Electroosmotic Flow in Nanotubes with High Surface Charge Densities

Nano Letters ◽  
2007 ◽  
Vol 8 (1) ◽  
pp. 42-48 ◽  
Author(s):  
Yunfei Chen ◽  
Zhonghua Ni ◽  
Guiming Wang ◽  
Dongyan Xu ◽  
Deyu Li
Keyword(s):  
Surface Charge ◽  
Electroosmotic Flow ◽  
High Surface ◽  
Charge Densities

Molecular Dynamics Simulation of Electroosmotic Flow in Nanotubes

2007 ◽  
Author(s):  
Yunfei Chen ◽  
Zhonghua Ni ◽  
Guiming Wang ◽  
Dongyan Xu ◽  
Deyu Li
Keyword(s):  
Molecular Dynamics ◽  
Surface Charge ◽  
Surface Charge Density ◽  
Electroosmotic Flow ◽  
Continuum Theory ◽  
Ion Distribution ◽  
Charge Inversion ◽  
Charge Densities ◽  
Simulation Results ◽  
The Continuum

The ion distribution and electroosmotic flow of sodium chloride solutions confined in cylindrical nanochannels with different surface charge densities are studied with molecular dynamics (MD). In order to obtain simulation results corresponding to more realistic situations, the MD simulation consists of two steps. The first step is used to equilibrate the system and obtain a more realistic ion distribution in the solution under different surface charge densities; and the second step is to apply an electrical field to drive the liquid and extract the electroosmotic flow information. Simulation results indicate that a higher surface-charge density corresponds to a higher peak of the counter ion concentration. Predictions based on the continuum theory were also calculated and compared with the molecular dynamics results. Even though the continuum theory cannot reflect the molecular nature of ions and water molecules, it is found that for low surface charge densities, the continuum theory can still give reasonable results if modified boundary conditions are applied. Charge inversion under high surface charge density has been predicted and observed recently, however, the simulation results do not indicate charge inversion even for a surface density as high as −0.34 C/m2. This might be due to the fact that we perform the MD simulations with monovalent ions, which have a tendency to suppress charge inversion, as demonstrated in the recent literature.

Electroosmotic Flow in “Click” Surface Modified Microfluidic Channels

2006 ◽  
Author(s):  
Shaurya Prakash ◽  
Timothy M. Long ◽  
Jonathan Wan ◽  
Jeffrey S. Moore ◽  
Mark A. Shannon
Keyword(s):  
Surface Charge ◽  
Photoelectron Spectroscopy ◽  
Electroosmotic Flow ◽  
Separation Efficiency ◽  
High Surface ◽  
High Surface Area ◽  
Attenuated Total Reflection ◽  
Covalent Attachment ◽  
Microfluidic Channels ◽  
Linear Polymers

A rapid, facile, and modular surface modification scheme for the covalent attachment of pre-formed polymer moieties to self-assembled monolayers via ‘click’ chemistry within glass microfluidic channels (3 cm long, 110 μm wide and 15 μm deep) is described. The effect that different moieties have on the electroosmotic flow (EOF) within the microchannels is evaluated. The application of linear polymers such as poly(ethylene glycol) (PEG) generates hydrophilic surfaces that reduce the analyte-wall interactions, thereby increasing separation efficiency and improving resolution, especially in bio-separations. Dendritic polymers such as poly(amido amine) (PAMAM) on channel walls can provide high-surface area structures with tunable surface charge depending on the generation of the dendrimer coating. Modified surfaces are characterized by X-ray photoelectron spectroscopy (XPS), Fourier Transform Infrared-Attenuated Total Reflection spectroscopy (FTIR-ATR), and contact angle measurements. EOF measurements in modified and unmodified channels provide information about wall-analyte interactions. A PAMAM dendrimer coated channel presents an amine terminated surface with a positive charge in contrast to a negatively charged bare-glass surface. Use of surface coatings can lead to an increase of the EOF by 15% as is the case for an azide terminated surface or reverse the direction of EOF as is the case for the PAMAM coatings by changing the surface charge polarity.

A multi-dielectric-layered triboelectric nanogenerator as energized by corona discharge

Nanoscale ◽  
2017 ◽  
Vol 9 (27) ◽  
pp. 9668-9675 ◽  
Author(s):  
Jia Jia Shao ◽  
Wei Tang ◽  
Tao Jiang ◽  
Xiang Yu Chen ◽  
Liang Xu ◽  
...  
Keyword(s):  
Charge Density ◽  
Surface Charge ◽  
Corona Discharge ◽  
Surface Charge Density ◽  
High Surface ◽  
Cycling Stability ◽  
Triboelectric Nanogenerator ◽  
Excellent Cycling Stability ◽  
Vertical Contact ◽  
High Surface Charge Density

A multi-dielectric-layered vertical contact-separation mode TENG through a corona discharge approach results in outstanding output performances, i.e., a high surface charge density of 283 μC m−2 and excellent cycling stability (92.6% retention after 200 000 cycles).

The surface charge on manganese dioxides

Soil Research ◽  
1981 ◽  
Vol 19 (1) ◽  
pp. 41 ◽  
Author(s):  
RM McKenzie
Keyword(s):  
Theoretical Model ◽  
Surface Charge ◽  
Charge Densities

Surface charge was measured on four synthetic manganese dioxides. Charge densities on two cryptomelanes followed closely the values predicted by a theoretical model. Charge densities on two birnessites were much higher, and did not fit the model.

scholarly journals Synthesis, and Characterization, and Evaluation of Cellular Effects of the FOL-PEG-g-PEI-GAL Nanoparticles as a Potential Non-Viral Vector for Gene Delivery

2010 ◽  
Vol 2010 ◽  
pp. 1-10 ◽  
Author(s):  
S. Ghiamkazemi ◽  
A. Amanzadeh ◽  
R. Dinarvand ◽  
M. Rafiee-Tehrani ◽  
M. Amini
Keyword(s):  
Gene Delivery ◽  
Zeta Potential ◽  
Surface Charge ◽  
Cell Line ◽  
Graft Copolymer ◽  
Viral Vector ◽  
Transfection Efficiency ◽  
High Surface ◽  
Liver Cells ◽  
Dna Complexes

In this manuscript, we synthesized the potential non viral vector for gene delivery with proper transfection efficiency and low cytotoxicity. Polyethylenimine (PEI) is a well-known cationic polymer which has high positive surface charge for condensing plasmid DNA. However; it is highly cytotoxic in many cell lines because of the high surface charge, non-biodegradability and non-biocompatibility. To enhance PEI biodegradability, the graft copolymer “PEG-g-PEI” was synthesized. To target cancer liver cells, two targeting ligands folic acid and galactose (lactobionic acid) which are over expressed on human hepatocyte carcinoma were attached to graft copolymer and “FOL-PEG-g-PEI-GAL” copolymer was synthesized. Composition of this grafted copolymer was characterized using1H-NMR and FTIR spectra. The molecular weight and zeta potential of this copolymer was compared to PEI. The particle size and zeta potential of FOL-PEG-g-PEI-GAL/DNA complexes at various N/P ratio were measured using dynamic light scattering (DLS). Cytotoxicity of the copolymer was also studied in cultured HepG2 human hepatoblastoma cell line. The FOL-PEG-g-PEI-GAL/DNA complexes at various N/P ratios exhibited no cytotoxicity in HepG2 cell line compared to PEI 25K as a control. The novel copolymer showed enhanced biodegradability in physiological conditions in compared with PEI and targeted cultured HepG2 cells. More importantly, significant transfection efficiency was exhibited in cancer liver cells. Together, our results showed that “FOL-PEG-g-PEI-GAL” nanoparticals could be considered as a useful non-viral vector for targeted gene delivery.

scholarly journals Mechano-Triboelectric Analysis of Surface Charge Generation on Replica-Molded Elastomeric Nanodomes

Micromachines ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1460
Author(s):  
Myung Gi Ji ◽  
Mohammed Bazroun ◽  
In Ho Cho ◽  
W. Dennis Slafer ◽  
Rana Biswas ◽  
...  
Keyword(s):  
Charge Density ◽  
Surface Charge ◽  
Electrostatic Force ◽  
High Surface ◽  
Interfacial Friction ◽  
Generation Process ◽  
Charge Generation ◽  
Replica Molding ◽  
Force Microscopy ◽  
Triboelectric Charging

Replica molding-based triboelectrification has emerged as a new and facile technique to generate nanopatterned tribocharge on elastomer surfaces. The “mechano-triboelectric charging model” has been developed to explain the mechanism of the charge formation and patterning process. However, this model has not been validated to cover the full variety of nanotexture shapes. Moreover, the experimental estimation of the tribocharge’s surface density is still challenging due to the thick and insulating nature of the elastomeric substrate. In this work, we perform experiments in combination with numerical analysis to complete the mechano-triboelectrification charging model. By utilizing Kelvin probe force microscopy (KPFM) and finite element analysis, we reveal that the mechano-triboelectric charging model works for replica molding of both recessed and protruding nanotextures. In addition, by combining KPFM with numerical electrostatic modeling, we improve the accuracy of the surface charge density estimation and cross-calibrate the result against that of electrostatic force microscopy. Overall, the regions which underwent strong interfacial friction during the replica molding exhibited high surface potential and charge density, while those suffering from weak interfacial friction exhibited low values on both. These multi-physical approaches provide useful and important tools for comprehensive analysis of triboelectrification and generation of nanopatterned tribocharge. The results will widen our fundamental understanding of nanoscale triboelectricity and advance the nanopatterned charge generation process for future applications.

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