Quantum dots-based nanobiosensors for simultaneous dynamic measurements of multiple intracellular ion concentrations

Lid B. Wong; Hua Mao; Yuchi Wang

doi:10.1117/12.908962

2 February 2012 Quantum dots-based nanobiosensors for simultaneous dynamic measurements of multiple intracellular ion concentrations

Lid B. Wong, Hua Mao, Yuchi Wang

Author Affiliations +

Proceedings Volume 8232, Colloidal Nanocrystals for Biomedical Applications VII; 823204 (2012) https://doi.org/10.1117/12.908962
Event: SPIE BiOS, 2012, San Francisco, California, United States

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-QD_630nm were constructed by conjugating the chloride ion receptor, MEPTU, and sodium ion receptor, 12-crown-4, within the FRET distances of their respective QD_525nm and QD_630nm. This enables FRET energy transferred from the QD (donor) to the receptor complexes (acceptor). The fluorescence intensities of Cl-QD₅₂₅ and QD_630nm 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.

Citation Download Citation

Lid B. Wong, Hua Mao, and Yuchi Wang "Quantum dots-based nanobiosensors for simultaneous dynamic measurements of multiple intracellular ion concentrations", Proc. SPIE 8232, Colloidal Nanocrystals for Biomedical Applications VII, 823204 (2 February 2012); https://doi.org/10.1117/12.908962

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