Browsing by Author "Vijay Kumar Sonkar"

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A coumarin-derived multi-faceted optical material with molecular logic gate for bioimaging
(Royal Society of Chemistry, 2025) Amit Kumar Singh; Pranjalee Yadav; Aayoosh Singh; Avanish Kumar Singh; Shashi Kant Sharma; Vijay Kumar Sonkar; Vinod Prasad Singh
The development of stimuli-responsive, multi-faceted chromic materials has gained the interest of the material science community recently, owing to their vast range of applications in several areas simultaneously, such as viscosity, temperature, and pressure detectors. In this context, a coumarin-derived organic luminophore, HCFH, has been designed and extensively investigated for its characteristics, such as aggregation-induced emission (AIE), viscochromism, piezochromism, thermochromism, and distinguishable fluorometric detection of Zn2+ and Cu2+ ions in water. The emission intensity of HCFH amplifies 111-fold with the addition of water in tetrahydrofuran (THF), validating its aggregation-induced emission (AIE) nature. Multi-colored piezochromism is observed in the ‘crystalline’, ‘pristine’, and ‘ground’ forms of HCFH as non-emissive, weakly cyan-emissive, and bright green-emissive, respectively. Further, powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) analyses indicate a crystalline-to-amorphous phase transition during grinding. HCFH exhibits remarkable photophysical properties, including viscosity, polarity, and temperature-dependent emissions. The probe selectively detects Zn2+ and Cu2+ ions with limits of detection (LOD) of 1.14 and 1.54 nM, respectively, employing chelation-enhanced fluorescence (CHEF) and inhibition of photo-induced electron transfer (PET) for Zn2+ and paramagnetic fluorescence quenching for Cu2+. The Job's plots indicate 1 : 2 and 1 : 1 (M : L) binding stoichiometries for Zn2+ and Cu2+, respectively, which are confirmed by their single-crystal structures. Molecular logic gates and paper strip kits are also developed utilizing their sensing capabilities. HCFH has been found highly effective in bio-imaging of Zn2+ and Cu2+ in HeLa cells. Microscopic examination of the cells indicates that the probe is localized in both the cytosol and mitochondria of the cells. © 2025 The Royal Society of Chemistry.
A highly selective coumarin-based chemosensor for dual sensing of Cu2+ and Zn2+ ions with logic gate integration and live cell imaging
(Royal Society of Chemistry, 2024) Avanish Kumar Singh; Amit Kumar Singh; Shashi Kant Sharma; Vijay Kumar Sonkar; Vinod P. Singh
In this paper, a coumarin-based Schiff base chemosensor has been synthesized and developed to detect Cu2+ and Zn2+ ions in nanomolar concentrations. The probe selectively distinguishes Cu2+ and Zn2+ from among several metal ions in DMF : H2O (7 : 3, v/v, pH 7.4) HEPES buffer. The structure of the probe and its sensing behavior were investigated by FT-IR, UV-vis, fluorescence, HRMS, and NMR analyses, along with X-ray crystallography and computational studies. CIH detects Zn2+ and Cu2+ using different strategies: CHEF-induced fluorescence enhancement and paramagnetic fluorescence quenching, respectively. Job's plots show a 1 : 1 binding interaction between CIH and Cu2+ or Zn2+ ions. The binding constant values for Cu2+ (1.237 × 105 M−1) and Zn2+ (1.24 × 104 M−1) suggest a better ability for Cu2+ to interact with CIH than Zn2+. An extremely high sensitivity of the probe was highlighted by its very low detection limits (LOD) of 5.36 nM for Cu2+ and 3.49 nM for Zn2+. The regeneration of the probe with the addition of EDTA in its complexes allows the formation of molecular logic gates. CIH has been successfully employed in mitotracking and intracellular detection of Zn2+ and Cu2+ in SiHa cells. © 2024 The Royal Society of Chemistry.
Synthesis and Study of pH Independent L-Cysteine Capped Zirconium Oxide Quantum Dots as a Potential Bio-Imaging Probe Using HeLa Cells
(Springer, 2025) Surya Pratap; Himanshu Meena; Shashi Kant Sharma; Vijay Kumar Sonkar; Sundeep Kumar; Horesh Kumar
Here we propose an eco-friendly hydrothermal approach to synthesise fluorescent L-cysteine capped zirconium oxide quantum dots (L-Cys-ZrO2 QDs). The UV–Vis absorption, PL-emission, pH independence, size, functional group attached over surface QDs, binding energy, and stability of QDs in aqueous solvent were systematically studied. The TEM results revealed the mean particle size ∼5.7 nm of QDs. The synthesised QDs have UV–Vis absorption peaks at 320 nm, 265 nm, and 245 nm with PL emission from 360 nm to 500 nm and have a quantum yield ∼3.6%. The functional groups attached over surface of QDs such as –CO, -NH2, SO4−− etc. were confirmed by FT-IR spectrum which were supported by XPS spectrum analysis. An in-vitro optical bio-imaging method was employed, focusing on cancer cell line such as HeLa Cells as a model cell. Cytotoxicity is analysed using MTT assay showing that QDs are biocompatible in nature. The photoluminescence properties of the synthesized L-Cys-ZrO2 QDs were examined on the HeLa cells under green laser. The quantum dots proved to be effective labels for bioimaging as evidenced by strong emission when observed under a confocal fluorescence microscope by green laser. © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2025.