writer：Jingyun Wang, Lei Zhang, Youju Huang,* A Dandapat, GG Zhang, JW Zhang,Weihua Lai* and Tao Chen*
keywords：Au-Ag NPs, Polymer modification, Immunochromatography Strip
source：期刊
specific source：Scientific Report, 2017, 7, 41419
Issue time：2017年

The probe materials play a significant role in improving the detection efficiency and sensitivity of lateral-flow immunochromatographic test strip (ICTS). Unlike conventional ICTS assay usually uses single-component, solid noble metal particles (e.g., gold nanoparticles) as labeled probes, in our present study, a bimetallic, hollow Au-Ag nanoparticles (NPs) labeled ICTS was successfully developed for the detection of clenbuterol (CLE). The hollow Au-Ag NPs with different Au/Ag mole ratio and tunable size were synthesized by varying the volume ratio of [HAuCl4]: [Ag NPs] via the galvanic replacement reaction. The surface of hollow Ag-Au NPs was functionalized with 11-mercaptoundecanoic acid (MUA) for further covalently bonded with anti-CLE monoclonal antibody to acquire highly stable hollow Au-Ag NPs probe. Overall size of the Au-Ag NPs, size of the holes within individual NPs and also Au/Ag mole ratio have been systematically optimized to amplify both the visual inspection signals and the quantitative data (optical densities) recorded using a bioassay reader. The sensitivity of optimized hollow Au-Ag NPs probes for the detection of CLE  has been achieved even as low as 2 ppb in a short time (within 15 min), which is superior over the detection performance of conventional test strip using Au NPs. The optimized hollow Au-Ag NPs labeled test strip can be used as an ideal candidate for the rapid screening of CLE in food samples.