scholarly journals The Modulation of Chitosan-DNA Interaction by Concentration and pH in Solution

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 646 ◽  
Author(s):  
Fangqin Ma ◽  
Yanwei Wang ◽  
Guangcan Yang
Keyword(s):  
Isoelectric Point ◽  
Solution Concentration ◽  
Dna Interaction ◽  
Critical Value ◽  
Magnetic Tweezers ◽  
Charge Neutralization ◽  
Force Microscopy ◽  
Chitosan Concentration ◽  
Atomic Force ◽  
Toxic Gene

Chitosan has been widely used to prepare a DNA carrier for highly efficient and non-toxic gene therapy. In the present study, we investigated DNA charge neutralization and compaction by chitosan in solutions of various pH levels by dynamic light scattering (DLS), magnetic tweezers (MT), and atomic force microscopy (AFM). We found that when chitosan concentration is higher than a critical value (0.2 µM), corresponding the ratio of phosphate and NH2 in chitosan k = 1.9 , the electrophoretic mobility of DNA-chitosan complex maintains an almost constant value when pH of solution is less 6.5, the isoelectric point of chitosan. Then it decreases with increasing pH of solution. However, when chitosan concentration is lower than the critical value, the mobility of the complex increases with pH in the range of acidity and reaches the maximum when the pH of the solution approaches the isoelectric point of chitosan. It finally decreases with increasing pH in solutions. The corresponding condensing force of the DNA-chitosan complex measured by single molecular MT changes accordingly with its charge neutralization in the same solution concentration (20 µM) and is consistent with the DLS measurements. This phenomenon might be related to the weakening interaction between DNA and chitosan in low pH solutions, and is verified by measuring the ratio of free chitosan to DNA complex in solutions. We also observed the various morphologies of DNA-chitosan complexes, such as ring, rod, flower, braid, and other structures, under different degrees of deacetylation, molecular weight, solution concentration and pH in solutions by AFM.

scholarly journals Interaction Mechanism between Molybdenite and Kaolinite in Gypsum Solution Using Kerosene as the Flotation Collector

Minerals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 304 ◽  
Author(s):  
Liqing Sun ◽  
Yijun Cao ◽  
Yinfei Liao ◽  
Zilong Ma
Keyword(s):  
Zeta Potential ◽  
Calcium Ion ◽  
Potential Distribution ◽  
Detrimental Effect ◽  
Adhesion Force ◽  
Interaction Mechanism ◽  
Solution Concentration ◽  
Force Microscopy ◽  
Atomic Force ◽  
Flotation Collector

This paper aims to understand the fundamental interaction mechanism between molybdenite and kaolinite in gypsum solution using kerosene as collector. Micro-flotation tests were conducted to study the effect of gypsum solution on the flotation performance of mixed −74 μm molybdenite and −10 μm kaolinite mineral. The results showed that the recovery of molybdenite decreased from 86% to 74% while the gypsum solution concentration increased from 0 to 800 mg/L, indicating the detrimental effect of kaolinite on molybdenite flotation could be enhanced by gypsum solution. This is mainly caused by the slime coating of kaolinite on molybdenite through dissolved calcium ion of gypsum solution. In order to confirm the slime coating phenomenon, zeta potential distribution, scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements were used to investigate interaction characteristics and mechanisms. The zeta potential distribution results revealed that mixed samples had the value between signal molybdenite and kaolinite samples in gypsum solution, which proved the coating phenomenon of kaolinite on molybdenite. Moreover, the coating phenomenon was becoming more and more obvious with the gypsum solution concentration. The coating phenomenon of kaolinite on molybdenite surface was also directly observed from SEM results. The AFM results provided further evidence for the possibility of slime coating, as the adhesion force increased with the gypsum solution concentration, which means the aggregates of molybdenite and kaolinite were becoming more stable.

scholarly journals DNA Interaction with Palladium Chelates of Biogenic Polyamines Using Atomic Force Microscopy and Voltammetric Characterization

2010 ◽  
Vol 82 (4) ◽  
pp. 1245-1252 ◽  
Author(s):  
O. Corduneanu ◽  
A.-M. Chiorcea-Paquim ◽  
V. Diculescu ◽  
S. M. Fiuza ◽  
M. P. M. Marques ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Dna Interaction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Biogenic Polyamines

DNA interaction of ruthenium(ii) complexes with imidazo[4,5-f][1,10]phenanthroline derivatives

2019 ◽  
Vol 48 (12) ◽  
pp. 3914-3921 ◽  
Author(s):  
Bole Yu ◽  
Thomas W. Rees ◽  
Jiewen Liang ◽  
Chengzhi Jin ◽  
Yu Chen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Atomic Force Microscopy ◽  
Light Scattering ◽  
Gel Electrophoresis ◽  
Dna Interaction ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Spectral Titration

The DNA interaction properties of four Ru(ii) complexes with imidazo[4,5-f][1,10]phenanthroline derivatives were investigated by spectral titration, gel electrophoresis (GAR), dynamic light scattering (DLS), zeta potential, atomic force microscopy (AFM), and transmission electron microscopy (TEM).

Si1-xGex Critical Thickness for Surface Wave Generation During UHV-CVD Growth at 525°C

1995 ◽  
Vol 399 ◽  
Author(s):  
H. Lafontaine ◽  
D.C. Houghton ◽  
B. Bahierathan ◽  
D.D. Perovic ◽  
J.-M. Baribeau
Keyword(s):  
Electron Microscopy ◽  
Surface Waves ◽  
Critical Thickness ◽  
Critical Value ◽  
Misfit Dislocations ◽  
Cross Sectional ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Cvd Growth

ABSTRACTSeveral Si1-xGex/Si heterostructures were grown at 525°C using a commercially available UHV-CVD reactor. Layers with a germanium fraction ranging from 0.15 to 0.5 were examined by means of cross-sectional transmission electron microscopy and atomic force microscopy. Surface waves were found in layers with a thickness above a critical value which decreases rapidly as the Ge fraction is increased. Both experimental and modeling results show that surface waves are generated before misfit dislocations for Ge fractions above 0.3.

Polyethylene glycol and divalent salt-induced DNA reentrant condensation revealed by single molecule measurements

Soft Matter ◽  
2015 ◽  
Vol 11 (19) ◽  
pp. 3927-3935 ◽  
Author(s):  
Chao Cheng ◽  
Jun-Li Jia ◽  
Shi-Yong Ran
Keyword(s):  
Atomic Force Microscopy ◽  
Polyethylene Glycol ◽  
Single Molecule ◽  
Magnetic Tweezers ◽  
Dna Condensation ◽  
Peg 6000 ◽  
Force Microscopy ◽  
Molecular Weights ◽  
Atomic Force ◽  
Peg 600

In this study, we investigated the DNA condensation induced by polyethylene glycol (PEG) with different molecular weights (PEG 600 and PEG 6000) in the presence of NaCl or MgCl2 by using magnetic tweezers (MT) and atomic force microscopy (AFM).

scholarly journals Bioconjugation Strategies for Connecting Proteins to DNA-Linkers for Single-Molecule Force-Based Experiments

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2424
Author(s):  
Lyan M. van der Sleen ◽  
Katarzyna M. Tych
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Optical Tweezers ◽  
Single Molecule ◽  
Short Range ◽  
Force Spectroscopy ◽  
Magnetic Tweezers ◽  
Single Molecule Force Spectroscopy ◽  
Force Microscopy ◽  
Atomic Force

The mechanical properties of proteins can be studied with single molecule force spectroscopy (SMFS) using optical tweezers, atomic force microscopy and magnetic tweezers. It is common to utilize a flexible linker between the protein and trapped probe to exclude short-range interactions in SMFS experiments. One of the most prevalent linkers is DNA due to its well-defined properties, although attachment strategies between the DNA linker and protein or probe may vary. We will therefore provide a general overview of the currently existing non-covalent and covalent bioconjugation strategies to site-specifically conjugate DNA-linkers to the protein of interest. In the search for a standardized conjugation strategy, considerations include their mechanical properties in the context of SMFS, feasibility of site-directed labeling, labeling efficiency, and costs.

Isoelectric Point of Fluorite by Direct Force Measurements Using Atomic Force Microscopy

Langmuir ◽  
2006 ◽  
Vol 22 (4) ◽  
pp. 1403-1405 ◽  
Author(s):  
Shoeleh Assemi ◽  
Jakub Nalaskowski ◽  
Jan D. Miller ◽  
William P. Johnson
Keyword(s):  
Atomic Force Microscopy ◽  
Isoelectric Point ◽  
Force Measurements ◽  
Force Microscopy ◽  
Atomic Force

New ruthenium(II) mixed metallocene derived complexes: Synthesis, characterization by X-ray diffraction and evaluation on DNA interaction by atomic force microscopy

2010 ◽  
Vol 363 (14) ◽  
pp. 3765-3775 ◽  
Author(s):  
M. Helena Garcia ◽  
Andreia Valente ◽  
Pedro Florindo ◽  
Tânia S. Morais ◽  
M. Fátima M. Piedade ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Dna Interaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force

Vibrational CD (VCD) and atomic force microscopy (AFM) study of DNA interaction with Cr3+ ions: VCD and AFM evidence of DNA condensation

Biopolymers ◽  
2002 ◽  
Vol 61 (4) ◽  
pp. 243-260 ◽  
Author(s):  
Valery Andrushchenko ◽  
Zoya Leonenko ◽  
David Cramb ◽  
Hans van de Sande ◽  
Hal Wieser
Keyword(s):  
Atomic Force Microscopy ◽  
Dna Interaction ◽  
Dna Condensation ◽  
Force Microscopy ◽  
Atomic Force
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