Browsing by Author "Lahiri J."

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    Biogenic synthesis of dual-emission chlorophyll-rich carbon quantum dots for detection of toxic heavy metal ions - Hg(ii) and As(iii) in water and mouse fibroblast cell line NIH-3T3
    (Royal Society of Chemistry, 2024) Pratap R.; Hassan N.; Yadav M.; Srivastava S.K.; Chaudhary S.; Verma A.K.; Lahiri J.; Parmar A.S.
    Due to the excessive residues and serious adverse effects, it is urgent to develop an efficient method to detect Hg2+ and As3+ in drinking water to protect human health. In this study, a novel fluorometric sensor based on chlorophyll-rich carbon quantum dots (CQDs) for the detection of Hg2+ and As3+ ions was developed. The dual emitting (blue-green and red) CQDs were synthesized by a one-step solvothermal method using plumeria plant leaves as precursors. When Hg2+ ions were added in the presence of CQDs, the red emission (676 nm) of the CQDs was quenched (OFF), while in the presence of As3+ ions, the blue-green emission (485 nm) was enhanced (ON). The detection limits of 0.99 nM for Hg2+ and 12.15 nM for As3+ were validated for the proposed sensor. The biocompatibility, cytotoxicity, and bioimaging of the CQDs were investigated in the mouse fibroblast cell line NIH-3T3. The cellular uptake was also studied under the influence of Hg2+ and As3+ ions. Moreover, the novel chlorophyll-rich CQD-based fluorometric �ON-OFF� dual probe sensor was successfully applied to detect Hg2+ and As3+ in real water systems as well as in the mouse fibroblast cell line. � 2024 The Royal Society of Chemistry.
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    Sensing of p-nitrophenol using highly selective and sensitive Boran, Nitrogen doped quantum dots
    (Elsevier B.V., 2024) Pratap R.; Pandey S.; Vishal V.; Raghuvanshi I.; Kumar S.; Lahiri J.; Parmar A.S.
    p-Nitrophenol (PNP) is a nitroaromatic compound that poses a significant threat to human health and the environment due to its carcinogenic, mutagenic, cytotoxic, and embryotoxic properties at low concentrations. Therefore, the selective and sensitive detection of PNP is crucial for both human health and environmental monitoring. Boron (B) and Nitrogen (N) doped quantum dots (B,NQDs) have been found to be effective as blue-green luminescent materials for this purpose. These B,NQDs were synthesized using a one-step hydrothermal method, resulting in the formation of highly stable quantum dot. The addition of trace amounts of PNP, the luminescence of the B,NQDs was significantly quenched, which was found to be linearly dependent on the PNP concentration in the range of 100pM to 6 ?M. Further analysis of steady-state absorption and emission, along with photoluminescence decay dynamics, revealed the formation of both static and dynamic quenching complexes. Our simple fluorimetry-based sensor demonstrated an impressive limit of detection (LOD) of 9.08 nM, making it highly selective and sensitive for the detection of PNP. Additionally, the B,NQDs exhibited exceptional stability with respect to pH, UV exposure, salinity, and storage conditions. Finally, we successfully demonstrated the detection of PNP in real water systems and pesticides. � 2024 The Authors
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    Surface enhanced Raman scattering-based sensing and ultrafast nonlinear optical properties of silver-hexagonal boron nitride nanocomposites achieved by femtosecond laser ablation
    (Elsevier B.V., 2024) Bera K.; Moram S.S.B.; Banerjee D.; Lahiri J.; Soma V.R.
    This study investigated the surface-enhanced Raman spectroscopy (SERS) properties and nonlinear optical (NLO) behavior of silver nanoparticles (Ag NPs) decorated hexagonal boron nitride (hBN) nanocomposites. Although Ag NPs are known for their excellent plasmonic properties, their susceptibility to oxidation in ambient conditions significantly reduces SERS activity. To overcome this, a femtosecond laser-assisted single-step novel approach is developed for synthesizing hybrid Ag-hBN nanocomposites via ablating Ag target in a solution of exfoliated hBN nanosheets, forming uniformly embedded Ag NPs on hBN nanosheets. The morphological characteristics and elemental compositions were validated by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). TEM analysis revealed that Ag NPs averaged 15 nm in size, while hBN nanosheets had lateral dimensions of approximately 250 nm. The SERS activity of the prepared nanocomposites was investigated using dye and explosive molecules, achieving detection sensitivities of 1 ?M and 100 ?M, respectively, with high reproducibility. These detection sensitivities are significant as they demonstrate the potential of the Ag-hBN nanocomposites for sensitive and reliable detection of trace amounts of analytes. Notably, the Ag-hBN nanocomposites showed enhanced SERS activity compared to pure Ag NPs, with a 2.5-fold improvement for Nile blue, 3.6-fold for methylene blue, and 2.4-fold for RDX. The current study also demonstrates that hBN prevents Ag NPs� oxidation and preserves the SERS functionality even at elevated temperatures. Furthermore, the NLO properties of the nanocomposites were investigated using the standard Z-scan technique, revealing two-photon and three-photon absorption coefficients of 3 � 10?4 cm/GW and 6.5 � 10?5 cm3/GW2, respectively. The findings highlight the potential of Ag-hBN nanocomposites to enhance SERS and NLO devices, enabling future applications in sensing and photonics. � 2024 Elsevier B.V.