scholarly journals MWNTs or PEG as Stability Enhancers for DNA–Cationic Surfactant Gel Particles

2021 ◽  
Vol 22 (16) ◽  
pp. 8801
Author(s):  
Amalia Mezei ◽  
Ramon Pons
Keyword(s):  
Cationic Surfactant ◽  
Acid Media ◽  
X Ray Scattering ◽  
Gel Particles ◽  
Composite Gel ◽  
Multi Walled Carbon Nanotubes ◽  
Formation And Evolution ◽  
Poly Ethylene ◽  
The Stability ◽  
Walled Carbon Nanotubes

Cationic surfactants interact with DNA (Deoxyribonucleic acid), forming surfactant-DNA complexes that offer particularly efficient control for encapsulation and release of DNA from DNA gel particles. In the present work, DNA-based particles were prepared using CTAB (Cetyltrimethylammonium bromide) as the cationic surfactant and modified using two different additives: (Multi-Walled Carbon Nanotubes) MWNT or PEG (Poly Ethylene Glycol). The use of both additives to form composites increased the stability of the gel particles. The stability was monitored by the release of DNA and CTAB in different pH solutions. However, not much is known about the influence of pH on DNA–surfactant interaction and the release of DNA and surfactant from gel particles. It was observed that the solubilization of DNA occurs only in very acid media, while that of CTAB does not depend on pH and gets to a plateau after about 8 h. Within 2 h in contact with a pH = 2 solution, about 1% DNA and CTAB was released. Complete destruction for the gel particles was observed in pH = 2 solution after 17 days for PEG and 20 days for MWNT. The composite particles show a considerably enlarged sustained release span compared to the unmodified ones. The dehydration-rehydration studies show that the structure of the composite gel particles, as determined from SAXS (Small-Angle-X-Ray-Scattering) experiments, is similar to that of the unmodified ones. These studies will allow a better knowledge of these particles’ formation and evolution in view of possible applications in drug delivery and release.

Green Synthesis of Poly(ethylene Glycol) Modified Multi-Walled Carbon Nanotubes and their Dispersibility

2013 ◽  
Vol 320 ◽  
pp. 456-459
Author(s):  
Jin Gang Yu ◽  
Xin Yu Jiang ◽  
Xiao Qing Chen ◽  
Fei Peng Jiao ◽  
Zhi Guang Peng ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Ethylene Glycol ◽  
Green Synthesis ◽  
Ethanol Solution ◽  
Poly Ethylene Glycol ◽  
Reduced Pressure ◽  
Multi Walled Carbon Nanotubes ◽  
Poly Ethylene ◽  
The Stability ◽  
Walled Carbon Nanotubes

Poly (ethylene glycol) modified multi-walled carbon nanotubes were prepared by a green synthesis procedure, including oxidation, acyl chlorination and alcoholysis. All the liquid reagents were recycled by distillation or reduced pressure distillation, and complicated washing or purification was simplified. Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis were used to characterize the samples. The results indicated that PEG was grafted to the functionalized carbon nanotubes (f-CNTs) and the mass percentage of the grafted PEG was about 12%. After sonicatingf-CNTs in ethanol, the dispersibility off-CNTs in ethanol was about 0.46 mg/mL. The stability off-CNTs in ethanol was also tested by left standing a 0.4 mg/mLf-CNT/ethanol solution, no precipitation was found after 10 days.

scholarly journals Stabilizing effect of methylcellulose on the dispersion of multi-walled carbon nanotubes in cementitious composites

2020 ◽  
Vol 9 (1) ◽  
pp. 93-104
Author(s):  
Mingrui Du ◽  
Yuan Gao ◽  
Guansheng Han ◽  
Luan Li ◽  
Hongwen Jing
Keyword(s):  
Carbon Nanotubes ◽  
Pore Solution ◽  
Cementitious Materials ◽  
High Ionic Strength ◽  
Cementitious Composites ◽  
Uniform Distributions ◽  
Stabilizing Effect ◽  
Multi Walled Carbon Nanotubes ◽  
The Stability ◽  
Walled Carbon Nanotubes

AbstractMulti-walled carbon nanotubes (MWCNTs) have been added in the plain cementitious materials to manufacture composites with the higher mechanical properties and smart behavior. The uniform distributions of MWCNTs is critical to obtain the desired enhancing effect, which, however, is challenged by the high ionic strength of the cement pore solution. Here, the effects of methylcellulose (MC) on stabilizing the dispersion of MWCNTs in the simulated cement pore solution and the viscosity of MWCNT suspensions werestudied. Further observations on the distributions of MWCNTs in the ternary cementitious composites were conducted. The results showed that MC forms a membranous envelope surrounding MWCNTs, which inhibits the adsorption of cations and maintains the steric repulsion between MWCNTs; thus, the stability of MWCNT dispersion in cement-based composites is improved. MC can also work as a viscosity adjuster that retards the Brownian mobility of MWCNTs, reducing their re-agglomerate within a period. MC with an addition ratio of 0.018 wt.% is suggested to achieve the optimum dispersion stabilizing effect. The findings here provide a way for stabilizing the other dispersed nano-additives in the cementitious composites.

Multi-Walled Carbon Nanotubes as Electrocatalyst Supports for H2O2 Reduction Reaction

2013 ◽  
Vol 860-863 ◽  
pp. 831-834
Author(s):  
Dan Zheng ◽  
Ting Fang Yang ◽  
Zhang Fei Guo
Keyword(s):  
Cyclic Voltammetry Curve ◽  
Chemical Reduction ◽  
Reduction Reaction ◽  
Carbon Substrate ◽  
Acid Media ◽  
Multi Walled Carbon Nanotube ◽  
Multi Walled Carbon Nanotubes ◽  
Current Densities ◽  
Reaction Activation Energy ◽  
Walled Carbon Nanotubes

This work studies the use of Multi-walled carbon nanotube (MWCNT) as catalyst supports for H2O2 electro-reduction in acid media. Using impregnation-chemical reduction method, we prepared Pt-Ag/CNTs, Pt-Co/CNTs, Pt-Ag/C and Pt-Co/C nanocatalysts. Four catalysts were analyzed by XRD and TEM. Their electrochemical performance was studied via cyclic voltammetry curve. The results show that: the nanoparticles have a better dispersion on CNTs substrate than on XC-72 carbon substrate. Comparing with Pt-Ag and Pt-Co on XC-72 carbon substrate, the H2O2 reduction reaction activation energy of catalysts on CNTs substrate is bigger, and the peak current densities of catalysts on CNTs substrate are larger than that on XC-72 carbon.

Thermal Conductivity Measurement for Carbon-Nanotube Suspensions with 3ω Method

2009 ◽  
Vol 60-61 ◽  
pp. 394-398 ◽  
Author(s):  
Gen Sheng Wu ◽  
Jue Kuan Yang ◽  
Shu Lin Ge ◽  
Yu Juan Wang ◽  
Min Hua Chen ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Volume Fraction ◽  
Aqueous Suspension ◽  
Conductivity Measurement ◽  
3Ω Method ◽  
Conductivity Enhancement ◽  
Multi Walled Carbon Nanotubes ◽  
The Stability ◽  
Walled Carbon Nanotubes

The stable and homogeneneous aqueous suspension of carbon nanotubes was prepared in this study. The stability of the nanofluids was improved greatly due to the use of a new dispersant, humic acid. The thermal conductivity of the aqueous suspension was measured with the 3ω method. The experimental results showed that the thermal conductivity of the suspensions increases with the temperature and also is nearly proportional to the loading of the nanoparticles. The thermal conductivity enhancement of single-walled carbon nanotubes (SWNTs) suspensions is better than that of the multi-walled carbon nanotubes (MWNTs) suspensions. Especially for a volume fraction of 0.3846% SWNTs, the thermal conductivity is enhanced by 40.5%. Furthermore, the results at 30°C match well with Jang and Choi’s model.

Noncovalent functionalization of hole-transport materials with multi-walled carbon nanotubes for stable inverted perovskite solar cells

2019 ◽  
Vol 7 (45) ◽  
pp. 14306-14313 ◽  
Author(s):  
Yu Lu ◽  
Xueping Zong ◽  
Yilei Wang ◽  
Wenhua Zhang ◽  
Quanping Wu ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Solar Cells ◽  
Perovskite Solar Cells ◽  
Hole Transport ◽  
Promising Strategy ◽  
Noncovalent Functionalization ◽  
Multi Walled Carbon Nanotubes ◽  
The Stability ◽  
Walled Carbon Nanotubes

A new promising strategy to improve the stability of inverted perovskite solar cells is reported.

Variational Principles for the Stability Analysis of Multi-Walled Carbon Nanotubes Based on a Nonlocal Elastic Shell Model

2010 ◽  
Author(s):  
Mohsen Asghari ◽  
Jacob Rafati
Keyword(s):  
Carbon Nanotubes ◽  
Stability Analysis ◽  
Inverse Method ◽  
Variational Principles ◽  
Elastic Shell ◽  
Multi Walled Carbon Nanotubes ◽  
Natural Boundary Conditions ◽  
The Stability ◽  
Walled Carbon Nanotubes ◽  
Continuum Theories

The nonlocal continuum theories are capable to reflect the small length characteristic of nanostructures. In this work, variational principles are presented for the stability analysis of multi-walled carbon nanotubes under various mechanical loadings based on the nonlocal elastic Donnell’s shell by the semi-inverse method. In this manner, a set of proper essential and natural boundary conditions for each layer of the multi-walled nanotube is derived.

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