Investigating structural aspects to understand the putative/claimed non-toxicity of the Hg-based Ayurvedic drugRasasindurausing XAFS

2015 ◽  
Vol 22 (5) ◽  
pp. 1233-1241 ◽  
Author(s):  
Nitya Ramanan ◽  
Debdutta Lahiri ◽  
Parasmani Rajput ◽  
Ramesh Chandra Varma ◽  
A. Arun ◽  
...  
Keyword(s):  
Single Phase ◽  
Organic Molecules ◽  
Structural Parameters ◽  
Synthesis Method ◽  
Nanoparticle Synthesis ◽  
Covalent Bond ◽  
Chemical Form ◽  
Size Dispersion ◽  
Structural Aspects ◽  
Coordination Configuration

XANES- and EXAFS-based analysis of the Ayurvedic Hg-based nano-drugRasasindurahas been performed to seek evidence of its non-toxicity.Rasasindurais determined to be composed of single-phase α-HgS nanoparticles (size ∼24 nm), free of Hg0or organic molecules; its structure is determined to be robust (<3% defects). The non-existence of Hg0implies the absence of Hg-based toxicity and establishes that chemical form, rather than content of heavy metals, is the correct parameter for evaluating the toxicity in these drugs. The stable α-HgS form (strong Hg—S covalent bond and robust particle character) ensures the integrity of the drug during delivery and prevention of its reduction to Hg0within the human body. Further, these comparative studies establish that structural parameters (size dispersion, coordination configuration) are better controlled inRasasindura. This places the Ayurvedic synthesis method on par with contemporary techniques of nanoparticle synthesis.

scholarly journals Enhanced Extracellular Synthesis of Gold Nanoparticles by Soluble Extracts from Escherichia coli Transformed with Rhizobium tropici Phytochelatin Synthase Gene

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 472
Author(s):  
Qunying Yuan ◽  
Manjula Bomma ◽  
Zhigang Xiao
Keyword(s):  
Gold Nanoparticles ◽  
Gold Nanoparticle ◽  
Synthesis Method ◽  
Nanoparticle Synthesis ◽  
Morphological Properties ◽  
Phytochelatin Synthase ◽  
Rhizobium Tropici ◽  
Whole Cells ◽  
E Coli ◽  
Recombinant Cells

Phytochelatins, the enzymatic products of phytochelatin synthase, play a principal role in protecting the plants from heavy metal and metalloid toxicity due to their ability to scavenge metal ions. In the present study, we investigated the capacity of soluble intracellular extracts from E. coli cells expressing R. tropici phytochelatin synthase to synthesize gold nanoparticle. We discovered that the reaction mediated by soluble extracts from the recombinant E. coli cells had a higher yield of gold nanoparticles, compared to that from the control cells. The compositional and morphological properties of the gold nanoparticles synthesized by the intracellular extracts from recombinant cells and control cells were similar. In addition, this extracellular nanoparticle synthesis method produced purer gold nanoparticles, avoiding the isolation of nanoparticles from cellular debris when whole cells are used to synthesize nanoparticles. Our results suggested that phytochelatins can improve the efficiency of gold nanoparticle synthesis mediated by bacterial soluble intracellular extracts, and the potential of extracellular nanoparticle synthesis platform for the production of nanoparticles in large quantity and pure form is worth further investigation.

scholarly journals Competitive Binding Investigations and Quantitation in Surface-Enhanced Raman Spectra of Binary Dye Mixtures

2017 ◽  
Vol 72 (1) ◽  
pp. 60-68 ◽  
Author(s):  
Mircea A. Comanescu ◽  
Cyril Muehlethaler ◽  
John R. Lombardi ◽  
Marco Leona ◽  
Thomas A. Kubic
Keyword(s):  
Spectral Characteristics ◽  
Synthesis Method ◽  
Nanoparticle Synthesis ◽  
Peak Height ◽  
Calibration Models ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Standard Calibration ◽  
One Year ◽  
Selection Of

This research presents a study in surface-enhanced Raman quantitation of dyes present in mixtures of alizarin and purpurin using standard calibration curves and Langmuir isotherm calibration models. Investigations of the nature of competitive adsorption onto silver nanoparticles by centrifugation indicates that both dyes in the mixture interact with the nanoparticles simultaneously, but only the stronger adsorbing one is seen to dominate the spectral characteristics. Calibration can be carried out by careful selection of peaks characteristic to each dye in the mixture. Comparisons of peak height and peak area calibrations reveal that peak heights, when selected by the maximum value and accounting for peak shifts, prove the better model for quantitation. It is also shown that the microwave nanoparticle synthesis method produces stable nanoparticles with a shelf-life of at least one year that give very little variation within and between uses.

scholarly journals Chemical and Laser Ablation Synthesis of Monometallic and Bimetallic Ni-Based Nanoparticles

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1453
Author(s):  
Niusha Lasemi ◽  
Günther Rupprechter
Keyword(s):  
Laser Ablation ◽  
Liquid Phase ◽  
Surface Composition ◽  
Structural Parameters ◽  
Nanoparticle Synthesis ◽  
Femtosecond Laser Ablation ◽  
Laser Ablation In Liquid ◽  
Electron Microscopic ◽  
Wet Chemical Synthesis ◽  
Bimetallic Nanoparticle

The catalytic properties of nanoparticles depend on their size, shape and surface/defect structure, with the entire catalyst performance being governed by the corresponding distributions. Herein, we present two routes of mono- and bimetallic nanoparticle synthesis that enable control of the structural parameters, i.e., wet-chemical synthesis and laser ablation in liquid-phase. The latter is particularly suited to create defect-rich nanoparticles. Impregnation routes were applied to prepare Ni and NiCu nanoparticles, whereas nano- and femtosecond laser ablation in liquid-phase were employed to prepare Ni and NiAu nanoparticles. The effects of the Ni:Cu ratio in impregnation and of laser fluence and liquid-medium on laser ablation are discussed. The atomic structure and (surface) composition of the nanoparticles were characterized by electron microscopic (BF-TEM, DF-TEM, HRTEM) and spectroscopic/diffraction techniques (EDX, SAED, XPS, IR), complemented by theory (DFT). The chemically synthesized bimetallic NiCu nanoparticles initially had Cu-rich surfaces, which changed to Ni-rich upon reaction. For laser ablation, depending on conditions (fluence, type of liquid), highly defective, ordered, or core/shell-like nanoparticles were produced. The case studies highlight the specific benefits of each preparation method for catalyst synthesis and discuss the potential of nanoparticles produced by pulsed laser ablation for catalytic applications.

scholarly journals A unified picture of the covalent bond within quantum-accurate force fields: From organic molecules to metallic complexes’ reactivity

2019 ◽  
Vol 5 (5) ◽  
pp. eaaw2210 ◽  
Author(s):  
Alessandro Lunghi ◽  
Stefano Sanvito
Keyword(s):  
Organic Molecules ◽  
Energy Surface ◽  
Force Fields ◽  
Covalent Bond ◽  
Organometallic Compounds ◽  
Molecular Systems ◽  
Physical Chemical ◽  
Atomistic Models ◽  
General Potential ◽  
Unified Description

Computational studies of chemical processes taking place over extended size and time scales are inaccessible by electronic structure theories and can be tackled only by atomistic models such as force fields. These have evolved over the years to describe the most diverse systems. However, as we improve the performance of a force field for a particular physical/chemical situation, we are also moving away from a unified description. Here, we demonstrate that a unified picture of the covalent bond is achievable within the framework of machine learning–based force fields. Ridge regression, together with a representation of the atomic environment in terms of bispectrum components, can be used to map a general potential energy surface for molecular systems at chemical accuracy. This protocol sets the ground for the generation of an accurate and universal class of potentials for both organic and organometallic compounds with no specific assumptions on the chemistry involved.

Distortion isomers of PtM, Pt2M, PtM2 and PtMM′ (M = non-transition metals) derivatives-structural aspects

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Milan Melník ◽  
Peter Mikuš
Keyword(s):  
Transition Metals ◽  
Structural Parameters ◽  
Bond Angles ◽  
Bond Lengths ◽  
Metal Atoms ◽  
Independent Molecules ◽  
Structural Aspects

Abstract An analysis of the structural parameters of PtM, Pt2M, PtM2 and PtMM′ (M = non-transition metals) derivatives shows that each complex contains two crystallographically independent molecules within the same crystal. The respective molecules differ by the degrees of distortion and exemplify the distortion isomerism. These are discussed in terms of the coordination with the platinum and the M atoms and the correlations are drawn among the metal atoms, donor atoms, bond lengths and bond angles. A wide variety of non-transition metals (Sn, Ga, In, Tl, Zn, Cd, Hg, Sb) exist, among which the most prevalent is Sn.

scholarly journals Influence of the Processing Method on the Properties of Ti-23 at.% Mo Alloy

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 931 ◽  
Author(s):  
Patrycja Sochacka ◽  
Andrzej Miklaszewski ◽  
Kamil Kowalski ◽  
Mieczyslaw Jurczyk
Keyword(s):  
Corrosion Resistance ◽  
Young’S Modulus ◽  
Hot Pressing ◽  
Single Phase ◽  
Young's Modulus ◽  
Synthesis Method ◽  
Indentation Modulus ◽  
Powder Preparation ◽  
Mechanically Alloyed ◽  
Β Phase

In this paper, binary β type Ti-23 at.% Mo alloys were obtained by arc melting as well as by mechanical alloying and powder metallurgical process with cold powder compaction and sintering or, interchangeably, hot pressing. The influence of the synthesis method on the microstructure and properties of bulk alloys were studied. The produced materials were characterized by an X-ray diffraction technique, scanning electron microscopy and chemical composition determination. Young’s modulus was evaluated with nanoindentation testing method based on the Oliver and Pharr approach. The mechanically alloyed Ti-23 at.% Mo powders, after inductively hot-pressed at 800 °C for 5 min, allowed the formation of single Ti(β) phase alloy. In this case, Young’s modulus and Vickers hardness were 127 GPa and 454 HV0.3, respectively. Among the examined materials, the porous (55%) single-phase scaffold showed the lowest indentation modulus (69.5 GPa). Analytical approach performed in this work focuses also on the surface properties. The estimation includes the corrosion resistance analyzed in the potentiodynamic test, and also some wettability properties as a contact angle, and surface free energy values measured in glycerol and diiodomethane testing fluids. Additionally, surface modification of processed material by micro-arc oxidation and electrophoretic deposition on the chosen samples was investigated. Proposed procedures led to the formation of apatite and fluorapatite layers, which influence both the corrosion resistance and surface wetting properties in comparison to unmodified samples. The realized research shows that a single-phase ultrafine-grained Ti-23 at.% Mo alloy for medical implant applications can be synthesized at a temperature lower than the transition point by the application of hot pressing of mechanically alloyed powders. The material processing, that includes starting powder preparation, bulk alloy transformation, and additional surface treatment functionalization, affect final properties by the obtained phase composition and internal structure.

scholarly journals An in situ SAXS investigation of the formation of silver nanoparticles and bimetallic silver–gold nanoparticles in controlled wet-chemical reduction synthesis

2020 ◽  
Vol 2 (1) ◽  
pp. 225-238 ◽  
Author(s):  
Paulo R. A. F. Garcia ◽  
Oleg Prymak ◽  
Viktoria Grasmik ◽  
Kevin Pappert ◽  
Wagner Wlysses ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Online Monitoring ◽  
Chemical Reduction ◽  
Structural Parameters ◽  
Nanoparticle Synthesis ◽  
Small Particles ◽  
Metallic Nanoparticle ◽  
Wet Chemical

In situ investigation of metallic nanoparticle synthesis with an online monitoring of the system by SAXS. Determination of structural parameters and growth processes. Ag-NP synthesis presented a bimodal system with the presence of small particles (∼3 nm).

scholarly journals Green solvent for green materials: a supercritical hydrothermal method and shape-controlled synthesis of Cr-doped CeO 2 nanoparticles

2015 ◽  
Vol 373 (2057) ◽  
pp. 20150012 ◽  
Author(s):  
Yuanzheng Zhu ◽  
Seiichi Takami ◽  
Gimyeong Seong ◽  
Mehdi Dejhosseini ◽  
Muhammad Zamir Hossain ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Synthesis Method ◽  
Nanoparticle Synthesis ◽  
Oxygen Storage Capacity ◽  
Oxygen Storage ◽  
Green Solvent ◽  
Green Materials ◽  
Transmission Electron ◽  
Supercritical Hydrothermal Synthesis

This paper describes a supercritical hydrothermal synthesis method as a green solvent process, along with products based on this method that can be used as green materials that contribute to solving environmental problems. The first part of this paper summarizes the basics of this method, including the mechanism of the reactions, specific features of the supercritical state for nanoparticle synthesis, the continuous flow-type reactor and applications; this provides a better understanding of the suitability of this method to synthesize green materials. The second part of the paper describes the method used to synthesize Cr-doped CeO 2 nanoparticles, which show an extremely high oxygen storage capacity, suggesting their high potential as an environmental catalyst. Transmission electron microscopy and scanning electron microscope images showed octahedral Cr-doped CeO 2 nanoparticles with sizes of 15–30 nm and cubic Cr-doped CeO 2 nanoparticles with sizes of 5–8 nm. Octahedral Cr-doped CeO 2 nanoparticles exposing (111) facets and cubic Cr-doped CeO 2 nanoparticles exposing (100) facets were determined by high-resolution transmission electron microscopy and selected area electron diffraction. The X-ray diffraction peaks shifted to a high angle because the radius of the Cr ion is smaller than that of the Ce ion.

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