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Quantum approach for nanoparticle fluorescence by sub‐ns photon detection
- Source :
- Cytometry Part A. 99:145-151
- Publication Year :
- 2021
- Publisher :
- Wiley, 2021.
-
Abstract
- Well defined detection and analysis of nanoparticle-sized samples such as extracellular vesicles or viruses may be important for potential disease diagnostics. However, using conventional flow-cytometry optical methods to evaluate such small particles is quite challenging. The reason is that the particle is smaller than the diffraction limit, making detection difficult. An alternative approach is fluorescence detection via conjugated fluorochromes attached to the nanoparticles; the challenge in this case is the limitation imposed upon detection of a very small number of emitted photons buried in high background photon counts. Emitted fluorescence is described by the well-known equation kf = σa I Q, which describes the emitted fluorescence rate (kf) (photons/s) as the multiplication of molecular absorption cross section(σa), excitation intensity (I), and quantum yield (Q). In addition, the excitation rate is equal to 1/t, which is the inverse of the lifetime of several ns representing the most typical conjugated fluorescent molecules used in flow cytometry. We recently developed a sub-ns photon sensor that is faster than most fluorescence lifetimes, since sub-ns speed is a critically important parameter for the separation of individual emitted photons. Based on our observation of fluorescence and background levels on typical commercial flow cytometers it is evident that a significant component of the background is induced by water-molecular vibrations. Therefore, understanding what constitutes all the components that contribute to the signals we measure in flow cytometry would help in defining what we currently call "background signals." We attempted to define a theoretical model to try to unravel these issues. This model was based on use of a reflective dry surface in the absence of water molecules. Our objective was to determine if it is possible to minimize background and enhance signal, and to provide valuable information on the contributing components of the signals collected. In order to test this model, we tested a single dried particle 50 nm in diameter on a reflective surface with minimum background. While this is clearly not a standard biological system, our results suggest that this quantum approach closely follows established photon base theory. Our goal was to define the parameters for practical nanoparticle-fluorescence analysis while enhancing our knowledge of the contribution of background properties.
- Subjects :
- 0301 basic medicine
Physics
Photons
Histology
Photon
Quantum yield
Cell Biology
Flow Cytometry
Signal
Fluorescence
Pathology and Forensic Medicine
Computational physics
03 medical and health sciences
Spectrometry, Fluorescence
030104 developmental biology
0302 clinical medicine
030220 oncology & carcinogenesis
Nanoparticles
Particle
Well-defined
Quantum
Excitation
Fluorescent Dyes
Subjects
Details
- ISSN :
- 15524930 and 15524922
- Volume :
- 99
- Database :
- OpenAIRE
- Journal :
- Cytometry Part A
- Accession number :
- edsair.doi.dedup.....b96bec537970e668e5a843bb263b1e1f