Zinc-doped MgO nanohybrids enable sensitive Salmonella typhimurium biosensing

Food-borne pathogens such as Salmonella typhimurium pose serious risks to food safety and public health, demanding rapid, sensitive, and reliable diagnostic tools. The current study reported the fabrication of a nanostructured zinc-magnesium oxide (Zn-MgO)-based electrochemical DNA biosensor for the detection of the Salmonella invA gene. Physicochemical characterization confirmed uniform nanostructure formation with efficient probe DNA immobilization and high surface coverage. Electrochemical investigations demonstrated diffusion-controlled charge transfer, with clear sequence specificity against complementary, non-complementary, and single-base mismatched targets. With a linear dynamic range spanning 0-150 aM, a sensitivity of 3.22 pA·aM^-1, and ultra-low detection limits (LOD 0.21 aM; LOQ 0.70 aM), the biosensor demonstrates robust analytical capability for trace-level genomic DNA quantification. Furthermore, the sensor exhibited excellent stability, retaining >85% activity after 60 days, and provided rapid responses within 5 s. The biosensor enabled rapid and selective detection of Salmonella Typhimurium in milk samples within 5s, demonstrating excellent sensitivity, reproducibility, and minimal matrix interference. Collectively, these results highlight the potential of the Zn-MgO bioelectrode as a robust, selective, and stable biosensing platform. The synergistic properties of Zn and MgO within the nanohybrid matrix not only enhanced probe immobilization but also improved electron conductance, which are critical for ultrasensitive biosensing applications. Taken together, the results illustrate that the Zn-MgO nanohybrid bioelectrode is a robust, selective, and stable platform with strong translational potential. Importantly, its promising analytical performance indicates strong applicability for real-sample testing in food, water, and clinical diagnostics, contributing to sustainable food safety monitoring and pathogen control.