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Open AccessFeature PaperArticle

Quantification and Imaging of Antigens on Cell Surface with Lipid-Encapsulated Fluorescent Nanodiamonds

1
Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
2
Taiwan International Graduate Program—Chemical Biology and Molecular Biophysics, Academia Sinica, Taipei 115, Taiwan
3
Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan
4
Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan
5
Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan
*
Author to whom correspondence should be addressed.
These two authors contributed equally to this work.
Micromachines 2019, 10(5), 304; https://doi.org/10.3390/mi10050304
Received: 16 April 2019 / Revised: 29 April 2019 / Accepted: 30 April 2019 / Published: 6 May 2019
(This article belongs to the Special Issue Nanostructures for Bioimaging)
Quantifying the density and locating the position of antigens on cell surface has been a challenge in molecular biology research. The challenge lies in the need for a chemically and photophysically stable fluorophore to achieve the required sensitivity and accuracy. Here, we present a method suitable for the purpose by using lipid-encapsulated fluorescent nanodiamonds (FNDs) of 35 nm in diameter as biolabels. The encapsulation of FNDs in biotinylated phospholipids not only facilitates good dispersion of the particles in biological buffers, but also endows them with high specific targeting ability. We demonstrated a viable application of the technique for biotin-mediated immunostaining of antigens on fixed human cells, identifying their positions by two-color confocal fluorescence imaging, and determining their densities by magnetically modulated fluorescence detection. A binding capacity of 6 ± 1 × 104 antigens/cell was measured specifically for CD44 on HeLa cell surface. The result agreed well with the assay of R-phycoerythrin-conjugated antibodies by flow cytometry, supporting the reliability of this new nanoparticle-based method. View Full-Text
Keywords: antigen; cell membrane; diamond nanoparticle; fluorescence microscopy; magnetic modulation antigen; cell membrane; diamond nanoparticle; fluorescence microscopy; magnetic modulation
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MDPI and ACS Style

Hsieh, F.-J.; Chen, Y.-W.; Hui, Y.Y.; Lin, C.-H.; Chang, H.-C. Quantification and Imaging of Antigens on Cell Surface with Lipid-Encapsulated Fluorescent Nanodiamonds. Micromachines 2019, 10, 304.

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