Nano cuboids: Impact of 8-hydroxyquinoline on tryptophan properties and its applications

N-terminal tryptophan residues can be labeled with fluorophore by chemical reaction. Here in we report conjugation of 8-hydroxyquinoline (as fluorophore) with tryptophan using Schiff-base condensation reaction to decipher the impact of 8-hydroxyquinoline on the fluorescence and self-assembly properties of tryptophan in water. This water-soluble hydroxyquinoline-tryptophan (HQ-W-1) conjugate has been demonstrated to have Aggregation Induced Emission (AIE) phenomena in water. HQ-W-1 undergo spontaneous self-assembly to form nano cuboidal superstructures having 200-500 nm diameter and 300-650 nm length. In metal-ion binding studies this HQ-W-1 shows selective fluorescence enhancement (14.5-fold) in the presence of Al3+ ions. The detection limit is 3.0 nM (UV method) and 3.53 nM (FL method). The AIE utility of HQ-W-1 has been demonstrated by developing latent fingerprints. (C) 2020 Elsevier Ltd. All rights reserved.