Related Experiment Video
Updated: Dec 25, 2025
Measurement of Scattering Nonlinearities from a Single Plasmonic Nanoparticle
Published on: January 3, 2016
Naked-Eye Enumeration of Single Chlamydia pneumoniae Based on Light Scattering of Gold Nanoparticle Probe
Fenglei Chen1, Tao Di1, Chih-Tsung Yang2
1College of Veterinary Medicine, Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Joint International Research Laboratory of Agriculture and Agri-Product Safety, The Ministry of Education of China, Yangzhou University, Yangzhou 225009, China.
Abstract:
Chlamydia pneumoniae is a spherical zoonotic pathogen with a diameter of ∼200 nm, which can lead to a wide range of acute and chronic diseases in human body. Early and reliable on-site detection of C. pneumoniae is the key step to control the spread of the pathogen. However, the lack of a current technology with advantages of rapidity, ultrasensitivity, and convenience limits the implementation of traditional techniques for on-site detection of C. pneumoniae. Herein, we developed a naked-eye counting of C. pneumoniae based on the light scattering properties of gold nanoparticle (GNP) under dark-field microscopy (termed "GNP-labeled dark-field counting strategy"). The recognition of single C. pneumoniae by anti-C. pneumoniae antibodies-functionalized GNP probes with size of 15 nm leads to the formation of wreath-like structure due to the strong scattered light resulted from hundreds of GNP probes binding on one C. pneumoniae under dark-field microscopy. Hundreds of GNP probes can bind to the surface of C. pneumoniae due to the high stability and specificity of the nucleic acid immuno-GNP probes, which generates by the hybridization of DNA-modified GNP with DNA-functionalized antibodies. The limit of detection (LOD) of the GNP-labeled dark-field counting strategy for C. pneumoniae detection in spiked samples or real samples is down to four C. pneumoniae per microliter, which is about 4 times more sensitive than that of quantitative polymerase chain reaction (qPCR). Together with the advantages of the strong light scattering characteristic of aggregated GNPs under dark-field microscopy and the specific identification of functionalized GNP probes, we can detect C. pneumoniae in less than 30 min using a cheap and portable microscope even if the sample contains only a few targets of interest and other species at high concentration. The GNP-labeled dark-field counting strategy meets the demands of rapid detection, low cost, easy to operate, and on-site detection, which paves the way for early and on-site detection of infectious pathogens.
Insights
A new gold nanoparticle (GNP) method enables naked-eye detection of Chlamydia pneumoniae. This rapid, ultrasensitive technique uses GNP probes and dark-field microscopy for on-site pathogen identification.
Area of Science:
- Biotechnology
- Pathogen Detection
- Nanotechnology
Background:
- Chlamydia pneumoniae causes various acute and chronic diseases.
- Early and on-site detection is crucial for controlling pathogen spread.
- Current methods lack rapidity, sensitivity, and convenience for on-site use.
Purpose of the Study:
- To develop a rapid, ultrasensitive, and convenient method for on-site Chlamydia pneumoniae detection.
- To utilize gold nanoparticles (GNPs) and dark-field microscopy for pathogen identification.
Main Methods:
- Developed a "GNP-labeled dark-field counting strategy" using anti-C. pneumoniae antibody-functionalized GNPs.
- Antibody-functionalized GNPs bind to C. pneumoniae, forming wreath-like structures visible under dark-field microscopy.
- Utilized the strong light scattering of aggregated GNPs for naked-eye counting.
Main Results:
- Achieved a limit of detection as low as four C. pneumoniae per microliter, surpassing qPCR sensitivity.
- Detection completed in under 30 minutes using a portable microscope.
- Demonstrated successful detection in spiked and real samples, even with high concentrations of other species.
Conclusions:
- The GNP-labeled dark-field counting strategy offers rapid, low-cost, and easy on-site detection of C. pneumoniae.
- This method facilitates early detection and control of infectious pathogens.
- Paves the way for improved on-site pathogen surveillance and diagnostics.
