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<p> The&#xa0;fabrication and characterization of a novel integrated electrochemical aptasensing device and its application to oxytetracycline (<i>OTC</i>) determination in milk&#xa0;is described. The microfabricated three-electrode chip is composed of gold working and counter electrodes and a silver reference electrode deposited on a Kapton film by physical vapor deposition. The working electrode is modified with <i>α-</i>lipoic acid-NHS, an antifouling linker, onto which an amine-modified <i>OTC</i>-specific aptamer is further attached. The label-free assay of <i>OTC</i> involves incubation of the sample with the linker/aptamer bioconjugate immobilized on the working electrode and monitoring of the <i>OTC</i>-aptamer binding event by means of the electrochemical response of the [Fe(CN)<sub>6</sub>]<sup>3−</sup>/[Fe(CN)<sub>6</sub>]<sup>4−</sup> redox couple, The decrease of the signal magnitude, induced by blocking the diffusion of the probe, is related to the concentration of <i>OTC</i>. The limit of detection for <i>OTC</i> is 7&#xa0;ng&#xa0;mL<sup>−1</sup> and the inter-sensor reproducibility is 13.7%. The sensor is applied to milk samples with recoveries between 107 and 110%. This aptasensing chip demonstrates strong potential for rapid on-site detection of <i>OTC</i> in the food industry due to its high degree of integration, easy functionalization, and potential for single-drop operation.</p> Graphical abstract <p></p>

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Microfabricated electrochemical aptasensing chip modified with dual-function antifouling linker for single-drop label-free assay of oxytetracycline in milk

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年7月28日

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  • Christina Bizinti,
  • Dionysios Soulis,
  • Dimitra Kourti,
  • Georgia Geka,
  • Christos Kokkinos,
  • Michael Thompson,
  • Lidia Nemtsov,
  • Thanassis Speliotis,
  • Anastasios Economou

摘要

The fabrication and characterization of a novel integrated electrochemical aptasensing device and its application to oxytetracycline (OTC) determination in milk is described. The microfabricated three-electrode chip is composed of gold working and counter electrodes and a silver reference electrode deposited on a Kapton film by physical vapor deposition. The working electrode is modified with α-lipoic acid-NHS, an antifouling linker, onto which an amine-modified OTC-specific aptamer is further attached. The label-free assay of OTC involves incubation of the sample with the linker/aptamer bioconjugate immobilized on the working electrode and monitoring of the OTC-aptamer binding event by means of the electrochemical response of the [Fe(CN)6]3−/[Fe(CN)6]4− redox couple, The decrease of the signal magnitude, induced by blocking the diffusion of the probe, is related to the concentration of OTC. The limit of detection for OTC is 7 ng mL−1 and the inter-sensor reproducibility is 13.7%. The sensor is applied to milk samples with recoveries between 107 and 110%. This aptasensing chip demonstrates strong potential for rapid on-site detection of OTC in the food industry due to its high degree of integration, easy functionalization, and potential for single-drop operation.

Graphical abstract