An azo based colorimetric probe for the detection of cysteine and lysine amino acids and its real application in human blood plasma

Abstract

The present work describes the rational design and synthesis of a simple azo based colorimetric chemodosimeter to selectively detect Cys and Lys in the environment of competitive different class of amino acids in HEPES buffer under physiological conditions. The probes 3a and 3b containing aldehyde functionality upon interaction with Cys and Lys afforded stable thiazolidine and aldimine derivatives and displayed a sensitive ratiometric response in the absorption spectra due to a change in the intramolecular charge transfer (ICT) process. The whole recognition process for amino acids gives rise to a rapid significant colorimetric response with readily detectable naked-eye sensitive color changes in the real biological sample. The mechanism of interaction between the probes and amino acids has been confirmed by the optical behavior, FT-IR, NMR and ESI-MS data analysis.