Centrifuge-free magnetic molecularly imprinted polymer for direct blood detection of Helicobacter-pylori–derived outer-membrane vesicles

Outer-membrane vesicles (OMVs) released by Helicobacter pylori (HP) play a critical role in bacterial pathogenicity and are emerging biomarkers for diverse diseases, including gastrointestinal, intestinal, and neuroinflammatory disorders. However, current methods for OMV isolation and analysis, such as ultracentrifugation and nanoparticle tracking analysis, suffer from limited specificity, low sensitivity, and poor suitability for complex biological samples, hindering their translational utility. Herein, we present a centrifuge-free core–shell magnetic molecularly imprinted polymer (MIP) platform for the direct detection of HP-derived OMVs (HP-OMVs) in blood. The MIP incorporates Fe₃O₄ magnetic cores, a polydopamine (PDA) imprinting layer, and lipopolysaccharide-targeting boronic-acid functional groups, while a carbon-nanotube–wrapped magnetic electrode facilitates simultaneous OMV capture and electrochemical quantification. The sensor exhibits high sensitivity toward HP-OMVs, with a detection limit of 25 µg/mL, and strong linearity (R² = 0.993), outperforming nonimprinted controls and conventional analytical methods. Notably, the platform maintains robust performance in serum and whole blood, facilitating detection down to 50 µg/mL, which is below the reported disease-inducing OMV levels in vivo . This study represents the first successful application of molecular imprinting technology for OMV detection, and establishes a rapid, selective, and clinically practical strategy for monitoring circulating HP-OMVs. The modular imprinting approach exhibits broad applicability to OMVs from other pathogenic bacteria also, offering a promising foundation for OMV-based diagnostics and early interventions in infection-associated and neurodegenerative disorders.