A Phytol-Modified Carbon Veil Paste DNA Sensor for Anticancer Drug Detection

Electrochemical DNA sensors offer a rapid and miniaturizable approach to monitoring drugs that interact with nucleic acids, but their performance depends on the electrode matrix and DNA immobilization strategy. Here, a renewable bulk-modified carbon veil paste DNA sensor was developed by synergistically combining a custom 3D-printed screw-driven housing and a phytol-derived dicationic amphiphile to retain DNA within a conductive fibrous matrix. Carbon veil paste electrode composition and interfacial properties were studied by voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy, and analytical performance was evaluated for doxorubicin and dacarbazine in buffer, synthetic plasma, and synthetic urine. The carbon veil matrix provided an effective electroactive area 5.06 times greater than its geometric area. Among the tested modifiers, the phytol-derived amphiphile produced the highest and most stable marker currents. Doxorubicin decreased, whereas dacarbazine increased, the ferrocyanide marker current. Responses were linear over the tested concentration ranges of 1 pM–0.1 µM for doxorubicin and 8 nM–1 µM for dacarbazine, and the determined detection limits were 19 fM and 8.0 nM, respectively. Recoveries in synthetic matrices were 94–99%. The platform provides a renewable DNA-containing electrode architecture for sensitive analysis of individual DNA-interacting drugs in model samples.