Research Institute for Electronic Science, Hokkaido University, Sapporo 001-0020, Japan.
J Phys Chem B. 2011 Sep 1;115(34):10385-90. doi: 10.1021/jp2058904. Epub 2011 Aug 9.
Fluorescence lifetime images of reduced nicotinamide adenine dinucleotide (NADH) that is a key cofactor in cellular metabolism were obtained in a cell at various values of intracellular pH. The average fluorescence lifetime of NADH is found to become shorter monotonically with increasing pH, indicating that pH in a single cell can be determined by fluorescence lifetime imaging of NADH without adding exogenous fluorescent probes. The magnitude of the pH-induced lifetime change is higher in cells than that in buffer solution. The fluorescence lifetime of NADH is not uniform inside a cell; the fluorescence lifetime of nuclear NADH is shorter than that of mitochondrial NADH at each pH, and the magnitude of the pH-induced change is larger in nuclei than in other areas. The local electric field effect on the fluorescence lifetime is discussed since this effect may be one of the strong possibilities for the nonuniformity of the autofluorescence lifetime of NADH in cells.
还原型烟酰胺腺嘌呤二核苷酸（NADH）的荧光寿命图像，NADH 是细胞代谢中的关键辅酶因子，在不同细胞内 pH 值条件下进行了获取。发现 NADH 的平均荧光寿命随着 pH 值的增加而单调变短，表明无需添加外源荧光探针，即可通过 NADH 的荧光寿命成像来确定单个细胞内的 pH 值。与缓冲溶液相比，细胞中 pH 诱导的寿命变化幅度更大。NADH 的荧光寿命在细胞内并不均匀；在每个 pH 值下，核 NADH 的荧光寿命短于线粒体 NADH，且核内 pH 诱导变化的幅度大于其他区域。讨论了对荧光寿命的局部电场效应，因为这可能是细胞内 NADH 自发荧光寿命不均匀的一种强可能性。
