Plasmonic nanosized molecularly imprinted polymer (nanoMIP) as innovative optical lateral flow immunoassay probes

Lateral flow immunoassays (LFIAs) are very popular as diagnostics, especially for point-of-care testing; they use antibodies as high affinity and specific ligands and therefore suffer from limited stability, batch variability, crossreactivity, high production costs, limited shelf life, and ethical concerns associated with antibody production. This study addresses these issues by introducing nanosized molecularly imprinted polymers (nanoMIPs) as specific ligands to replace antibodies in LFIA. Silica-coated gold nanoparticles (Au@SiO2 NPs) and nanoMIPs that recognize bovine immunoglobulins G (BIgGs) were synthesized and conjugated to prepare a novel probe with optical properties and specific binding capabilities. The successful synthesis of this nanosized hybrid material was confirmed by transmission electron microscopy and dynamic light scattering. The probe was incorporated into a model LFIA containing a bacterial protein that binds to mammalian immunoglobulins as a reactive test line. Visual and instrumental detection of BIgG showed detection limits of 0.25 mu g/mL and 0.1 mu g/mLl, respectively, in 15 minutes, meeting the requirements for rapid testing. The probe demonstrated high selectivity for IgGs from different animal species, with cross-reactivities of 1.1 % and 1.8 % for mouse and horse IgGs, respectively. The potential of the new nanoMIP-based probe was further validated by successfully detecting BIgGs in whole soy and goat milk samples.