DETERMINATION OF SOME FOOD CARCINOGENS USING CHEMICAL SENSORS WITH MOLECULARLY IMPRINTED POLYMER RECOGNITION FILMS

Wlodzimierz Kutner^1,2

¹Institute of Physical Chemistry, Polish Academy of Sciences,

Kasprzaka 44/52, 01 224 Warsaw, Poland

²Faculty of Mathematics and Natural Sciences, School of Sciences,

Cardinal Stefan Wyszynski University in Warsaw, Poland

wkutner@ichf.edu.pl

Improper food processing like grilling, smoking, curing, pickling, etc., may result in generating different carcinogenic heteroaromatic amines (HAAs) and nitrosamines (NAs). For detection and determination of these toxins, we devised and fabricated dedicated chemical sensors.¹ Conducting polymers molecularly imprinted (MIPs) with these carcinogens, used as templates, served as recognition units of these chemosensors.² DFT computational molecular modeling guided us in selecting most suitable functional monomers. Derivatized bis(2,2′-bithien-5-yl)methane as well as thiosalenCo(III) and salenNi(II), used as these monomers, formed stable pre-polymerization complexes with the carcinogens. Inspired by quinoxaline HAAs easy intercalation in dsDNAs, we synthesized thymine and adenine derivatives of bis(2,2′-bithien-5-yl)methanes to serve as functional monomers for constructing MIPs for determination of these HAAs. These MIPs were designed to mimic allosteric molecular recognition in biological dsDNA receptors.³ The Gibbs free energy gain due to formation of the pre-polymerization complexes with a series of NAs and HAAs was proportional to the determined by UV-vis spectroscopy stability constants of these complexes. We electropolymerized these complexes under potentiodynamic conditions, achieving appreciable apparent imprinting factors, and the resulting thin MIP films simultaneously deposited on different electrode substrates to fabricate MIP chemosensors. After template extracting, and then characterizing analytical parameters, we used these chemosensors for determination of the HAA and NA analytes in extracts of smoked pork ham. For analytical signal transduction, we used piezoelectric microgravimetry at Au-QCR/MIP electrodes of EQCM as well as DPV and EIS at Pt/MIP electrodes.⁴ Limits of detection were in the nano- and picomolar concentration ranges. The chemosensors selectively responded to target carcinogens in the presence of interferences of similar composition and structure.

References

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