Plasmonic nanosized molecularly imprinted polymer (nanoMIP) as innovative optical lateral flow immunoassay probes
Thea Serra, Salvatore Nieddu, Simone Cavalera, Jorge Pérez‐Juste, Isabel Pastoriza‐Santos, Fabio Di Nardo, Valentina Testa, Claudio Baggiani, Laura Anfossi
Abstract
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, cross-reactivity, 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@SiO 2 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 µg/mL and 0.1 µg/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. • Nanosized molecularly imprinted polymers (nanoMIP) specific to bovine immunoglobulins G were attached to gold nanoparticles to prepare plasmonic nanoMIP • Silica-coated gold nanoparticles with amine functionalities were covalently linked to nanoMIPs containing carboxylic from acrylic acid through carbodiimide chemistry • TEM images showed that nanoMIPs were decorated by silica-coated gold nanoparticles • The new plasmonic nanoMIP were incorporated into a lateral flow immunoassay enabling qualitative (visual) and quantitative detection of the target analyte • The probe allowed for the selective and rapid detection of for detecting bovine immunoglobulins G (bIgG) in milk