Nanobody-Functionalized Magnetic Beads for Enrichment of Foodborne Botulinum Toxin Type A Light Chain

In this study, for the first time, nanobody conjugated beads were developed to enrich botulinum serotype A. We evaluated two types of nanobody A8-functionalized magnetic beads, both of which effectively captured and enriched BoNT/A from dilute solutions and complex protein mixtures, achieving a concentration increase of approximately 12- to 30-fold. The A8@N-beads showed higher binding capacity than the A8@S-beads, suggesting that our self-synthesized NH₂ beads work well in this application. Our data serve as evidence that using different bead types with nanobody conjugation is a promising enrichment approach for further detection of Lc/A, particularly in applications involving low-abundance targets or complex sample matrices, such as food safety screening or clinical diagnostics.