Synergistic MnO₂/PANI/rGO ternary nanohybrid for highly sensitive electrochemical determination of doxorubicin at physiological pH

Monitoring doxorubicin (DOX) at clinically relevant levels is essential due to its narrow therapeutic index and dose-dependent cardiotoxicity, necessitating sensitive and reliable analytical tools. In this work, a ternary MnO₂/polyaniline/reduced graphene oxide (MnO₂/PANI/rGO) nanocomposite was rationally engineered and employed to modify a glassy carbon electrode for the electrochemical detection of DOX under physiological conditions (pH 7.0). The nanocomposite was synthesized via a stepwise procedure and thoroughly characterized by FE-SEM and TEM analyses. Electrochemical investigations revealed that the MnO₂/PANI/rGO-modified electrode exhibits a dramatically enhanced oxidation response toward DOX compared with bare, single-component, and binary-component electrodes, confirming the presence of a pronounced synergistic effect among MnO₂, PANI, and rGO. This synergistic ternary architecture provided an increased electroactive surface area, improved charge-transfer kinetics, and accelerated DOX redox behavior. Under optimized conditions, the sensor delivered a linear response over 0.01–3 μM with a detection limit of 0.0055 μM (S/N = 3). The practical performance of the sensor was validated using commercial human serum analyzed via the standard addition method, achieving high recovery and precision. These findings demonstrate that the synergistic MnO₂/PANI/rGO ternary nanohybrid offers a robust and highly sensitive platform for the electrochemical determination of doxorubicin in biologically relevant matrices.