Novel pyridoxal based molecular sensor for selective turn-on fluorescent switching functionality towards Zn(II) in live cells

A new facile molecular sensor (HL), 4-((3-(cyclohexylamino)propylimino)methyl)-5-(hydroxymethyl)-2-methylpyridin-3-ol, constructed with pyridoxal moiety, selectively detects Zn2+ ion in solid and solution medium. The structure of this newly synthesized sensor is confirmed by single crystal X-ray diffraction study. The rapid selective fluorescence 'turn-on' response of Zn2+ ion in aqueous ethanolic (9:1, v/v) HEPES buffer (pH = 7.0) medium was studied. The synthesized molecular sensor shows the lowest limit of detection (LOD) for Zn2+ ion (9.5850 +/- 0.3835 nM). The sensing behavior of the molecular sensor towards Zn2+ can be ascribed to the formation of complex. Density functional theory (DFT) and time dependent density functional theory (TD-DFT) calculations were carried out to support the proposed tetrahedral geometry of zinc(II) complex and to explore the electronic properties of HL and its zinc complex (ZnL2). The molecular sensor shows the practical application to detect zinc(II) qualitatively on TLC plate based test strips. In addition to that, it also gives insight into the design of protocols required for successful imaging of intracellular zinc(II) ions in HeLa cells.

Automated summary

This study reports a new facile molecular sensor for the selective detection of Zn2+ ions in solid and solution medium. The synthesized sensor shows a low limit of detection and practical applications in qualitative detection of zinc(II) on TLC plate based test strips and imaging of intracellular zinc(II) ions in HeLa cells.