Aptamer‐Based Inhibition Assay for the Electrochemical Detection of Tobramycin Using Magnetic Microparticles

The detection of small molecules using aptamers is not straightforward when the induced fit triggered by the analyte is also small. Herein a labeling strategy is explored for the voltammetric detection of the antibiotic tobramycin using magnetic microparticles (MPs). A competition between MPs‐immobilized tobramycin and free tobramycin for the limited amount of the biotinylated‐aptamer was established. The addition of the enzymatic conjugate and the substrate generated a product that was electrochemically oxidized on screen‐printed carbon electrodes. The analytical signal was proportional to the antibiotic concentration from 5–500 µM and the reproducibility was 5.7 %. The assay selectivity was also studied.