Related Experiment Video
Updated: Dec 24, 2025
Rapid Nanoprobe Signal Enhancement by In Situ Gold Nanoparticle Synthesis
Published on: March 7, 2018
Gold-modified silver nanorod arrays for SERS-based immunoassays with improved sensitivity
Chunyuan Song1, Jing Chen, Yiping Zhao
1Key Lab for Organic Electronics & Information Displays (KLOEID), Institute of Advanced Materials (IAM), Synergetic Innovation Center for Organic Electronics and Information Displays, Nanjing University of Posts & Telecommunications, Nanjing 210023, China. iamcysong@njupt.edu.cn iamlhwang@njupt.edu.cn.
This study introduces highly sensitive sandwich immunoassays using gold-modified silver nanorod arrays. These substrates enhance detection sensitivity for biomarkers like human IgG, achieving ultra-low limits of detection.
Area of Science:
- Nanotechnology
- Analytical Chemistry
- Biomedical Engineering
Background:
- Surface-enhanced Raman scattering (SERS) immunoassays rely heavily on SERS-active substrates for sensitive detection.
- Silver nanorod (AgNR) arrays fabricated by oblique angle deposition (OAD) offer excellent analytical properties for SERS applications.
Purpose of the Study:
- To report highly sensitive sandwich immunoassays on OAD-AgNR substrates for the first time.
- To utilize 4-mercaptobenzoic acid (4-MBA)-labeled immuno-gold nanoparticles (Im-AuNPs) as SERS tags.
- To evaluate the performance of bare AgNR arrays and Au-modified AgNR arrays in immunoassay sensitivity.
Main Methods:
- Fabrication of aligned AgNR arrays on glass slides via OAD.
- Surface modification of AgNR arrays with gold (Au) using a galvanic replacement reaction.
- Performance evaluation of immunoassays on different SERS substrates using human IgG detection.
Main Results:
- Au-modified AgNR arrays demonstrated higher detection sensitivity in sandwich immunoassays compared to bare AgNR arrays and self-assembled silver nanoparticle substrates.
- Despite AgNRs having better intrinsic SERS activity, the Au modification enhanced immunoassay sensitivity due to increased and more uniform Im-AuNP capture.
- The developed immunoassay showed a good linear response for human IgG from 100 fg mL⁻¹ to 100 ng mL⁻¹, with a limit of detection (LOD) of 2.5 fg mL⁻¹.
Conclusions:
- OAD-AgNR substrates, particularly when modified with gold, are highly effective for sensitive sandwich SERS immunoassays.
- The enhanced sensitivity is attributed to improved specific capture and uniform distribution of SERS tags on the Au-modified nanorod surface.
- This approach offers a promising platform for ultra-sensitive detection of biomarkers.
