Noninvasive electrochemical biosensor for rapid detection of Helicobacter pylori in patient saliva
Stella Schuster da Silva, Tatiana Lima Valério, Bruna M. Hryniewicz, Hussamaldeen Jaradat, Mel De Souza Wendhausen Araújo, Carla Adriane Royer, Beatriz Borba Ortiz, Andrei E. Deller, Leandro Yoshimi Kashiwagui, Paulo de Souza Fonseca Guimarães, João Victor Araújo de Oliveira, Daniela Fiori Gradia, Olfa Kanoun, Carolina Camargo de Oliveira, Márcio Vidotti
Abstract
ABSTRACT 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 minutes. 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.