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Selection of DNA aptamers against penicillin G using Capture-SELEX for the development of an impedimetric sensor

Paniel, Nathalie, Istamboulié, Georges, Triki, Athar, Lozano, Clément, Barthelmebs, Lise, Noguer, Thierry
Talanta 2017 v.162 pp. 232-240
benzylpenicillin, dielectric spectroscopy, electrochemistry, filtration, isopropyl alcohol, laws and regulations, maximum residue limits, milk, milk analysis, oligonucleotides, single-stranded DNA, systematic evolution of ligands by exponential enrichment
This paper describes for the first time the selection of aptamers selective to penicillin. Aptamers were selected using a specific process called Capture-SELEX (Systematic Evolution of Ligands by Exponential Enrichment). This technique is based on the selection of DNA aptamers using penicillin G in solution while the ssDNA library is fixed on a support. One aptamer showing a good affinity to penicillin was finally selected and tested in electrochemical sensor configuration, using electrochemical impedance spectroscopy as detection technique. The developed aptasensor allowed the detection of penicillin in a wide concentration range, comprised between 0.4 and 1000µgL−1 Such performance was compatible with milk analysis, as the maximum residue limit tolerated in this matrix is 4µgL−1. The selectivity of the developed sensor was also studied, showing that the sensor was also able to bind other beta-lactam antibiotics, although with a weaker affinity. Finally the sensor was used for detection of penicillin G in milk. It was shown that a simple sample treatment with isopropanol followed by filtration was sufficient to eliminate matrix effects, allowing the determination of penicillin in milk at concentrations compatible with legislation requirements.