Integrated graphene quantum dot decorated functionalized nanosheet biosensor for mycotoxin detection
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RESEARCH PAPER
Integrated graphene quantum dot decorated functionalized nanosheet biosensor for mycotoxin detection Hema Bhardwaj 1,2 & Christophe A. Marquette 3 & Priyanka Dutta 1,2 & Rajesh 1 & Gajjala Sumana 1,2 Received: 5 June 2020 / Revised: 3 July 2020 / Accepted: 23 July 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Decoration of graphene quantum dots (GQDs) on molybdenum disulfide (MoS2) nanosheets serves as an active electrode material which enhances the electrochemical performance of the analyte detection system. Herein, ionic surfactant cetyltrimethylammonium bromide (CTAB)-exfoliated MoS2 nanosheets decorated with GQD material are used to construct an electrochemical biosensor for aflatoxin B1 (AFB1) detection. An antibody of AFB1 (aAFB1) was immobilized on the electrophoretically deposited MoS2@GQDs film on the indium tin oxide (ITO)-coated glass surface using a crosslinker for the fabrication of the biosensor. The immunosensing study investigated by the electrochemical method revealed a signal response in the range of 0.1 to 3.0 ng/mL AFB1 concentration with a detection limit of 0.09 ng/mL. Also, electrochemical parameters such as diffusion coefficient and heterogeneous electron transfer (HET) were calculated and found to be 1.67 × 10−5 cm2/s and 2 × 10−5 cm/s, respectively. The effective conjugation of MoS2@GQDs that provides abundant exposed edge sites, large surface area, improved electrical conductivity, and electrocatalytic activity has led to an excellent biosensing performance with enhanced electrochemical parameters. Validation of the fabricated immunosensor was performed in a spiked maize sample, and a good percentage of recoveries within an acceptable range were obtained (80.2 to 98.3%). Keywords Molybdenum disulfide . Graphene quantum dots . Electrochemical impedance spectroscopy . Immunosensor . Aflatoxin B1
Introduction Worldwide contamination in food products by mycotoxins is a critical concern leading to causes of industrial and agricultural losses of billions of dollars, and their consumption shows a significant impact on human health and animal welfare [1]. Among the various mycotoxins, AFB1 is one of the potent
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00216-020-02840-0) contains supplementary material, which is available to authorized users. * Gajjala Sumana [email protected] 1
CSIR-National Physical Laboratory, Dr. KS Krishnan Marg, New Delhi 110012, India
2
Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
3
3d.FAB, CNRS, INSA, CPE-Lyon, ICBMS, University Lyon1, 69100 Villeurbanne cedex, France
toxins produced by multiple strains of the fungus, i.e., Aspergillus flavus, and Aspergillus parasiticus under specific temperature (24–36 °C), and humid conditions (> 7%). AFB1 occurring in the food includes grains, maize, groundnuts, and peanuts [2, 3]. AFB1 responsible for severe consequences from acute hepatic toxicity to chronic diseases includes liver cancer
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