Gold nanoparticle-modified screen-printed carbon electrodes for label-free detection of SARS-CoV-2 RNA using drop casting and spray coating methods

UNPAD Researchers Advance Label-Free RNA Detection on Low-Cost Printed Electrodes (SDG 3 & SDG 9)
A Universitas Padjadjaran team optimized gold-nanoparticle (AuNP) modified screen-printed carbon electrodes (SPCE) for label-free detection of SARS-CoV-2 RNA. Using two scalable routes—drop casting (DC) and spray coating (SC)—the group achieved robust Au–S immobilization of thiolated DNA probes and readout by differential pulse voltammetry (DPV)/electrochemical impedance spectroscopy (EIS). DC yielded higher current (12.267 μA) and lower charge-transfer resistance (Rct 2.534 kΩ), while SC improved AuNP distribution. The optimized sensor (Box–Behnken design) reached limits of detection 0.166 μg/mL (DC) and 0.694 μg/mL (SC) across 0.5–10 μg/mL RNA. This work supports accessible infectious-disease diagnostics and manufacturable biosensors.