Nanostructured MgO Enabled Electrochemical Biosensing Strategies for Ultrasensitive Detection of Salmonella typhimurium

ABSTRACT

Nanostructured magnesium oxide (MgO)‐modified indium tin oxide electrode was developed as an electrochemical DNA biosensing interface for ultrasensitive detection of the invA gene of Salmonella typhimurium . MgO nanoparticles synthesized via a sol–gel route were electrophoretically deposited to form a high‐surface‐area sensing layer that promotes efficient probe immobilization and interfacial charge transfer. A single‐stranded DNA probe was immobilized on the MgO surface, and hybridization with complementary target DNA was monitored using methylene blue (MB) as a redox indicator. Structural and morphological characterization confirmed the crystalline nanoscale nature of the MgO film, while cyclic voltammetry and electrochemical impedance spectroscopy verified the stepwise electrode fabrication and hybridization response. The biosensor exhibited a linear response over the attomolar concentration range with a detection limit of 8.03 aM and high analytical sensitivity. The sensing platform demonstrated strong sequence selectivity, reproducible response, and operational stability over extended storage. Successful detection in spiked milk samples and rapid electrochemical signal readout following hybridization indicate the practical applicability of the developed MgO interface for food‐safety monitoring and portable pathogen diagnostics. Compared with earlier MgO‐based genosensor demonstrations, the present system achieves substantially improved detection sensitivity together with validated performance in real food matrices.