{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,13]],"date-time":"2026-10-13T23:45:18Z","timestamp":1791935118134,"version":"4.3.4"},"reference-count":36,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2025,5,15]],"date-time":"2025-05-15T00:00:00Z","timestamp":1747267200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"framework of State assignment","award":["075-00223-25-00"],"award-info":[{"award-number":["075-00223-25-00"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Biosensors"],"abstract":"<jats:p>The performance of heterophase immunoassays is often limited by the kinetics of analyte binding. This problem is partially solved by bead-based assays, which are characterized by rapid diffusion in the particle suspension. However, at low analyte concentrations, the binding rate is still low. Here, we demonstrate a further improvement of analyte binding kinetics in bead-based immunoassays by simultaneously concentrating both an analyte and magnetic beads in a compact spatial region where binding occurs. The analyte is electrophoretically concentrated in a flow cell where beads are magnetically retained and dragged along the channel by viscous force. The flow cell is integrated with a microarray-based signal detection module, where beads with bound analyte scan the microarray surface and are retained on it by single specific interactions, assuring ultra-high sensitivity of the method. Thus, a continuous flow assay system is formed. Its performance is demonstrated by simultaneous detection of model pathogen biomarkers, cholera toxin (CT) and staphylococcal enterotoxin B (SEB), with a detection limit of 0.1 fM and response time of under 10 min. The assay is capable of real-time online sample monitoring, as shown by a 12 h long continuous flow analysis of tap water for SEB and CT.<\/jats:p>","DOI":"10.3390\/bios15050316","type":"journal-article","created":{"date-parts":[[2025,5,15]],"date-time":"2025-05-15T04:39:16Z","timestamp":1747283956000},"page":"316","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Ultrasensitive Bead-Based Immunoassay for Real-Time Continuous Sample Flow Analysis"],"prefix":"10.3390","volume":"15","author":[{"given":"Yuri M.","family":"Shlyapnikov","sequence":"first","affiliation":[{"name":"Institute of Theoretical and Experimental Biophysics of the Russian Academy of Sciences, Institutskaya 3, 142290 Pushchino, Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Elena A.","family":"Shlyapnikova","sequence":"additional","affiliation":[{"name":"Institute of Theoretical and Experimental Biophysics of the Russian Academy of Sciences, Institutskaya 3, 142290 Pushchino, Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,5,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1038\/s41551-020-00661-1","article-title":"A fluorescence sandwich immunoassay for the real-time continuous detection of glucose and insulin in live animals","volume":"5","author":"Poudineh","year":"2021","journal-title":"Nat. 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