Electrochemical Aptasensing Utilizing Titania-Based Surfaces for Tetracycline Detection

Electrochemical aptasensors have been successfully applied in a number of fields, including food safety, environmental monitoring, and the health sector. They offer a robust and environmentally friendly alternative to antibody-based detection, with the added benefits of flexible design, high chemical and thermal stability, and low immunogenicity. In this work, we present an electrochemical aptasensor based on a semiconducting mesoporous TiO2:Mn working electrode (WE) for the sensitive detection of tetracycline (TET). The TiO2:Mn electrodes were fabricated using a scalable screen-printing process, providing a cost-efficient and reproducible platform for sensor development. Specifically, a 5 μM solution of the DNA aptamer with the sequence 5′-CCC CCG GCA GGC CAC GGC TTG GGTTGG TCC CAC TGC GCG-3′ was utilized for the detection of tetracycline (TET) in spiked aqueous samples, across a concentration range of 0.3 to 25.0 ng/mL. Detection was performed via differential pulse voltammetry (DPV) using a Pt wire cathode. The buffer used in the experiment was Tris–HCl (20 mM, pH 7.6), 100 mM of NaCl, MgCl2 (2 mM), KCl (5 mM), and CaCl2 (1 mM). The limit of detection (LOD) was calculated to be approximately 1 ng/mL.