Highly Sensitive and Stable Enzymatic Platform for the Ultra-Trace Determination of Dichlorprop-P in Surface Waters

Water pollution caused by pesticides, such as the toxic herbicide Dichlorprop-P (2,4-DP), represents a major global concern. This study reports a novel inhibition-based electrochemical biosensor for the ultra-trace determination of Dichlorprop-P in surface waters, fabricated by modifying a screen-printed carbon electrode with Prussian Blue and tyrosinase. The optimized platform was obtained after 30 drop-casting steps, corresponding to 75 μL Prussian Blue at 8.59 mg/mL, followed by immobilization of 10 μL tyrosinase solution at 50 mg/mL. Fourier-transform infrared spectroscopy and cyclic voltammetry confirmed the successful deposition of the mediator and enzyme. To the best of our knowledge, this is the first tyrosinase-based biosensor proposed for Dichlorprop-P detection. The sensing principle relies on the decrease in the catalytic current generated by tyrosinase-mediated tyrosine oxidation in the presence of the Prussian Blue mediator. The biosensor showed a linear response between 0 and 0.1 μM, with a detection limit of 0.02 μM, a quantification limit of 0.09 μM, and good linearity (R2 = 0.9906). Application to Danube River water samples yielded recoveries of 97–105%, supporting its suitability for environmental monitoring.