N-Aminofluorescein is a highly selective and sensitive fluorescent probe for Cu2+ and can be used to detect Cu2+ in biological systems (λex/em=495/516 nm).

N-Aminofluorescein consists of a fluorescein molecule and a hydrazide group that recognizes and binds to Cu2+, thereby promoting hydrolysis of the amide. [1]
N-Aminofluorescein (abbreviated as FG) is specific for Cu2+, and an absorption peak at 632 nm is observed in 70% HEPES buffer (pH 7.4) containing Cu2+. absorption peak and emission peak was observed at 515 nm. [2]

Cu2+ Assay
1. Prepare a 1.0 mM ethanol stock solution of helical fluorescein amidoxime.
2. Perform the fluorescence reaction in 0.01 M Tris-HCl buffer (pH 7.2) using 10 μM N-aminofluorescein.
3. Add an appropriate amount of sample solution to the solution so that the final Cu2+ concentration does not exceed 10 μM, and adjust the final volume to 10 mL with 0.01 M Tris-HCl buffer (pH 7.2).
4. After 2 hours of reaction, transfer 3 mL of the solution to a 1 cm quartz cuvette and measure the fluorescence intensity/spectrum at room temperature with an excitation wavelength of 495 nm and an emission wavelength of 516 nm, respectively, and an excitation and emission slit width of 5 nm.
5. At the same time, prepare a blank solution without Cu2+ and measure it under the same conditions for comparison.
6. Detection:
Use a fluorescence microscope, flow cytometer, or fluorescence spectrophotometer to detect the labeled samples.
Set the instrument parameters according to the excitation and emission wavelengths of N-aminofluorescein (e.g., excitation wavelength is about 496 nm, emission wavelength is about 519 nm).

The above information is based on published literature. Experimental procedures should be appropriately modified to meet specific research demands.

DMSO: 100 mg/mL (288.73 mM), Sonication is recommended.