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Proceedings Paper

Quantum dots-based nanobiosensors for simultaneous dynamic measurements of multiple intracellular ion concentrations
Author(s): Lid B. Wong; Hua Mao; Yuchi Wang
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Paper Abstract

Cells maintain their homeostatic functions by dynamically regulating the concentrations of intracellular ions via ionic channels. Using two recently developed QD-based nanobiosensors for Cl- and Na+ that emit separate wavelengths, herein we report the fluorescence microscopy measurements of the concentrations of intracellular chloride ([Cl-]i) and sodium ([Na+]i) simultaneously in intact cells using a 405 nm excitation wavelength. The Cl-QD525 and Na-QD630nm were constructed by conjugating the chloride ion receptor, MEPTU, and sodium ion receptor, 12-crown-4, within the FRET distances of their respective QD525nm and QD630nm. This enables FRET energy transferred from the QD (donor) to the receptor complexes (acceptor). The fluorescence intensities of Cl-QD525 and QD630nm determined by photon counting were inversely proportional to the increased concentrations of the respective Cl- and Na+ according to Stern- Volmer. By co-loading Cl-QD525 TM and Na-QD630 TM into HEK-293F or T84 cells, we have determined the dynamic responses of [Cl-]i and [Na+]i by pharmacologically manipulating the chloride and sodium channels using their respective agonists and antagonists. The measurements of the dynamics of [Cl-]i and [Na+]i have not heretofore been possible without these QD-based nanobiosensors. The predictable physio-pharmacological responses elicited by these agents indicate that the regulatory mechanisms of [Cl-]i and [Na+]i are independent but coupled. Investigations into the mechanisms of the [Cl-]i and [Na+]i signal transduction pathways and for translational ion channel drug discovery can now be performed using this assay.

Paper Details

Date Published: 2 February 2012
PDF: 6 pages
Proc. SPIE 8232, Colloidal Nanocrystals for Biomedical Applications VII, 823204 (2 February 2012); doi: 10.1117/12.908962
Show Author Affiliations
Lid B. Wong, Cytoptics Corp. (United States)
Hua Mao, Cytoptics Corp. (United States)
Yuchi Wang, Cytoptics Corp. (United States)

Published in SPIE Proceedings Vol. 8232:
Colloidal Nanocrystals for Biomedical Applications VII
Wolfgang J. Parak; Kenji Yamamoto M.D.; Marek Osinski, Editor(s)

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