Enhanced sensitivity of lateral flow immunoassays by using water-soluble nanofibers and silver-enhancement reactions

Abstract

We developed a facile method for enhancing the sensitivity of lateral flow immunoassays (LFIAs) using core-shell hybrid nanofibers comprising a water-soluble polymer in the shell and silver-reducing reagents in the core. These nanofibers were produced using a coaxial electrospinning method and directly deposited in front of the test line on a nitrocellulose (NC) membrane. When a human serum spiked with various concentrations of Troponin I (TnI), a cardiac biomarker, was dropped on the absorption pad, a color change was induced by the binding of TnI-gold nanoparticle complexes to the antibodies at the test line. The silver-reducing reagents were subsequently released from the nanofibers via dissolution, which reduced silver ions to metallic silver around the gold nanoparticles and darkened the color of the test line. The hybrid nanofibers enhanced the detection limit of a commercial LFIA by up to 10 times when viewed with the naked eye while maintaining the assay time and convenience characteristics of this analysis.