Computational modeling and characterization methods for rotating magnetic nanochain-enhanced lateral flow immunoassays

This article provides comprehensive methodological guidance for implementing rotating magnetic nanochain-enhanced lateral flow immunoassays with volumetric magnetic detection. Rotating magnetic nanochains act as microscale stirrers that substantially enhance antibody-antigen binding kinetics through convective mixing, yet their integration into lateral flow platforms presents unique technical challenges requiring both computational optimization and specialized characterization. We describe complete workflows for: (i) computational fluid dynamics modeling using COMSOL Multiphysics to simulate nanochain rotation, fluid flow, and mass transport enhancement; (ii) electron microscopy characterization of magnetic nanochain morphology and size distributions; (iii) rotating magnetic field generator design and operation; and (iv) magnetic particle quantification measurement procedures for volumetric signal readout. Each section provides step-by-step instructions with sufficient detail to enable independent replication. The described methods enable development of lateral flow assays achieving sub-nanogram detection limits with rapid (6-minute) analysis times, addressing critical needs in point-of-care diagnostics. These methods complement our related research article in Biosensors and Bioelectronics by providing the technical foundation necessary for adoption and adaptation of this technology by other laboratories. • COMSOL Multiphysics workflow for modeling convective enhancement by rotating magnetic nanochains • Electron microscopy procedures for comprehensive nanochain characterization • Instrumentation methods for rotating field generation and volumetric magnetic particle quantification