Analytical and Bioanalytical Chemistry

, Volume 410, Issue 9, pp 2291–2303 | Cite as

Functionalized Au@Ag-Au nanoparticles as an optical and SERS dual probe for lateral flow sensing

  • Tingting Bai
  • Meng Wang
  • Min Cao
  • Juan Zhang
  • Kangzhen Zhang
  • Ping Zhou
  • Zhengxia Liu
  • Ying Liu
  • Zhirui GuoEmail author
  • Xiang LuEmail author
Paper in Forefront


Lateral flow assay strips (LFASs) with Au nanoparticles (NPs) have been widely used as a probe for biomarkers in point-of-care testing; however, there still remain challenges in detection sensitivity and quantitative analysis. In this study, we developed a surface-enhanced Raman scattering (SERS)-based LFAS for quantitative analysis of a biomarker in the low concentration range. Moreover, apart from conventional Au NPs, three other types of citrate-capped Au-Ag bimetallic NPs: Au core with Ag shell NPs (Au@Ag NPs), rattle-like Au core in Ag-Au shell NPs (Au@Ag-Au NPs) and Ag-Au NPs were prepared and functionalized, and their solution-based SERS activities were comprehensively studied by experimental measurement and theoretical analysis. The results clearly indicated that the citrate-capped Au@Ag-Au NPs exhibited the highest SERS activity among the probes tested. Au@Ag-Au NPs were used as both optical and SERS probes in a SERS-based LFAS. In the presence of the analyte at high concentrations, a purple color appeared in the test zone. Highly sensitive and quantitative analysis was realized by measurement of SERS signals from the test lines. One of the most specific markers for cardiac injury, cardiac troponin I (cTnI), was chosen as the detection model. The detection limit of the SERS-based LFAS for cardiac troponin I was 0.09 ng/mL, lowered by nearly 50 times compared with visual results, and could be further lowered by optimization. These results demonstrated that the SERS-based LFAS using citrate-capped Au@Ag-Au NPs as probes can be a powerful tool for highly sensitive and quantitative detection of biomarkers.

Graphical abstract

A surface-enhanced Raman scattering (SERS)-based lateral flow assay strip using rattle-like Au core in Ag-Au shell (Au@Ag-Au) nanoparticles as probes was developed for quantitative analysis of a biomarker, with a detection limit nearly 50 times lower than that of visual assessment. C control line, T test line


Lateral flow assay strip Au nanoparticles Au-Ag bimetallic nanoparticles Surface-enhanced Raman scattering 



This work was supported by the National Natural Science Foundation of China (81471783, 81701849, 61601251), the Key Project of Jiangsu Province for Research and Development (BE2017763), the Key Project of Science and Technology Development Fund of Nanjing Medical University (2016NJMUZD033), and the Talents Planning of Six Summit Fields of Jiangsu Province (WSN-055).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no competing interests.

Supplementary material

216_2018_850_MOESM1_ESM.pdf (883 kb)
ESM 1 (PDF 882 kb)


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • Tingting Bai
    • 1
  • Meng Wang
    • 2
  • Min Cao
    • 2
  • Juan Zhang
    • 1
  • Kangzhen Zhang
    • 1
  • Ping Zhou
    • 1
  • Zhengxia Liu
    • 1
  • Ying Liu
    • 1
  • Zhirui Guo
    • 1
    Email author
  • Xiang Lu
    • 1
    Email author
  1. 1.Department of Geriatrics, The Second Affiliated Hospital, Key Laboratory for Aging & DiseaseNanjing Medical UniversityNanjingChina
  2. 2.School of ScienceNantong UniversityNantongChina

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