scholarly journals Formation of Myoglobin Corona at Polymer Microparticles

2021 ◽  
Vol 5 (2) ◽  
pp. 27
Author(s):  
Zbigniew Adamczyk ◽  
Małgorzata Nattich-Rak
Keyword(s):  
Electrophoretic Mobility ◽  
Physicochemical Characteristics ◽  
Force Microscopy ◽  
Atomic Force ◽  
In Situ Conditions ◽  
Nacl Concentration ◽  
Polymer Microparticles ◽  
The Stability ◽  
Ph Range ◽  
Polystyrene Microparticles

Adsorption of myoglobin molecules at negatively charged polystyrene microparticles was studied using the dynamic light scattering (DLS), electrophoresis (LDV) and the solution depletion method involving atomic force microscopy (AFM). The measurements were carried out at pH 3.5 and NaCl concentration of 10−2 and 0.15 M. Initially, the stability of myoglobin solutions and the particle suspensions as a function of pH were determined. Afterward, the formation of myoglobin molecule corona was investigated via the direct electrophoretic mobility measurements, which were converted to the zeta potential. The experimental results were quantitatively interpreted in terms of the general electrokinetic model. This approach yielded the myoglobin corona coverage under in situ conditions. The maximum hard corona coverage was determined using the AFM concentration depletion method. It was equal to 0.9 mg m−2 for the NaCl concentration in the range 0.01 to 0.15 M and pH 3.5. The electrokinetic properties of the corona were investigated using the electrophoretic mobility measurements for a broad pH range. The obtained results confirmed that thorough physicochemical characteristics of myoglobin molecules can be acquired using nM amounts of the protein. It was also argued that this method can be used for performing electrokinetic characteristics of other proteins such as the SARS-Cov-2 spike protein exhibiting, analogously to myoglobin, a positive charge at acidic pHs.

Growth of 4H-SiC Single Crystals on 6H-SiC Seeds with an Open Backside by PVT Method

2009 ◽  
Vol 615-617 ◽  
pp. 15-18 ◽  
Author(s):  
Emil Tymicki ◽  
Krzysztof Grasza ◽  
Katarzyna Racka ◽  
Marcin Raczkiewicz ◽  
Tadeusz Łukasiewicz ◽  
...  
Keyword(s):  
Single Crystals ◽  
Electron Backscatter Diffraction ◽  
Structural Defects ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Optical Scanning ◽  
Atomic Force ◽  
The Stability ◽  
Backscatter Diffraction ◽  
Source Materials

4H-SiC single crystals grown by the seeded physical vapour transport method have been investigated. These crystals were grown on 6H-SiC seeds. The influence of the seed temperature, form and granulation of SiC source materials on the stability and efficiency of the 4H polytype growth have been investigated. A new way of the seed mounting - with an open backside - has been used. Crystals obtained were free of structural defects in the form of hexagonal voids. The crystalline structure of SiC crystals was investigated by EBSD (Electron Backscatter Diffraction) and X-Ray diffraction methods. Moreover, defects in crystals and wafers cut from these crystals were examined by optical, scanning electron and atomic force microscopy combined with KOH etching.

scholarly journals Flotation Behavior of Diatomite and Albite Using Dodecylamine as a Collector

Minerals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 371 ◽  
Author(s):  
Ying Gao ◽  
Yuexin Han ◽  
Wenbo Li
Keyword(s):  
Unit Area ◽  
Alkaline Ph ◽  
Force Microscopy ◽  
Atomic Force ◽  
Mineral Flotation ◽  
Alkaline Conditions ◽  
Negative Surface ◽  
Negative Surface Charge ◽  
Ph Range ◽  
First Time

The flotation behaviors of diatomite and albite using dodecylamine (DDA) as a collector were investigated and compared. The pure mineral flotation results indicate that the flotability difference between albite and diatomite is above 87% at pH 5.5 to 10.5. The recovery of albite improves with increasing DDA dosage at pH 5.5 to 10.5. In the same pH range, diatomite has weaker flotability than albite, particularly in alkaline pH pulp. Zeta potential measurements indicate that diatomite has a higher negative surface charge than albite at pH 7 to 12, DDA interacts strongly with albite and weakly with diatomite. Thus, DDA preferentially absorbs on albite surface rather than diatomite under alkaline conditions. Fourier transform infrared spectra (FTIR) indicate that the amount of DDA adsorbed to albite is greater than that adsorbed to diatomite, under the same conditions. The adsorption of DDA on the surface of diatomite is investigated by using atomic force microscopy (AFM) for the first time. The adsorption of the collector DDA on the surface of albite per unit area is greater than that on diatomite. This accounts for the lower recovery of diatomite than that of albite.

scholarly journals Probing surface interactions of underwater oleophobic polyelectrolyte multilayers

2020 ◽  
Author(s):  
Kai Li ◽  
Wei Wang ◽  
Zhi-Peng Yu ◽  
Hang Jin ◽  
Yun-Tong Ge ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Interaction Mechanism ◽  
Polyelectrolyte Multilayers ◽  
Layer By Layer ◽  
Surface Wetting ◽  
Force Microscopy ◽  
Atomic Force ◽  
Layer Deposition ◽  
Nacl Concentration ◽  
Force Curves

Abstract In the present work, the interaction mechanism of specific polyelectrolyte multilayers (PEMs), fabricated by layer-by-layer deposition of polydiallyldimethylammonium chloride (PDDA) and poly(sodium 4-styrenesulfonate) (PSS), is studied using atomic force microscopy. The underwater oil-repellency of PSS-capped PEMs was further explored by measuring the interaction forces between tetradecane droplets and PEMs-coated silica substrates under various salinities. The force curves were analyzed following the Stokes–Reynolds–Young–Laplace theoretical model. Desirable consistency was achieved between the experimental and theoretical calculations at low NaCl concentrations (0.1 mM and 1 mM); however, underestimation of the attractive force was found as the NaCl concentration increases to moderate (10 mM) and high (100 mM) levels. Discrepancy analyses and incorporated features toward a reduced surface charge density were considered based on the previous findings of the orientation of anionic benzenesulfonate moieties (Liu et al. in Angew Chem Int Ed 54(16):4851–4856, 2015. https://doi.org/10.1002/anie.201411992). Short-range steric hindrance interactions were further introduced to simulate “brush” effect stemming from nanoscale surface roughness. It is demonstrated in our work that the PSS-capped PEMs remains a stable underwater lipophobicity against high salinity, which renders it potential application in surface wetting modification and anti-fouling.

In Situ and Real-Time Atomic Force Microscopy Studies of the Stability of Oligothiophene Langmuir–Blodgett Monolayers in Liquid

2014 ◽  
Vol 118 (11) ◽  
pp. 5789-5795 ◽  
Author(s):  
Nai-Ning Yin ◽  
Alexander Buyanin ◽  
Shawn L. Riechers ◽  
Olivia P. Lee ◽  
Jean M. J. Fréchet ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Real Time ◽  
Force Microscopy ◽  
Langmuir Blodgett ◽  
Atomic Force ◽  
The Stability

Ta2O5-Incorporated WO3 Nanocomposite Film for Improved Electrochromic Performance in an Acidic Condition

2006 ◽  
Vol 6 (11) ◽  
pp. 3572-3576 ◽  
Author(s):  
Hee-Sang Shim ◽  
Hyo-Jin Ahn ◽  
Youn-Su Kim ◽  
Yung-Eun Sung ◽  
Won Bae Kim
Keyword(s):  
Surface Roughness ◽  
Photoelectron Spectroscopy ◽  
Potential Cycling ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Continuous Potential ◽  
Chemical States ◽  
The Stability

We report electrochromic and electrochemical properties of a WO3-Ta2O5 nanocomposite electrode that was fabricated from co-sputtering. Transmission electron microscopy (TEM)images of the WO3-Ta2O5 nanocomposite electrode revealed that morphology of the WO3 film was changed by incorporation of Ta2O5 nanoparticles, and their chemical states were confirmed to be W6+ and Ta5+ oxides from X-ray photoelectron spectroscopy (XPS). The introduction of Ta2O5 to the WO3 film played a role in alleviating surface roughness increase during continuous potential cycling; whereas the surface roughness of the WO3 film was increased from ca. 3.0 nm to ca. 13.4 nm after 400 cycles, the roughness increase on the WO3-Ta2O5 was significantly reduced to 4.2 nm after 400 cycles, as investigated by atomic force microscopy (AFM). This improvement of the stability by adding Ta2O5 may be responsible for the enhanced electrochemical and optical properties over long-term cycling with the WO3-Ta2O5 nanocomposite electrode.

Uniform Ultimate Boundedness of Probe-to-Probe Dynamics in Dual Probe Atomic Force Microscopy

2014 ◽  
Author(s):  
Ayad Al-Ogaidi ◽  
Douglas Bristow
Keyword(s):  
Switched Systems ◽  
Ultimate Boundedness ◽  
Contact Mode ◽  
Force Microscopy ◽  
Simultaneous Imaging ◽  
Atomic Force ◽  
State Dependent ◽  
Uniform Ultimate Boundedness ◽  
The Stability ◽  
Dual Probe

Atomic force microscopes use a probe to interface with matter at the nanoscale through a variety of imaging or manipulation methods. A dual-probe atomic force microscope (DP-AFM) has been proposed for simultaneous imaging and manipulation. One challenge of DP-AFM is probe-to-probe contact, which may occur intentionally such as when locating one probe with the other. This work studies the stability for such interactions where the 1st probe is in the tapping mode (typically used for imaging) and 2nd probe is in the contact mode (typically used for manipulation). A state dependent switched model is proposed for DP-AFM. A theorem is proposed for uniformly ultimately bounded (UUB) stability of switched systems under a sequence nonincreasing condition and applied to the DP-AFM problem.

scholarly journals The Influence of the Preparation and Stability of Nanofluids for Heat Transfer

2019 ◽  
Vol 25 (4) ◽  
pp. 45-54 ◽  
Author(s):  
Noor Sabih Majeed ◽  
Basma A. Abdulmajeed ◽  
Anwar Khudhur Yaseen
Keyword(s):  
Heat Transfer ◽  
Electron Microscopy ◽  
Base Fluid ◽  
X Ray Diffraction ◽  
Step Method ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Stability ◽  
Scanning Electron

Recently the use of nanofluids represents very important materials. They are used in different branches like medicine, engineering, power, heat transfer, etc. The stability of nanofluids is an important factor to improve the performance of nanofluids with good results. In this research two types of nanoparticles, TiO2 (titanium oxide) and γ-Al2O3 (gamma aluminum oxide) were used with base fluid water. Two-step method were used to prepare the nanofluids. One concentration 0.003 vol. %, the nanoparticles were examined. Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and X-ray diffraction (XRD) were used to accomplish these tests. The stability of the two types of nanofluids is measured by zeta potential and UV-vis spectrophotometer. The results showed that γ-Al2O3/water has more stable than TiO2/ water for the same period of time.  

Synergistic effect of polyvinylpyrrolidone noncovalently modified graphene and epoxy resin in anticorrosion application

2020 ◽  
pp. 095400832094229
Author(s):  
Shifeng Wen ◽  
Jiacheng Ma
Keyword(s):  
Epoxy Resin ◽  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Covalent Modification ◽  
Original Structure ◽  
Graphene Layers ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Stability ◽  
Modified Graphene

In this article, polyvinylpyrrolidone (PVP) was used for the noncovalent modification on the surface of graphene. Compared with covalent modification, this method maintained the original structure of graphene layers, thereby maximizing the original properties of graphene. The π–π noncovalent bond was formed between PVP and graphene by X-ray photoelectron spectroscopy analysis, indicating that PVP successfully modified graphene. The thickness of graphene layer was measured by atomic force microscopy, which showed that the distance between graphene layers was increased by 5–6 nm, and the stability of the modified graphene in N, N-dimethylformamide was remarkably improved. The obtained composite coating by combination of the modified graphene and the epoxy resin was subjected to electrochemical impedance test to obtain the best anticorrosive effect of the coating with the graphene content of 0.3 wt%. The results showed that the addition of graphene to the epoxy resin could effectively improve the anticorrosive effect. Meanwhile, the good electrical conductivity allowed the electrons which lost from the substrate to led to air or saline rapidly, thereby reducing the combination of iron ions with oxygen and the generation of corrosion products (iron oxides).

High Resolution DNA Imaging by Dynamic Atomic Force Microscopy: The Effect of the Substrate and Sample Preparation

2014 ◽  
Vol 1652 ◽  
Author(s):  
Tzu-Chieh Tang ◽  
Carlo A. Amadei ◽  
Matteo Chiesa
Keyword(s):  
Atomic Force Microscopy ◽  
Metal Ions ◽  
Physicochemical Characteristics ◽  
Temporal Variations ◽  
Point Of View ◽  
Ion Distribution ◽  
Nickel Ion ◽  
Force Microscopy ◽  
Atomic Force ◽  
Force Profile

ABSTRACTAdsorption of charged biomolecules onto atomically flat mica substrates is facilitated by the deposition of metal ions. Despite successfully acting as preferential anchoring sites, the presence of ions on the mica surface also changes its physicochemical characteristics something that is rarely quantified from a nanoscale point of view. In this study the nanoscale physicochemical properties of nickel-functionalized Muscovite mica are investigated by reconstructing the conservative force profile between an atomic force microscopy (AFM) tip and the surface. Various nickel ion concentrations (i.e. 1.0 mM to 20.0 mM) along with different incubation times (30 seconds and 5 minutes) are directly analyzed. Details in the spatial and temporal variations in surface properties due to the ion mediated adsorption of water are presented in details and in light of the binding efficiency of the metal ions. This insight benefits our understanding in the behavior of ion distribution that plays a crucial role in biomolecule imaging using AFM.

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