An advanced carbon/bismuth oxide nanoparticle-based filament for multifunctional 3D-printed electrochemical sensors toward paracetamol and lead in pharmaceutical, clinical, and environmental electroanalysis

3D printing offers a powerful, scalable approach to fabricating low-cost, high-performance electrochemical sensors for pharmaceutical and bioanalytical applications. We report the development of a 3D-printed graphite/polylactic acid (G/PLA) conductive composite electrode modified with bismuth oxide nanoparticles (Bi 2 O 3 NPs) to enhance paracetamol (PCT) detection. The optimized composition (G/Bi 2 O 3 NPs/PLA, 30:12.5:57.5% wt. ) was processed by 3D printing to obtain electrodes without the need for complex post-treatment or electrochemical activation. Electrochemical impedance spectroscopy (EIS) revealed a marked decrease in the charge-transfer resistance (Rct) after Bi 2 O 3 NPs incorporation, indicating improved interfacial electron transfer. Electrochemical characterization demonstrated a significant increase in the PCT oxidation current and a shift in the peak potential toward less positive values, indicating the electrocatalytic role of Bi 2 O 3 NPs. Under optimized batch injection analysis with amperometric detection (BIA-AD) conditions, the sensor exhibited a wide linear dynamic range of 0.05–300 µmol L⁻¹, a low limit of detection of 0.006 µmol L⁻¹, and precision (RSD < 5%). Inter-electrode reproducibility was satisfactory (RSD < 5%), highlighting the robustness of the fabrication process. The proposed platform also demonstrated applicability to Pb(II) detection, evidencing the versatility of the G/Bi 2 O 3 NPs/PLA composite and expanding its potential for environmental monitoring and heavy metal analysis. Furthermore, selectivity studies conducted in the presence of common interferents showed negligible changes in the PCT response, confirming the sensor’s reliability for pharmaceutical quality control applications. Overall, the 3D-printed G/Bi 2 O 3 NPs/PLA electrode combines analytical performance with simplicity of fabrication, low cost, and scalability, positioning it as a promising alternative to conventional electrochemical sensors for routine PCT determination.