Browsing by Author "Upadhyay, K.K."

Now showing 1 - 5 of 5
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    A coumarin based fluorescent probe enabling nanomolar detection of Zn2+ and Cu2+
    (Elsevier B.V., 2022) Kumar, Virendra; Diwan, Uzra; Tyagi, Nidhi; Mishra, Rakesh K.; Singh, Manish Kumar; Upadhyay, K.K.
    A rationally designed fluorescent probe constructed on a coumarin platform (R-1) distinguished sequentially & distinctly two vital ions viz. Zn2+ and Cu2+ through different mechanistic approaches at their nanomolar concentrations. The native dark state (off-state) of R-1 was illuminated (on-state) upon its interaction with Zn2+ and further reverted back to its natural dark state in the presence of Cu2+ in aqueous medium. The structural details of R-1 and its ensemble with Zn2+ were unambiguously elucidated through their single-crystal XRD studies. The single crystals of R-1-Zn2+ with chloride and acetate counter anions displayed a fascinating 1-D co-ordination polymeric supramolecular structures. The strategic incorporation of pyridine �N in R-1 introduced a yet another binding site and consequently modulated its optical characteristics, while the analogous derivative R-3, inspite of having electron withdrawing �NO2 group, (instead of pyridine �N as in R-1 and R-2) was unable to produce any significant sensing response under similar conditions. The corresponding optical responses with Zn2+/Cu2+ were equated with INHIBIT logic- gate function. Moreover, the R-1 was deployed for imaging the above ionic analytes in rat glioblastoma cell lines (c6) through confocal laser scanning microscopy. � 2021 Elsevier B.V.
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    A low cost yet highly sensitive silver nanoprobe for naked eye detection and determination of bisulphate (HSO4-) in a few real samples
    (Elsevier B.V., 2022) Singh, Raksha; Yadav, Minu; Kumar Singh, Anurag; Mishra, S.K.; Upadhyay, K.K.
    Herein, we report a simple and economical yet highly sensitive and efficient silver nanoresonators based protocol for naked eye detection of a janus-faced ion like bisulphate from its two real samples in real time. The SEM-TEM, DLS, AFM and EDAX alongwith spectroscopic studies have further substantiated our observation in the same context. The quantification of bisulphate in one of its real sample through UV�Vis spectroscopy using these nanoprobes as indicator has also been carried out successfully. The Raman measurements have clearly indicated the rich SERS potential of these silver nanoresonators. � 2022 Elsevier B.V.
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    A rapid and sensitive colorimetric discrimination and detection of cysteine, homocysteine and glutathione by phloroglucinol-functionalized silver nanoresonators with real applications
    (Royal Society of Chemistry, 2023) Singh, Anurag Kumar; Singh, Raksha; Yadav, Minu; Sharma, Manish; Tiwari, Ida; Upadhyay, K.K.
    This study describes the preparation and application of simple yet effective silver nanoprobes for the facile colorimetric discrimination and detection of cysteine, homocysteine and glutathione in real time at the micro molar levels with three distinct colors. These nanoprobes were further exploited to detect and determine cysteine and glutathione from their respective commercial samples, with recoveries exceeding 80%. FT-IR spectroscopy, UV-Vis spectroscopy, SEM, TEM, EDAX, AFM and DLS studies have supported our findings. � 2023 The Royal Society of Chemistry.
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    Naked-eye detection of cysteine/homocysteine through silver nano-resonators and specific identification of homocysteine through nanoresonator-thiosulphate conjugate
    (Royal Society of Chemistry, 2022) Singh, Raksha; Singh, Anurag Kumar; Yadav, Minu; Sharma, Manish; Tiwari, Ida; Upadhyay, K.K.
    This study presents simultaneous colorimetric detection of two very similar amino thiols viz. cysteine and homocysteine at their micro and sub-micromolar levels, respectively, through the aggregation of citrate capped silver nanoparticles. A rare kind of categorical naked-eye detection of homocysteine over cysteine was accomplished through the conjugation of these AgNPs with thiosulphate. The UV-Vis and SERS characteristics of these AgNPs were also more prominent with homocysteine compared to cysteine. The quantification of cysteine was performed in a pharmaceutic sample with an accuracy of 89 � 5%. � 2022 The Royal Society of Chemistry.
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    Salicylazine activated plasmonic silver nanoprisms for identification of Fe(ii) and Fe(iii) from aqueous solutions
    (Royal Society of Chemistry, 2021) Singh, Deovrat; Singh, Raksha; Kumar, Abhay; Singh, Anurag Kumar; Yadav, Minu; Upadhyay, K.K.
    Herein, we report the synthesis and characterization, along with the successful application, of silver nanoprisms for the identification of Fe(ii)/Fe(iii) at the nanomolar level. A few real samples have also been analyzed successfully. The scanning electron microscopy (SEM)-transmission electron microscopy (TEM) imaging of the sensing events indicate analyte induced changes in the morphology and geometrical pattern of the silver nanoparticles. � The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2021.