N-Aminofluorescein

N-Aminofluorescein is a fluorescein hydrazide with spiro form, a highly selective and sensitive fluorescence probe for Cu2+. N-Aminofluorescein has no selective fluorescence response to other common metal ions, can be used for direct detection of Cu2+ in biological systems with λex/em=495/516 nm[1][2].

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Guidelines (Following is our recommended protocol. This protocol only provides a guideline, and should be modified according to your specific needs). N-Aminofluorescein consists of a fluorescein moiety and a hydrazide group to recognize and bind Cu2+, can promote the hydrolysis of amide[1]. N-Aminofluorescein (FG) shows selectivity on Cu2+ and shows the absorption and emission bands at 632 nm and 515 nm in 70% aqueous HEPES buffered solution (pH 7.4) containing Cu2+[2]. Guidelines (Following is our recommended protocol. This protocol only provides a guideline, and should be modified according to your specific needs). General procedure for Cu2+ determination[1]: 1.Prepare the 1.0 mM stock solution of spiro form fluorescein hydrazide in ethanol; 2.Conduct the fluorescence-on reaction in 0.01 M Tris-HCl buffer (pH 7.2), with 10 μM N-Aminofluorescein; 3.Add an appropriate volume of sample solution with a final Cu2+ concentration of not more than 10 μM, and adjust the final volume 10 mL with 0.01 M Tris-HCl buffer (pH 7.2); 4.After 2 h, transfer a 3-mL portion of the solution to a 1-cm quartz cell, and measure the fluorescence intensity/spectrum at room temperature with λex/em = 495/516 nm and both excitation and emission slit widths of 5 nm;  5.In the meantime, prepare a blank solution containing no Cu2+ and measure with the same conditions for comparison.

[1]. Chen X, et al. A selective fluorescence-on reaction of spiro form fluorescein hydrazide with Cu(II). Anal Chim Acta. 2006 Aug 11;575(2):217-22.

[2]. Uzra Diwan, et al. A water compatible turn ‘on’ optical probe for Cu2+ based on a fluorescein-sugar conjugate. Sensors and Actuators B: Chemical. 2014;196:345-351.