Abstract
Detection of mycotoxins by conventional methods such as ELISA or LC-MS can be expensive and time-consuming. Therefore, paper-based biosensors can be effectively used for on-site analysis, due to their low cost and easy detection procedures. Nevertheless, even when the application of colorimetric methods on paper enhance the simplicity and affordability of multiple determinations, the signal intensity and final readout can be affected by a limited color uniformity. In this work, Ellman’s method for the quantification of aflatoxin B1 was utilized as a model colorimetric assay on paper, in which the test zones were modified with chitosan-immobilized enzyme (AChE). A comparison of the cross-linking effect of genipin on two chitosans of varying molar mass and degree of acetylation, exhibited a greater signal enhancement from the sample with a higher degree of acetylation and molecular weight.
Highlights
From the different metabolites affecting crops and human health, mycotoxins represent a big concern when ingested through different food products
The sole application of ink by mixing with chitosan and water led to sample accumulation on specific areas of the test zone; suggesting that this coating method is not the most suitable for immobilization on 3MM chromatography paper, unlike its adequate deposition behavior seen on metallic electrodes [16]
Such behavior could be explained as a result of the higher degree of acetylation of chitosan B, which has been correlated with greater hydrophobicity, rigidity and steric effects [23]
Summary
From the different metabolites affecting crops and human health, mycotoxins represent a big concern when ingested through different food products. Among the diverse group of mycotoxins, aflatoxins have been widely studied and controlled as they represent a main issue in food safety and agricultural economy [1]. Conventional analysis methods for aflatoxin B1 include ELISA or LCMS; despite their high sensitivity, they normally require long detection times and complicated procedures [5]. One of the main advantages of paper-based biosensors is the flow of samples promoted by capillary forces, which can be translated to reductions on the analysis time and the application of specialized instruments [6]. To control the diffusing behavior of varied solutions, a hydropobic detection area can be delimited on the paper-based biosensor through painted, stamped and printed wax [7,8,9] or laser cutting [10]. Permanent markers are a low cost and affordable option for designing hydrophobic barriers on paper [11]
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