Study of the nucleation and growth of antibiotic labeled Au NPs and blue luminescent Au8 quantum clusters for Hg2+ ion sensing, cellular imaging and antibacterial applications

Nanoscale ◽  
2015 ◽  
Vol 7 (47) ◽  
pp. 19985-20002 ◽  
Author(s):  
Puneet Khandelwal ◽  
Dheeraj K. Singh ◽  
Subha Sadhu ◽  
Pankaj Poddar
Keyword(s):  
Antibacterial Activity ◽  
Nucleation And Growth ◽  
Cellular Imaging ◽  
Mercury Ion ◽  
Mechanistic Study ◽  
Au Nps ◽  
Ion Sensing ◽  
Quantum Clusters

We report a mechanistic study for AuNPs and Au8QCs synthesis by cefradine (an antibiotic) molecule, and their application in mercury ion sensing, imaging and antibacterial activity.

The solid state dehydration of d lithium potassium tartrate monohydrate is complete in two rate processes I. The deceleratory diffusion-controlled first reaction

1994 ◽  
Vol 347 (1682) ◽  
pp. 139-156 ◽  
Keyword(s):  
Activation Energy ◽  
Vacancy Concentration ◽  
Nucleation And Growth ◽  
Crystalline Hydrate ◽  
Rate Equations ◽  
Mechanistic Study ◽  
Crystal Thickness ◽  
Potassium Tartrate ◽  
Diffusion Controlled ◽  
Rate Processes

A kinetic and mechanistic study of the dehydration of d lithium potassium tartrate monohydrate has been undertaken. Water evolution is completed through two separate rate processes. The first reaction is the deceleratory, diffusion-controlled release of water from the superficial zones of the reactant crystals. The yield of this process corresponds to the dehydration of a superficial layer of crystal, thickness 10 µm. About 4% of the constituent water was evolved from the single crystals studied, rising to 50% from crushed powder reactants. The second reaction, reported in Part II, is a nucleation and growth process yielding the crystalline anhydrous salt. Gravimetric measurements for the first reaction identified three distinct dehydration processes. The first step was the rapid release of loosely bonded superficial water. The subsequent two deceleratory stages are characterized as diffusive loss of H 2 O molecules from a crystal zone that is at first ordered but later becomes disordered as the water-site vacancy concentration increases. Rate measurements based on water evolution measured the activation energy of this third step as 153 + 4 kJ mol -1 . Irreproducibility of rate data is ascribed to variations in numbers and distributions of imperfections between individual crystals. The extent and rate of the first reaction increased when initiated in small pressures of water vapour. Electron microscope observations identified a structural discontinuity ca. 1 µm below reacted crystal faces, evidence of superficial retexturing of the reactant. Rates of powder dehydrations were more reproducible than those of crystals but the kinetic behaviour was similar. The same rate equations were obeyed and the activation energy was unaltered. Water loss during the first reaction of this crystalline hydrate gives a comprehensive layer of extensively dehydrated material across all surfaces. Subsequently, in or under this water depleted layer, salt is recrystallized and dehydration continues as a nucleation and growth reaction (part II, following paper).

Mechanistic Study of Sn Electrodeposition on TiO2 Nanotube Layers: Thermodynamics, Kinetics, Nucleation, and Growth Modes

2009 ◽  
Vol 113 (48) ◽  
pp. 20568-20575 ◽  
Author(s):  
Ilie Hanzu ◽  
Thierry Djenizian ◽  
Gregorio F. Ortiz ◽  
Philippe Knauth
Keyword(s):  
Nucleation And Growth ◽  
Tio2 Nanotube ◽  
Mechanistic Study ◽  
Growth Modes

The solid state dehydration of d lithium potassium tartrate monohydrate is complete in two rate processes II. The nucleation and growth second reaction and dehydration mechanism

1994 ◽  
Vol 347 (1682) ◽  
pp. 157-184 ◽  
Keyword(s):  
Water Loss ◽  
Vacancy Concentration ◽  
Preceding Paper ◽  
Nucleation And Growth ◽  
Mechanistic Study ◽  
Water Losses ◽  
Water Release ◽  
Kinetic Measurements ◽  
Potassium Tartrate ◽  
Rate Processes

A kinetic and mechanistic study has been undertaken of the nucleation and growth reaction that is the second of the two consecutive rate processes that occur during the dehydration of d lithium potassium tartrate monohydrate. Electron microscopic examinations of the cleaved surfaces of partly reacted crystals show the development of three-dimensional nuclei that are composed of small crystals of the anhydrous product and above 450 K there is evidence of intranuclear melting. Consistent with this model, the second reaction obeys the Avrami-Erofe’ev equation {[ — ln (1 — α)] 1/2 = kt }. Overall rates of the dehydrations of single crystals and of crushed powder samples were closely similar. The activation energy for dehydration was 150-160 kJ mol -1 for both first (reported in part I, preceding paper) and second reactions and for both single crystal and crushed powder reactants. The addition of product crystallites to the reactant reduced sharply, or eliminated, the induction period to the nucleation and growth process. From consideration of the kinetic characteristics, together with the textural changes observed microscopically, we conclude that the following mechanism very satisfactorily accounts for our results. The first reaction proceeds to the dehydration of all crystal surfaces, representing water losses from a layer ca . 10 µm thickness. This deceleratory process occurs initially in a structure resembling that of the reactant but later the increasing water site vacancy concentration results in increasing reactant disorder and possibly includes fusion of the outer layer. When the first reaction water evolution has slowed, recrystallization to the structure of the anhydrous product occurs at a limited number of sites to generate germ nuclei that effectively act as seed crystals for nucleus growth. During the second reaction the reactant—product contact interface is identified as a zone of diffusive water loss, similar to that described for the first reaction. Here, however, the product crystallites promote reorganization of dehydrated material, thereby opening channels for water escape and continually exposing new hydrate surfaces at which dehydration continues. This product recrystallization enables advance of the nucleus interface to be maintained, so that rates of both first and second reactions are subject to control by diffusive loss of water from an active boundary of the reactant. Product reorganization removes the inhibiting character of accumulated product layer by introducing escape channels for water loss so that interface advance continues and, although spasmodic, this migrates forward at a constant average linear rate. The work is of interest because kinetic measurements have been obtained for both of the consecutive rate processes that contribute to the overall reaction. The controls of both are shown to be closely similar. The reaction model proposed here provides insight into the structure of the dehydration interface and the mechanism of water release.

A Mechanistic Study on the Nucleation and Growth of Au on Pd Seeds with a Cubic or Octahedral Shape

ChemCatChem ◽  
2012 ◽  
Vol 4 (10) ◽  
pp. 1668-1674 ◽  
Author(s):  
Guannan He ◽  
Jie Zeng ◽  
Mingshang Jin ◽  
Hui Zhang ◽  
Ning Lu ◽  
...  
Keyword(s):  
Nucleation And Growth ◽  
Mechanistic Study

Ultrasensitive electrochemical sensor for mercury ion detection based on molybdenum selenide and Au nanoparticles via thymine-Hg2+- thymine

2021 ◽  
Author(s):  
Ting Zhou ◽  
Meijuan Li ◽  
Na Li ◽  
Yulin Dong ◽  
Dan Liu ◽  
...  
Keyword(s):  
Electrochemical Sensor ◽  
Au Nanoparticles ◽  
Mercury Ion ◽  
Ion Detection ◽  
Au Nps ◽  
Molybdenum Selenide ◽  
Mercury Ion Detection

An ultrasensitive and specific-selection electrochemical sensor was constructed for Hg2+ detection based on Au nanoparticles and molybdenum selenide (Au NPs@MoSe2) as well as the thymine-Hg2+-thymine (T-Hg2+-T) coordination. Herein, Au NPs@MoSe2...

Schiff Based Silatranyl Compounds Exhibiting ‘Fe3+ and Mn2+ Fluorescence Dual Ion Sensing and Antibacterial Activity’

Silicon ◽  
2018 ◽  
Vol 10 (6) ◽  
pp. 2817-2827
Author(s):  
Gurjaspreet Singh ◽  
Jasbhinder Singh ◽  
Jandeep Singh ◽  
Akshpreet Singh ◽  
Kshitiz Gupta ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Ion Sensing
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