Low-cost printed circuit board (PCB) electrochemical biosensors for rapid and label-free detection of Streptococcus pneumoniae

Abstract

Severe sepsis presents a critical healthcare challenge where rapid pathogen identification is vital for timely intervention. Current diagnostic methods, however, remain inadequate, often delaying targeted treatment. Using readily available printed circuit board (PCB) electrodes, we address this need by developing a low-cost electrochemical DNA biosensor for rapid detection of Streptococcus pneumoniae using the lytA gene as a biomarker. Through systematic evaluation of commercial and custom PCB designs (P1–P4), gold-plated PCB P4 was found as the optimal platform, demonstrating sensitive detection of lytA sequences (20 bp at 4.50 pM limit of detection in buffer) and clinically relevant 235 bp polymerase chain reaction (PCR) amplicons in 100% human serum (1.0–100 pM) within 15 min at room temperature using electrochemical impedance spectroscopy. The performance of the biosensor originates from the optimized electrode geometry, surface properties, and robust self-assembled monolayer functionalization, enabling specific recognition of bacterial DNA without sample pretreatment. This work establishes PCB-based biosensors as a promising solution for point-of-care sepsis diagnostics, offering significant advantages in speed, cost, and operational simplicity compared to conventional methods.