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Open AccessArticle

Cadmium-Free Quantum Dots as Fluorescent Labels for Exosomes

1
The MacDiarmid Institute, Wellington 6012, New Zealand
2
School of Chemical Physical Sciences, Victoria University of Wellington, Kelburn, Wellington 6012, New Zealand
*
Author to whom correspondence should be addressed.
Sensors 2018, 18(10), 3308; https://doi.org/10.3390/s18103308
Received: 31 August 2018 / Revised: 29 September 2018 / Accepted: 29 September 2018 / Published: 2 October 2018
(This article belongs to the Special Issue Biosensors for the Detection of Biomarkers)
Quantum dots are attractive alternatives to organic fluorophores for the purposes of fluorescent labeling and the detection of biomarkers. They can also be made to specifically target a protein of interest by conjugating biomolecules, such as antibodies. However, the majority of the fluorescent labeling using quantum dots is done using toxic materials such as cadmium or lead due to the well-established synthetic processes for these quantum dots. Here, we demonstrate the use of indium phosphide quantum dots with a zinc sulfide shell for the purposes of labeling and the detection of exosomes derived from the THP-1 cell line (monocyte cell line). Exosomes are nano-sized vesicles that have the potential to be used as biomarkers due to their involvement in complex cell processes. However, the lack of standardized methodology around the detection and analysis of exosomes has made it difficult to detect these membrane-containing vesicles. We targeted a protein that is known to exist on the surface of the exosomes (CD63) using a CD63 antibody. The antibody was conjugated to the quantum dots that were first made water-soluble using a ligand-exchange method. The conjugation was done using carbodiimide coupling, and was confirmed using a range of different methods such as dynamic light scattering, surface plasmon resonance, fluorescent microscopy, and Fourier transform infrared spectroscopy. The conjugation of the quantum dot antibody to the exosomes was further confirmed using similar methods. This demonstrates the potential for the use of a non-toxic conjugate to target nano-sized biomarkers that could be further used for the detection of different diseases. View Full-Text
Keywords: quantum yields; bioimaging; extracellular vesicles; antibodies quantum yields; bioimaging; extracellular vesicles; antibodies
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MDPI and ACS Style

Dobhal, G.; Ayupova, D.; Laufersky, G.; Ayed, Z.; Nann, T.; Goreham, R.V. Cadmium-Free Quantum Dots as Fluorescent Labels for Exosomes. Sensors 2018, 18, 3308.

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