Formation of hemoglobin photoproduct is responsible for two-photon and single photon-excited fluorescence of red blood cells. (30th May 2018)

• Record Type: Journal Article
• Authors: Shirshin, Evgeny A; Yakimov, Boris P; Rodionov, Sergey A; Omelyanenko, Nikolai P; Priezzhev, Alexander V; Fadeev, Victor V; Lademann, Juergen; Darvin, Maxim E
• Is Part Of: Laser physics letters. Volume 15:Number 7(2018:Jul.)
• Publication Date: 2018-05-30
• Subjects: two-photon tomography -- erythrocyte -- hemoglobin -- photophysical processes -- fluorescence lifetime -- fluorescence spectroscopy; Lasers -- Periodicals; Physics -- Periodicals; 621.366
• DOI: 10.1088/1612-202X/aac003
• Languages: English
• ISSNs: 1612-2011

Abstract

Abstract: Two-photon excited fluorescence of red blood cells (RBC) has been reported to be applicable for their assessment in vitro and in vivo . The corresponding fluorescence emission was ascribed to hemoglobin (Hb), however, as Hb is essentially non-fluorescent at single-photon excitation, the mechanism of two-photon excited fluorescence of RBC remains debatable. Here we show that a fluorescent photoproduct, characterized by an ultrafast decay of excitation, is formed after irradiation of Hb with femtosecond laser pulses with ca. 8 · 10 −5 quantum yield, and that it is also fluorescent at single-photon excitation. The formation of a similar photoproduct was also shown for Hb continuous wave irradiation with blue light with ca. 10 −5 formation quantum yield. The kinetics of the Hb photoproduct formation and its spectral properties were investigated. The obtained results clarify the processes responsible for RBC fluorescence observed in two-photon microscopy experiments.