Fig. 2. Spectra of TR-H2S (5 μM) upon titration of H2S (Na2S, 0–200 μM) in phosphate buffered saline (PBS) buffer (pH = 7.4, 2% DMSO, 1 mg mL–1 human serum albumin (HSA)): (a) one-photon excitation emission spectra (λ
ex = 378 nm); (b) absorption spectra; (c) two-photon excitation emission spectra (λ
ex = 760 nm). (d) Two-photon absorption cross section of TR-H2S in the absence (
) and presence of H2S (
) (200 μM).
