Gold and silver-gold alloy nanoparticles with mean diameter of 10 nm and narrow size distribution were prepared by reduction of the correspondent metal precursors using aqueous dextran solution which acts as both a reducing and capping agent. The formation of nanoparticles was characterized by UV-vis spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and dynamic light scattering (DLS). The silver and gold nanoparticles exhibited absorption maxima at 425 and 551 nm respectively; while for the bimetallic Ag-Au alloy appeared 520 nm in between them. TEM images showed monodispersed particles in the range of 8-10 nm. The crystallinity of the nanoparticles was assured by XRD analysis. DLS data gave particle size distribution. The dextran stabilized Au nanoparticles used as a colorimetric sensor for detection and estimation of pesticide present in water. The dextran stabilized Ag-Au alloy nanoparticles exhibited interesting antimicrobial activity against bacteria at micromolar concentrations. © 2014 Elsevier Ltd.

KRISHNENDU ACHARYA

Botany

DIPANKAR CHATTOPADHYAY

Polymer Science and Technology

K BANKURA

D MAITY

M M R MOLLICK

D MONDAL

B BHOWMICK

I ROY

T MIDYA

J SARKAR

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Carbohydrate Polymers

A facile one-pot approach for rapid synthesis of silver and gold nanoparticles (Ag NPs and Au NPs) with narrow size distribution and good stability was described by reducing silver nitrate and chloroauric acid with polysaccharide dextrin. Here, dextrin was used as both a reducing and stabilizing agent for synthesis of NPs. The as-synthesized Ag NPs and Au NPs were characterized by UV-visible absorption spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD). The Ag NPs and Au NPs exhibited an absorption maxima at 404 and 547nm respectively. TEM images showed NPs in the range of 8-28nm. The crystallinity of the NPs was measured by XRD analysis. Furthermore, the as-prepared Ag NPs revealed colorimetric sensor property for detection of Cu2+ ions based on changes in absorbance resulting from metal ion-induced aggregation of NPs or direct deposition of metal ions onto NPs. The as-prepared Au NPs exhibited a notable catalytic activity toward the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4. © 2015 Elsevier B.V.

International Journal of Biological Macromolecules

Dextrin-mediated synthesis of Ag NPs for colorimetric assays of Cu2+ ion and Au NPs for catalytic activity

Poly(butylene adipate-co-terephthalate) (PBAT) nanocomposites films are prepared by a solution intercalation process using natural montmorillonite (MMT) and cetyltrimethylammonium bromide (CTAB)-modified montmorillonite (CMMT). Cation exchange technique has been used for modification of MMT by CTAB and characterized by Fourier transform infrared analysis, thermo-gravimetric analysis, and X-ray diffraction (XRD) studies. CMMT gives better dispersion in the PBAT matrix than MMT and is confirmed by XRD and transmission electron microscopy. Because of better compatibility of CMMT, water vapor transmission rate of PBAT decreases more in the presence of CMMT than MMT. The biodegradability of PBAT and its nanocomposite films are studied in compost and from the morphological analysis it is apparent that the PBAT/CMMT shows a lower biodegradation rate in comparison to the PBAT/MMT. The antimicrobial activity of PBAT and its nanocomposite films is tested by an inhibition zone method. Because of the presence of the quaternary ammonium group of CTAB-modified MMT, PBAT/CMMT nanocomposites show adequate antimicrobial activity. © 2013 Wiley Periodicals, Inc.

Journal of Applied Polymer Science

Antimicrobial activity and biodegradation behavior of poly(butylene adipate-co-terephthalate)/clay nanocomposites

Silver nanoparticles were successfully synthesized from AgNO3 through a reliable, ecofriendly and simple green route using Paederia foetida L. leaf extract as a reducing cum stabilizing agent. UV-Visible Spectroscopy, dynamic light scattering, atomic force microscopy, transmission electron microscopy, and X-ray diffraction analysis were used for characterization of silver nanoparticles. The synthesized silver nanoparticles were spherical in shape with size range of 4-15 nm. The nanoparticles were face-centered cubic crystal structure. The adopted technique for silver nanoparticle synthesis is suitable for large-scale production. The as-prepared silver nanoparticles revealed excellent antibacterial activity against different gram classes of bacteria and would be a promising candidate for various pharmaceutical, biomedical, and environmental applications. © Taylor &amp; Francis Group, LLC.

International Journal of Green Nanotechnology: Biomedicine

Green synthesis of silver nanoparticles using Paederia foetida L. leaf extract and assessment of their antimicrobial activities

In this paper we reported preparation of methylcellulose-silver nanocomposite films by mixing of aqueous solution of methylcellulose with silver nitrate followed by casting. The silver nanoparticles were generated in methylcellulose matrix through reduction and stabilization by methylcellulose. The surface plasmon band at 412 nm indicated the formation of Ag nanoparticles. The MC-Ag nanocomposite films were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR). The X-ray diffraction analysis of synthesized MC-Ag nanocomposite films revealed that metallic silver was present in face centered cubic crystal structure. Average crystallite size of silver nanocrystal was 22.7 nm. The FTIR peaks of as-synthesized MC-Ag nanocomposite fully designated the strong interaction between Ag nanoparticles and MC matrix. Nano-sized silver modified methylcellulose showed enhanced mechanical properties i.e. the introduction of Ag leading to both strengthening and toughening of MC matrix. The methylcellulose-silver nanocomposite films offered excellent antimicrobial activity against various microorganisms. © 2012 Elsevier Ltd. All rights reserved.

Synthesis of methylcellulose-silver nanocomposite and investigation of mechanical and antimicrobial properties

A simple one-step rapid synthetic route is described for the preparation of silver nanoparticles by reduction of silver nitrate (AgNO 3) using aqueous dextran solution which acts as both reducing and capping agent. The formation of silver nanoparticles is assured by characterization with UV-vis spectroscopy, atomic force microscopy (AFM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The absorbance of the silver nanoparticles is observed at 423 nm. The AFM image clearly shows the surface morphology of the well-dispersed silver nanoparticles with size range of 10-60 nm. TEM images show that the nanoparticles are spherical in shape with ∼5-10 nm dimensions. The crystallinity of Ag nanoparticles is assured by XRD analysis. The antimicrobial activity of as synthesized silver nanoparticles is tested against the bacteria, Bacillus subtilis, Bacillus cereus, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. The bacterial growth is inhibited by gradual reduction of the concentration of the silver nanoparticles. © 2012 Elsevier Ltd. All rights reserved.

Synthesis, characterization and antimicrobial activity of dextran stabilized silver nanoparticles in aqueous medium

The culture filtrate of the fungus, Alternaria alternata, was used for the bio-reduction of sodium selenate to produce selenium nanoparticles. Change in colour to dark red of the reaction mixture signifies the development of nano-α-selenium. Dynamic light scattering experiments, atomic force microscopy, scanning and transmission electron microscopic images explained the formation of monodisperse spherical α-selenium nanoparticles in the range of 30-150nm. X-ray diffraction spectrum of the nano-Se exhibited a broad peak at the 2θ angles of 15-35°, signifying its amorphous nature. Energy-dispersive X-ray study revealed the presence of selenium in the nanoparticles. Fourier transform infrared spectroscopy confirmed the presence of a protein shell outside the nanoparticles, which in turn support their stabilisation. A novel method has been presented here to synthesise nano-selenium in which the fungal culture filtrate was used and up-to-date literature survey showed that this is the first report on mycosynthesis of selenium nanoparticles. © 2011 The Institution of Engineering and Technology.

Journal	Data powered by TypesetCarbohydrate Polymers
Publisher	Data powered by TypesetElsevier Ltd
ISSN	0144-8617
Open Access	No