Pyridoxamine driven selective turn-off detection of picric acid using glutathione stabilized fluorescent copper nanoclusters and its applications with chemically modified cellulose strips

The present work reports the interaction of various vitamin B6 cofactors with the red emitting glutathione stabilized copper nanoclusters (GSH-CuNCs). Addition of pyridoxamine (PM) resulted a new turn-on band at 410 nm due to the possible adsorption over the surface of GSH-CuNCs. The nano-assembly PM-GSH-CuNCs was applied for the selective detection of nitro-aromatic compounds. Upon addition of picric acid (PA), the fluorescence of PM-GSH-CuNCs was selectively quenched at 410 nm and ~ 625 nm among the other tested nitro-aromatic compounds. With a linearity range from 9.9 μM to 43 μM, the concentration of PA can be detected down to 2.74 μM. The high selectivity exhibited by the nano-assembly allows to detect PA in real samples like tap water, river water and matchstick. Advantageously, the nano-assembly PM-GSH-CuNCs was chemically adsorbed over the cellulosic strips and applied for the naked-eye detection of PA down to 1 μM.