Abstract
This study introduces the use of an IgA isotype aflatoxin (AF) specific monoclonal antibody for the development of a highly sensitive Quartz Crystal Microbalance (QCM) immunobiosensor for the detection of AF in inhibitory immunoassay format. The higher molecular weight of IgA antibodies proved an advantage over commonly used IgG antibodies in label free immunobiosensor measurements. IgA and IgG antibodies with similar affinity for AF were used in the comparative studies. Sensor surface was prepared by covalent immobilization of AFB1, using self assembled monolayer (SAM) formed on gold coated Quartz Crystal, with 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxy succinimide (EDC/NHS) method using a diamine linker. Nonspecific binding to the surface was decreased by minimizing the duration of EDC/NHS activation. Sensor surface was chemically blocked after AF immobilization without any need for protein blocking. This protein free sensor chip endured harsh solutions with strong ionic detergent at high pH, which is required for the regeneration of the high affinity antibody-antigen interaction. According to the obtained results, the detection range with IgA antibodies was higher than IgG antibodies in QCM immunosensor developed for AFB1.
Highlights
Aflatoxins (AF) are secondary metabolites of fungi from Aspergillus spp. and can cause acute and chronic toxicity in both humans and animals when ingested [1,2]
Carboxylic acid groups of 11-mercaptoundecanoic acid (MUA) were converted to amine in order to provide binding sites for carboxyl bearing
The surface was activated with Ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxy succinimide (EDC/NHS) solution for either 10 or 15 min to evaluate the effect of duration on nonspecific binding of proteins to the prepared sensor surface
Summary
Aflatoxins (AF) are secondary metabolites of fungi from Aspergillus spp. and can cause acute and chronic toxicity in both humans and animals when ingested [1,2]. They are amongst the most abundant food and feed contaminants, and directives are employed in order to prevent the associated health risks [3]. The availability of rapid and on-site systems for the analysis of AF will both provide better control of AF contamination in food and feedstuff, and decrease the related analytical costs. A biosensor is defined as a bioanalytical device incorporating a molecular recognition element associated or integrated with a physicochemical transducer [4]
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