Anirban Som

Indian Institute of Technology Madras

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Thalappil Pradeep

Indian Institute of Technology Madras

Depanjan Sarkar

University of Manchester

Biswajit Mondal

Indian Institute of Technology Madras

Amrita Chakraborty

Rice University

Ganesan Paramasivam

Indian Institute of Technology Madras

Nonappa Nonappa

Tampere University

Mohammad Bodiuzzaman

King Abdullah University of Science and Technology

Ananya Baksi

TU Dortmund University

Ananthu Mahendranath

Indian Institute of Technology Madras

Ganapati Natarajan

Indian Institute of Technology Madras

Cooperative Institutions

Indian Institute of Technology Madras

Rice University

Aalto University

Indian Institute of Technology Kharagpur

Indian Institute of Science Bangalore

Espoo Music Institute

Purdue University West Lafayette

University of California, Los Angeles

Indian Institute of Technology Kanpur

Universidade Estadual de Campinas (UNICAMP)

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Selective and Practical Graphene-Based Arsenite Sensor at 10 ppb

ACS Applied Nano Materials (2022)

S. Jana Kamalesh Chaudhari Md Rabiul Islam Ganapati Natarajan Tripti Ahuja

Arsenic detection in field water samples at concentrations of relevance with affordable and simple equipment is of global interest. We report a biomimetic electrode using electrochemically reduced graphene oxide (ERGO) for highly selective and sensitive reagent-free arsenite (As3+) detection in field water samples, down to the ten parts per billion level, enabling measurement of drinking water quality affordably for millions of arsenic-affected people. This electronically and structurally optimized ERGO electrode shows selective detection of As3+ in both phosphate buffered saline (PBS, pH ∼7) and field water samples, even though more than 100 times larger conductivity and total dissolved solids (TDS), respectively, are present in them. Raman and FTIR spectroscopies were used to understand the mechanism of selectivity and sensitivity. The sensing mechanism involved two processes, namely, selective binding of As3+ with the −COOH groups of ERGO followed by its electro-oxidation by an applied potential. Density functional theory (DFT) and force-field calculations were used to obtain crucial insights into the site selectivity and mechanism of oxidation of As3+. A two-electron transfer process from As3+ to ERGO followed by associative O ligand addition to As3+ by a ketone oxygen atom, and concomitant regeneration of −COOH group is presented. The ion selectivity depends both on structural and electronic factors. First, the compact pyramidal-shaped As3+ species may closely approach the edge −COOH functional group to a greater extent than the other ions enabling covalent binding of the As center with the ketone O atom. Furthermore, closer proximity of the lowest unoccupied molecular orbital (LUMO) acceptor level of the positively charged ERGO and the highest occupied molecular orbital (HOMO) donor level of the As3+ species suggests that a uniquely selective resonant charge-transfer effect occurs between the As3+ species and ERGO.

HOMO/LUMO

10.1021/acsanm.2c02860

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Citations (7)

Atomically Precise Nanocluster Assemblies Encapsulating Plasmonic Gold Nanorods

Angewandte Chemie (2018)

Amrita Chakraborty Ann Fernandez Anirban Som Biswajit Mondal Ganapati Natarajan

Abstract The self‐assembled structures of atomically precise, ligand‐protected noble metal nanoclusters leading to encapsulation of plasmonic gold nanorods (GNRs) is presented. Unlike highly sophisticated DNA nanotechnology, this strategically simple hydrogen bonding‐directed self‐assembly of nanoclusters leads to octahedral nanocrystals encapsulating GNRs. Specifically, the p ‐mercaptobenzoic acid ( p MBA)‐protected atomically precise silver nanocluster, Na 4 [Ag 44 ( p MBA) 30 ], and p MBA‐functionalized GNRs were used. High‐resolution transmission and scanning transmission electron tomographic reconstructions suggest that the geometry of the GNR surface is responsible for directing the assembly of silver nanoclusters via H‐bonding, leading to octahedral symmetry. The use of water‐dispersible gold nanoclusters, Au ≈250 ( p MBA) n and Au 102 ( p MBA) 44 , also formed layered shells encapsulating GNRs. Such cluster assemblies on colloidal particles are a new category of precision hybrids with diverse possibilities.

Nanoclusters

Nanorod

Noble metal

10.1002/ange.201802420

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Citations (11)

Nonstoichiometric Copper Sulfide Nanostructures at the Brass–Rubber Interface: Implications for Rubber Vulcanization Temperature in the Tire Industry

ACS Applied Nano Materials (2020)

M. P. Kannan Anirban Som Tripti Ahuja Vidhya Subramanian A. Sreekumaran Nair

Brass (which is an alloy of copper and zinc)-coated steel cords (BCSCs) in the form of belts are embedded in a rubber compound in radial tires (beneath the tread) to give stability and strength to the tread region of the tires. The life of the tires also depends on the strength and durability of the bond between the BCSCs and rubber. During the vulcanization process with sulfur, a series of sulfide and oxide nanostructures of copper and zinc are formed at the brass–rubber interface. These nanostructures have a dendritic morphology that can reinforce rubber primarily through mechanical interlocking created through the flow of rubber chains into the dendritic cavities followed by formation of cross-links between rubber chains during vulcanization. The strength and durability of the bonding depend on a number of parameters such as rubber compound formulation, vulcanization temperature (VT) and time, nanostructure thickness (height), and chemical composition of the nanostructures (the so-called adhesion interface). A few methods have been stated in the literature for assessing the chemical composition and thickness of the adhesion interface. However, simple, reliable, and newer methodologies are needed for a better understanding of the same. This paper details a new approach called the "brass mesh experiment" to assess the thickness of the adhesion interface formed under particular vulcanization conditions using microscopy. Raman imaging and spectroscopy were employed to determine the chemical composition of the interface with complementary data from X-ray photoelectron spectroscopy and X-ray diffraction. Using the methodologies, VT optimization was done for a tire compound formulation, and this was verified by the generally accepted pull-out force method. We believe that the methodologies outlined in this paper can trigger further research for a better understanding of the adhesion interface in radial tires.

Brass

10.1021/acsanm.0c01298

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Citations (10)

Nanoscience in India: a perspective

Nanoscience (2012)

Anirban Som Ammu Anna Mathew P. Lourdu Xavier T. Pradeep

India has emerged as a leading player in the field of nanoscience and nanotechnology over the last decade. The Indian nano-endeavor got its initial push through the Nano Science and Nano Technology (NS&NT) initiative (now the Nano Mission) of the Department of Science and Technology (DST), Government of India in 2002 and has accelerated very fast since then. This article is intended to sketch a brief picture of the recent nanoscience and technology activities in India with special emphasis on synthesis of nanomaterials and emergence of new properties in them. Application of nanomateials into the very basic needs of India like water purification and energy creation along with the recent developments at the bio-nano interface will be discussed. State of nanoscience education at educational institutions in India and nanoscience based industrial initiatives will be touched upon.

10.1039/9781849734844-00244

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Unusual reactivity of MoS₂nanosheets

Nanoscale (2016)

Biswajit Mondal Anirban Som Indranath Chakraborty Ananya Baksi Depanjan Sarkar

The reactivity of the 2D nanosheets of MoS2 with silver ions in solution, leading to their spontaneous morphological and chemical transformations, is reported. This unique reactivity of the nanoscale form of MoS2 was in stark contrast to its bulk counterpart. While the gradual morphological transformation involving several steps has been captured with an electron microscope, precise chemical identification of the species involved was achieved by electron spectroscopy and mass spectrometry. The energetics of the system investigated supports the observed chemical transformation. The reaction with mercury and gold ions shows similar and dissimilar reaction products, respectively and points to the stability of the metal-sulphur bond in determining the chemical compositions of the final products.

Reactivity

Chemical transformation

Chemical Stability

10.1039/c6nr00878j

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Citations (9)

Selection of alloys for hardfacing screws of extruders

Chemical and Petroleum Engineering (1987)

Anirban Som P. V. Gladkii E. F. Perepletchikov A. N. Gladchenko

Hardfacing

10.1007/bf01149385

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Plasma transferred arc surfacing of composite alloys with separate feed of tungsten carbides and matrix alloy

The Paton Welding Journal (2020)

Anirban Som B.A. Halahuz

Substantiation of extension of safe operating life of the vessels of WWER-1000 reactors in service requires taking into account the residual stresses, arising during fabrication as a result of heating at welding or surfacing heating and their redistribution after heat treatment.Automatic submerged-arc surfacing with strip electrodes was used for the cylindrical part of the vessels, and manual coated electrode arc surfacing was applied for the nozzle zone surface (internal surface of nozzles Dn850 and their fillets), as well as other difficult-of-access places of the vessel.The process and parameters of the mode of anticorrosion arc surfacing can markedly influence the microstructural phase composition of the HAZ of base material, 15Kh2NMFA vessel steel, as well as residual stress distribution.Mathematical modeling was used for prediction of microstructural phase transformations in the HAZ, at deposition of the protective anticorrosion layer, based on experimental welding thermokinetic diagram of austenite decomposition of 15Kh2NMFA steel, and distribution of residual stresses in WWER-1000 reactor vessel was derived, allowing for microstructural transformations at different technological modes of arc surfacing.Comparison of the results on residual stress distribution after deposition and heat treatment at different technological modes showed the presence of the zone of compressive stresses, which arise in the HAZ of 15Kh2NMFA steel, as a result of martensite-bainite transformation.24 Ref., 6 Tables, 15 Figures.

Tungsten Carbide

Plasma arc welding

Matrix (chemical analysis)

10.37434/tpwj2020.12.05

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Citations (5)

Interfacial Growth of Large Area Single‐Crystalline Silver Sheets Through Ambient Microdroplets

Small (2024)

Depanjan Sarkar Anirban Som Keerthana Unni Sujan Manna Thalappil Pradeep

Abstract The creation of micrometer‐sized sheets of silver at the air–water interface by direct deposition of electrospray‐generated silver ions (Ag + ) on an aqueous dispersion of reduced graphene oxide (RGO), in ambient conditions, is reported. In the process of electrospray deposition (ESD), an electrohydrodynamic flow is created in the aqueous dispersion, and the graphene sheets assemble, forming a thin film at the air–water interface. The deposited Ag + coalesce to make single‐crystalline Ag sheets on top of this assembled graphene layer. Fast neutralization of Ag + forming atomic Ag, combined with their enhanced mobility on graphene surfaces, presumably facilitates the growth of larger Ag clusters. Moreover, restrictions imposed by the interface drive the crystal growth in 2D. By controlling the precursor salt concentration, RGO concentration, deposition time, and ion current, the dimensionality of the Ag sheets can be tuned. These Ag sheets are effective substrates for surface‐enhanced Raman spectroscopy (SERS), as demonstrated by the successful detection of methylene blue at nanomolar concentrations.

10.1002/smll.202400159

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Internalization of a Preformed Atomically Precise Silver Cluster in Proteins by Multistep Events and Emergence of Luminescent Counterparts Retaining Bioactivity

The Journal of Physical Chemistry C (2019)

Debasmita Ghosh Mohammad Bodiuzzaman Anirban Som Sebastian Raja Ananya Baksi

A new synthetic protocol is introduced which preserves the secondary structure of protecting proteins encapsulating a luminescent atomically-precise silver cluster. This was achieved by using a preformed triphenylphosphine (TPP)-protected silver cluster as the precursor forming bovine serum albumin (BSA)- and human serum albumin (HSA)-protected Ag18 clusters. This is the first example of the formation of luminescent protein-protected clusters in a neutral medium, without using any reducing agent, which results in minimal alteration of the protein structure during cluster growth. The cluster formed showed exceptional stability, unlike other silver clusters of this class. The formation of these red luminescent clusters was visualized by UV–vis and photoluminescence spectroscopy. The identification of Ag18 core was made through matrix-assisted laser desorption ionization mass spectrometry (MALDI MS), and a plausible mechanism of the formation was identified by monitoring the systematic growth of the cluster core by time-dependent MALDI MS experiments and electrospray ionization mass spectrometry (ESI MS) of the reaction mixture. The cluster was successfully employed as a luminescent probe for cancer cell imaging. Retention of protein conformation in the clusters was confirmed through circular dichroism (CD) spectroscopy, and the same was reflected in the retention of 89% of the esterase activity of BSA in the Ag18@BSA clusters synthesized by this method, compared to only 28.7% for AgQC@BSA clusters synthesized using previous protocols, conducted in basic medium.

Bovine serum albumin

10.1021/acs.jpcc.9b07765

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Citations (16)

Nanocluster reaction-driven in-situ transformation of colloidal nanoparticles to mesostructures

Nanoscale (2024)

Paulami Bose Pillalamarri Srikrishnarka Matias Paatelainen Nonappa Nonappa Amoghavarsha Ramachandra Kini

Atomically precise noble metal nanoclusters (NCs) are molecular materials known for their precise composition, electronic structure, and unique optical properties, exhibiting molecular reactivity. Herein, we demonstrated a simple one-pot method...

Nanoclusters

Reactivity

Noble metal

10.1039/d4nr02820a

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