scholarly journals On the Development of All-Cellulose Capsules by Vesicle-Templated Layer-by-Layer Assembly

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 589
Author(s):  
Alireza Eivazi ◽  
Bruno Medronho ◽  
Björn Lindman ◽  
Magnus Norgren
Keyword(s):  
Low Cost ◽  
Core Shell ◽  
Cellulose Derivatives ◽  
Layer By Layer ◽  
Reaction Conditions ◽  
Didodecyldimethylammonium Bromide ◽  
Shell Particles ◽  
Micrometer Scale ◽  
Oppositely Charged ◽  
Scale Deposition

Polymeric multilayer capsules formed by the Layer-by-Layer (LbL) technique are interesting candidates for the purposes of storage, encapsulation, and release of drugs and biomolecules for pharmaceutical and biomedical applications. In the current study, cellulose-based core-shell particles were developed via the LbL technique alternating two cellulose derivatives, anionic carboxymethylcellulose (CMC), and cationic quaternized hydroxyethylcellulose ethoxylate (QHECE), onto a cationic vesicular template made of didodecyldimethylammonium bromide (DDAB). The obtained capsules were characterized by dynamic light scattering (DLS), ζ potential measurements, and high-resolution scanning electron microscopy (HR-SEM). DLS measurements reveal that the size of the particles can be tuned from a hundred nanometers with a low polydispersity index (deposition of 2 layers) up to micrometer scale (deposition of 6 layers). Upon the deposition of each cellulose derivative, the particle charge is reversed, and pH is observed to considerably affect the process thus demonstrating the electrostatic driving force for LbL deposition. The HR-SEM characterization suggests that the shape of the core-shell particles formed is reminiscent of the spherical vesicle template. The development of biobased nano- and micro-containers by the alternating deposition of oppositely charged cellulose derivatives onto a vesicle template offers several advantages, such as simplicity, reproducibility, biocompatibility, low-cost, mild reaction conditions, and high controllability over particle size and composition of the shell.

scholarly journals Mechanical Fracturing of Core-Shell Undercooled Metal Particles for Heat-Free Soldering

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Simge Çınar ◽  
Ian D. Tevis ◽  
Jiahao Chen ◽  
Martin Thuo
Keyword(s):  
Phase Change Materials ◽  
Low Cost ◽  
Liquid Core ◽  
Oxide Shell ◽  
Core Shell ◽  
Ambient Conditions ◽  
Complex Shapes ◽  
Droplet Emulsion ◽  
Shell Particles ◽  
Poor Stability

Abstract Phase-change materials, such as meta-stable undercooled (supercooled) liquids, have been widely recognized as a suitable route for complex fabrication and engineering. Despite comprehensive studies on the undercooling phenomenon, little progress has been made in the use of undercooled metals, primarily due to low yields and poor stability. This paper reports the use of an extension of droplet emulsion technique (SLICE) to produce undercooled core-shell particles of structure; metal/oxide shell-acetate (‘/’ = physisorbed, ‘-’ = chemisorbed), from molten Field’s metal (Bi-In-Sn) and Bi-Sn alloys. These particles exhibit stability against solidification at ambient conditions. Besides synthesis, we report the use of these undercooled metal, liquid core-shell, particles for heat free joining and manufacturing at ambient conditions. Our approach incorporates gentle etching and/or fracturing of outer oxide-acetate layers through mechanical stressing or shearing, thus initiating a cascade entailing fluid flow with concomitant deformation, combination/alloying, shaping, and solidification. This simple and low cost technique for soldering and fabrication enables formation of complex shapes and joining at the meso- and micro-scale at ambient conditions without heat or electricity.

scholarly journals Conductive Nanofilms with Oppositely Charged Reduced Graphene Oxides as a Base for Electroactive Coatings and Sensors

2021 ◽  
Vol 5 (2) ◽  
pp. 20
Author(s):  
Tomasz Kruk ◽  
Piotr Warszyński
Keyword(s):  
Thin Films ◽  
Graphene Oxide ◽  
Low Cost ◽  
Thermal Reduction ◽  
Layer By Layer ◽  
Graphene Oxides ◽  
Lbl Assembly ◽  
Reduced Graphene ◽  
Amidation Reaction ◽  
Oppositely Charged

We demonstrate a method for the formation of multilayers composed of reduced graphene oxide (rGO), which can be used for transparent, conducting thin films. Using the layer-by-layer (LbL) assembly of positively and negatively charged GO sheets, we could obtain thin films with highly controllable sheet resistance. The natural negative charge of graphene oxide was turned to positive by the amidation reaction. After forming the multilayer films, the graphene oxide underwent thermal reduction at temperatures above 150 °C. The (rGO+/rGO−) films were characterized by UV-Vis and scanning electron microscopy (SEM), and their conductivity was measured by the four-point method. We found that after deposition of five (rGO+/rGO−), the coating structure reached the percolation limit, and the film resistance decreased more gradually to around 20 kΩ/sq for the films obtained by eleven deposition cycles with graphene oxide reduced at 250 °C. The formation of thin films on polyimide allows the forming of new flexible conductive materials, which can find applications, e.g., in biomedicine as new electroactive, low-cost, disposable sensors.

Novel Core-Shell Hybrid Polymers Designed as Dual Functional Additives for Concrete

2013 ◽  
Vol 687 ◽  
pp. 77-83
Author(s):  
Thomas Pavlitschek ◽  
Markus Gretz ◽  
Johann Plank
Keyword(s):  
Core Shell ◽  
Hardened Cement ◽  
Layer By Layer ◽  
Cement Slurry ◽  
Potential Measurement ◽  
Latex Particles ◽  
Dual Functional ◽  
Layer Deposition ◽  
Multifunctional Additives ◽  
Shell Particles

Novel hybrid admixtures for construction applications were prepared by layer-by-layer deposition technique. Colloidal core templates consisting of styrene/n-butylacrylate latex particles were coated with multilayers of superplasticizers commonly used in concrete. This way, core-shell particles possessing both dispersing and film-forming properties were achieved. Incorporation of the latex@dispersant hybrid additive into a cement paste results in a slow release of the superplasticizer as a result of gradual shell disintegration which instigates prolonged plastification (long ”slump life”) of the cement slurry. Once the shell has been dissolved, latex particles are released into the pore solution and can coalesce into a polymer film which improves the mechanical properties of the hardened cement. Characterization of the templates and novel additives was performed by means of zeta potential measurement, dynamic light scattering and electron microscopy. Our method allows to synthesize multifunctional additives with time-controlled release effect.

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.

An Update on the Use of Alginate in Additive Biofabrication Techniques

2019 ◽  
Vol 25 (11) ◽  
pp. 1249-1264 ◽  
Author(s):  
Amoljit Singh Gill ◽  
Parneet Kaur Deol ◽  
Indu Pal Kaur
Keyword(s):  
Fused Deposition Modeling ◽  
Low Cost ◽  
Selective Laser Sintering ◽  
Layer By Layer ◽  
Three Dimension ◽  
Anionic Polymer ◽  
Fused Deposition ◽  
The Status ◽  
Deposition Modeling ◽  
Extrusion Printing

Background: Solid free forming (SFF) technique also called additive manufacturing process is immensely popular for biofabrication owing to its high accuracy, precision and reproducibility. Method: SFF techniques like stereolithography, selective laser sintering, fused deposition modeling, extrusion printing, and inkjet printing create three dimension (3D) structures by layer by layer processing of the material. To achieve desirable results, selection of the appropriate technique is an important aspect and it is based on the nature of biomaterial or bioink to be processed. Result & Conclusion: Alginate is a commonly employed bioink in biofabrication process, attributable to its nontoxic, biodegradable and biocompatible nature; low cost; and tendency to form hydrogel under mild conditions. Furthermore, control on its rheological properties like viscosity and shear thinning, makes this natural anionic polymer an appropriate candidate for many of the SFF techniques. It is endeavoured in the present review to highlight the status of alginate as bioink in various SFF techniques.

scholarly journals Facile Synthesis of Carboxymethyl Cellulose Coated Core/Shell SiO2@Cu Nanoparticles and Their Antifungal Activity against Phytophthora capsici

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 888
Author(s):  
Nguyen Thi Thanh Hai ◽  
Nguyen Duc Cuong ◽  
Nguyen Tran Quyen ◽  
Nguyen Quoc Hien ◽  
Tran Thi Dieu Hien ◽  
...  
Keyword(s):  
Antifungal Activity ◽  
Carboxymethyl Cellulose ◽  
Chemical Reduction ◽  
Low Cost ◽  
Phytophthora Capsici ◽  
Reduction Process ◽  
Spherical Shape ◽  
Core Shell ◽  
Cu Nanoparticles ◽  
Average Size

Cu nanoparticles are a potential material for creating novel alternative antimicrobial products due to their unique antibacterial/antifungal properties, stability, dispersion, low cost and abundance as well as being economical and ecofriendly. In this work, carboxymethyl cellulose coated core/shell SiO2@Cu nanoparticles (NPs) were synthesized by a simple and effective chemical reduction process. The initial SiO2 NPs, which were prepared from rice husk ash, were coated by a copper ultrathin film using hydrazine and carboxymethyl cellulose (CMC) as reducing agent and stable agent, respectively. The core/shell SiO2@Cu nanoparticles with an average size of ~19 nm were surrounded by CMC. The results indicated that the SiO2@Cu@CMC suspension was a homogenous morphology with a spherical shape, regular dispersion and good stability. Furthermore, the multicomponent SiO2@Cu@CMC NPs showed good antifungal activity against Phytophthora capsici (P. capsici). The novel Cu NPs-based multicomponent suspension is a key compound in the development of new fungicides for the control of the Phytophthora disease.

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.

scholarly journals Encapsulation of Phase Change Materials Using Layer-by-Layer Assembled Polyelectrolytes

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Qiangying Yi ◽  
Gleb B. Sukhorokov ◽  
Jin Ma ◽  
Xiaobo Yang ◽  
Zhongwei Gu
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Low Cost ◽  
Sodium Dodecyl ◽  
Layer By Layer ◽  
Latent Heat Storage ◽  
Good Thermal Stability ◽  
Lbl Assembly ◽  
Acid Sodium Salt ◽  
Assembly Technique

Phase change materials absorb the thermal energy when changing their phases (e.g., solid-to-liquid) at constant temperatures to achieve the latent heat storage. The major drawbacks such as limited thermal conductivity and leakage prevent the PCMs from wide application in desired areas. In this work, an environmentally friendly and low cost approach, layer-by-layer (LbL) assembly technique, was applied to build up ultrathin shells to encapsulate the PCMs and therefore to regulate their changes in volume when the phase change occurs. Generally, the oppositely charged strong polyelectrolytes Poly(diallyldimethylammonium chloride) (PDADMAC) and Poly(4-styrenesulfonic acid) sodium salt (PSS) were employed to fabricate multilayer shells on emulsified octadecane droplets using either bovine serum albumin (BSA) or sodium dodecyl sulfate (SDS) as surfactant. Specifically, using BSA as the surfactant, polyelectrolyte encapsulated octadecane spheres in size of ∼500 nm were obtained, with good shell integrity, high octadecane content (91.3% by mass), and good thermal stability after cycles of thermal treatments.

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