Blue spherical gold nanoparticles for lateral flow analysis

Lateral flow assays (LFAs) have evolved significantly, expanding well beyond clinical diagnostics into a versatile, rapid, and cost-effective platform for point-of-care applications. Gold nanoparticles (AuNPs) are the most used nanomaterial for the preparation of labels in LFA devices. However, their monochromaticity limits the advantage of human eyes in detecting many colors simultaneously and, therefore, the potentiality of LFA. To address this limitation, this work reports a facile and robust synthesis of blue dielectric-coated gold core-shell nanospheres engineered for LFA applications. This innovative nanostructure modulates the localized surface plasmon resonance to achieve a distinct color contrast, opening new avenues for the simultaneous co-detection of multiple antigens on a single test strip without compromising the simplicity of visual inspection.