Au@Pt bimetallic nanoparticles and blue silica nanoparticles nanocomposite as probe of immunochromatographic assay for HBsAg detection
In this article, a sensitive, visual and quantitative immunochromatographic assay (ICA) was described by using novel Au@Pt-nanoparticle-decorated blue-silica-nanoparticles nanocomposite (Au@Pt/blue SiNPs) as reporter probe. The Au@Pt/ blue SiNPs were prepared by using post-modification methods, in which Au@Pt NPs synthesized on the surface of blue SiNPs. Antibody against HBsAg was conjugated with Au@Pt/blue SiNPs, due to the convenient surface modification and biocompatibility of Au@Pt nanoparticles, which were used as labels for ICA. The detection was performed on an ICA strip by using the sandwich immunoreaction between the HBsAg and the anti-HBsAg antibody and accumulation of Au@Pt/blue SiNPs on the test zone. The results were qualitatively analyzed by the naked eyes and quantitatively analyzed by the combination of a camera and “ImageJ” software, eliminating any lab equipment. The sensitivity of the Au@Pt/blue SiNPs based ICA was lowered 20 times and 10 times comparing with blue silica nanoparticles (blue SiNPs) and gold nanoparticles (GNPs) as reporter probe, respectively. Under optimal conditions, a linear relationship between the color intensity and HBsAg over the range of 0.5−10 ng/mL was achieved, and the detection limit was estimated to be 0.13 ng/mL (S/N =3). The Au@Pt/blue SiNPs based ICA, thus, offered a sensitive method for rapidly detecting HBsAg. Although the proof-of-concept of Au@Pt/blue SiNPs based ICA was demonstrated using HBsAg as a model analyte, this nanocomposite label based ICA is easily developed to be a universal signal amplification technique and applied to detection of other protein biomarkers.