Phyto engineered Ag decorated ZrO2 nanohybrid: A sustainable strategy for sensitive and reliable electrochemical sensing of dopamine

The detection of dopamine (DA) is of considerable importance because of its essential role in neurological functions and its association with various physiological and neurological disorders. Although several analytical approaches have been developed for DA determination, enzyme-free electrochemical sensors have attracted increasing attention owing to their rapid response, operational simplicity, reliability, and high sensitivity. In this study, ZrO 2 and Ag-decorated ZrO 2 (Zr@Ag) nanostructures were synthesized using an eco-friendly green approach using Ficus religiosa bark extract and employed as electrode modifiers for dopamine sensing. The structural, morphological, optical, and surface properties of the synthesized materials were investigated using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and complementary characterization techniques. The Zr@Ag nanocomposite exhibited an optical band gap of 2.3 eV, a zeta potential of −113 mV, and a particle size of approximately 80.1 nm, indicating favorable surface and physicochemical characteristics for electrochemical sensing. The Zr@Ag nanocomposite was integrated onto a screen-printed gold electrode (SPGE) to fabricate an enzyme-free Zr@Ag/SPGE sensing platform. Compared with ZrO 2 /SPGE, the Zr@Ag/SPGE exhibited markedly enhanced electrochemical performance, delivering sensitivities of 80.97 and 1735.63 μA mM -1 cm -2 and detection limits of 0.005 μM (5 nM) and 0.003 μM (3 nM) (S/N = 3), respectively. The improved sensing performance of Zr@Ag/SPGE can be attributed to the synergistic interaction between ZrO 2 and Ag, which promotes efficient electron transfer and enhances the electrochemically active surface characteristics of the electrode. Furthermore, the practical applicability of the developed sensor was evaluated using goat serum (GS), sheep serum (SS), and fetal bovine serum (FBS), yielding satisfactory dopamine recoveries of 98–101%. The consistent dopamine responses obtained in these biological matrices further demonstrate the reliability of the sensor for real-sample analysis. Overall, the green-synthesized Zr@Ag/SPGE provides a sensitive, selective, enzyme-free, and cost-effective platform for dopamine detection, with promising potential for practical applications in biological and clinical analysis.