Gold-Nanoparticle-Decorated Silica Nanorods for Sensitive\nVisual Detection of Proteins

Abstract

We\nreport a rapid and highly sensitive approach based on gold-nanoparticle-decorated\nsilica nanorods (GNP-SiNRs) label and lateral-flow strip biosensor\n(LFSB) for visually detecting proteins. Owing to its biocompatibility\nand convenient surface modification, SiNRs were used as carriers to\nload numerous GNPs, and the GNP-SiNRs were used as labels for the\nlateral-flow assay. The LFSB detection limit was lowered 50 times\ncompared to the traditional GNP-based lateral-flow assay. Rabbit IgG\nwas used as a model target to demonstrate the proof-of-concept. Sandwich-type\nimmunoreactions were performed on the immunochromatographic strips,\nand the accumulation of GNP-SiNRs on the test zone produced the characteristic\ncolored bands, enabling visual detection of proteins without instrumentation.\nThe quantitative detection was performed by reading the intensities\nof the colored bands with a portable strip reader. The response of\nthe optimized device was highly linear for the range of 0.05–2\nng mL^–1, and the detection limit was estimated to\nbe 0.01 ng mL^–1. The GNP-SiNR-based LFSB, thus,\noffered an ultrasensitive method for rapidly detecting trace amounts\nof proteins. This method has a potential application with point-of-care\nscreening for clinical diagnostics and biomedical research.