Noninvasive electrochemical biosensor for rapid detection of Helicobacter pylori in patient saliva

The carcinogenic bacterium Helicobacter pylori infect over half the global population, with a higher prevalence in low-income countries. It is linked to diseases such as chronic gastritis, peptic ulcers, and gastric cancer, a leading cause of cancer-related deaths worldwide. The gold standard diagnostic method involves histopathological evaluation of gastric biopsy tissue via upper gastrointestinal endoscopy—an invasive, complex, and time-intensive procedure requiring specialized professionals. This study presents a noninvasive alternative: an impedimetric electrochemical biosensor for H. pylori antigen detection in saliva. The biosensor was developed using a screen-printed carbon electrode modified with polypyrrole nanotubes and carboxylated multi-walled carbon nanotubes. Monoclonal antibodies targeting CagA, a cytotoxic effector protein of H. pylori, were immobilized on carbon nanotubes using EDC/NHS chemistry. The platform was characterized via scanning electron microscopy and electrochemical techniques. Electrochemical impedance spectroscopy (EIS) was employed for analyte detection, with an analytical curve constructed in phosphate-buffered saline (PBS) spiked with CagA protein. The biosensor demonstrated a linear detection range of 0.5 pg mL⁻¹ to 3.3 ng mL⁻¹ and a detection limit of 109.9 fg mL⁻¹ . Validation with patient saliva samples, confirmed by histopathology and rapid urease testing, yielded 97 % accuracy, 80 % sensitivity, and 100 % specificity. Results were obtained within 15 min. This EIS-based biosensor offers a sensitive, innovative, and noninvasive platform for early H. pylori diagnosis, which is essential for preventing severe diseases such as gastric cancer.