Mechanism of two-photon excited hemoglobin fluorescence emission.
Hemoglobin, one of the most important proteins in the human body, is composed of “heme” groups (iron-containing rings) and “globins” (proteins). We investigate the two-photon excited fluorescence of hemoglobin and its subunit components (heme and globin). We measure the hemoglobin fluorescence lifetime by using a streak camera of ps resolution and confirm that its lifetime is in femtosecond scale. In the study of the fluorescence properties of heme and globin, the experimental results reveal that heme is the sole fluorophore of hemoglobin. Hemoglobin fluorescence can be effectively excited only via two-photon process, because heme has a centrosymmetric molecular structure and two-photon allowed transition is forbidden for single-photon process and vice versa due to the Laporte parity selection rule.
Hong Kong University of Science and Technology, Department of Electronic and Computer Engineering, Clear Water Bay, Kowloon, Hong Kong SAR, China.
Qiqi
Q
Sun
Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.
Wei
W
Zheng
Hong Kong University of Science and Technology, Department of Physics, Clear Water Bay, Kowloon, Hong Kong SAR, China.
Jiannong
J
Wang
University of Science and Technology of China, Bio-X Division, Hefei National Laboratory for Physical Science at the Microscale, Hefei, Anhui, China.
Yi
Y
Luo
Hong Kong University of Science and Technology, Department of Electronic and Computer Engineering, Clear Water Bay, Kowloon, Hong Kong SAR, ChinaeHong Kong University of Science and Technology, Center of Systems Biology and Human Health, School of Science.
Jianan Y
JY
Qu
D000818:Animals; D003198:Computer Simulation; D006454:Hemoglobins / Q000737:chemistry* / Q000528:radiation effects; D008027:Light; D008856:Microscopy, Fluorescence / Q000379:methods*; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D008956:Models, Chemical; D057054:Molecular Imaging / Q000379:methods*; D051381:Rats; D012542:Scattering, Radiation
D006454:Hemoglobins