Abstract
The determination of antibiotics in food is important due to their negative effect on human health related to antimicrobial resistance problem, renal toxicity, and allergic effects. We propose an impedimetric aptasensor for the determination of kanamycin A (KANA), which was assembled on the glassy carbon electrode by the deposition of carbon black in a chitosan matrix followed by carbodiimide binding of aminated aptamer mixed with oligolactide derivative of thiacalix[4]arene in a cone configuration. The assembling was monitored by cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy. In the presence of the KANA, the charge transfer resistance of the inner interface surprisingly decreased with the analyte concentration within 0.7 and 50 nM (limit of detection 0.3 nM). This was attributed to the partial shielding of the negative charge of the aptamer and of its support, a highly porous 3D structure of the surface layer caused by a macrocyclic core of the carrier. The use of electrostatic assembling in the presence of cationic polyelectrolyte decreased tenfold the detectable concentration of KANA. The aptasensor was successfully tested in the determination of KANA in spiked milk and yogurt with recoveries within 95% and 115%.
Highlights
Antibiotics of bacterial origin are widely applied in human and veterinary medicine [1]
We suggested a similar platform to assemble an impedimetric aptasensor to kanamycin A (KANA)
The deposition of carbon black (CB) is mostly performed from its suspension in chitosan or dimethylformamide as binders required for the formation of a more stable film [35]
Summary
Antibiotics of bacterial origin are widely applied in human and veterinary medicine [1] Their use has revolutionized the treatment of many diseases, antimicrobial resistance has been found since the very beginning of antibiotics therapy as a result of drug overuse or misuse [2,3]. Starting from mastitis treatment in dairy cows, antibiotics have become an indispensable part of the modern livestock sector. This is especially true for kanamycin A (KANA), an aminoglycoside antibiotic (see Figure 1 for structural formula), where the Sensors 2020, 20, 4738; doi:10.3390/s20174738 www.mdpi.com/journal/sensors residue level where (MRL) the in milk is limited in the European
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