Enhanced Specificity of Immunomagnetic Separation of Bacteria in Milk Via Hydration Layer Modulation of Iron Oxide Particles

Abstract

Efficient capture and separation of target bacteria in complex food matrices remain challenging due to bacterial non-specific binding (NSB) to the surface of separating carrier. This study investigates the impact of surface functionalities on NSB to develop a highly specific magnetic separation system for Salmonella Typhimurium in whole milk. A comparative analysis of surface-modified iron oxide particles (IOPs) revealed that hydroxyl-rich surfaces suppressed NSB more effectively than carboxyl-based modifications, with hydration layer density playing a key role. Based on these insights, dextrin-functionalized immuno-IOPs were optimized, achieving over 80% capture efficiency while maintaining minimal NSB, even in the presence of high concentration of non-target bacteria. This study provides fundamental insights into surface modification strategies for pathogen separation, offering a promising platform for accurate bacterial detection in food safety and diagnostics.

Keywords: non-specific binding, Foodborne pathogen, iron oxide particles, hydration layer, dextrin, immuno-magnetic separation