14 research outputs found
Degradation versus self-assembly of block copolymer micelles
The stability of micelles self-assembled from block copolymers can be altered
by the degradation of the blocks. Slow degradation shifts the equilibrium size
distribution of block copolymer micelles and change their properties.
Quasi-equilibrium scaling theory shows that the degradation of hydrophobic
blocks in the core of micelles destabilize the micelles reducing their size,
while the degradation of hydrophilic blocks forming coronas of micelles favors
larger micelles and may, at certain conditions, induce the formation of
micelles from individual chains.Comment: Published in Langmuir http://pubs.acs.org/doi/pdf/10.1021/la204625
Surface patterning of carbon nanotubes can enhance their penetration through a phospholipid bilayer
Nanotube patterning may occur naturally upon the spontaneous self-assembly of
biomolecules onto the surface of single-walled carbon nanotubes (SWNTs). It
results in periodically alternating bands of surface properties, ranging from
relatively hydrophilic to hydrophobic, along the axis of the nanotube. Single
Chain Mean Field (SCMF) theory has been used to estimate the free energy of
systems in which a surface patterned nanotube penetrates a phospholipid
bilayer. In contrast to un-patterned nanotubes with uniform surface properties,
certain patterned nanotubes have been identified that display a relatively low
and approximately constant system free energy (10 kT) as the nanotube traverses
through the bilayer. These observations support the hypothesis that the
spontaneous self-assembly of bio-molecules on the surface of SWNTs may
facilitate nanotube transduction through cell membranes.Comment: Published in ACS Nano http://pubs.acs.org/doi/abs/10.1021/nn102763
A Machine Learning-Based Study of Li<sup>+</sup> and Na<sup>+</sup> Metal Complexation with Phosphoryl-Containing Ligands for the Selective Extraction of Li<sup>+</sup> from Brine
The growth of technologies concerned with the high demand in lithium (Li) sources dictates the need for technological solutions garnering Li supplies to preserve the sustainability of the processes. The aim of this study was to use a machine learning-based search for phosphoryl-containing podandic ligands, potentially selective for lithium extraction from brine. Based on the experimental data available on the stability constant values of phosphoryl-containing organic ligands with Li+ and Na+ cations at 4:1 THF:CHCl3, candidate di-podandic ligands were proposed, for which the stability constant values (logK) with Li+ and Na+ as well as the corresponding selectivity values were evaluated using machine learning methods (ML). The modelling showed a reasonable predictive performance with the following statistical parameters: the determination coefficient R2= 0.75, 0.87 and 0.83 and root-mean-square error RMSE = 0.485, 0.449 and 0.32 were obtained for the prediction of the stability constant values with Li+ and Na+ cations and Li+/Na+ selectivity values, respectively. This ML-based analysis was complemented by the preliminary estimation of the host–guest complementarity of metal–ligand 1:1 complexes using the HostDesigner software
A New Extraction System Based on Isopropyl Salicylate and Trioctylphosphine Oxide for Separating Alkali Metals
It was established that isopropyl salicylate can be used similarly to 1,3-diketones as a key component for a new efficient extraction system for selective separation of alkali metal cations. According to DFT modeling of complexes of isopropyl salicylate and 1,3-diketone with alkali metal cations (Li+, Na+, K+), six-membered metallacycles are formed whose stability decreases along the series Li > Na > K, which results in the observed enhanced affinity to lithium. The extraction ability of isopropyl salicylate is manifested in the presence of trioctylphosphine oxide (TOPO). The newly obtained complexes of isopropyl salicylate with alkali metal cations as well as their extracts in a mixture with TOPO are characterized by means of FT-IR, Raman, and NMR spectroscopy. The probable structure of the extracted lithium complex is presumed and the role of TOPO in the extraction process is investigated in detail. Extraction experiments showed extremely high separation coefficients for Li/Na and Li/K pairs in the extraction from a model multi-component solution
Recovery of Uranium, Thorium, and Other Rare Metals from Eudialyte Concentrate by a Binary Extractant Based on 1,5-bis[2-(hydroxyethoxyphosphoryl)-4-ethylphenoxy]-3-oxapentane and Methyl Trioctylammonium Nitrate
Eudialyte-group minerals are of scientific interest as important concentrators of rare elements (mainly Zr and REE) in agpaitic alkaline rocks and a potential source of REE, Zr, Hf, Nb, and Ta for industrial use. Extraction of uranium(VI), thorium(IV), zirconium(IV), hafnium(IV), titanium(IV), and scandium(III) by a binary extractant based on 1,5-bis[2-(hydroxyethoxyphosphoryl)-4-ethylphenoxy]-3-oxapentane and methyl trioctylammonium nitrate from eudialyte breakdown solutions is studied. Extraction isotherms were obtained and exhaustive extraction was investigated. It is shown that uranium, thorium, hafnium, zirconium, scandium, and titanium are almost completely recovered in two-stage extraction by a mixture of 1,5-bis[2-(hydroxyethoxyphosphoryl)-4-ethylphenoxy]-3-oxapentane and methyltrioctylammonium nitrate in 1,2-dichloroethane. Quantitative characteristics were compared for uranium(VI), thorium(IV), zirconium(IV), hafnium(IV), titanium(IV), and scandium(III). It was shown that the extraction efficiency of the metals by the binary extractant based on 1,5-bis[2-(hydroxyethoxyphosphoryl)-4-ethylphenoxy]-3-oxapentane and methyltrioctylammonium nitrate in 1,2-dichloroethane is much higher in comparison with the commercially available tributyl phosphate
Recovery of Uranium, Thorium, and Other Rare Metals from Eudialyte Concentrate by a Binary Extractant Based on 1,5-bis[2-(hydroxyethoxyphosphoryl)-4-ethylphenoxy]-3-oxapentane and Methyl Trioctylammonium Nitrate
Eudialyte-group minerals are of scientific interest as important concentrators of rare elements (mainly Zr and REE) in agpaitic alkaline rocks and a potential source of REE, Zr, Hf, Nb, and Ta for industrial use. Extraction of uranium(VI), thorium(IV), zirconium(IV), hafnium(IV), titanium(IV), and scandium(III) by a binary extractant based on 1,5-bis[2-(hydroxyethoxyphosphoryl)-4-ethylphenoxy]-3-oxapentane and methyl trioctylammonium nitrate from eudialyte breakdown solutions is studied. Extraction isotherms were obtained and exhaustive extraction was investigated. It is shown that uranium, thorium, hafnium, zirconium, scandium, and titanium are almost completely recovered in two-stage extraction by a mixture of 1,5-bis[2-(hydroxyethoxyphosphoryl)-4-ethylphenoxy]-3-oxapentane and methyltrioctylammonium nitrate in 1,2-dichloroethane. Quantitative characteristics were compared for uranium(VI), thorium(IV), zirconium(IV), hafnium(IV), titanium(IV), and scandium(III). It was shown that the extraction efficiency of the metals by the binary extractant based on 1,5-bis[2-(hydroxyethoxyphosphoryl)-4-ethylphenoxy]-3-oxapentane and methyltrioctylammonium nitrate in 1,2-dichloroethane is much higher in comparison with the commercially available tributyl phosphate
Nanotopography as a trigger for the microscale, autogenous and passive lysis of erythrocytes
Microscale devices are increasingly being developed for diagnostic analysis although conventional lysis as an initial step presents limitations due to its scale or complexity. Here, we detail the physical response of erythrocytes to the surface nanoarchitecture of black Si (bSi) and foreshadow their potential in microanalysis. The physical interaction brought about by the spatial convergence of the two topologies: (a) the nanopillar array present on the bSi and (b) the erythrocyte cytoskeleton present on the red blood cells (RBCs), provides spontaneous stress-induced cell deformation, rupture and passive lysis within an elapsed time of ∼3 min from immobilisation to rupture and without external chemical or mechanical intervention. The mechano-responsive bSi surface provides highly active yet autogenous RBC lysis and a prospect as a front-end platform technology in evolving micro-fluidic platforms for cellular analyses
Subtle Variations in Surface Properties of Black Silicon Surfaces Influence the Degree of Bactericidal Efficiency
Abstract One of the major challenges faced by the biomedical industry is the development of robust synthetic surfaces that can resist bacterial colonization. Much inspiration has been drawn recently from naturally occurring mechano-bactericidal surfaces such as the wings of cicada (Psaltoda claripennis) and dragonfly (Diplacodes bipunctata) species in fabricating their synthetic analogs. However, the bactericidal activity of nanostructured surfaces is observed in a particular range of parameters reflecting the geometry of nanostructures and surface wettability. Here, several of the nanometer-scale characteristics of black silicon (bSi) surfaces including the density and height of the nanopillars that have the potential to influence the bactericidal efficiency of these nanostructured surfaces have been investigated. The results provide important evidence that minor variations in the nanoarchitecture of substrata can substantially alter their performance as bactericidal surfaces
Bactericidal activity of black silicon
Black silicon is a synthetic nanomaterial that contains high aspect ratio nanoprotrusions on its surface, produced through a simple reactive-ion etching technique for use in photovoltaic applications. Surfaces with high aspect-ratio nanofeatures are also common in the natural world, for example, the wings of the dragonfly Diplacodes bipunctata. Here we show that the nanoprotrusions on the surfaces of both black silicon and D. bipunctata wings form hierarchical structures through the formation of clusters of adjacent nanoprotrusions. These structures generate a mechanical bactericidal effect, independent of chemical composition. Both surfaces are highly bactericidal against all tested Gram-negative and Gram-positive bacteria, and endospores, and exhibit estimated average killing rates of up to ~450,000 cells min−1 cm−2. This represents the first reported physical bactericidal activity of black silicon or indeed for any hydrophilic surface. This biomimetic analogue represents an excellent prospect for the development of a new generation of mechano-responsive, antibacterial nanomaterials
“Race for the Surface”: Eukaryotic Cells Can Win
With an aging population and the
consequent increasing use of medical implants, managing the possible
infections arising from implant surgery remains a global challenge.
Here, we demonstrate for the first time that a precise nanotopology
provides an effective intervention in bacterial cocolonization enabling
the proliferation of eukaryotic cells on a substratum surface, preinfected
by both live Gram-negative, <i>Pseudomonas aeruginosa</i>, and Gram-positive, <i>Staphylococcus aureus</i>, pathogenic
bacteria. The topology of the model black silicon (bSi) substratum
not only favors the proliferation of eukaryotic cells but is biocompatible,
not triggering an inflammatory response in the host. The attachment
behavior and development of filopodia when COS-7 fibroblast cells
are placed in contact with the bSi surface are demonstrated in the
dynamic study, which is based on the use of real-time sequential confocal
imaging. Bactericidal nanotopology may enhance the prospect for further
development of inherently responsive antibacterial nanomaterials for
bionic applications such as prosthetics and implants