scholarly journals Preparation and study of the physicochemical characteristics of multilayer polymer composites based on poly(ethyleneimine)-stabilized copper nanoparticles and poly(sodium 2-acrylamide-2-methyl-1-propanesulfonate)

2021 ◽  
pp. 22-31
Author(s):  
Bagadat Selenova ◽  
Aigerim Ayazbayeva ◽  
Alexsey Shakhvorostov ◽  
Sana Kabdrakhmanova ◽  
Saule Nauryzova ◽  
...  
Keyword(s):  
Copper Nanoparticles ◽  
Acidic Medium ◽  
Multilayer Film ◽  
Physicochemical Characteristics ◽  
Layer By Layer ◽  
Membrane Catalysis ◽  
Amino Groups ◽  
Interpolyelectrolyte Complex ◽  
Average Size ◽  
Positively Charged

Multilayer films were synthesized from a complex of branched polyethyleneimine (PEI) with copper nanoparticles (PEI-CuNPs) and sodium poly-2-acrylamide-2-methyl-1-propanesulfonate (PAMPSNa), applied layer-by-layer (LbL) on a solid support in an acidic medium. Protonation of the amino groups of PEI in an acidic medium increases the positive charge of the PEI-CuNPs system to +43.5 mV and promotes the formation of an interpolyelectrolyte complex between the positively charged PEI-CuNPs and the highly charged anionic polyelectrolyte PAMPS, the ζ-potential of which was -141 mV. AFM images and SEM micrographs showed a uniform distribution of spherical copper nanoparticles in the homogeneous structure of the multilayer film. The optical characteristics and hydrodynamic dimensions of PEI-CuNPs indicate the formation of PEI-CuNPs nanoparticles with sizes of 60-300 nm, with an average size of up to 100 nm. Copper nanoparticles distributed uniformly in a multilayer PEI-CuNPs/PAMPS film may be of interest for applications in the field of membrane catalysis, biochips, sensor membranes, and controlled drug delivery.

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.

Multilayer composite beads constructed via layer-by-layer self-assembly for lysozyme controlled release

RSC Advances ◽  
2014 ◽  
Vol 4 (46) ◽  
pp. 24369-24376 ◽  
Author(s):  
Jiemin Zhao ◽  
Xiaoping Wang ◽  
Yanshen Kuang ◽  
Yufeng Zhang ◽  
Xiaowen Shi ◽  
...  
Keyword(s):  
Controlled Release ◽  
Self Assembly ◽  
Cross Linking ◽  
Layer By Layer ◽  
Multilayer Composite ◽  
Composite Beads ◽  
Assembly Technique ◽  
Positively Charged

Alginate (ALG)–lysozyme (LZ) beads were fabricated by a cross-linking process. Negatively charged ALG and positively charged LZ were alternately deposited on the positively charged ALG–LZ beads via a layer-by-layer (LBL) self-assembly technique.

Biological Multilayer Films Assembled by Redox Polymer and HRP on Screen-Printed Carbon Electrode

2012 ◽  
Vol 571 ◽  
pp. 56-59
Author(s):  
Yu Fang Sha ◽  
Mei Zhao ◽  
Ming Quan Yang ◽  
Hai Xin Bai ◽  
Man Zhao
Keyword(s):  
Horseradish Peroxidase ◽  
Electrostatic Interaction ◽  
Electrode Surface ◽  
Multilayer Films ◽  
Carbon Electrode ◽  
Layer By Layer ◽  
Redox Polymer ◽  
Screen Printed Carbon Electrode ◽  
Positively Charged ◽  
Screen Printed

Biological multilayer films of redox polymer and horseradish peroxidase (HRP) were successfully assembled on a screen-printed carbon electrode using layer-by-layer (LBL) assembled method based on the electrostatic interaction. The screen-printed carbon electrode surface was modified by the positively charged redox polymer, and the negatively charged HRP by LBL method.

scholarly journals Effects of Positioning Conditions on Material Properties In Powder bed Fusion Additive Manufacturing

2021 ◽  
Author(s):  
Mevlüt Yunus Kayacan ◽  
Nihat Yılmaz
Keyword(s):  
Additive Manufacturing ◽  
Material Properties ◽  
Layer By Layer ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Cooling Rates ◽  
Powder Bed ◽  
Manufacturing Technologies ◽  
Average Size ◽  
Hardness Values

Abstract Among additive manufacturing technologies, Laser Powder Bed Fusion (L-PBF) is considered the most widespread layer-by-layer process. Although the L-PBF, which is also called as SLM method, has many advantages, several challenging problems must be overcome, including part positioning issues. In this study, the effect of part positioning on the microstructure of the part in the L-PBF method was investigated. Five Ti6Al4V samples were printed in different positions on the building platform and investigated with the aid of temperature, porosity, microstructure and hardness evaluations. In this study, martensitic needles were detected within the microstructure of Ti6Al4V samples. Furthermore, some twins were noticed on primary martensitic lines and the agglomeration of β precipitates was observed in vanadium rich areas. The positioning conditions of samples were revealed to have a strong effect on temperature gradients and on the average size of martensitic lines. Besides, different hardness values were attained depending on sample positioning conditions. As a major result, cooling rates were found related to positions of samples and the location of point on the samples. Higher cooling rates and repetitive cooling cycles resulted in microstructures becoming finer and harder.

scholarly journals Layer-by-Layer 3D Constructs of Fibroblasts in Hydrogel for Examining Transdermal Penetration Capability of Nanoparticles

2016 ◽  
Vol 22 (4) ◽  
pp. 447-453 ◽  
Author(s):  
Xiaochun Hou ◽  
Shiying Liu ◽  
Min Wang ◽  
Christian Wiraja ◽  
Wei Huang ◽  
...  
Keyword(s):  
Transdermal Delivery ◽  
Three Dimensional ◽  
Layer By Layer ◽  
Surface Charges ◽  
Skin Model ◽  
Collagen Hydrogel ◽  
Penetration Ability ◽  
Charged Nanoparticles ◽  
Transdermal Penetration ◽  
Positively Charged

Nanoparticles are emerging transdermal delivery systems. Their size and surface properties determine their efficacy and efficiency to penetrate through the skin layers. This work utilizes three-dimensional (3D) bioprinting technology to generate a simplified artificial skin model to rapidly screen nanoparticles for their transdermal penetration ability. Specifically, this model is built through layer-by-layer alternate printing of blank collagen hydrogel and fibroblasts. Through controlling valve on-time, the spacing between printing lines could be accurately tuned, which could enable modulation of cell infiltration in the future. To confirm the effectiveness of this platform, a 3D construct with one layer of fibroblasts sandwiched between two layers of collagen hydrogel is used to screen silica nanoparticles with different surface charges for their penetration ability, with positively charged nanoparticles demonstrating deeper penetration, consistent with the observation from an existing study involving living skin tissue.

Fibrinogen C-terminal peptidic sequences (Haptides) modulate fibrin polymerization

2004 ◽  
Vol 91 (01) ◽  
pp. 43-51 ◽  
Author(s):  
Matti Ben-Moshe ◽  
Sholomo Magdassi ◽  
Raphael Gorodetsky ◽  
Gerard Marx
Keyword(s):  
Platelet Aggregation ◽  
Cell Attachment ◽  
Fibrin Clot ◽  
Nano Particles ◽  
Amino Acid Residues ◽  
Fibrin Gel ◽  
Transmission Microscopy ◽  
Average Size ◽  
Β Chain ◽  
Positively Charged

SummaryWe previously described synthetic peptides of 19-21 amino acid residues, homologous to the C-termini of fibrinogen Fib340 and Fib420, from the β-chain (Cβ), the extended αE chain (CαE) and near the end of the γ-chain (preCγ) which elicited attachment (haptotactic) responses from mesenchymal cells. We named these haptotactic peptides -Haptides. The effects of Haptides on fibrin clot formation was evaluated and their possible effects on platelet aggregation was examined. The Haptides Cβ, CαE and preCγ, (2-10 μM) increased fibrin clot turbidity and also decreased thrombin-induced clotting time. Higher concentrations (>120 μM of Cβ or preCγ) induced fibrinogen precipitation even without thrombin. These precipitates exhibited different ultrastructure from thrombin-induced fibrin by scanning and transmission microscopy. C-terminal peptides of the other fibrinogen chains exerted no such effects. Sepharose beads covalently coated with either whole fibrinogen or Haptides (SB-Fib or SB-Haptide) highly adsorbed free FITCHaptides. In aqueous solution, Haptides formed nano-particles with average size of ∼150nm in diameter. We suggest that such positively charged aggregates could serve to nucleate and accelerate fibrin gel formation. These results also indicate that Cβ and preCγ sequences within fibrin(ogen) participate in the docking and condensation of fibrin(ogen) during its assembly into a fibrin clot. By contrast, Haptides up to 100µM did not bind to platelets, and had no effect on platelet aggregation. Our findings highlight the roles of the C-terminal sequences of the β and γ chains in fibrin(ogen) polymerization as well as in cell attachment.

Preparation of CPC-Fe3O4-MMT/PEG Magnetic Films via Layer-by-Layer Assembly under the Assistance of Magnetic Field

2016 ◽  
Vol 852 ◽  
pp. 1034-1038
Author(s):  
Li Nan Xu ◽  
Shu Chen Tu ◽  
Feng Zhu Lv ◽  
Qi An ◽  
Yi He Zhang
Keyword(s):  
Magnetic Field ◽  
Self Assembly ◽  
Present Method ◽  
Multilayer Film ◽  
Composite Films ◽  
Deposition Efficiency ◽  
Magnetic Films ◽  
Layer By Layer ◽  
Film Fabrication ◽  
Layer Assembly

Polyethylene glycol (PEG), which was not a traditional building block of layer by layer (LBL) self-assembly, was used to fabricate multilayer films by the combination of LBL and magnetic field induction. The UV-abs absorbance of the composite films increases linearly with the number of bilayers, indicating uniform fabrication of each layer. By this method, the multilayers can consist of up to 15 bilayers. The applied magnetic field not only enhances the compactness of the CPC-Fe3O4-MMT, but also improves the deposition efficiency of the films. The present method can be an effective method for multilayer film fabrication from non polyelectrolyte.

Amperometric Glucose Biosensor on Layer by Layer Assembled Carbon Nanotube and Polypyrrole Multilayer Film

2008 ◽  
Vol 20 (2) ◽  
pp. 150-156 ◽  
Author(s):  
Mahendra D. Shirsat ◽  
Chee O. Too ◽  
Gordon G. Wallace
Keyword(s):  
Carbon Nanotube ◽  
Multilayer Film ◽  
Glucose Biosensor ◽  
Layer By Layer

Luminescent multilayer film based on mixed-addenda polyoxometalates and polyethyleneimine by layer-by-layer assembly

2004 ◽  
Vol 233 (1-4) ◽  
pp. 14-19 ◽  
Author(s):  
Huiyuan Ma ◽  
Jun Peng ◽  
Baibin Zhou ◽  
Zhangang Han ◽  
Yuhua Feng
Keyword(s):  
Multilayer Film ◽  
Layer By Layer ◽  
Layer By Layer Assembly ◽  
Layer Assembly
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