Integrated graphene quantum dot decorated functionalized nanosheet biosensor for mycotoxin detection

Abstract

Decoration of graphene quantum dots (GQDs) on molybdenum disulfide (MoS 2 ) nanosheets serves as an active electrode material which enhances the electrochemical performance of the analyte detection system. Herein, ionic surfactant cetyltrimethylammonium bromide (CTAB)-exfoliated MoS 2 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 MoS 2 @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 cm 2 /s and 2 × 10 −5 cm/s, respectively. The effective conjugation of MoS 2 @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%).

Carbon-Based Nanocomposite Smart Sensors for the Rapid Detection of Mycotoxins

“…A label-free electrochemical ultrasensitive biosensor was fabricated for AFB1 detection using MoS2@GQDs as an electrode surface transducer material. The immunosensor via the electrochemical method showed a signal response in the AFB1 concentration range of 0.1 to 3.0 ng/mL in a spiked maize sample with a detection limit of 0.09 ng/mL [70].…”

Recent Progress in Nanotechnology-Based Approaches for Food Monitoring

“…As another strategy for electrode modification, quantum dots as zero-dimensional nanomaterials with negligible size and extremely high surface-to-volume ratio are excellent nanomaterials. Quantum dot-based electrodes could be used to enhance the sensitivity of aflatoxin B1—a toxin produced by fungus occurring in food, i.e., grains, peanuts, maize, and groundnuts—detection in maize samples with a detection limit of 0.09 ng/mL [ 197 ]. The quantum dots@porous carbon platform for the electrochemical detection of oxytetracycline—an antibiotic—was developed by Lin et al with the limit of detection of 3.23 × 10 −9 mol/L [ 198 ].…”

Recent trends in analysis of mycotoxins in food using carbon-based nanomaterials

“…The antibodies are immobilized by several techniques including covalent binding, self-assembly and electrostatic deposition, in which the covalent binding technique is often used due to the uniform immobilization of antibody attained through the amide bond formation between carboxylic acid groups on CNMs and amine groups on antibodies [ 22 ]. Prior to antibody immobilization, the carboxy-functionalized CNMs are usually activated using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxy succinimide (EDC/NHS) coupling/activating agent for effective binding of antibody on the electrode surface [ 35 – 38 ]. Different electrodes employed include glassy carbon electrode (GCE), carbon screen printed electrode (CSPE), carbon electrode (CE), indium tin oxide electrode (ITO), dispense printed electrode (DPE) and GO-based microelectrode, while differential pulse voltammetry (DPV), cyclic voltammetry (CV), amperometry (AMP), electrochemical impedance spectroscopy (EIS), alternating current voltammetry (ACV) and linear sweep voltammetry (LSV) are among the electrochemical detection systems frequently used [ 23 ].…”

“…In two different studies by the same research group, GQDs conjugated with AuNPs or MoS 2 nanosheets were reported to enhance the electrochemical immunosensing performance for sensitive detection of AFB1 in maize samples [ 37 , 38 ]. In the former study, the GQDs-AuNPs nanocomposite fabricated through conjugation of carboxyl groups of GQDs and amino groups of the crosslinker 2-aminothiophenol was dispersed on an ITO electrode and subsequently immobilized with AFB1 antibody for AFB1 detection in maize samples [ 37 ].…”

“…This immunoelectrode also showed acceptable stability with 94% current signal retained after storage at 4 °C for 4 weeks. Comparatively, the latter study demonstrated a more pronounced electrochemical response of GQDs upon conjugating with CTAB-exfoliated MoS 2 nanosheets for detection of AFB1 in maize samples [ 38 ]. After electrophoretic deposition of MoS 2 @GQDs on ITO electrode and immobilization with AFB1 antibody by EDC/NHS crosslinker, a linear signal response in the same AFB1 concentration range (0.1–3.0 ng/mL) with LOD at 0.09 ng/mL was shown, while a high recovery ranging from 80.2 to 98.3% was reached from the AFB1-spiked maize samples [ 38 ].…”