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(searched for: doi:10.3390/s18020598)
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Published: 27 April 2022
by MDPI
Journal: Toxins
Abstract:
Aflatoxin, a type of mycotoxin, is mostly produced by Aspergillus flavus and Aspergillus parasiticus. It is responsible for the loss of billions of dollars to the world economy, by contaminating different crops such as cotton, groundnut, maize, and chilies, and causing immense effects on the health of humans and animals. More than eighteen different types of aflatoxins have been reported to date, and among them, aflatoxins B1, B2, G1, and G2 are the most prevalent and lethal. Early detection of fungal infection plays a key role in the control of aflatoxin contamination. Therefore, different methods, including culture, chromatographic techniques, and molecular assays, are used to determine aflatoxin contamination in crops and food products. Many countries have set a maximum limit of aflatoxin contamination (2–20 ppb) in their food and agriculture commodities for human or animal consumption, and the use of different methods to combat this menace is essential. Fungal infection mostly takes place during the pre- and post-harvest stage of crops, and most of the methods to control aflatoxin are employed for the latter phase. Studies have shown that if correct measures are adopted during the crop development phase, aflatoxin contamination can be reduced by a significant level. Currently, the use of bio-pesticides is the intervention employed in many countries, whereby atoxigenic strains competitively reduce the burden of toxigenic strains in the field, thereby helping to mitigate this problem. This updated review on aflatoxins sheds light on the sources of contamination, and the on occurrence, impact, detection techniques, and management strategies, with a special emphasis on bio-pesticides to control aflatoxins.
Rong Zhang, Huaibao Xiao, Guizhen Lu
Abstract:
The Surface plasma resonance (SPR) sensor with a type of slanted grooves metal grating structure based on the Otto prism-coupling is proposed and the equivalent relationship of the dispersion relation between the slanted and rectangular groove is established, which based on the resonance frequency obtained by numerical simulations. The results show that the refractive index of the sucrose solution is range from 1.33 to 1.37 when the concentration is lower than 25%, the sensing sensitivity is up to 4.94THz/RIU. The structure possesses the advantages of simple operation, low cost and high sensitivity, which has considerable application prospects in liquid sensing detection.
Melvin S. Samuel, Kanimozhi Jeyaram, Saptashwa Datta, Narendhar Chandrasekar, Ramachandran Balaji,
Journal of Agricultural and Food Chemistry, Volume 69, pp 13974-13989; https://doi.org/10.1021/acs.jafc.1c05994

The publisher has not yet granted permission to display this abstract.
Shirin Eyvazi, Behzad Baradaran, ,
Published: 19 June 2021
Trends in Food Science & Technology, Volume 114, pp 712-721; https://doi.org/10.1016/j.tifs.2021.06.024

The publisher has not yet granted permission to display this abstract.
Hui Fang Chen, Fei Han, Bangning Mao, Ju Gu, Yudi Li, , Yi Wang, , Jing Zhan
Published: 25 February 2021
Journal: Applied optics
Applied optics, Volume 60, pp 1924-1929; https://doi.org/10.1364/ao.414332

Abstract:
A rapid and label free aflatoxin B1 ( AFB1 ) microfluid sensor was proposed and tested. The device was fabricated with hollow-core photonics crystal fiber infiltrated with the AFB1 solution. The autofluorescence emitting from the AFB1 molecules was detected. The sensor length was optimized. The AFB1 concentration was tested with a 4 cm long sensor. The best limit of detection was achieved as low as 1.34 ng/ml, which meets the test requirement of the national standards for AFB1 in food. The effectiveness of this sensor being applied in beer solution was also verified to be a little more sensitive than in aqueous solution. Compared with traditional AFB1 detection methods, the proposed single-ended device perfectly satisfies the demand of process control in alcoholic beverages manufacture.
Published: 5 February 2021
by MDPI
Journal: Sensors
Sensors, Volume 21; https://doi.org/10.3390/s21041118

Abstract:
In this paper, a polyimide (PI)/Si/SiO2-based piezoresistive microcantilever biosensor was developed to achieve a trace level detection for aflatoxin B1. To take advantage of both the high piezoresistance coefficient of single-crystal silicon and the small spring constant of PI, the flexible piezoresistive microcantilever was designed using the buried oxide (BOX) layer of a silicon-on-insulator (SOI) wafer as a bottom passivation layer, the topmost single-crystal silicon layer as a piezoresistor layer, and a thin PI film as a top passivation layer. To obtain higher sensitivity and output voltage stability, four identical piezoresistors, two of which were located in the substrate and two integrated in the microcantilevers, were composed of a quarter-bridge configuration wheatstone bridge. The fabricated PI/Si/SiO2 microcantilever showed good mechanical properties with a spring constant of 21.31 nN/μm and a deflection sensitivity of 3.54 × 10−7 nm−1. The microcantilever biosensor also showed a stable voltage output in the Phosphate Buffered Saline (PBS) buffer with a fluctuation less than 1 μV @ 3 V. By functionalizing anti-aflatoxin B1 on the sensing piezoresistive microcantilever with a biotin avidin system (BAS), a linear aflatoxin B1 detection concentration resulting from 1 ng/mL to 100 ng/mL was obtained, and the toxic molecule detection also showed good specificity. The experimental results indicate that the PI/Si/SiO2 flexible piezoresistive microcantilever biosensor has excellent abilities in trace-level and specific detections of aflatoxin B1 and other biomolecules.
Published: 30 November 2020
by MDPI
Journal: Chemosensors
Abstract:
Aflatoxins are highly toxic fungal secondary metabolites that often contaminate food and feed commodities. An electrochemical immunosensor for the determination of aflatoxin B1 (AFB1) was fabricated by immobilizing monoclonal AFB1 antibodies onto a screen-printed gold electrode that was modified with carbo-methyldextran by N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide cross-linking. An electrochemical interfacial modelling of biomolecular recognition was suggested and reasonably interpreted. Impedance technology was employed for the quantitative determination of AFB1. The limit of detection concentration of AFB1 for standard solutions and spiked pistachio samples was 0.5 ng/mL and 1 ng/mL, respectively. The immunosensor was able to successfully determine AFB1 concentrations in the range of 4.56–50.86 ng/mL in unknown pistachio samples. Comparative chromatographic analysis revealed that AFB1 concentrations that were higher than 345 ng/mL were not within the immunosensor’s upper limits of detection. Selectivity studies against Ochratoxin A and Aflatoxin M1 demonstrated that the proposed AFB1 immunosensor was able to differentiate between these other fungal mycotoxins. The novel electrochemical immunosensor approach has the potential for rapid sample screening in a portable, disposable format, thus contributing to the requirement for effective prevention and the control of aflatoxin B1 in pistachios.
Valerii Myndrul, , Mikhael Bechelany,
Published: 22 August 2020
Materials Science and Engineering: C, Volume 118; https://doi.org/10.1016/j.msec.2020.111401

Abstract:
The precise and rapid detection of hazardous molecules, microorganisms, pollutants, and toxins currently remains a global challenge. Aflatoxin B1 (AFB1) is a toxic and dangerous product of fungi that considered as cancerogenic, mutagenic, and immunosuppressive for humans and animals. Therefore, the screening of AFB1 in food and beverages plays an important role in preventing foodborne illnesses. In this study, AFB1 molecules were detected in a microfluidic device with integrated polyacrylonitrile/zinc oxide (PAN/ZnO) nanofibers fabricated via a combination of the electrospinning, and atomic layer deposition (ALD) techniques. The structural and optical analyses of PAN/ZnO nanofibers were performed and samples with the most suitable properties were utilized for AFB1 detection. In order to obtain the biorecognition layer towards AFB1, PAN/ZnO samples were modified by (3-Aminopropyl) triethoxysilane (APTES), and glutaraldehyde (GA), bovine serum albumin (BSA) and monoclonal antibodies (Anti-AFB1). Subsequently, photoluminescence (PL)-based immunosensor was integrated into a microfluidic cell and tested for AFB1 detection. The mechanism of PL changes caused by AFB1 & Anti-AFB1 complex formation was analyzed and developed. The proposed approach enables the detection of AFB1 with the lowest concentration (LOD) of about 39 pg/ml, while the sensitivity range was evaluated as 0.1–20 ng/ml. The obtained values of LOD and sensitivity, as well as the simplicity of the detection method, make this approach a prospect for further application.
Qi Wang, Qingli Yang, Wei Wu
Published: 27 March 2020
Frontiers in Microbiology, Volume 11; https://doi.org/10.3389/fmicb.2020.00408

Abstract:
Aspergillus exists commonly in many crops and any process of crop growth, harvest, storage, and processing can be polluted by this fungus. Once it forms a biofilm, Aspergillus can produce many toxins, such as aflatoxin B1 (AFB1), ochratoxin, zearalenone, fumonisin, and patulin. Among these toxins, AFB1 possesses the highest toxicity and is labeled as a group I carcinogen in humans and animals. Consequently, the proper control of AFB1 produced from biofilms in food and feed has long been recognized. Moreover, many biosensors have been applied to monitor AFB1 in biofilms in food. Additionally, in recent years, novel molecular recognition elements and transducer elements have been introduced for the detection of AFB1. This review presents an outline of recent progress made in the development of biosensors capable of determining AFB1 in biofilms, such as aptasensors, immunosensors, and molecularly imprinted polymer (MIP) biosensors. In addition, the current feasibility, shortcomings, and future challenges of AFB1 determination and analysis are addressed.
Vasileios Anastasiadis, , , Anastasios Economou, James Dekker, Mikko Harjanne, Paivi Heimala, Dimitris Goustouridis, Ioannis Raptis, Sotirios E. Kakabakos
Published: 18 January 2020
Biosensors and Bioelectronics, Volume 153; https://doi.org/10.1016/j.bios.2020.112035

The publisher has not yet granted permission to display this abstract.
Hema Bhardwaj, Gajjala Sumana,
Published: 1 October 2019
Journal: Food chemistry
Abstract:
The Surface Plasmon resonance (SPR) based label-free detection of small targeted molecules is a great challenge and require substantial signal amplification for the accurate and precise quantification. The incorporation of noble metal nanoparticles (NPs) like gold (Au) NPs for the fabrication of SPR biosensor has shown remarkable impact both for anchoring the signal amplification and generate plasmonic resonant coupling between NPs and chip surface. In this work, we present comparative studies related to the fabrication of self-assembled monolayer (SAM) and the influence of AuNPs on Au chip for Aflatoxin B1 (AFB1) detection using SPRi apparatus. The SAM Au chip was sequentially modified by EDC-NHS crosslinkers, grafting of protein-A and finally interaction with anti-AFB1 antibodies. Similar multilayer chip surface was prepared using functionalized lipoic acid AuNPs deposited on SAM Au chips followed by in situ activation of functional groups using EDC-NHS crosslinkers, grafting of protein-A and immobilization of anti-AFB1 antibodies. This multilayer functionalized AuNPs modified Au chip was successfully utilized for AFB1 detection ranging from 0.01 to 50 nM with a limit of detection of 0.003 nM. When compared to bare self-assembled Au chip which was shown to exhibit a limit of detection of 0.19 nM and a linear detection ranging from 1 to 50 nM, the AuNPs modified Au chip was proven to clearly be a better analytical tool. Finally, validation of the proposed biosensor was evaluated by spiked wheat samples and average recoveries (93 and 90.1%) were found to be acceptable.
Tao Wei, Pingping Ren, Linli Huang, Zicheng Ouyang, Ziying Wang, Xiangfeng Kong, Tiejun Li, Yulong Yin, ,
Published: 13 July 2019
Journal: Food chemistry
Abstract:
Mycotoxins are toxic metabolites produced by fungi or molds, which may cause serious harm to human health through polluted cereal foods. In order to measure the typical mycotoxin contaminations in wheat and corn, a surface plasmon resonance (SPR) method was established using SPR sensor chip that was fabricated based on self-assembled monolayer. The minimum detection limit of aflatoxin B1, ochratoxin A, zearalenone and deoxynivalenol were identified as 0.59 ng/mL, 1.27 ng/mL, 7.07 ng/mL and 3.26 ng/mL, respectively. The cross-reactivity for all four mycotoxins were demonstrated to be low. Moreover, the test data were compared with HPLC-MS/MS confirmatory analysis results and good agreement was found between them. In conclusion, the SPR method for simultaneously detecting four mycotoxins has been developed with high sensitivity, good linearity and specificity, which can meet the detection requirements of cereal foods.
Zeineb Ben Abdallah, Christine Grauby-Heywang, , Sebastien Cassagnere, Fabien Moroté, Eddie Maillard, Halim Sghaier,
Published: 15 June 2019
Biochemical Engineering Journal, Volume 150; https://doi.org/10.1016/j.bej.2019.107262

The publisher has not yet granted permission to display this abstract.
Seong Uk Son, Seung Beom Seo, Soojin Jang, Jongmin Choi, Jae-Woo Lim, Do Kyung Lee, Hyeran Kim, Sungbaek Seo, , , et al.
Published: 17 April 2019
Sensors and Actuators. B, Chemical, Volume 291, pp 257-265; https://doi.org/10.1016/j.snb.2019.04.081

The publisher has not yet granted permission to display this abstract.
Yueyue Yao, Haixia Wang, , Xiaojie Wang,
Published: 1 April 2019
Journal: Talanta
Talanta, Volume 201, pp 52-57; https://doi.org/10.1016/j.talanta.2019.03.109

Abstract:
More and more attention about food safety leads to a research hotspot to develop new detection methods for food contaminant. To address the problems of serious interference and low sensitivity, a chemiluminescent aptasensor for the detection of aflatoxin B1(AFB1) in food was developed in this paper. It is based on horseradish peroxidase (HRP) catalyze the luminol chemiluminescence reaction. The hybridization chain reaction (HCR) signal amplification strategy has been used to improve the detection sensitivity. Magnetic separation could further reduce background signal obviously at the same time. AFB1 as a model of analyte to test the capability of our developed assay system. Under the optimal experimental conditions, CL intensity showed a good linear correlation with the concentrations of AFB1 ranging from 0.5 to 40 ng mL−1. The limit of detection was estimated 0.2 ng mL−1 based on 3 times of the signal-to-noise ratio which is lower than those of the previously reported sensors. It could be used to detect AFB1 content in real samples, such as peanuts and milk which were purchased in local supermarket. The results proved that the sensing system has good anti-interference and selectivity. In all, it has potential for practical application in food safety field.
Published: 11 August 2018
by MDPI
Journal: Toxins
Abstract:
In sub-Saharan Africa, there is a high demand for affordable and accessible methods for on-site detection of aflatoxins for appropriate food safety management. In this study, we validated an electrochemical immunosensor device by the on-site detection of 60 maize flour samples from six markets and 72 samples from households in Kampala. The immunosensor was successfully validated with a linear range from 0.7 ± 0.1 to 11 ± 0.3 µg/kg and limit of detection (LOD) of 0.7 µg/kg. The maize flour samples from the markets had a mean total aflatoxin concentration of 7.6 ± 2.3 µg/kg with approximately 20% of the samples higher than 10 µg/kg, which is the maximum acceptable level in East Africa. Further down the distribution chain, at the household level, approximately 45% of the total number contained total aflatoxin levels higher than the acceptable limit. The on-site detection method correlated well with the established laboratory-based HPLC and ELISA-detection methods for aflatoxin B1 with the correlation coefficients of 0.94 and 0.98, respectively. This study shows the feasibility of a novel on-site detection method and articulates the severity of aflatoxin contamination in Uganda.
, Dongmin Shi, Shengmei Zhu, , , Guangfeng Wang
Published: 26 June 2018
Journal: ACS Sensors
ACS Sensors, Volume 3, pp 1368-1375; https://doi.org/10.1021/acssensors.8b00304

Abstract:
Despite of some recent development on the portable sensor for the on-site detection of Aflatoxin B1 (AFB1), the complex and expensive preparation of recognition elements still limited their wide applications. In this paper, by the fast, low-cost and stable recognition of aptamer DNA-AFB1, a portable aptasensor was fabricated for the on-site sensitive detection of the AFB1 in food matrixes, with the personal glucose meter (PGM) as readout and DNA walking machine for signal probe separation. In such an assay protocol, the target could trigger the DNA walker autonomously moving on the electrode surface, propelled by unidirectional Pb2+-specific DNAzyme digestion, which could amplify the signal and separate the signal probe as well for further quantification by the PGM. Under optimal conditions, the PGM signal increased with the increment of AFB1 concentration in the range from 0.02 to 10 nM with a limit of detection (LOD) of 10 pM (S/N=3). With the advantages of portability, user-friendly and low-cost, the method presented here has potential for portable and quantitative detection of various other targets for different Point-of-care (POC) testing scenarios.
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