Anoop Kumar Saini

The development of fluorescence turn-on probe for Al(III) sensing and live cell nucleus-nucleoli staining

The morphology of nucleus and nucleolus is powerful indicator of physiological and pathological conditions. The specific staining of nucleolus recently gained much attention due to the limited and expensive availability of the only existing stain “SYTO RNA-Select”. Here, a new multifunctional salen type ligand (L1) and its Al3+ complex (1) are designed and synthesized. L1 acts as a chemosensor for Al3+ whereas 1 demonstrates specific staining of nucleus as well as nucleoli. The binding of 1 with nucleic acid is probed by DNase and RNase digestion in stained cells. 1 shows an excellent photostability, which is a limitation for existing nucleus stains during long term observations. 1 is assumed to be a potential candidate as an alternative to expensive commercial dyes for nucleus and nucleoli staining.

A highly selective and sensitive chemosensor for L-tryptophan by employing a Schiff based Cu(II) complex

A new Cu(II) complex C40H38N4CuO2 (1) was synthesized and characterized by elemental analysis, mass spectrometry and also authenticated by single crystal X-ray studies. Structural analysis of 1 reveals the distorted square planar geometry around the Cu(II) centre and the presence of C–H⋯O and N–H⋯π hydrogen bonding interactions. The sensing behaviour of 1 towards L-tryptophan (L-Trp) was identified by UV-vis spectroscopic and cyclic voltammetry experiments. In the UV titration of 1 with L-Trp, four distinct isosbestic points were observed. Furthermore, on modifying the surface of the glassy carbon electrode (GCE) by 1 (1-GCE) the oxidation potential of L-Trp at +0.32 V is revealed, which is considerably lower than the values previously reported for other electrodes. Additionally, the 1-GCE can detect L-Trp with a noteworthy detection limit (185 nM), sensitivity (3.156 μA μM−1 cm−2) and with distinguished selectivity in the presence of various other amino acids. The 1-GCE also displays excellent reproducibility, repeatability and long term stability. Finally, electrochemical impedance spectroscopy (EIS) investigations were carried out to gauge the effects of modification with 1 on the characteristics of the GCE. Moreover, the molecular docking study of 1 with various proteins reveals the π–π stacking interaction with L-Trp.