scholarly journals Solubilization of Charged Porphyrins in Interpolyelectrolyte Complexes: A Computer Study

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 502
Author(s):  
Karel Šindelka ◽  
Zuzana Limpouchová ◽  
Karel Procházka
Keyword(s):  
Dissipative Particle Dynamics ◽  
Water Soluble ◽  
Coarse Grained ◽  
Core Shell ◽  
Computer Study ◽  
Interpolyelectrolyte Complex ◽  
The Core ◽  
Porphyrin Derivatives ◽  
Oppositely Charged ◽  
Positively Charged

Using coarse-grained dissipative particle dynamics (DPD) with explicit electrostatics, we performed (i) an extensive series of simulations of the electrostatic co-assembly of asymmetric oppositely charged copolymers composed of one (either positively or negatively charged) polyelectrolyte (PE) block A and one water-soluble block B and (ii) studied the solubilization of positively charged porphyrin derivatives (P+) in the interpolyelectrolyte complex (IPEC) cores of co-assembled nanoparticles. We studied the stoichiometric mixtures of 137 A10+B25 and 137 A10−B25 chains with moderately hydrophobic A blocks (DPD interaction parameter aAS=35) and hydrophilic B blocks (aBS=25) with 10 to 120 P+ added (aPS=39). The P+ interactions with other components were set to match literature information on their limited solubility and aggregation behavior. The study shows that the moderately soluble P+ molecules easily solubilize in IPEC cores, where they partly replace PE+ and electrostatically crosslink PE− blocks. As the large P+ rings are apt to aggregate, P+ molecules aggregate in IPEC cores. The aggregation, which starts at very low loadings, is promoted by increasing the number of P+ in the mixture. The positively charged copolymers repelled from the central part of IPEC core partially concentrate at the core-shell interface and partially escape into bulk solvent depending on the amount of P+ in the mixture and on their association number, AS. If AS is lower than the ensemble average ⟨AS⟩n, the copolymer chains released from IPEC preferentially concentrate at the core-shell interface, thus increasing AS, which approaches ⟨AS⟩n. If AS>⟨AS⟩n, they escape into the bulk solvent.

Medicated structural PVP/PEG composites fabricated using coaxial electrospinning

e-Polymers ◽  
2017 ◽  
Vol 17 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Yong-Hui Wu ◽  
Deng-Guang Yu ◽  
Hai-Peng Li ◽  
Xiang-Yang Wu ◽  
Xiao-Yan Li
Keyword(s):  
Electron Microscope ◽  
Citric Acid ◽  
Shell Structure ◽  
Water Soluble ◽  
Working Fluid ◽  
Coaxial Electrospinning ◽  
Core Shell ◽  
The Core ◽  
Poorly Water Soluble ◽  
Core Shell Structure

AbstractA new type of medicated polymeric composite consisting of acyclovir (ACY), polyvinylpyrrolidone K60 (PVP) and polyethylene glycol 6000 (PEG) with core-shell structure were prepared by a coaxial electrospinning process. The composites could enhance the dissolution of the poorly water-soluble drug. The shell layers were formed from a spinnable working fluid containing the filament-forming PVP and citric acid while the core parts were prepared from an un-spinnable co-dissolving solution composed of ACY, sodium hydrate and PEG. Scanning electron microscope and transmission electron microscope observations demonstrated that the composites had a homogeneous linear topography with a slippery surface, a diameter of 670±130 nm, and an obvious core-shell structure. X-ray diffraction (XRD) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy results demonstrated that the drug and citric acid contained in the core and shell parts were in an amorphous status. In vitro dissolution experiments exhibited that ACY was able to be free within 1 min, and the dissolution media were neutral due to acid-basic action within the core-shell structures. The medicated nanocomposites resulted from a combined usage of hydrophilic polymeric excipients PVP and PEG could provide a new solution to the problem associated with the dissolution of poorly water-soluble drugs.

Mesoscale Simulation of the Structure of Star Acrylated Poly(ethylene glycol-co-lactide) Hydrogels

2012 ◽  
Vol 1418 ◽  
Author(s):  
Seyed Sina Moeinzadeh ◽  
Esmaiel Jabbari
Keyword(s):  
Ethylene Glycol ◽  
Volume Fraction ◽  
Equations Of Motion ◽  
Dissipative Particle Dynamics ◽  
Random Force ◽  
Dynamics Simulation ◽  
Coarse Grained ◽  
Poly Ethylene Glycol ◽  
The Core ◽  
Poly Ethylene

ABSTRACTIn this work the microstructures of star acrylated poly(ethylene glycol-co-lactide) (SPELA) with different LA:EG ratios in the aqueous solution have been simulated via Dissipative Particle Dynamics (DPD) approach at the mesoscale. The system components were coarse-grained into different beads (set of atoms) which moved according to the Newton’s equations of motion integrated via a modified Velocity-Verlet algorithm. The force acting on each bead, in a specific cutoff distance (rc), was divided into a conservative force (FC), random force (FR), dissipative force (FD), bond force (FS) and bond angle force (FE). The repulsion parameters of the conservative force (αij) were calculated from the solubility parameter of the beads, each of which were extracted from an atomistic molecular dynamics simulation (MD). Simulations showed the formation of micelles with lactide and acrylate beads occupied the core and hydrophilic ethylene oxide segments extending through the water to form the corona. The micelles showed an increasing trend in size and decreasing trend in number density with increase in LA:EG ratio. Results showed that the acrylate density decreased from the center of the micelles to the core surface although the overall amount of acrylates increased due to the increase in volume. Furthermore, the running integration number of acrylate-water beads showed decreasing accessibility of acrylates to water with increasing PLA volume fraction.

Computer study of the solubilization of polymer chains in polyelectrolyte complex cores of polymeric nanoparticles in aqueous media

2018 ◽  
Vol 20 (47) ◽  
pp. 29876-29888 ◽  
Author(s):  
Karel Šindelka ◽  
Zuzana Limpouchová ◽  
Karel Procházka
Keyword(s):  
Computer Simulations ◽  
Polyelectrolyte Complex ◽  
Polymeric Nanoparticles ◽  
Aqueous Media ◽  
Polymer Chains ◽  
Coarse Grained ◽  
Computer Study ◽  
Interpolyelectrolyte Complex ◽  
Structure Of Nanoparticles ◽  
Polar Polymer

The formation and structure of nanoparticles containing non-polar polymer chains solubilized in interpolyelectrolyte complex (IPC) cores and the partitioning of non-polar chains between bulk solvent and IPC cores were studied by coarse-grained computer simulations.

Synthesis of CdTe and CdTe/CdS Core-Shell Quantum Dots and their Optical Properties

2011 ◽  
Vol 306-307 ◽  
pp. 1350-1353 ◽  
Author(s):  
Juan Juan Lu ◽  
Shen Guang Ge ◽  
Fu Wei Wan ◽  
Jing Hua Yu
Keyword(s):  
Quantum Dots ◽  
Thioglycolic Acid ◽  
Water Soluble ◽  
Molar Ratio ◽  
Core Shell ◽  
The Core ◽  
Cdte Qds ◽  
Quality Water ◽  
Synthesis Procedure ◽  
Pl Emission

This paper describes the synthesis of CdTe and CdTe/CdS core-shell quantum dots (QDs) in aqueous solution. The quantum dots are prepared by using thioglycolic acid (TGA) as stabilizers. The synthesis procedure is simple and controllable. Different sized CdTe QDs with tuned PL wavelengths from 550 to 640 nm was synthesized by controlling reaction time within 5 h in aqueous solutions at a temperature of 100 °C. We also investigated the influence of precursor Cd/Te molar ratio for the prepared QDs. It was showed that the core-shell CdTe/CdS QDs have larger photoluminescence (PL) emission intensity than the original CdTe QDs. The synthesized core-shell CdTe/ZnS QDs have high quality, water-soluble and will be useful in applications of biolabeling, biosensing, and imaging.

Core/shell-structured bimetallic nanocluster catalysts for visible-light-induced electron transfer

2000 ◽  
Vol 72 (1-2) ◽  
pp. 317-325 ◽  
Author(s):  
Naoki Toshima
Keyword(s):  
Electron Transfer ◽  
Visible Light ◽  
Hydrogen Generation ◽  
Cation Radical ◽  
Water Soluble ◽  
Core Shell ◽  
Metal Nanoclusters ◽  
Water Soluble Polymer ◽  
The Core ◽  
Bimetallic Nanoclusters

It has been found that the bimetallic nanoclusters often have so-called core/shell structure if they are prepared by alcohol-reduction of two kinds of noble metal ions in the presence of a water-soluble polymer like poly(N-vinyl-2-pyrolidone)(PVP), and that the core/ shell structured bimetallic nanoclusters have much higher catalytic activity than the corresponding monometallic nanoclusters. Here, several kinds of monometallic and bimetallic nanoclusters are synthesized by the similar method, and the catalyses are measured. Thus, the colloidal dispersions of Au, Pt, Pd, Rh, and Ru monometallic, and Au/Pt, Au/Pd, Au/Rh, and Pt/Ru bimetallic nanoclusters were synthesized and applied as the catalysts for visible-light- induced hydrogen generation. The core/shell structures are analyzed mainly by UV–vis spectra. The rate of electron transfer from the methyl viologen cation radical to the metal nanoclusters is proportional to the hydrogen generation rate at the steady state. All the electrons accepted by the metal nanoclusters are used for the hydrogen generation. Both electron transfer and hydrogen generation rates increase when the bimetallic nanoclusters are used in place of the corresponding monometallic nanoclusters. The most active catalysts were Au/Rh and Pt/Ru bimetallic nanoclusters.

scholarly journals Preparation and Deep Characterization of Composite/Hybrid Multi-Scale and Multi-Domain Polymeric Microparticles

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3921 ◽  
Author(s):  
Wei Yu ◽  
Nikunjkumar Visaveliya ◽  
Christophe A. Serra ◽  
J. Michael Köhler ◽  
Shukai Ding ◽  
...  
Keyword(s):  
Miniemulsion Polymerization ◽  
Elongational Flow ◽  
Water Soluble ◽  
Shell Morphology ◽  
Core Shell ◽  
X Rays ◽  
Multi Scale ◽  
The Core ◽  
Step Procedure ◽  
Polymeric Microparticles

Polymeric microparticles were produced following a three-step procedure involving (i) the production of an aqueous nanoemulsion of tri and monofunctional acrylate-based monomers droplets by an elongational-flow microemulsifier, (ii) the production of a nanosuspension upon the continuous-flow UV-initiated miniemulsion polymerization of the above nanoemulsion and (iii) the production of core-shell polymeric microparticles by means of a microfluidic capillaries-based double droplets generator; the core phase was composed of the above nanosuspension admixed with a water-soluble monomer and gold salt, the shell phase comprised a trifunctional monomer, diethylene glycol and a silver salt; both phases were photopolymerized on-the-fly upon droplet formation. Resulting microparticles were extensively analyzed by energy dispersive X-rays spectrometry and scanning electron microscopy to reveal the core-shell morphology, the presence of silver nanoparticles in the shell, organic nanoparticles in the core but failed to reveal the presence of the gold nanoparticles in the core presumably due to their too small size (c.a. 2.5 nm). Nevertheless, the reddish appearance of the as such prepared polymer microparticles emphasized that this three-step procedure allowed the easy elaboration of composite/hybrid multi-scale and multi-domain polymeric microparticles.

Magnetic Properties of Fe3O4/CoFe2O4 Composite Nanoparticles with Core/Shell Architecture

2020 ◽  
Vol 65 (10) ◽  
pp. 904
Author(s):  
V. O. Zamorskyi ◽  
Ya. M. Lytvynenko ◽  
A. M. Pogorily ◽  
A. I. Tovstolytkin ◽  
S. O. Solopan ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Spinel Ferrite ◽  
Composite Nanoparticles ◽  
Core Shell ◽  
Cofe2o4 Nanoparticles ◽  
Core Diameter ◽  
The Core ◽  
Shell Particles ◽  
Interface Parameters ◽  
Shell Composite

Magnetic properties of the sets of Fe3O4(core)/CoFe2O4(shell) composite nanoparticles with a core diameter of about 6.3 nm and various shell thicknesses (0, 1.0, and 2.5 nm), as well as the mixtures of Fe3O4 and CoFe2O4 nanoparticles taken in the ratios corresponding to the core/shell material contents in the former case, have been studied. The results of magnetic research showed that the coating of magnetic nanoparticles with a shell gives rise to the appearance of two simultaneous effects: the modification of the core/shell interface parameters and the parameter change in both the nanoparticle’s core and shell themselves. As a result, the core/shell particles acquire new characteristics that are inherent neither to Fe3O4 nor to CoFe2O4. The obtained results open the way to the optimization and adaptation of the parameters of the core/shell spinel-ferrite-based nanoparticles for their application in various technological and biomedical domains.

scholarly journals Iron Based Core-Shell Structures as Versatile Materials: Magnetic Support and Solid Catalyst

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 72
Author(s):  
Christian Zambrzycki ◽  
Runbang Shao ◽  
Archismita Misra ◽  
Carsten Streb ◽  
Ulrich Herr ◽  
...  
Keyword(s):  
Water Purification ◽  
Functional Materials ◽  
Core Material ◽  
Solid Catalyst ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
The Core ◽  
Shell Nanostructures ◽  
Sio2 Shell ◽  
Iron Based

Core-shell materials are promising functional materials for fundamental research and industrial application, as their properties can be adapted for specific applications. In particular, particles featuring iron or iron oxide as core material are relevant since they combine magnetic and catalytic properties. The addition of an SiO2 shell around the core particles introduces additional design aspects, such as a pore structure and surface functionalization. Herein, we describe the synthesis and application of iron-based core-shell nanoparticles for two different fields of research that is heterogeneous catalysis and water purification. The iron-based core shell materials were characterized by transmission electron microscopy, as well as N2-physisorption, X-ray diffraction, and vibrating-sample magnetometer measurements in order to correlate their properties with the performance in the target applications. Investigations of these materials in CO2 hydrogenation and water purification show their versatility and applicability in different fields of research and application, after suitable individual functionalization of the core-shell precursor. For design and application of magnetically separable particles, the SiO2 shell is surface-functionalized with an ionic liquid in order to bind water pollutants selectively. The core requires no functionalization, as it provides suitable magnetic properties in the as-made state. For catalytic application in synthesis gas reactions, the SiO2-stabilized core nanoparticles are reductively functionalized to provide the catalytically active metallic iron sites. Therefore, Fe@SiO2 core-shell nanostructures are shown to provide platform materials for various fields of application, after a specific functionalization.

scholarly journals Light-Scattering Simulations from Spherical Bimetallic Core–Shell Nanoparticles

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 359
Author(s):  
Francesco Ruffino
Keyword(s):  
Optical Properties ◽  
Light Scattering ◽  
Bimetallic Nanoparticles ◽  
Dominant Role ◽  
Scattered Light ◽  
Specific Interaction ◽  
Surface Enhanced Raman Spectroscopy ◽  
Localized Surface Plasmon ◽  
Core Shell ◽  
The Core

Bimetallic nanoparticles show novel electronic, optical, catalytic or photocatalytic properties different from those of monometallic nanoparticles and arising from the combination of the properties related to the presence of two individual metals but also from the synergy between the two metals. In this regard, bimetallic nanoparticles find applications in several technological areas ranging from energy production and storage to sensing. Often, these applications are based on optical properties of the bimetallic nanoparticles, for example, in plasmonic solar cells or in surface-enhanced Raman spectroscopy-based sensors. Hence, in these applications, the specific interaction between the bimetallic nanoparticles and the electromagnetic radiation plays the dominant role: properties as localized surface plasmon resonances and light-scattering efficiency are determined by the structure and shape of the bimetallic nanoparticles. In particular, for example, concerning core-shell bimetallic nanoparticles, the optical properties are strongly affected by the core/shell sizes ratio. On the basis of these considerations, in the present work, the Mie theory is used to analyze the light-scattering properties of bimetallic core–shell spherical nanoparticles (Au/Ag, AuPd, AuPt, CuAg, PdPt). By changing the core and shell sizes, calculations of the intensity of scattered light from these nanoparticles are reported in polar diagrams, and a comparison between the resulting scattering efficiencies is carried out so as to set a general framework useful to design light-scattering-based devices for desired applications.

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