Abstract
Palm kernel cake (PKC) is the solid residue following oil extraction of palm kernels and useful to fatten animals either as a single feed with only minerals and vitamins supplementation, or mixed with other feedstuffs such as corn kernels or soy beans. The occurrence of mycotoxins (aflatoxins, ochratoxins, zearalenone, and fumonisins) in feed samples affects the animal’s health and also serves as a secondary contamination to humans via consumption of eggs, milk and meats. Of these, aflatoxin B1 (AFB1) is the most toxically potent and a confirmed carcinogen to both humans and animals. Methods such as High Performance Liquid Chromatography (HPLC) and Liquid Chromatography–Mass Spectrometry (LC-MS/MS) are common in the determination of mycotoxins. However, these methods usually require sample pre-treatment, extensive cleanup and skilled operator. Therefore, in the present work, a rapid method of electrochemical immunosensor for the detection of AFB1 was developed based on an indirect competitive enzyme-linked immunosorbent assay (ELISA). Multi-walled carbon nanotubes (MWCNT) and chitosan (CS) were used as the electrode modifier for signal enhancement. N-ethyl-N′-(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS) activated the carboxyl groups at the surface of nanocomposite for the attachment of AFB1-BSA antigen by covalent bonding. An indirect competitive reaction occurred between AFB1-BSA and free AFB1 for the binding site of a fixed amount of anti-AFB1 antibody. A catalytic signal based on horseradish peroxidase (HRP) in the presence of hydrogen peroxide (H2O2) and 3,3′,5,5′-tetramethylbenzidine (TMB) mediator was observed as a result of attachment of the secondary antibody to the immunoassay system. As a result, the reduction peak of TMB(Ox) was measured by using differential pulse voltammetry (DPV) analysis. Based on the results, the electrochemical surface area was increased from 0.396 cm2 to 1.298 cm2 due to the electrode modification with MWCNT/CS. At the optimal conditions, the working range of the electrochemical immunosensor was from 0.0001 to 10 ng/mL with limit of detection of 0.1 pg/mL. Good recoveries were obtained for the detection of spiked feed samples (PKC, corn kernels, soy beans). The developed method could be used for the screening of AFB1 in real samples.
Highlights
To lessen the feeding cost of livestock, which competes directly with humans for the same food crops, attempts have been made to use alternative sources of protein and energy
We have successfully developed a sensitive immunosensor for the detection of aflatoxin B1 (AFB1) in Palm kernel cake (PKC) and other feed samples
The electrochemical conditions had to be properties of the modified electrode were characterized by cyclic voltammetry (CV) analysis, as re-optimized since different type of potentiostat was used
Summary
To lessen the feeding cost of livestock, which competes directly with humans for the same food crops, attempts have been made to use alternative sources of protein and energy. These have mostly been of agro-industrial byproduct origin, which is not directly utilizable by human. Malaysia is one of the world’s leading producers of palm oil, and the availability of palm is extensive. Palm kernel cake (PKC), as shown, is a byproduct of oil extraction from palm [1]. 22 of of 10 known as palm kernel meal (PKM) or palm kernel expeller (PKE). PKC is either produced from known as palm kernel meal (PKM)
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