Comparison of the Stability of Surface-Modified SWNTs and DWNTs Network Films

2010 ◽  
Vol 114 (10) ◽  
pp. 4394-4398 ◽  
Author(s):  
Seung Bo Yang ◽  
Byung-Seon Kong ◽  
Dae-Woo Kim ◽  
Hee-Tae Jung
Keyword(s):  
The Stability ◽  
Surface Modified

scholarly journals Silver Nanoparticles Surface-Modified with Carbosilane Dendrons as Carriers of Anticancer siRNA

2020 ◽  
Vol 21 (13) ◽  
pp. 4647 ◽  
Author(s):  
Elżbieta Pędziwiatr-Werbicka ◽  
Michał Gorzkiewicz ◽  
Katarzyna Horodecka ◽  
Viktar Abashkin ◽  
Barbara Klajnert-Maculewicz ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Silver Nanoparticles ◽  
Lymphocyte Proliferation ◽  
Intracellular Transport ◽  
Genetic Material ◽  
Hydrodynamic Diameter ◽  
Transmission Electron ◽  
The Stability ◽  
Surface Modified ◽  
Sites Of Action

Gene therapy is a promising approach in cancer treatment; however, current methods have a number of limitations mainly due to the difficulty in delivering therapeutic nucleic acids to their sites of action. The application of non-viral carriers based on nanomaterials aims at protecting genetic material from degradation and enabling its effective intracellular transport. We proposed the use of silver nanoparticles (AgNPs) surface-modified with carbosilane dendrons as carriers of anticancer siRNA (siBcl-xl). Using gel electrophoresis, zeta potential and hydrodynamic diameter measurements, as well as transmission electron microscopy, we characterized AgNP:siRNA complexes and demonstrated the stability of nucleic acid in complexes in the presence of RNase. Hemolytic properties of free silver nanoparticles and complexes, their effect on lymphocyte proliferation and cytotoxic activity on HeLa cells were also examined. Confocal microscopy proved the effective cellular uptake of complexes, indicating the possible use of this type of silver nanoparticles as carriers of genetic material in gene therapy.

scholarly journals Evaluating the potential of surface-modified silica nanoparticles using internal olefin sulfonate for enhanced oil recovery

2019 ◽  
Vol 17 (3) ◽  
pp. 722-733 ◽  
Author(s):  
Afaque Ahmed ◽  
Ismail Mohd Saaid ◽  
Abdelazim Abbas Ahmed ◽  
Rashidah M. Pilus ◽  
Mirza Khurram Baig
Keyword(s):  
Silica Nanoparticles ◽  
Rheological Properties ◽  
Oil Recovery ◽  
Displacement Efficiency ◽  
Shear Rates ◽  
Oil Water ◽  
Core Flood ◽  
The Stability ◽  
Modified Silica Nanoparticles ◽  
Surface Modified

AbstractRecently, nanoparticles have proven to enhance oil recovery on the core-flood scale in challenging high-pressure high-temperature reservoirs. Nanomaterials generally appear to improve oil production through wettability alteration and reduction in interfacial tension between oil and water phases. Besides, they are environmentally friendly and cost-effective enhanced oil recovery techniques. Studying the rheological properties of nanoparticles is critical for field applications. The instability of nanoparticle dispersion due to aggregation is considered as an unfavorable phenomenon in nanofluid flooding while conducting an EOR process. In this study, wettability behavior and rheological properties of surface-treated silica nanoparticles using internal olefins sulfonates (IOS20–24 and IOS19–23), anionic surfactants were investigated. Surface modification effect on the stability of the colloidal solution in porous media and oil recovery was inspected. The rheology of pure and surface-treated silica nanoparticles was investigated using a HPHT rheometer. Morphology and particle size distributions of pure and coated silica nanoparticles were studied using a field emission scanning electron microscope. A series of core-flood runs was conducted to evaluate the oil recovery factor. The coated silica nanoparticles were found to alter rheological properties and exhibited a shear-thinning behavior as the stability of the coated silica nanoparticles could be improved considerably. At low shear rates, the viscosity slightly increases, and the opposite happens at higher shear rates. Furthermore, the surface-modified silica nanoparticles were found to alter the wettability of the aqueous phase into strongly water-wet by changing the contact angle from 80° to 3° measured against glass slides representing sandstone rocks. Oil–water IFT results showed that the surface treatment by surfactant lowered the oil–water IFT by 30%. Also, the viscosity of brine increased from 0.001 to 0.008 Pa s by introducing SiO2 nanoparticles to the aqueous phase for better displacement efficiency during chemical-assisted EOR. The core-flood experiments revealed that the ultimate oil recovery is increased by approximately 13% with a surfactant-coated silica nanofluid flood after the conventional waterflooding that proves the potential of smart nanofluids for enhancing oil recovery. The experimental results imply that the use of surfactant-coated nanoparticles in tertiary oil recovery could facilitate the displacement efficiency, alter the wettability toward more water-wet and avoid viscous fingering for stable flood front and additional oil recovery.

Physicochemical properties and tribological performance of motorbike lubricant dispersed with surface-modified WS2 nanoparticles

2019 ◽  
Vol 233 (9) ◽  
pp. 1379-1388 ◽  
Author(s):  
V Srinivas ◽  
RN Thakur ◽  
AK Jain ◽  
M Saratchandra Babu
Keyword(s):  
Physicochemical Properties ◽  
Fuel Consumption ◽  
Viscosity Index ◽  
Tribological Performance ◽  
Engine Oil ◽  
Engine Wear ◽  
Endurance Tests ◽  
The Stability ◽  
Surface Modified ◽  
Engine Components

This paper investigates the effect of dispersion of surface-modified WS2 nanoparticles on the tribological performance and physicochemical properties of motorbike lubricant. Surface-assisted WS2 nanoparticles were dispersed in motorbike engine oil and an optimum amount of surfactant for best stability of the lubricant suspension was found by investigating the changes in the physicochemical properties of lubricant. The stability analysis using light scattering techniques confirmed the stability of nanoparticles dispersed in lubricant medium and surface-modified WS2 nanoparticles remained stable for 180 days. The physicochemical properties were evaluated as per ASTM standards over a period of two months to check the state of lubricant and observable changes in the properties during this period. The tribological performance of the lubricants was assessed by conducting endurance tests on a 100 cc motor bike. The performance was evaluated by checking the wear of the engine components and fuel consumption. It was found that there were no abnormal changes in the physicochemical properties of lubricant up to a certain surfactant to nanoparticle ratio indicating its utility in automotive engines. However, if the amount of surfactant was increased beyond optimum quantity abnormal changes are seen in the viscosity index, leading to the deterioration of key lubricant properties. Lubricant dispersed with WS2 nanoparticles gave good performance characterized by the reduction in both engine wear and fuel consumption. Worn surfaces of the oil rings after the endurance test were assessed for deposits and it was found that a layer of WS2 deposited on the oil ring surface that reduced friction and wear.

Effects of Rhamnolipids on Enzymatic Hydrolysis of Bamboo Biomass and Mechanism

2020 ◽  
Vol 14 (4) ◽  
pp. 453-460
Author(s):  
Ruyi Sha ◽  
Zhan Yu ◽  
Zhenzhen Wang ◽  
Edwin Menledy Gbor ◽  
Ligang Jiang ◽  
...  
Keyword(s):  
Enzymatic Hydrolysis ◽  
Fluorescence Probe ◽  
Economic Losses ◽  
Dilute Acid ◽  
Site Of Action ◽  
The Stability ◽  
Surface Modified ◽  
Hydrolysis Of ◽  
Positive Effect

The lignin present in lignocellulose seriously affects the efficiency of cellulose enzymatic hydrolysis. In addition, lignin adsorbs high-cost cellulase, causing greater economic losses. Lignin can also disturb the site of action of cellulase and reduce the efficiency of hydrolysis. Therefore, if lignin is removed or surface modified before cellulose enzymatic hydrolysis, the enzymatic hydrolysis efficiency of lignocellulosic biomass will be greatly improved. In this paper, the cellulose enzymatic properties of bamboo biomass being treated with dilute acid and alkaline under the intervention of biosurfactant rhamnolipid were evaluated. The effects of rhamnolipids on the adsorption characterization of cellulose on pretreated bamboo were studied. Besides, the inter-communication between rhamnolipids and cellulose was investigated by fluorescence probe. The results showed that rhamnolipids could have a positive effect on the enzymatic hydrolysis of bamboo biomass by reducing the non-productive adsorption of cellulase on the surface of lignocellulose. The outcome illustrated that cellulase could be combined with rhamnolipids micelles, participating in the formation of rhamnolipids micelles, thereby increasing the internal hydrophobicity of the micelles, but could not change the properties of rhamnolipids micelles higher than one CMC (Critical Micelle Concentration). It can be seen that the interaction between rhamnolipids and cellulase is beneficial to enhance the stability and enzymatic activity of cellulase, thereby improving the enzymatic hydrolysis efficiency of cellulose in biomass. Based on these results, a theoretical knowledge about the mechanism of enhancing the enzymatic hydrolysis efficiency of lignocellulose by biosurfactants rhamnolipids is provided.

scholarly journals Characterization and Nanofluid Stability of CoFe2O4-APTES and CoFe2O4-PVA Nanoparticles

2020 ◽  
Vol 78 (1) ◽  
pp. 79-87
Author(s):  
Anis Arisa Roslan ◽  
Hasnah Mohd Zaid ◽  
Siti Nur Azella Zaine ◽  
Mursyidah Umar ◽  
Beh Hoe Guan
Keyword(s):  
Surface Modification ◽  
Zeta Potential ◽  
Performance Studies ◽  
Colloidal Stability ◽  
Amino Silane ◽  
Cobalt Iron Oxide ◽  
One Step ◽  
The Stability ◽  
Surface Modified ◽  
Surface Modified Nanoparticles

Nanofluid contains nanoparticles that enhanced the property of the base fluid. However, the separating layer between the nanoparticles and base fluids may interfere the nanofluids performance. Studies have been made that surface modification of nanoparticles may improve the dispersion of nanoparticles in base fluids. This paper reports the study of the colloidal stability of surface modified nanoparticles using a polymer and an amino-silane. The nanoparticles were prepared by one-step and two-step methods using cobalt iron oxide nanoparticles with brine solution and deionized water as the base fluids. Functionalization by surface modification of the nanoparticles to enhance the nanofluids stability was carried out using (3-aminopropyl) triethoxysilane (APTES) and polyvinyl alcohol (PVA). Characterization using Fourier Transform Infrared (FTIR), Field Emission Scanning Electron Microscope (FESEM) and X-ray Powder Diffraction (XRD) were performed to study the functionality and morphology of the synthesized nanoparticles. The extra IR peaks such as Si-O-Si at 1063 cm-1 for CoFe2O4-APTES and C=O at 1742 cm-1 for CoFe2O4-PVA showed that there are additional elements in the cobalt ferrite due to functionalization. The size of synthesized CoFe2O4-APTES ranged between 15.99 nm to 26.89 nm while CoFe2O4-PVA is from 25.70 nm to 54.16 nm. The stability of the nanofluid were determined via zeta potential measurements. CoFe2O4-APTES nanofluid has zeta potential of -35.7 mV compared to CoFe2O4-PVA at -15.5 mV.

scholarly journals Transformation and Cytotoxicity of Surface-Modified Silver Nanoparticles Undergoing Long-Term Aging

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2255 ◽  
Author(s):  
Chengfang Pang ◽  
Panhong Zhang ◽  
Yunsong Mu ◽  
Jingzheng Ren ◽  
Bin Zhao
Keyword(s):  
Silver Nanoparticles ◽  
Life Cycle ◽  
Aging Process ◽  
Consumer Products ◽  
Risk Assessments ◽  
The Stability ◽  
Surface Modified ◽  
Phosphate Buffered Saline ◽  
Shape Changes

Silver nanoparticles (AgNPs) are constituents of many consumer products, but the future of their production depends on ensuring safety. The stability of AgNPs in various physiological solutions and aging in storage may affect the accuracy of predicted nanoparticle toxicity. The goal of this study was to simulate the transformation of AgNPs in different media representatives to the life cycle in the environment and to identify their toxicity to Hepa1c1c7 cells in a long-term aging process. AgNPs coated with citrate, polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), and branched polyethyleneimine (BPEI) were studied. Our results show that the exposure media had a significant impact on the transformation of AgNPs. Citrate-coated AgNPs showed significant aggregation in phosphate-buffered saline. The aging of AgNPs in optimal storage showed that the charge-stabilized particles (citrate) were more unstable, with significant aggregation and shape changes, than sterically stabilized particles (PEG AgNPs, PVP AgNPs). The BPEI AgNPs showed the highest dissolution of AgNPs, which induced significantly increased toxicity to Hepa1c1c7 cells. Overall, our findings showed that storage and media of AgNPs influenced the transformation of AgNPs and that the resulting changes in the AgNPs’ physicochemical properties influenced their toxicity. Our study contributes to the understanding of AgNPs’ transformations under realistic exposure scenarios and increasing the predictability of risk assessments.

scholarly journals Stabilization of β-Galactosidase on Modified Gold Nanoparticles: A Preliminary Biochemical Study to Obtain Lactose-Free Dairy Products for Lactose-Intolerant Individuals

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1226
Author(s):  
Asim Muhammed Alshanberi ◽  
Rukhsana Satar ◽  
Shakeel Ahmed Ansari
Keyword(s):  
Gold Nanoparticles ◽  
Dairy Products ◽  
Biochemical Study ◽  
Volume Ratio ◽  
Surface Characteristics ◽  
Uv Spectra ◽  
Temperature Ranges ◽  
The Stability ◽  
Operational Activity ◽  
Surface Modified

The unique chemical, optical, and electrical characteristics of nanoparticles make their utilization highly successful in every field of biological sciences as compared to their bulk counterpart. These properties arise as a result of their miniature size, which provides them an excellent surface area-to-volume ratio, inner structure, and shape, and hence increases their surface characteristics. Therefore, this study was undertaken to engineer gold nanoparticles (AuNPs) for improving their catalytic activity and stability in biotechnological processes. The characterization of AuNPs was performed by XRD, UV spectra, and TEM. The synthesized AuNPs were surface-modified by polyvinyl alcohol (PVA) for binding the enzyme in excellent yield. The developed immobilized enzyme system (PVA-AuNPs-β-galactosidase) displayed pH optima at pH 7.0 and temperature optima at 40 °C. Moreover, the stability of PVA-AuNPs-β-galactosidase was significantly enhanced at wider pH and temperature ranges and at higher galactose concentrations, in contrast to the free enzyme. β-galactosidase bound to PVA-modified AuNPs exhibited greater operational activity, even after its sixth reuse. The developed nanosystem may prove useful in producing lactose-free dairy products for lactose-intolerant patients.

Investigation of the stability in emulsions stabilized with different surface modified titanium dioxides

2004 ◽  
Vol 232 (2-3) ◽  
pp. 261-267 ◽  
Author(s):  
S. Stiller ◽  
H. Gers-Barlag ◽  
M. Lergenmueller ◽  
F. Pflücker ◽  
J. Schulz ◽  
...  
Keyword(s):  
The Stability ◽  
Surface Modified ◽  
Titanium Dioxides

scholarly journals Structural Changes in the PACVD -Modified Para-Aramid, Ballistic Textiles During the Accelerated Ageing

2017 ◽  
Vol 25 (0) ◽  
pp. 36-41
Author(s):  
Marcin Struszczyk ◽  
Wiesława Urbaniak–Domagała ◽  
Adam Puszkarz ◽  
Bożena Wilbik-Hałgas ◽  
Magdalena Cichecka ◽  
...  
Keyword(s):  
Structural Properties ◽  
Surface Properties ◽  
Structural Changes ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Woven Fabrics ◽  
Accelerated Ageing ◽  
The Stability ◽  
Surface Modified ◽  
And Storage

The process of textile modification using Plasma Assisted Chemical Vapour Deposition (PACVD) results in significant changes in surface properties with high effectivity. However, the main problem of the above-mentioned modification is to obtain a stable modification effect during standard use and storage. The aim of the study was to determine the stability of structural properties of PACVD-modified para-aramid ballistic woven fabrics during accelerated ageing using temperature or simultaneously temperature and humidity as the accelerated ageing factors. For identification of potential changes in the textile surface modified by PACVD with deposition of the polymer formed based on tetradecafluorohexane, the ATR-FTIR and SEM/EDS techniques were applied. The PACVD-modified textiles showed insignificant changes in structural properties after accelerated ageing using the above-men -tioned ageing factors. This confirms the stability of the PACVD-resulted modification during simulated conditions of standard use.

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