity. Pregnant women and their foetuses present a vulnerable group for exposure to mycotoxins that can cross the placenta. Human biomonitoring of mycotoxins provides a real-life approach to estimate internal exposure. In this pilot study, 24-h urine samples from 36 pregnant Dutch women were analysed for aflatoxin M1 (AFM1), total deoxynivalenol (DON), de-epoxy-deoxynivalenol (DOM-1), total zearalenone (ZEN), total α-zearalenol (α-ZEL), total β-zearalenol (β-ZEL) and total zearalanone (ZAN), where 'total' refers to mycotoxins and their conjugated forms. Serum samples from these women were analysed for fumonisin B1 (FB1) and ochratoxin A (OTA). All samples were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The most prevalent mycotoxins were total DON, total ZEN and OTA, with a detection frequency of 100%. DOM-1, total α-ZEL and total β-ZEL were detected but to a lesser extent, while AFM1, total ZAN and FB1 were undetected. Median concentrations were 4.75 μg total DON/L, 0.0350 μg DOM-1/L, 0.0413 μg total ZEN/L, 0.0379 μg total α-ZEL/L, 0.0189 μg total β-ZEL/L, and 0.121 μg OTA/L. The calculated median concentration for total ZEN and its metabolites was 0.105 μg/L. Based on two separate risk assessment approaches, total DON exposure in this group was considered to be of low concern. Similarly, exposure to total ZEN and its metabolites in this group was of low concern. For OTA, the risk of non-neoplastic effects was of low concern based on exposure in this group, and the risk of neoplastic effects was of low concern in the majority of participants in this group. The findings of this pilot study confirm the presence of mycotoxins in the urine and serum of pregnant Dutch women, with total DON, total ZEN, and OTA most frequently detected. Exposure to all measured mycotoxins was considered to be of low concern in this group, except for exposure to OTA, which was of low concern for the majority of participants. The study's findings offer valuable insights but should be confirmed using a larger and more diverse sample of the Dutch general population.

Graphene oxide-Mn3O4 nanocomposites for advanced electrochemical biosensor for fumonisin B1 detection

Occurrence of mycotoxins in food samples threat to its safety issue due to the presence of high toxicity and carcinogenic behavior, thus requiring highly sensitive and selective detection. Herein, the trimanganese tetraoxide (Mn3O4) nanoparticles in combination with graphene oxide (GO) nanocomposite were used to enhance the electrochemical performance for fabrication of electrochemical biosensor for fumonisin B1 (FB1) detection. The various characterization tools were used to validate the fabrication of GOMn3O4 nanocomposites. To fabricate the electrochemical biosensor on an indium tin oxide (ITO) coated glass substrate, a thin film of GOMn3O4 nanocomposite was prepared using electrophoretic deposition technique, and antibodies (ab-FB1) were immobilized onto the electrode for selective FB1 detection. The differential pulse voltammetry technique was used to observe the sensing performance. The non-binding sites of the ab-FB1 on the immunoelectrode were blocked with bovine serum albumin (BSA). The biosensor electrode was fabricated as BSA/ab-FB1/GOMn3O4/ITO for the detection of FB1. The sensitivity of the biosensor was obtained as 10.08 μA ml ng−1 cm−2 in the detection range of 1 pg ml−1 to 800 ng ml−1 with a limit of detection of 0.195 pg ml−1. In addition, the recovery of BSA/ab-FB1/GOMn3O4/ITO immunoelectrodes was also performed on sweet corn samples and is calculated to be 98.91%.

Tetrahedral DNA nanostructure-based ratiometric electrochemical aptasensor for fumonisin B1: A unity of opposites in binding site and steric hindrance of large-sized DNA for signal amplification

Large-sized DNA structures have been extensively explored in electrochemical sensing for abundant binding sites or large steric hindrance, yet large steric hindrance could hinder electron transfer of probes on DNA, depressing their efficiency for signal amplification. Herein, a ratiometric electrochemical aptasensor was designed to take advantage of abundant binding sites and large steric hindrance of the tetrahedral DNA nanostructure (TDN) for efficient signal amplification. The working principle is that the recognition of the target leads to a decrease in binding sites and a reduction in steric hindrance, which in turn leads to the opposite change in the two signals. Ferrocene (Fc)-labeled complementary DNA acted as a substrate, while a TDN containing aptamer was used for fumonisin B1 (FB1) recognition and methylene blue (MB) absorption. The binding of FB1 triggered the stripping of TDN, leading to a decreased current of MB (IMB) and an increased current of Fc (IFc). In this way, TDN allowed the enlarged variations in IFc and IMB by the significant change in steric hindrance and binding sites in ratiometric electrochemical sensing, respectively. Consequently, the developed aptasensor offered a linear range of 0.1–100 pg mL−1 and a detection limit of 0.087 pg mL−1 for FB1. This strategy offers a new way to fabricate high-performance sensors with large DNA structures.

Survey and toxigenic abilities of Aspergillus, Fusarium, and Alternaria fungi from wheat and paddy grains in Shanghai, China.

A systematic study was carried out on 638 wheat and paddy grains (including fresh and stored samples) collected in 2021 from Shanghai, China, to identify the major mycobiota and their toxigenic abilities. A total of 349 fungi, namely, 252 Fusarium, 53 Aspergillus, and 44 Alternaria, were characterized by morphological and molecular identification. Fusarium and Aspergillus were more frequently isolated in paddy with Fusarium sambucinum species complex and Aspergillus section flavi as the predominant species, respectively. The genus Alternaria was the most frequently isolated fungal species in wheat. The toxin-producing potentials of the identified fungi were further evaluated in vitro. Deoxynevalenol (DON) was produced by 34.5% of Fusarium isolates and zearalenone (ZEN) was produced by 47.6% of them, and one isolate also processed the abilities for fumonisin B1 (FB1), B2 (FB2), and B3 (FB3) productions. Aflatoxin B1 (AFB1), B2 (AFB2), and G1 (AFG1) were only generated by Aspergillus section flavi, with the production rate of 65.5%, 27.6%, and 13.8%, respectively. Alternariol (AOH) was the most prevalent Alternaria toxin, which could be produced by 95.5% of the isolates, followed by alternariol monomethyl ether (AME) (72.7%), altenuene (ALT) (52.3%), tenuazonic acid (TeA) (45.5%), tentoxin (TEN) (29.5%), and altenusin (ALS) (4.5%). A combinational analysis of mycobiota and toxigenic ability allowed us to provide comprehensive information about the production mechanisms of mycotoxins in wheat and paddy in a specific geographic area, and will be helpful for developing efficient prevention and control programs.

Novel electrochemiluminescence biosensor of fumonisin B1 detection using MWCNTs-PDMS flexible bipolar electrode

A novel portable and disposable bipolar electrode (BPE)-electrochemiluminescence (ECL) device was fabricated for fumonisin B1 (FB1) detection. BPE was fabricated by using MWCNTs and polydimethylsiloxane (PDMS) due to their excellent electrical conductivity and good mechanical stiffness. After the deposition of Au NPs on the cathode of BPE, the ECL signal could be improved 89-fold. Then a specific aptamer-based sensing strategy was constructed by grafting capture DNA on Au surface, followed by hybridizing with aptamer. Meanwhile, an excellent catalyst, Ag NPs was labeled on aptamer to activate oxygen reduction reaction, leading to a 13.8-fold enhancement in ECL signal at the anode of BPE. Under the optimal conditions, the biosensor exhibited a wide linear range of 0.10 pg/mL to 10 ng/mL for FB1 detection. Meanwhile, it demonstrated satisfactory recoveries for real sample detection with good selectivity, making it to be a convenient and sensitive device for mycotoxin assay.

Comparative Study of the Performance of Two Different Luciferases for the Analysis of Fumonisin B1 in Wheat Samples

AbstractThe development of two different immunoassays for the determination of fumonisin B1 in wheat samples is reported. A previously described mimopeptide for fumonisin B1 (FB1) was used to produce fusion proteins in combination with two different luciferases: Gaussia luciferase (GLuc) and NanoLuc luciferase (NLuc). The production, expression and the development of two immunoassays based on these fusion proteins (A2‐GLuc and A2‐NLuc) is detailed. The assay showing the best performance, A2‐NLuc, with a limit of detection of 0.61 ng mL−1 and a dynamic range from 1.9 to 95 ng mL−1, was employed for the analysis of spiked wheat samples, a reference matrix material, as well as naturally contaminated wheat samples. The recoveries obtained in the spiked samples were acceptable, between 81.5 and 109 %, with relative standard deviations lower than 14 %. The analysis of naturally contaminated wheat was validated by a liquid chromatography coupled to tandem mass detection method.

A highly sensitive and reproducible multiplex mycotoxin SERS array based on AuNPs-loaded inverse opal silica photonic crystal microsphere

A highly sensitive and reproducible multiplex mycotoxin SERS array has been established based on gold nanoparticles (AuNPs)-loaded inverse opal silica photonic crystal microsphere (SIPCM). Three types of Raman nanotags were synthesized by covalently grafting different antibodies and non-covalently loading different organic dyes onto the AuNPs for coding corresponding mycotoxins. To enhance Raman signal, AuNPs were loaded on the surface of SIPCM to create hot-spots once the Raman nanotags came closely. The maximal electric field enhancing effect in SIPCM with AuNP dimer could reach to 8 times. The assay principle was based on the competition immunoassay between the mycotoxins in sample and the artificial antigens immobilized on the surface of SIPCM. The three Raman nanotags could be integrated into an array to qualitatively and quantitatively detect multiplex mycotoxins in a sample. Such SERS-based assay displayed wide linear detection ranges of 0.001–10 ng/mL for ochratoxin A (OTA), 0.001–10 ng/mL for fumonisin B1 (FB1), and 0.1–1000 ng/mL for deoxynivalenol (DON), and low limits of detection (LOD) of 2.46 pg/mL for OTA, 0.20 pg/mL for FB1, and 68.98 pg/mL for DON. The recovery rates of the new method were measured to be 77.68–104.69% for OTA, 76.39–117.73% for FB1, and 70.95–113.16% for DON, in agreement with that of the classical ELISA method. The SERS-based method shows obvious advantages over fluorescence label or enzyme catalytic chemiluminescence methods, having a great application potential in rapidly screening multiplex mycotoxins in real samples.

Gold Nanobeads with Enhanced Absorbance for Improved Sensitivity in Competitive Lateral Flow Immunoassays.

Background: Colloidal gold based lateral flow immunoassay (LFIA) commonly suffers from relatively low detection sensitivity due to the insufficient brightness of conventional gold nanoparticles (AuNPs) with the size of 20–40 nm. Methods: Herein, three kinds of gold nanobeads (GNBs) with the size of 94 nm, 129 nm, and 237 nm, were synthesized by encapsulating numerous hydrophobic AuNPs (10 nm) into polymer matrix. The synthesized GNBs exhibited the enhanced colorimetric signal intensity compared with 20–40 nm AuNPs. The effects of the size of GNBs on the sensitivity of LFIA with competitive format were assessed. Results: The results showed that the LFIA using 129 nm GNBs as amplified signal probes exhibits the best sensitivity for fumonisin B1 (FB1) detection with a cut-off limit (for visual qualitative detection) at 125 ng/mL, a half maximal inhibitory concentration at 11.27 ng/mL, and a detection limit at 1.76 ng/mL for detection of real corn samples, which are 8-, 3.82-, and 2.89-fold better than those of conventional AuNP40-based LFIA, respectively. The developed GNB-LFIA exhibited negligible cross-reactions with other common mycotoxins. In addition, the accuracy, precision, reliability, and practicability were demonstrated by determining real corn samples. Conclusions: All in all, the proposed study provides a promising strategy to enhance the sensitivity of competitive LFIA via using the GNBs as amplified signal probes.

Determination of fumonisin B1 and B2 in corn products

An analytical method using immunoaffinty column and HPLC was developed for determination fumonisins in corn and corn products. The detection limits for fumonisin B1 (FB1) and fumonisin B2 (FB2) were 0.03 ppm and 0.07 ppm, respectively. Spiked FB1 in dried corn (kernel and flour), fresh corn, corn snack and corn flake are at 0.2-3.0 ppm level, with recovery ranged from 79.2-108.8% and relative standard deviation (RSD) of 2.9-21.9%. FB2 spiked under the same condition as FB1 had recovery ranges of 70.0-106.0% and RSD of 4.7-20.0%. A total of 76 samples were collected, including 20 dried corn (kernel or flour), 5 fresh corn, 15 corn snacks, 10 corn flakes, 5 corn starch, 5 canned corn from commercial markets and 16 raw corn materials were purchased from corn snack manufacturers. From the total 76 samples, 11 samples (14.5%) were detected with FB1 and/or FB2. Seven samples of corn were at 0.05-0.13 ppm level, 1 fresh corn with 0.15 ppm, 2 corn snacks with 0.5 and 0.16 ppm, respectively, where as 1 corn raw material was at the 0.09 ppm level. The highest contamination was only 0.16 ppm. Nevertheless, no fumonisin was detected in corn flake, corn starch and canned corn samples.

Quantum dot nanobead-based fluorescent immunochromatographic assay for simultaneous quantitative detection of fumonisin B1, dexyonivalenol, and zearalenone in grains

The mycotoxins in grains is a serious threat to the health of humans and animals. In this study, we demonstrated an approach for development of a fast and sensitive fluorescent immunochromatographic assay for fumonisin B1 (FB1), deoxynivalenol (DON) and zearalenone (ZEN) detection using quantum dots nanobeads (QDNBs, 100 nm). Amplification of the fluorescence signal of the quantum dot by nanosphere coating can significantly improve the sensitivity of immunochromatographic test strip. The detection probes (FB1-McAb@QDNBs, DON-McAb@QDNBs, and ZEN-McAb@QDNBs) were prepared using the QDNBs with 615 nm emissions coupling with three monoclonal antibodies (McAb) against FB1, DON, and ZEN, respectively, in a competitive immunochromatography platform. The surface of the QDNBs is modified with a carboxyl functional group, which facilitates the coupling of the antibody and significantly improves the sensitivity of test strip. Compared with traditional ELISA, the immunoassay based on the McAb@QDNBs is more sensitive, with IC50 of 12.66 ng/mL (FB1), 2.97 ng/mL (DON), and 0.87 ng/mL (ZEN), of which the linear range were from 2.295 ng/mL to 69.867 ng/mL (FB1), 0.465 ng/mL to 16.19 ng/mL (DON), and 0.295 ng/mL to 2.575 ng/mL (ZEN), respectively. The accuracy, repeatability, and specificity of the established test strip was evaluated by testing the spiked and natural samples. Furthermore, a high agreement was observed between the developed test strips and LC-MS/MS in simultaneously and quantitative detection of three mycotoxins. In brief, the developed approach was feasible and could be employed for simultaneously and quantitative mycotoxins detection in agricultural products.

A novel electrochemical aptasensor for fumonisin B1 determination using DNA and exonuclease-I as signal amplification strategy

In this work, using DNA and exonuclease-I (Exo-I) as signal amplification strategy, a novel and facile electrochemical aptasensor was constructed for fumonisin B1 (FB1) detection. The G-rich complementary DNA (cDNA) was immobilized onto the electrode surface. Then, aptamer of FB1 was hybridized with cDNA to form double-stranded DNA. In the absence of FB1, double-stranded DNA and G-rich cDNA on the electrode surface promoted effectively methylene blue (MB) enrichment and amplified the initial electrochemical response. In the presence of FB1, the combination of aptamer and FB1 led to the release of aptamer from the electrode surface and the expose of 3′ end of single-stranded cDNA. When Exo-I was added onto the electrode surface, the single-stranded cDNA was degraded in the 3′–5′ direction. The decrease of double-stranded DNA and G-rich cDNA resulted in the less access of MB to the electrode surface, which decreased the electrochemical signal. The experimental conditions including incubation time of FB1, the amount of Exo-I and incubation time of Exo-I were optimized. Under the optimal conditions, the linear relationship between the change of peak current and the logarithmic concentration of FB1 was observed in the range of 1.0 × 10−3–1000 ng mL−1 with a low limit of detection of 0.15 pg mL−1. The experimental results showed that the prepared aptasensor had acceptable specificity, reproducibility, repeatability and stability. Therefore, this proposed aptasensor has a potential application in the food safety detection.

Visual Non-Instrumental On-Site Detection of Fumonisin B1, B2, and B3 in Cereal Samples Using a Clean-Up Combined with Gel-Based Immunoaffinity Test Column Assay

A visual immunoaffinity test column (IATC) assay was developed to detect fumonisins in cereal samples for spot tests without the need for special instruments. The developed IATC assay had equivalent recognition capability for fumonisin B1 (FB1), fumonisin B2 (FB2), or fumonisin B3 (FB3), and exhibited no cross-reactivity with aflatoxin B1, ochratoxin A, zearalenone, or the T-2 toxin. The sample pretreatment was accomplished more rapidly and with greater ease, the entire assay procedure was completed in approximately 10 min, including sample pretreatment and testing. The limits of detection (LODs) of the IATC assay to detect fumonisins in the maize, barley, oat, and millet samples were 20 μg kg−1. The results of the spiked maize, barley, oat, and millet and real maize samples by the IATC assay agreed well with the results obtained by the commercial fumonisin enzyme-linked immunosorbent assay (ELISA) test kit and liquid chromatography-tandem mass spectrometry (LC-MS/MS), respectively. The developed IATC assay can serve as a useful screening tool for the rapid, qualitative, and semi-quantitative detection of the total content of fumonisins (sum of FB1, FB2, and FB3) in cereal samples on-site.

TiO2 Nanolayer-Enhanced Fluorescence for Simultaneous Multiplex Mycotoxin Detection by Aptamer Microarrays on a Porous Silicon Surface.

A new aptamer microarray method on the TiO2-porous silicon (PSi) surface was developed to simultaneously screen multiplex mycotoxins. The TiO2 nanolayer on the surface of PSi can enhance the fluorescence intensity 14 times than that of the thermally oxidized PSi. The aptamer fluorescence signal recovery principle was performed on the TiO2-PSi surface by hybridization duplex strand DNA from the mycotoxin aptamer and antiaptamer, respectively, labeled with fluorescence dye and quencher. The aptamer microarray can simultaneously screen for multiplex mycotoxins with a dynamic linear detection range of 0.1-10 ng/mL for ochratoxin A (OTA), 0.01-10 ng/mL for aflatoxins B1 (AFB1), and 0.001-10 ng/mL for fumonisin B1 (FB1) and limits of detection of 15.4, 1.48, and 0.21 pg/mL for OTA, AFB1, and FB1, respectively. The newly developed method shows good specificity and recovery rates. This method can provide a simple, sensitive, and cost-efficient platform for simultaneous screening of multiplex mycotoxins and can be easily expanded to the other aptamer-based protocol.

Determination of mycotoxins in pu-erh tea, black tea, and green tea samples

To establish a robust method for the determination of mycotoxins in tea samples, and to provide means for the quality and safety control of tea products. Samples of 20 tea products acquired from international market were extracted by organic solvents (acetonitrile containing 0.1% formic acid) or hot water, respectively. The extracts were analyzed by UPLC-MS/MS.A good linear regression was achieved in a range of 39.1 to 5 000 ng•L⁻¹ for aflatoxin B1 (AFB1) and aflatoxin G1 (AFG1), 117 to 15 000 ng•L⁻¹ for aflatoxin B2 (AFB2) and aflatoxin G2 (AFG2), 2.44 to 313 ng•L⁻¹ for fumonisin B1 (FB1), fumonisinB2 (FB2) and fumonisin B3 (FB3), and 3 125 to 5 000 ng•L⁻¹ for deoxynivalenol, with recovery rates between 85.7% and 99.6%. The coefficient of the linear equation for all standards was greater than 0.999 0, and the RSD value was less than 10%. Mycotoxins were detected in several tea samples using the two extraction methods but with different outcomes. The levels of mycotoxins detected ranging from 0.15 to 7.31 μg•kg⁻¹ were well below the State or US FDA regulation limits of mycotoxins in food products. Both methods are simple, accurate, and sensitive, and thus, suitable for the quantitative determination of mycotoxins in different food products. The method with the 80 ℃ hot-water extraction is more appropriate to determine the trace amounts of mycotoxins in tea leaves that are likely to be present in brewed tea liquor, while organic solvent method is more suitable for the detection of mycotoxins in ingestible foods.

Multi-branched gold nanoflower-embedded iron porphyrin for colorimetric immunosensor

Here, we for the first time used a thiolated amino-ligand modified multi-branched gold nanoflower as skeleton to encapsulate iron porphyrins (AuNF@FeTPPCl) as alternatives to horseradish peroxidase (HRP). After the FeTPPCl encapsulation, the HRP mimicking activity of FeTPPCl was effectively blocked by the steric hindrance of the hydrophobic layer on the AuNF surface. Upon the addition of ethanol, the loaded FeTPPCl was released into the solution in its free format and exposed the catalytic sites, resulting in the recovery of catalytic activity. The proposed encapsulation method effectively avoided the loss of catalytic activity that originated from the blocking of the catalytic active sites during immobilization. Additionally, the resultant AuNF@FeTPPCl nanocomposite exhibited a high loading level with 2.4 × 106 FeTPPCl molecules per AuNF, and showed considerably high catalytic activity for hydrogen peroxide and 3, 3′ 5, 5′-tetramethylbenzidine, which is approximately 40- and 172-folds higher than native HRP. Through using the as-prepared AuNF@FeTPPCl as an alternative of HRP for trace labeling, we successfully developed colorimetric immunosensors for fumonisin B1 (FB1) and hepatitis B surface antigen (HBsAg) with competitive and sandwich-type formats, respectively. The developed AuNF@FeTPPCl-based colorimetric immunosensor exhibited higher detection sensitivity for FB1 and HBsAg than the corresponding HRP-based immunosensors. Thus, the proposed AuNF@FeTPPCl can be used as HRP mimicking analogs for developing highly sensitive colorimetric immunosensor and for loading other hydrophobic iron porphyrins or catalysts.

Mycotoxin patterns in ear rot infected maize: A comprehensive case study in Nigeria

The levels of mycotoxin contamination in 78 ear rot infected maize sampled from nine states of northern Nigeria were determined by a straight-forward LC-MS/MS-based ‘dilute and shoot’ approach. Overall, 93 metabolites were identified whereof most can be assigned either to Aspergillus or Fusarium toxins with 37 and 34% occurrence respectively. Fusarium toxins typically occurred in higher concentrations above 320,000 μg/kg for fumonisin B1 (FB1) and 1,000,000 μg/kg for hydrolysed FB1. The fumonisins (FB1, FB2 and FB4) were also most widespread, occurring in all samples. Aflatoxin B1 (mean: 800 μg/kg) was found in samples from all states, but in 63% of all samples. Less frequently reported aflatoxins (AFM1 and AFP1) were identified at a comparatively low level in the samples exhibiting the highest aflatoxin levels. Citrinin, cyclopiazonic acid, deoxynivalenol, nivalenol, ochratoxin A (OTA) and zearalenone also occurred in the samples. Total fumonisins, AFB1, total aflatoxin and OTA levels exceeded the EU limits in 76, 50, 47 and 1.3% of all samples respectively. The wide array of metabolites and exceptionally high concentrations of mycotoxins pose a substantial risk to food and feed safety in the event that the grains enter the animal and human food chain which is common in rural settings.

Fate of Free and Conjugated Mycotoxins within the Production of Distiller's Dried Grains with Solubles (DDGS).

Contamination of feed with mycotoxins represents a serious worldwide problem concerning animal health and related economic losses. The present paper provides comprehensive knowledge about the fate of mycotoxins during the production of distiller's dried grains with solubles (DDGS). The study was carried out using naturally infected maize material in five repetitions. For mycotoxin analysis, a QuEChERS-like ("Quick, Easy, Cheap, Effective, Rugged, and Safe") isolation approach and ultrahigh-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) was used. A significant increase of deoxynivalenol (DON) and its glycosylated form, DON-3-glucoside (DON-3-Glc), was observed during the first part of fermentation, when hydrolytic enzymes were added. After yeast addition, the total DON content rapidly decreased. An opposite trend was observed for fumonisin B1 (FB1), in which yeast addition contributed to increase of its content. Further considerable change in mycotoxin content occurred during the drying step, in which approximately two-thirds of the original content was lost.

Label Free Poly(2,5-dimethoxyaniline)-Multi-Walled Carbon Nanotubes Impedimetric Immunosensor for Fumonisin B₁ Detection.

An impedimetric immunosensor for fumonisin B1 (FB1) was developed from a poly(2,5-dimethoxyaniline)-multi-walled carbon nanotube (PDMA-MWCNT) composite on the surface of glassy carbon electrode (GCE). The composite was prepared electrochemically and characterized using cyclic voltammetry. The preparation of the FB1 immunosensor involved the drop-coating of a bovine serum albumin mixture of the anti-fumonisin antibody (anti-Fms) onto the composite polymer-modified GCE. The electrochemical impedance spectroscopy (EIS) responses of the FB1 immunosensor (GCE/PDMA-MWCNT/anti-Fms) have a linear range of 7 to 49 ng·L−1, and the corresponding sensitivity and detection limits are 0.272 kΩ L·ng−1 and 3.8 pg·L−1, respectively. The limit of detection of the immunosensor for certified corn sample (i.e., certified reference material) is 0.014 ppm FB1, which is in excellent agreement with the value published by the vendors and significantly more accurate than that obtained with enzyme-linked immunosorbent assay (ELISA).

Characterization of fumonisin A-series by high-resolution liquid chromatography-orbitrap mass spectrometry.

Fumonisin A-series (FAs) in a reference material of corn sample that was naturally contaminated with fumonisins was characterized using high-resolution liquid chromatography-Orbitrap mass spectrometry (LC-Orbitap MS). Peaks for fumonisin B1 (FB1), fumonisin B2 (FB2), and fumonisin B3 (FB3), in addition to three peaks corresponding to unknown compounds I, II, and III, were detected in the chromatogram for the corn sample. Fragment ion analysis for FB1, FB2, and FB3 showed that while the ions formed at m/z values of 200–800 were similar to those formed by the cleavage of the tricarballylic acids and the hydroxyl groups, the fragmentation patterns at m/z values of 50–200 varied depending on the hydroxyl group locations in the compounds. Fragment ion analysis of compounds I–III revealed structural similarities to FBs, only differing by an additional C2H2O in the unknown compounds. Using these results and by comparing the product ion mass spectra of compound I with fumonisin A1 (FA1) synthesized from FB1 standards, compounds I–III were hypothesized to be N-acetyl analogs of FBs: fumonisins A1 (FA1), A2 (FA2), and A3 (FA3). The method for determining concentrations was validated with FA1, FB1, FB2, and FB3 standards and applied to analyze the reference material. The FB1, FB2, and FB3 analytical levels were within acceptance limits and the amount of FA1 in the material was ~15% of FB1 amount at 4.2 mg/kg.

Homogenous detection of fumonisin B1 with a molecular beacon based on fluorescence resonance energy transfer between NaYF4: Yb, Ho upconversion nanoparticles and gold nanoparticles

In this work, we presented a new aptasensor for fumonisin B1 (FB1) based on fluorescence resonance energy transfer (FRET) between NaYF4: Yb, Ho upconversion fluorescent nanoparticles (UCNPs) and gold nanoparticles (AuNPs). The quenchers (AuNPs) were attached to the 5′ end of the molecular beacon (MB), and the donors (UCNPs) were attached to the 3′ end of the MB. In the absence of target DNA (DNA complementary to FB1 aptamers), the energy donors and acceptors were placed in close proximity, leading to quenching of the fluorescence of the UCNPs. Due to the combination of FB1 and FB1-specific aptamers, this caused some complementary DNA dissociating from the magnetic nanoparticles (MNPs). In the presence of the complementary DNA, the MBs underwent spontaneous conformational change and caused the UCNPs and AuNPs to detach from each other, resulting in restoration of the upconversion fluorescence. Therefore, the fluorescence of UCNPs was restored in a FB1 concentration-dependent manner, which was the basis of the FB1 quantification. The aptasensors showed a linear relationship from 0.01 to 100ngmL−1 for FB1 with a detection limit of 0.01ngmL−1 in an aqueous buffer. As a practical application, the aptasensor was used to monitor FB1 levels in naturally contaminated maize samples. The results were consistent with that of a classic ELISA method, indicating that the UCNPs–FRET aptasensor, which benefited from the near infrared excitation of NaYF4: Yb, Ho UCNPs, was effective for directly sensing FB1 in foodstuff samples without optical interference. This work also created the opportunity to develop aptasensors for other targets using this FRET system.