Electrochemical DNA Biosensor Based on Pt 2+ -Doped ZnCo 2 O 4 for Sensitive Detection of the Anti-Cancer Drug Sunitinib

In this study, a Pt 2+ -doped ZnCo 2 O 4 nanocomposite was synthesized through a simple one-step method and used to fabricate a double-stranded DNA (ds-DNA)/Pt 2+ -doped ZnCo 2 O 4 /carbon paste electrode (CPE) for the electrochemical determination of Sunitinib (STB) in acetate buffer. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) confirmed that Pt 2+ incorporation significantly improved the conductivity and charge-transfer properties of ZnCo 2 O 4 . The modified electrode provided efficient interaction between Sunitinib and DNA, with the guanine oxidation signal serving as a sensitive marker for drug quantification. Calibration curve displayed a linear response in the range of 0.01–80.0 μM with a detection limit (LOD) of 0.007 μM. The biosensor exhibited good selectivity, reproducibility, and stability. Analysis of pharmaceutical formulations and urine samples yielded recoveries of 97%–103% with relative standard deviations (RSDs) of 2.3%–3.5%, demonstrating satisfactory accuracy and precision. Complementary spectrophotometric and molecular docking studies confirmed the strong DNA–drug interaction and suggested a groove-binding mode. The combination of a wide linear range, a low detection limit, and reliable recoveries demonstrates the novelty and practical applicability of this Pt 2+ -doped ZnCo 2 O 4 -based biosensor for the selective and sensitive monitoring of Sunitinib in real samples.