Abstract
We report a paper-based electrochemical immunosensor made with sustainable materials to detect aflatoxin B1 (AFB1), a highly toxic, carcinogenic mycotoxin found in food. The immunosensor was prepared with a waterproof paper substrate and low-cost graphite-based conductive ink through a simple cut-printing method. The working electrode was functionalized with a drop-cast film of multiwalled carbon nanotubes (MWCNT)/chitosan on which a layer of anti-AFB1 monoclonal antibodies was immobilized covalently. The architecture of the immunosensor was confirmed with polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) and electrochemical impedance spectroscopy (EIS), including the effective immobilization of the active layer of anti-AFB1. With EIS as the principle of detection, the immunosensor could detect AFB1 in the range from 1 to 30 ng·mL−1, and detection limit of 0.62 ng·mL−1. This sensitivity is sufficient to detect AFB1 in food according to regulatory agencies. The immunosensor exhibited good repeatability, reproducibility, stability, and selectivity in experiments with a possible interferent. Furthermore, detection of AFB1 in maize flour samples yielded recovery of 97–99%, in a demonstration of the possible use of the paper-based immunosensor to detect AFB1 using extraction solutions from food samples.
Highlights
Aflatoxin B1 (AFB1) is a highly toxic mycotoxin secreted as a secondary metabolite by fungi species such as Aspergillus flavus and Aspergillus parasiticus [1]
Functionalized multiwalled carbon nanotubes (MWCNTs) have been employed in electrochemical immunosensors [29,30] in order to exploit their electrical properties in addition to their large surface area-to-volume ratios and presence of functional groups for binding antibodies [31,32,33]
Multiwalled carbon nanotubes functionalized with carboxylic acid (MWCNT), aflatoxin B1, anti-AFB1 antibody, ochratoxin A, N-ethyl-N’-(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDC), N-hydroxyl succinimide (NHS), and MES buffer were purchased from Sigma-Aldrich
Summary
Aflatoxin B1 (AFB1) is a highly toxic mycotoxin secreted as a secondary metabolite by fungi species such as Aspergillus flavus and Aspergillus parasiticus [1]. Functionalized multiwalled carbon nanotubes (MWCNTs) have been employed in electrochemical immunosensors [29,30] in order to exploit their electrical properties in addition to their large surface area-to-volume ratios and presence of functional groups for binding antibodies [31,32,33]. They may be used in conjunction with chitosan, a biopolymer with outstanding characteristics for matrices in biosensors for its biocompatibility, biodegradability, and non-toxicity. The developed platforms were successfully applied to the rapid, sensitive, and specific determination of AFB1 on extraction solutions from real food samples, being promising for food safety monitoring
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