Selective Zinc(II)‐Ion Fluorescence Sensing by a Functionalized Mesoporous Material Covalently Grafted with a Fluorescent Chromophore and Consequent Biological Applications

Abstract

Abstract A highly ordered 2D‐hexagonal mesoporous silica material is functionalized with 3‐aminopropyltriethoxysilane. This organically modified mesoporous material is grafted with a dialdehyde fluorescent chromophore, 4‐methyl‐2,6‐diformyl phenol. Powder X‐ray diffraction, transmission electron microscopy, N 2 sorption, Fourier transform infrared spectroscopy, and UV‐visible absorption and emission have been employed to characterize the material. This material shows excellent selective Zn 2+ sensing, which is due to the fluorophore moiety present at its surface. Fluorescence measurements reveal that the emission intensity of the Zn 2+ ‐bound mesoporous material increases significantly upon addition of various concentrations of Zn 2+ , while the introduction of other biologically relevant (Ca 2+ , Mg 2+ , Na + , and K + ) and environmentally hazardous transition‐metal ions results in either unchanged or weakened intensity. The enhancement of fluorescence is attributed to the strong covalent binding of Zn 2+ , evident from the large binding constant value (0.87 × 10 4 M −1 ). Thus, this functionalized mesoporous material grafted with the fluorescent chromophore could monitor or recognize Zn 2+ from a mixture of ions that contains Zn 2+ even in trace amounts and can be considered as a selective fluorescent probe. We have examined the application of this mesoporous zinc(II) sensor to cultured living cells (A375 human melanoma and human cervical cancer cell, HeLa) by fluorescence microscopy.