Pattern recognition of amino acids based on highly fluorescent SDS modified pyridyl thiazole derivative

Abstract

Selective and sensitive detection of amino acids is extremely significant as they play a key role in many biological processes. Herein, a pyridyl-thiazole based fluorophore (PTCN), modified with sodium dodecyl sulphate (SDS) assemblies, has been employed for the sensing of AA in aqueous solution. PTCN molecule exhibited excellent pH response due to the protonation of pyridyl nitrogen followed by the intramolecular charge transfer. PTCN showed dual emission along with enhanced quantum yield in SDS micellar assemblies. This improved the sensitivity of the PTCN –SDS system (PS), not only by lowering the limit of detection but also by detecting basic AA along with acidic AA. A fluorescence turn on response of PS system with acidic AA i.e. Asp and Glu has been observed. However, the PS system exhibited a ratiometric sensing pattern for basic AA i.e. Arg, Lys and Hys. Protonation and deprotonation of the fluorophore in presence of different types of AA are responsible for the changes observed in fluorescence spectra. The detection limits for Asp and Glu were found to be 0.47 μM and 0.64 μM respectively. Arg, Lys and Hys showed a detection limit of 8.36 μM, 26.6 μM and 51.9 μM respectively. Principal component analysis (PCA) effectively demonstrated discrimination of acidic, basic and neutral AA clusters. This study demonstrates the efficiency of the PS ensemble for selective, sensitive and discriminative sensing of AA.