Tryptophan functionalized framework of nanoporous material as fluorescent sensor for trace detection of Zn2+ ions

A novel fluorescent sensor of tryptophan functionalized mesoporous silica (Trp-Meso-Si) for detecting Zn2+ ion was designed by modifying the framework of nanoporous material with Tryptophan organic silicon source under the template via co-condensation method. Tryptophan organic silicon source was first synthesized by selecting natural amino acid as reagent via multi-steps reactions. The sensing material Trp-Meso-Si was well characterized by various spectroscopic techniques. The results indicate that material 5%-Trp-Meso-Si with low amounts of Tryptophan exhibits well-ordered one-dimensional hexagonal P6mm structure. However, the sample 15%-Trp-Meso-Si with high amounts of Tryptophan shows strongest fluorescent intensity at the same excited wavelength of 285 nm. All the materials Trp-Meso-Si indicate fluorescent signal at excited wavelength because of tryptophan as fluorophore moiety. In the fluorescent recognition experiments, Trp-Meso-Si could selectively and sensitively detect trace concentrations of Zn2+ ions in aqueous solution with satisfactory detection limits of 0.9 × 10−7 M. Tryptophan within the framework of mesoporous silica material showed strong affinity for Zn2+ ions according to a 3:1 ratio of [tryptophan] and [Zn2+] by plenty of groups with lone pair electrons. [Display omitted] •A novel sensor based on nanoporous material with functional framework of natural amino acid is first developed.•A new tryptophan silane precursor is designed and prepared via multi-step reactions.•Tryptophan as fluorescent moiety is immobilized within the skeleton of mesoporous silica material.•High sensitive and selective fluorescent trace detection of Zn2+ ion is accomplished in aqueous media.