scholarly journals A reversible B–A transition of DNA duplexes induced by synthetic cationic copolymers

2016 ◽  
Vol 52 (47) ◽  
pp. 7446-7449 ◽  
Author(s):  
Nonoka Yamaguchi ◽  
Yu-ki Zouzumi ◽  
Naohiko Shimada ◽  
Shu-ichi Nakano ◽  
Naoki Sugimoto ◽  
...  
Keyword(s):  
Dna Duplexes ◽  
Anionic Polymers ◽  
Cationic Copolymers

Reversible B–A transitions of DNA duplexes were induced by synthetic cationic and anionic polymers.

scholarly journals INFLUENCE OF FLOCCULANT TYPE ON STRENGTH CHARACTERISTICS OF FLOCS IN CLAY-SALT SUSPENSIONS

2020 ◽  
Vol 63 (6) ◽  
pp. 30-36
Author(s):  
Olga R. Seredkina ◽  
Olesya V. Rakhimova ◽  
Sergey V. Lanovetskiy
Keyword(s):  
Strength Characteristics ◽  
Ionic Polymers ◽  
Partial Restoration ◽  
Anionic Polymers ◽  
Cationic Flocculant ◽  
Potential Possibility ◽  
Floc Strength ◽  
Cationic Copolymers ◽  
Hydrodynamic Effects ◽  
Flocculated Suspension

The results of studies on the effect of the flocculant type on the strength characteristics of floccules in clay-salt suspensions, obtained using a laser analyzer of particle size Lasentec D600L FBRM systems were presented in the article. The coefficients of strength and reduction of aggregates formed by polyacrylamide and its anionic and cationic copolymers were determined. Increasing the speed of mixing by using of polymers various types leads to the destruction of the formed aggregates in the flocculated suspension. The size of flocs induced by a cationic flocculant is reduced from 250 to 110 mm, for anionic and non-ionic flocculants - from 500 to 250 mm. The dependence of floc strength on the macromolecules adsorption mechanism on a solid surface was established. The decrease in hydrodynamic effects entails the partial restoration of floccules. It was shown that the recovery of flocs for all studied polymers was limited, which indicates a significant irreversibility of the aggregates destruction process. When using cationic flocculant, the ability to restore the aggregates is 2.5 times lower compared to anionic and non-ionic polymers. For nonionic and anionic polymers, the dependence of flocs coefficients of strength and recovery on the flocculant dosage was established. Dosage of cationic polymer does not affect these indicators. The dynamics of flocculation, destruction and reflocculation processes using various flocculants was considered. The influence of the charge type and polymer consumption on the mechanism of particles interaction was established. The potential possibility of using the obtained results to improve the technology of potassium chloride production at the stages of thickening and dehydrating clay-salt sludge was shown.

Flocculation of Waste Waters from Petroleum Refineries

1974 ◽  
Vol 9 (1) ◽  
pp. 302-314
Author(s):  
André Hade ◽  
Acher Elcabetz
Keyword(s):  
Electrophoretic Mobility ◽  
Light Transmittance ◽  
Waste Waters ◽  
Critical Coagulation Concentration ◽  
Mobility Rate ◽  
Anionic Polymers ◽  
Petroleum Refineries ◽  
Binary Suspension

Abstract Waste waters from petroleum refineries can be considered as a ternary-like system, the components of which have been characterized. They are: the alkaline liquor, the hydrocarbon rich oil in suspension and the silica rich solid also in suspension. The parameters controlling the destabilization and the flocculation of these suspensions have been studied by light transmittance and electrophoretic mobility. Rate of flocculation, critical coagulation concentration (CCC) , critical restabilization concentration and optimum flocculation conditions have been determined for different combinations of added polyelectrolytes and/or simple electrolytes. Among eleven different polyelectrolytes, four of the cationic type were selected for their property to flocculate the suspension. It has been shown that an excess of polyelectrolyte brings about the restabilization of the particules. No flocculation has been observed for any of the anionic polymers tested. Simple electrolytes are found to obey the Schulze-Hardy rule in their flocculation capacity. Various combinations of a polyelectrolyte with a simple salt lead to a lower CCC together with a broader concentration range between destabilization and restabilization. It is concluded that this binary suspension behaved essentially like a classical lyophobic sol.

scholarly journals Probing the Hydrogen-Bonding Environment of Individual Bases in DNA Duplexes with Isotope-Edited Infrared Spectroscopy

2021 ◽  
Author(s):  
Robert J. Fick ◽  
Amy Y. Liu ◽  
Felix Nussbaumer ◽  
Christoph Kreutz ◽  
Atul Rangadurai ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Infrared Spectroscopy ◽  
Dna Duplexes

scholarly journals Natural steroid-based cationic copolymers cholesterol/diosgenin-r-PDMAEMAs and their pDNA nanoplexes: impact of steroid structures and hydrophobic/hydrophilic ratios on pDNA delivery

RSC Advances ◽  
2021 ◽  
Vol 11 (32) ◽  
pp. 19450-19460
Author(s):  
Zhao Wang ◽  
Jingjing Sun ◽  
Mingrui Li ◽  
Ting Luo ◽  
Yulin Shen ◽  
...  
Keyword(s):  
Structure Function ◽  
Cationic Copolymers

Using natural-based lipids to construct biocompatible, controllable and efficient nanocarriers and elucidating their structure–function relationships, was regarded as an important area for creating sustainable biomaterials.

scholarly journals Combined Effects of Methylated Cytosine and Molecular Crowding on the Thermodynamic Stability of DNA Duplexes

2021 ◽  
Vol 22 (2) ◽  
pp. 947
Author(s):  
Mitsuki Tsuruta ◽  
Yui Sugitani ◽  
Naoki Sugimoto ◽  
Daisuke Miyoshi
Keyword(s):  
Molecular Crowding ◽  
Dna Duplexes ◽  
Crowding Effect ◽  
Backbone Flexibility ◽  
Cpg Dinucleotides ◽  
Key Factor ◽  
Dna Backbone ◽  
A Cell ◽  
Stabilization Effect ◽  
And Function

Methylated cytosine within CpG dinucleotides is a key factor for epigenetic gene regulation. It has been revealed that methylated cytosine decreases DNA backbone flexibility and increases the thermal stability of DNA. Although the molecular environment is an important factor for the structure, thermodynamics, and function of biomolecules, there are few reports on the effects of methylated cytosine under a cell-mimicking molecular environment. Here, we systematically investigated the effects of methylated cytosine on the thermodynamics of DNA duplexes under molecular crowding conditions, which is a critical difference between the molecular environment in cells and test tubes. Thermodynamic parameters quantitatively demonstrated that the methylation effect and molecular crowding effect on DNA duplexes are independent and additive, in which the degree of the stabilization is the sum of the methylation effect and molecular crowding effect. Furthermore, the effects of methylation and molecular crowding correlate with the hydration states of DNA duplexes. The stabilization effect of methylation was due to the favorable enthalpic contribution, suggesting that direct interactions of the methyl group with adjacent bases and adjacent methyl groups play a role in determining the flexibility and thermodynamics of DNA duplexes. These results are useful to predict the properties of DNA duplexes with methylation in cell-mimicking conditions.

scholarly journals Low-Molecular-Weight Polyethyleneimine Grafted Polythiophene for Efficient siRNA Delivery

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Pan He ◽  
Kyoji Hagiwara ◽  
Hui Chong ◽  
Hsiao-hua Yu ◽  
Yoshihiro Ito
Keyword(s):  
Molecular Weight ◽  
Sirna Delivery ◽  
Fluorescent Microscopy ◽  
Molar Ratio ◽  
Low Molecular Weight ◽  
Label Free ◽  
Endosomal Membrane ◽  
Cationic Copolymers ◽  
Interfering Rna

Owing to its hydrophilicity, negative charge, small size, and labile degradation by endogenous nucleases, small interfering RNA (siRNA) delivery must be achieved by a carrier system. In this study, cationic copolymers composed of low-molecular-weight polyethylenimine and polythiophenes were synthesized and evaluated as novel self-tracking siRNA delivery vectors. The concept underlying the design of these copolymers is that hydrophobicity and rigidity of polythiophenes should enhance the transport of siRNA across the cell membrane and endosomal membrane. A gel retardation assay showed that the nanosized complexes formed between the copolymers and siRNA were stable even at a molar ratio of 1 : 2. The high cellular uptake (>80%) and localization of the copolymer vectors inside the cells were easily analyzed by tracking the fluorescence of polythiophene using fluorescent microscopy and cytometry. Anin vitroluciferase knockdown (KD) assay in A549-luc cells demonstrated that the siRNA complexes with more hydrophobic copolymers achieved a higher KD efficiency of 52.8% without notable cytotoxicity, indicating protein-specific KD activity rather than solely the cytotoxicity of the materials. Our polythiophene copolymers should serve as novel, efficient, low cell toxicity, and label-free siRNA delivery systems.

Sign in / Sign up

Export Citation Format

Share Document