Beyond the Passive Diffusion: Core@Satellite Magneto‐Plasmonic Particles for Rapid and Sensitive Colorimetric Immunosensor Response

Magneto‐plasmonic particles, comprising gold and iron oxide, exhibit substantial potential for biosensing applications due to their distinct properties. Gold nanoparticles (AuNPs) provide plasmonic features, while iron oxide composites, responsive to an external magnetic field, significantly reduce detection time compared to passive diffusion. This study explores core@satellite magneto‐plasmonic particles (CSMPs), featuring magnetic nanoparticle clusters and numerous satellite‐like AuNPs, to amplify the optical response on a nanostructured gold surface. Using a sandwich scheme, target analytes are detected as hybrid nanoparticles bind to the pre‐immobilized target on the AuNPs surface, inducing changes in the immunosensor's extinction spectrum. Application of an external magnetic field notably enhances biosensor response and sensitivity, reducing assay time from hours to minutes. Leveraging the properties of CSMPs, the immunosensor detects specific immune protein at low concentrations within minutes. CSMPs hold considerable promise for precise and sensitive analyte detection, offering potential applications in rapid testing and mass screening. A rapid and sensitive colorimetric immunosensor is developed, by employing core‐satellite magneto‐plasmonic particles to enhance the optical response of a gold nanostructured surface. By applying an external magnetic field, these particles are swiftly attracted and bind to the target analyte, effectively detecting low concentrations of the inflammatory protein pentraxin3 (PTX3) within minutes.