A fraction of NADH in solution is "dark": Implications for metabolic sensing via fluorescence lifetime.

The metabolic cofactor and energy carrier NADH (nicotinamide adenine dinucleotide, reduced) has fluorescence yield and lifetime that depends strongly on conformation, a fact that has enabled metabolic monitoring of cells via FLIM (Fluorescence Lifetime Microscopy). Using femtosecond fluorescence upconversion, we show that this molecule in solution participates in ultrafast self-quenching along with both bulk solvent relaxation and spectral relaxation on 1.4 and 26 ps timescales. This, in effect, means up to a third of NADH is effectively "dark" for FLIM in the 400-500 nm observation window commonly employed. Methods to compensate for, avoid or measure dark species corrections are outlined.

Citation

Simin Cao, Zhongneng Zhou, Haoyang Li, Menghui Jia, Yangyi Liu, Mengyu Wang, Mengjie Zhang, Sanjun Zhang, Jinquan Chen, Jianhua Xu, Jay R Knutson. A fraction of NADH in solution is "dark": Implications for metabolic sensing via fluorescence lifetime. Chemical physics letters. 2019 Jul;726:18-21

PMID: 32921799

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