scholarly journals Multi-Scale Modelling of Aggregation of TiO2 Nanoparticle Suspensions in Water

Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 217
Author(s):  
Giulia Mancardi ◽  
Matteo Alberghini ◽  
Neus Aguilera-Porta ◽  
Monica Calatayud ◽  
Pietro Asinari ◽  
...  

Titanium dioxide nanoparticles have risen concerns about their possible toxicity and the European Food Safety Authority recently banned the use of TiO2 nano-additive in food products. Following the intent of relating nanomaterials atomic structure with their toxicity without having to conduct large-scale experiments on living organisms, we investigate the aggregation of titanium dioxide nanoparticles using a multi-scale technique: starting from ab initio Density Functional Theory to get an accurate determination of the energetics and electronic structure, we switch to classical Molecular Dynamics simulations to calculate the Potential of Mean Force for the connection of two identical nanoparticles in water; the fitting of the latter by a set of mathematical equations is the key for the upscale. Lastly, we perform Brownian Dynamics simulations where each nanoparticle is a spherical bead. This coarsening strategy allows studying the aggregation of a few thousand nanoparticles. Applying this novel procedure, we find three new molecular descriptors, namely, the aggregation free energy and two numerical parameters used to correct the observed deviation from the aggregation kinetics described by the Smoluchowski theory. Ultimately, molecular descriptors can be fed into QSAR models to predict the toxicity of a material knowing its physicochemical properties, enabling safe design strategies.

Author(s):  
Giulia Mancardi ◽  
Matteo Alberghini ◽  
Neus Aguilera-Porta ◽  
Monica Calatayud ◽  
Pietro Asinari ◽  
...  

Titanium dioxide nanoparticles have risen concerns about their possible toxicity and the European Food Safety Authority recently banned the use of TiO2 nano-additive in food products. Following the intent of relating nanomaterials atomic structure with their toxicity without having to conduct large scale experiments on living organisms, we investigate the aggregation of titanium dioxide nanoparticles using a multi-scale technique: starting from ab initio Density Functional Theory to get an accurate determination of the energetics and electronic structure, we switch to classical Molecular Dynamics simulations to calculate the Potential of Mean Force for the connection of two identical nanoparticles in water; the fitting of the latter by a set of mathematical equations is the key for the upscale. Lastly, we perform Brownian Dynamics simulations where each nanoparticle is a spherical bead. This coarsening strategy allows studying the aggregation of a few thousand nanoparticles. Applying this novel procedure, we find three new molecular descriptors, namely, the aggregation free energy and two numerical parameters used to correct the observed deviation from the aggregation kinetic described by the Smoluchowski theory. Molecular descriptors can be fed into QSAR models to predict the toxicity of a material knowing its physicochemical properties, without having to conduct large scale experiments on living organisms.


2006 ◽  
Vol 6 (1) ◽  
pp. 87-90 ◽  
Author(s):  
Giannis Mpourmpakis ◽  
Emmanuel Tylianakis ◽  
George Froudakis

A Combination of quantum and classical calculations has been performed to investigate the hydrogen storage in single-walled carbon nanotubes (SWNTs). The ab-initio calculations at the Density Functional level of Theory (DFT) show the nature of hydrogen interaction in selected sites of a (5,5) tube walls. On top of this, Molecular Dynamics simulations model large scale nanotube systems and reproduce the storage capacity under variant temperature conditions. Our results indicate that the interaction of hydrogen with SWNTs is very weak and slightly increase of temperature, causes hydrogen diffusion from the tube walls.


2005 ◽  
Vol 109 (32) ◽  
pp. 15243-15249 ◽  
Author(s):  
Pavan K. Naicker ◽  
Peter T. Cummings ◽  
Hengzhong Zhang ◽  
Jillian F. Banfield

2018 ◽  
Author(s):  
sigbjoern Loeland Bore ◽  
Hima Bindu Kolli ◽  
Toshihiro Kawakatsu ◽  
Giuseppe Milano ◽  
Michele Cascella

<div>We introduce a density functional-based formalism to compute the electrostatic energy and forces for a mesoscopic system in the condensed phase, described with molecular resolution. The dielectric permittivity is variable in space, and it is dependent on the density fields of the individual particles present in the system. The electrostatic potential is obtained from standard numerical solutions of the generalized Poisson equation. The presence of a particle-dependent varying dielectrics produces the appearance of mesoscopic polarization forces, which are dependent on the local fluctuations of the permittivity, as well as of the electrostatic field. The proposed implementation is numerically robust, with an error on the Coulomb forces that can be systematically controlled by the mesh of spatial grid used for solving the generalized Poisson equation. We show that the method presented here is able to reproduce the concentration-dependent partitioning of an ideal salt in water/oil mixtures, in particular, reproducing the ∝ 1/epsilon dependency of the partition coefficient for the free ions predicted by Born theory. Moreover, this approach reproduces the correct electrostatic features of both dipolar and charged lipid bilayers, with positive membrane and dipole potentials. The sum of both Coulomb and polarization interactions inside the membrane yields a globally repulsive potential of mean force for the ions, independently on their charge. The computational efficiency of the method makes it particularly suitable for the description of large scale polyelectrolyte soft-matter systems.</div>


RSC Advances ◽  
2015 ◽  
Vol 5 (129) ◽  
pp. 106877-106885 ◽  
Author(s):  
Tianshi Zhang ◽  
Patrick Wojtal ◽  
Oleg Rubel ◽  
Igor Zhitomirsky

The outstanding adsorption properties of proteins, containing catecholic amino acid, 1,3,4-dihydroxyphenylalanine, and recent advances in nanoparticle functionalization using catecholates have generated interest in catecholate adsorption.


2013 ◽  
Vol 4 ◽  
pp. 567-587 ◽  
Author(s):  
Pavel V Komarov ◽  
Pavel G Khalatur ◽  
Alexei R Khokhlov

Atomistic and first-principles molecular dynamics simulations are employed to investigate the structure formation in a hydrated Nafion membrane and the solvation and transport of protons in the water channel of the membrane. For the water/Nafion systems containing more than 4 million atoms, it is found that the observed microphase-segregated morphology can be classified as bicontinuous: both majority (hydrophobic) and minority (hydrophilic) subphases are 3D continuous and organized in an irregular ordered pattern, which is largely similar to that known for a bicontinuous double-diamond structure. The characteristic size of the connected hydrophilic channels is about 25–50 Å, depending on the water content. A thermodynamic decomposition of the potential of mean force and the calculated spectral densities of the hindered translational motions of cations reveal that ion association observed with decreasing temperature is largely an entropic effect related to the loss of low-frequency modes. Based on the results from the atomistic simulation of the morphology of Nafion, we developed a realistic model of ion-conducting hydrophilic channel within the Nafion membrane and studied it with quantum molecular dynamics. The extensive 120 ps-long density functional theory (DFT)-based simulations of charge migration in the 1200-atom model of the nanochannel consisting of Nafion chains and water molecules allowed us to observe the bimodality of the van Hove autocorrelation function, which provides the direct evidence of the Grotthuss bond-exchange (hopping) mechanism as a significant contributor to the proton conductivity.


2006 ◽  
Vol 21 (3) ◽  
pp. 563-573 ◽  
Author(s):  
John A. Moriarty ◽  
Lorin X. Benedict ◽  
James N. Glosli ◽  
Randolph Q. Hood ◽  
Daniel A. Orlikowski ◽  
...  

First-principles generalized pseudopotential theory (GPT) provides a fundamental basis for transferable multi-ion interatomic potentials in transition metals and alloys within density-functional quantum mechanics. In the central body-centered cubic (bcc) metals, where multi-ion angular forces are important to materials properties, simplified model GPT (MGPT) potentials have been developed based on canonical d bands to allow analytic forms and large-scale atomistic simulations. Robust, advanced-generation MGPT potentials have now been obtained for Ta and Mo and successfully applied to a wide range of structural, thermodynamic, defect, and mechanical properties at both ambient and extreme conditions. Selected applications to multiscale modeling discussed here include dislocation core structure and mobility, atomistically informed dislocation dynamics simulations of plasticity, and thermoelasticity and high-pressure strength modeling. Recent algorithm improvements have provided a more general matrix representation of MGPT beyond canonical bands, allowing improved accuracy and extension to f-electron actinide metals, an order of magnitude increase in computational speed for dynamic simulations, and the development of temperature-dependent potentials.


2003 ◽  
Vol 68 (12) ◽  
pp. 2231-2282 ◽  
Author(s):  
Jiří Šponer ◽  
Pavel Hobza

Ab initio quantum-chemical calculations with inclusion of electron correlation significantly contributed to our understanding of molecular interactions of DNA and RNA bases. Some of the most important findings are introduced in the present overview: structures and energies of hydrogen bonded base pairs, nature of base stacking, interactions between metal cations and nucleobases, nonplanarity of isolated nucleobases and other monomer properties, tautomeric equilibria of nucleobases, out-of-plane hydrogen bonds and amino acceptor interactions. The role of selected molecular interactions in nucleic acids is discussed and representative examples where these interactions occur are given. Also, accuracy of density functional theory, semiempirical methods, distributed multipole analysis and empirical potentials is commented on. Special attention is given to our very recent reference calculations on base stacking and H-bonding. Finally, we briefly comment on the relationship between advanced ab initio quantum-chemical methods and large-scale explicit solvent molecular dynamics simulations of nucleic acids.


2018 ◽  
Author(s):  
sigbjoern Loeland Bore ◽  
Hima Bindu Kolli ◽  
Toshihiro Kawakatsu ◽  
Giuseppe Milano ◽  
Michele Cascella

<div>We introduce a density functional-based formalism to compute the electrostatic energy and forces for a mesoscopic system in the condensed phase, described with molecular resolution. The dielectric permittivity is variable in space, and it is dependent on the density fields of the individual particles present in the system. The electrostatic potential is obtained from standard numerical solutions of the generalized Poisson equation. The presence of a particle-dependent varying dielectrics produces the appearance of mesoscopic polarization forces, which are dependent on the local fluctuations of the permittivity, as well as of the electrostatic field. The proposed implementation is numerically robust, with an error on the Coulomb forces that can be systematically controlled by the mesh of spatial grid used for solving the generalized Poisson equation. We show that the method presented here is able to reproduce the concentration-dependent partitioning of an ideal salt in water/oil mixtures, in particular, reproducing the ∝ 1/epsilon dependency of the partition coefficient for the free ions predicted by Born theory. Moreover, this approach reproduces the correct electrostatic features of both dipolar and charged lipid bilayers, with positive membrane and dipole potentials. The sum of both Coulomb and polarization interactions inside the membrane yields a globally repulsive potential of mean force for the ions, independently on their charge. The computational efficiency of the method makes it particularly suitable for the description of large scale polyelectrolyte soft-matter systems.</div>


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