School Of Basic And Applied Sciences

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    Green Synthesis of Bimetallic Au/Ag Nanostructures Using Aqueous Extract of Eichhornia crassipes for Antibacterial Activity
    (Springer, 2022-02-12T00:00:00) Halder, Arindom; Biswas, Rathindranath; Kushwaha, Prem Prakash; Halder, Krishna Kamal; Ahmed, Imtiaz; Singh, Harjinder; Kumar, Shashank; Haldar, Krishna Kanta
    Biosynthesis of nanostructured materials is an arising feature of the interdisciplinary relationship between nanotechnology and biotechnology and acquiring consideration because of developing interest to foster ecologically favorable innovations in material preparation. In the present study, we synthesized an environmentally friendly and green method for the synthesis of gold/silver bimetallic nanostructure using Eichhornia crassipes leaf extract as reducing and capping agent. Au/Ag nanostructures were characterized by UV�Visible spectroscopy, X-ray photoelectron spectroscopy, and power X-ray diffraction. Transmission electron microscopy images also confirmed the formation of Au/Ag nanostructures. Antibacterial activity of Au/Ag nanostructures was studied and it has been found that Ag/Au nanostructure at 100��M concentration significantly inhibited the bacterial growth of Escherichia coli bacteria. Moreover, the Hoechst 33342 staining method was used to study the effect of Ag/Au nanostructure particles on the morphological changes in breast cancer cell (MDA-MB-231) nucleus. Staining of the Ag/Au nanostructure particle�treated MDA-MB-231 cells (4�h treatments) showed the appearance of emblematic features of apoptosis such as cell membrane blabbing and shrinkage. Graphical Abstract: [Figure not available: see fulltext.]. � 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
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    Core-Size-Dependent Catalytic Properties of Bimetallic Au/Ag Core− Shell Nanoparticles
    (ACS Publications, 2017) Haldar, Krishna Kanta; Kundu, Simanta; Patra, Amitava
    Bimetallic core−shell nanoparticles have recently emerged as a new class of functional materials because of their potential applications in catalysis, surface enhanced Raman scattering (SERS) substrate and photonics etc. Here, we have synthesized Au/Ag bimetallic core−shell nanoparticles with varying the core diameter. The red-shifting of the both plasmonic peaks of Ag and Au confirms the core−shell structure of the nanoparticles. Transmission electron microscopy (TEM) analysis, line scan EDS measurement and UV−vis study confirm the formation of core−shell nanoparticles. We have examined the catalytic activity of these core−shell nanostructures in the reaction between 4- nitrophenol (4-NP) and NaBH4 to form 4-aminophenol (4-AP) and the efficiency of the catalytic reaction is found to be increased with increasing the core size of Au/Ag core−shell nanocrystals. The catalytic efficiency varies from 41.8 to 96.5% with varying core size from 10 to 100 nm of Au/Ag core−shell nanoparticles, and the Au100/Ag bimetallic core−shell nanoparticle is found to be 12-fold more active than that of the pure Au nanoparticles with 100 nm diameter. Thus, the catalytic properties of the metal nanoparticles are significantly enhanced because of the Au/Ag core−shell structure, and the rate is dependent on the size of the core of the nanoparticles.