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

  • Mikrochim Acta. 2025 Jul 28;192(8):527. doi: 10.1007/s00604-025-07387-4.
Christina Bizinti  1 ,  Dionysios Soulis  1 ,  Dimitra Kourti  1 ,  Georgia Geka  1 ,  Christos Kokkinos  1 ,  Michael Thompson  2 ,  Lidia Nemtsov  2 ,  Thanassis Speliotis  3 ,  Anastasios Economou  4
Affiliations
  • 1. Department of Chemistry, National and Kapodistrian University of Athens, Athens, 15771, Greece.
  • 2. Department of Chemistry, University of Toronto, 80 St. George St, Toronto, ON, M5S 3H6, Canada.
  • 3. Institute of Nanoscience and Nanotechnology, N.C.S.R. Demokritos, P.O. Box 60037, Agia Paraskevi, 15310, Greece.
  • 4. Department of Chemistry, National and Kapodistrian University of Athens, Athens, 15771, Greece. [email protected].
PMID: 40719766 DOI: 10.1007/s00604-025-07387-4
Abstract

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.

Keywords
Antifouling linker; Aptasensor; Differential pulse voltammetry; Electrochemical detection; Microfabrication; Oxytetracycline.
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