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

Abstract

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 5 min 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.