Facile fabrication of net-like fluorescent microsphere/AuNP tags for a dual-modal colorimetric/fluorescence lateral flow assay

Abstract

Lateral flow assays (LFAs) offer a simple and rapid option for diagnosis, widely utilized for point-of-care or at-home testing. However, they often suffer from low sensitivity and high false positive owing to the single output signal. Herein, we developed a dual-mode colorimetry/fluorescence LFA via employing a novel net-like nanprobe as a reporter tag, which was obtained by coupling the fluorescent microspheres (FMs) with gold nanoparticles (AuNPs). Upon the introduction of the target (using miRNA-21 as a model), it hybridizes with the net-like nanprobe, subsequently trapped by the capture DNA immobilized on the test line, producing a prominent visual and fluorescent signal. Benefiting from the outstanding signal amplification capability of FMs/AuNPs nanoprobe, the developed dual-mode LFA enables highly sensitive detection of miRNA-21, with a detection limit (LOD) as low as 1 pM, which is 10 times and 20 times more sensitive than conventional FMs or AuNPs-based LFA, respectively. Additionally, in comparison to the LFA with single output signal, the analytical results of the dual-mode LFA are more reliable owing to the mutual verification of two different signals. Importantly, the platform can detect miRNA-21 in complex serum samples and distinguish cancer cells from normal cells in cell extract samples analysis, determining its great potential for point-of-care tests.