Gold Nanoparticle Coated Silica Nanorods for Sensitive Visual Detection of microRNA on a Lateral Flow Strip Biosensor

We present a rapid and highly sensitive approach for visual detection of microRNA (miRNA) using a gold nanoparticles coated silica nanorod label and lateral flow strip biosensor. Gold nanoparticles were decorated on the silica nanorod surface by a seeding and growth procedure. A single strand DNA probe was immobilized on the gold nanoparticles-silica nanorod surface by a self-assembling process, and the formed DNA-gold nanoparticles-silica nanorod conjugate was used to construct the lateral flow nucleic acid biosensor for detecting miRNA. The captured gold nanoparticles-silica nanorods by sandwich-type hybridization reactions (DNA-RNA-DNA) on the test zone of the lateral flow nucleic acid biosensor produced the characteristic color bands, enabling visual detection of miRNA. After systematic optimization, the new lateral flow nucleic acid biosensor was capable of detecting 10 pM of the miRNA target without instrumentation, which is six times lower than that obtained with the gold nanoparticle-based lateral flow nucleic acid biosensor. The gold nanoparticles coated silica nanorod thus provides a new and sensitive nanolabel for visual detection of biological molecules on the lateral flow biosensor.