Colorimetric chemosensor based on a carminic acid and Pb2+ complex for selective detection of cysteine over homocysteine and glutathione in aqueous solution

摘要

We have developed a colorimetric chemosensor for the selective and sensitive detection of Cys based on the complex (CA-2Pb(2+)) between a commercially available natural organic dye, carminic acid (CA) and Pb2+ in pure aqueous solution at physiological pH. The addition of Cys to the CA-2Pb(2+) solution resulted in a distinct color change from purple to red together with a remarkable absorption spectral change by the restoration of CA through a displacement mechanism with formation of the Cys-Pb2+ complex, whereas other amino acids and glutathione induce no or minimal spectral and color changes. Moreover, the other amino acids and GSH do not affect the detection ability of CA-2Pb(2+) for Cys. The reversibility even through several cycles was established for practical applications. The results indicate that CA-2Pb(2+) may be useful as a potential colorimetric and naked-eye chemosensor for Cys over Hcy and GSH in aqueous solution.