Quantification of ATP in cell by fluorescence spectroscopy based on generalized ratio quantitative analysis model

In this contribution, fluorescence spectroscopy based on G-quadruplex formation was developed for the quantification of ATP in cell. In the absence of ATP, thioflavin T (ThT) dye can combine with the G-rich ATP aptamer to form an ATP aptamer-ThT G-quandruplex complex, resulting in the enhancement of fluorescence intensity; otherwise, fluorescence intensity of the system will weaken with the addition of ATP, because ATP has a strong affinity with G-rich ATP aptamer and can replace ThT to form an ATP aptamer-ATP complex. A calibration model based on generalized ratio quantitative analysis model was employed to mitigate the influence of scatterers and background absorbers in cell suspensions. The proposed fluorescence method was applied to the quantitative analysis of ATP in two type of cell lines, and achieved satisfactory quantitative results with accuracy comparable to that of the reference method–ATP detection kit. The limit of detection and limit of quantification of the proposed method for ATP in cell were estimated to be 0.22 and 0.66 μM, respectively. This proposed fluorescence method is highly simple and rapid, and does not require the use of fluorescent labeling.