Development of a smartphone-based biomimetic sensor for aflatoxin B1 detection using molecularly imprinted polymer membranes

A novel smartphone-based optical biomimetic sensor based on free-standing molecularly imprinted polymer (MIP) membranes was developed for rapid and sensitive point-of-care detection of aflatoxin B1. The developed MIP membranes were capable of selective recognition of the target analyte and, at the same time, of generation of a fluorimetric sensor response, which could be registered using the camera of a smartphone and analysed using image analysis. The developed system provides a possibility of synchronous detection of aflatoxin B1 in 96 channels. UV irradiation of aflatoxin B1, selectively bound by the MIP membranes from the analysed samples, initiated fluorescence of aflatoxin B1 with intensity directly proportional to its concentration. The composition of the MIP membranes used as a recognition element was optimised taking into account data of computational modelling. Two functional monomers (2-acrylamido-2-methyl-1-propansulfonic acid and acrylamide) were identified as optimal for the formation of aflatoxin B1-selective binding sites in the structure of the MIP membranes. Working characteristics of the smartphone-based sensor system were also estimated. The influence of pH and of buffer and NaCl concentrations on the smartphone-based sensor responses were studied. High selectivity of the developed sensor system towards aflatoxin B1 was confirmed in experiments with the close structural analogue of the target analyte - aflatoxin G2, and ochratoxin A. The detection limit for aflatoxin B1 using the smartphone-based sensor systems was found to be 20 ng mL^-1 for the sensor based on MIP membranes synthesised with acrylamide as a functional monomer. The storage stability of the recognition elements of the developed sensors was estimated as one year when stored at 22 °C. The possibility to detect the aflatoxin B1 in contaminated food samples was shown. The MIP-membrane-based sensor system provided a convenient point-of-care approach in food safety testing.