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Naked-Eye Enumeration of Single Chlamydia pneumoniae Based on Light Scattering of Gold Nanoparticle Probe
journal contribution
posted on 2020-03-31, 19:46 authored by Fenglei Chen, Tao Di, Chih-Tsung Yang, Tianyu Zhang, Benjamin Thierry, Xin ZhouChlamydia 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.