Volume 4, 2025

Detection of C-reactive protein using single cluster analysis of gold nanoparticle aggregates using a dark-field microscope equipped with a smartphone

Abstract

Gold nanoparticles (AuNPs), which have been used as colorimetric biosensors, show strong light scattering, allowing individual AuNPs to be identified using a dark-field microscope (DFM). In this study, we developed a method of observing the target molecule-derived aggregation of AuNPs modified with DNA aptamers at the single-cluster level using the DFM. C-Reactive protein (CRP) is an important clinical biomarker of inflammatory and cardiovascular diseases, for which a simple, inexpensive, and sensitive detection method is needed. In this study, the CRP-mediated aggregate formation of CRP aptamer-modified AuNPs was evaluated with single-cluster analysis using the DFM, and the detection limit was 17 nM, which was sufficient as a diagnostic indicator for CRP. We also developed a portable DFM equipped with a smartphone and a stage adjustment system, which enables single-cluster observation of AuNPs, and showed that 50 nM of CRP could be detected, indicating that this approach is suitable for point-of-care diagnosis. With the selection of appropriate aptamers, this method can be applied for the detection of various molecules.

Graphical abstract: Detection of C-reactive protein using single cluster analysis of gold nanoparticle aggregates using a dark-field microscope equipped with a smartphone

Supplementary files

Article information

Article type
Paper
Submitted
11 Oct 2024
Accepted
20 Dec 2024
First published
23 Dec 2024
This article is Open Access
Creative Commons BY license

Sens. Diagn., 2025,4, 159-165

Detection of C-reactive protein using single cluster analysis of gold nanoparticle aggregates using a dark-field microscope equipped with a smartphone

N. Fukuzumi, T. Nakagawa, G. Hirao, A. Ogawa, M. Maeda, T. Asahi and T. Zako, Sens. Diagn., 2025, 4, 159 DOI: 10.1039/D4SD00329B

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