Fluorescence behavior of NpFR1 (SIH-181) in the oxidized (black) and reduced (red) forms, using 50 µM. Excitation: 405 or 488 nm (not shown). Emission: 490 – 600 nm, with peak at 545 nm.

Chemical structure of NpFR1 (SIH-181), a reversible fluorescence intensity-based redox sensor. This image is from Chem. Commun., 2014, 50, 8181, and licensed under a Creative Commons Attribution 3.0 Unported Licence (http://creativecommons.org/licenses/by/3.0/).

Fluorescence emission of NpFR1 (SIH-181, 5 mM, lex = 405 nm) with the incremental addition of sodium dithionite. All spectra were acquired in HEPES buffer (100 mM, pH 7.4). This image is from Chem. Commun., 2014, 50, 8181, and licensed under a Creative Commons Attribution 3.0 Unported Licence (http://creativecommons.org/licenses/by/3.0/).

Fluorescence response of NpFR1 (SIH-181) to cycles of oxidation and reduction. Reduction was achieved with sodium dithionite (100mM) followed by re-oxidation with 250mM H2O2. Spectra were recorded 5 min after the addition of reducing and oxidising agents. All spectra were acquired in HEPES buffer (100 mM, pH 7.4). This image is from Chem. Commun., 2014, 50, 8181, and licensed under a Creative Commons Attribution 3.0 Unported Licence (http://creativecommons.org/licenses/by/3.0/).

Imaging of NpFR1 (SIH-181) in 3T3-L1 preadipocytes treated with (a) vehicle control (b) H2O2 (100 mM, 2 min), (c) NpFR1 (50 mM, 2 h) and (d) NpFR1 (50 mM, 2 h) followed by H2O2 (100 mM, 2 min). Scale bar represents 50 mm, lex = 405 nm. (e) Integrated emission from 510 nm to 610 nm. Values are the mean ratio generated from the intensity from five fields of cells. Error bars represent standard error measurement (s.e.m.). The layout of this image was modified for optimal display from the original Chem. Commun., 2014, 50, 8181, and licensed under a Creative Commons Attribution 3.0 Unported Licence (http://creativecommons.org/licenses/by/3.0/).