Portable cotton swab biosensor for rapid naked-eye detection of Helicobacter pylori

To better understand the oral cavity's role as a potential reservoir and transmission route for Helicobacter pylori ( H. pylori ), the development of a diagnostic test that is not only rapid and highly specific but also user-friendly is essential. In response to this need, a colorimetric cotton swab biosensor was designed to enable visual detection of H. pylori presence or absence. This study presents the development of a rapid, simple and cost-effective cotton swab-based colorimetric biosensor for the visual detection of H. pylori in saliva. The biosensor utilizes a lactoferrin-functionalized cotton platform for bacterial capture, followed by signal generation using polymeric nanobeads conjugated to specific anti- H. pylori antibodies. The assay enables direct, naked-eye detection without the need for amplification steps or specialized instrumentation. A visual limit of detection between 10 CFU/mL was achieved within five minutes in solution and in spiked saliva samples, offering both qualitative and semi-quantitative results. The biosensor exhibited high specificity, showing no cross-reactivity with E. coli or S. aureus , and maintained analytical performance despite the presence of mucin in Saliva. Moreover, the device demonstrated operational stability over extended storage periods. These findings support the biosensor’s utility as a point-of-care diagnostic tool in low-resource settings for the early detection and surveillance of H. pylori infections. • Development of portable colorimetric biosensor for the detection of H. pylori. • Naked-eye detection within 5 minutes, with a detection limit of 10 CFU/mL in both buffer and saliva. • Lactoferrin-functionalized cotton swab for H. pylori capturing and blue colored polymeric nanobeads for signal generation. • The biosensor illustrates high sensitivity and specificity without pre-enrichment. • Point-of-care cotton-based biosensor.