scholarly journals AFM Study of the Influence of Glycerol Flow on Horseradish Peroxidase near the in/out Linear Sections of a Coil

2021 ◽  
Vol 11 (4) ◽  
pp. 1723
Author(s):  
Yuri D. Ivanov ◽  
Tatyana O. Pleshakova ◽  
Ivan D. Shumov ◽  
Andrey F. Kozlov ◽  
Irina A. Ivanova ◽  
...  
Keyword(s):  
Horseradish Peroxidase ◽  
Enzymatic Activity ◽  
Protein Adsorption ◽  
Substrate Surface ◽  
Control Sample ◽  
Thermal Stabilization ◽  
Heat Transfer Fluid ◽  
Force Microscopy ◽  
Model Protein ◽  
Linear Sections

Flow-based coiled systems, through which a heat transfer fluid (such as glycerol) is pumped, are widely used for thermal stabilization of bioreactors and biosensor cuvettes and cells. Previously, using horseradish peroxidase (HRP) as a model protein, we have demonstrated that the incubation of a protein solution in a flow-based system over coiled pipe with flowing glycerol leads to a change in the adsorption properties of the protein macromolecules. Herein, we have studied the effect of the glycerol flow on the properties of HRP, the solution of which was placed differently: i.e., near either the inflow or the outflow linear sections of the pipe, while the coiled section of the pipe was shielded with a grounded metallic cover. Atomic force microscopy (AFM) has been employed in order to visualize the HRP protein macromolecules adsorbed from its solution onto the mica substrate surface. The quantity of adsorbed protein was estimated based on the AFM data. The enzymatic activity of HRP was estimated by spectrophotometry. We demonstrate that a change in the properties of HRP enzyme was observed after the incubation of its solution near the inflow/outflow linear sections of the pipe with flowing glycerol. Namely, after the incubation of HRP solution near the inflow section, a decrease in the protein adsorption onto mica was observed, but its enzymatic activity remained unchanged in comparison to the control sample. In another case, when the HRP solution was incubated near the outflow section, an increased protein adsorption was observed, while the enzyme exhibited considerably lower activity.

scholarly journals AFM and FTIR Investigation of the Effect of Water Flow on Horseradish Peroxidase

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 306
Author(s):  
Yuri D. Ivanov ◽  
Tatyana O. Pleshakova ◽  
Ivan D. Shumov ◽  
Andrey F. Kozlov ◽  
Anastasia A. Valueva ◽  
...  
Keyword(s):  
Horseradish Peroxidase ◽  
Enzymatic Activity ◽  
Substrate Surface ◽  
Solid Substrate ◽  
Attenuated Total Reflection ◽  
Flow Section ◽  
Force Microscopy ◽  
Atomic Force ◽  
Influence Of Water ◽  
Actual Direction

Atomic force microscopy (AFM)-based fishing is a promising method for the detection of low-abundant proteins. This method is based on the capturing of the target proteins from the analyzed solution onto a solid substrate, with subsequent counting of the captured protein molecules on the substrate surface by AFM. Protein adsorption onto the substrate surface represents one of the key factors determining the capturing efficiency. Accordingly, studying the factors influencing the protein adsorbability onto the substrate surface represents an actual direction in biomedical research. Herein, the influence of water motion in a flow-based system on the protein adsorbability and on its enzymatic activity has been studied with an example of horseradish peroxidase (HRP) enzyme by AFM, attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) and conventional spectrophotometry. In the experiments, HRP solution was incubated in a setup modeling the flow section of a biosensor communication. The measuring cell with the protein solution was placed near a coiled silicone pipe, through which water was pumped. The adsorbability of the protein onto the surface of the mica substrate has been studied by AFM. It has been demonstrated that incubation of the HRP solution near the coiled silicone pipe with flowing water leads to an increase in its adsorbability onto mica. This is accompanied by a change in the enzyme’s secondary structure, as has been revealed by ATR-FTIR. At the same time, its enzymatic activity remains unchanged. The results reported herein can be useful in the development of models describing the influence of liquid flow on the properties of enzymes and other proteins. The latter is particularly important for the development of biosensors for biomedical applications—particularly for serological analysis, which is intended for the early diagnosis of various types of cancer and infectious diseases. Our results should also be taken into account in studies of the effects of protein aggregation on hemodynamics, which plays a key role in human body functioning.

scholarly journals Growth of Ordered Graphene Ribbons by Sublimation Epitaxy

Crystals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 449
Author(s):  
Shuxian Cai ◽  
Xingfang Liu ◽  
Xin Zheng ◽  
Zhonghua Liu
Keyword(s):  
Substrate Surface ◽  
Graphene Film ◽  
Graphene Ribbon ◽  
High Quality ◽  
Graphene Layers ◽  
Force Microscopy ◽  
Layer Graphene ◽  
Micro Raman Spectroscopy ◽  
Atomic Force ◽  
Few Layer Graphene

Ordered graphene ribbons were grown on the surface of 4° off-axis 4H-SiC wafers by sublimation epitaxy, and characterized by using scanning electron microscopy (SEM), atomic force microscopy (AFM) and micro-Raman spectroscopy (μ-Raman). SEM showed that there were gray and dark ribbons on the substrate surface, and AFM further revealed that these ordered graphene ribbons had clear stepped morphologies due to surface step-bunching. It was shown by μ-Raman that the numbers of graphene layers of these two types of regions were different. The gray region was composed of mono- or bilayer ordered graphene ribbon, while the dark region was of tri- or few-layer ribbon. Meanwhile, ribbons were all homogeneous and had a width up to 40 μm and a length up to 1000 μm, without micro defects such as grain boundaries, ridges, or mono- and few-layer graphene mixtures. The results of this study are useful for optimized growth of high-quality graphene film on silicon carbide crystal.

scholarly journals Lectins at Interfaces—An Atomic Force Microscopy and Multi-Parameter-Surface Plasmon Resonance Study

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2348 ◽  
Author(s):  
Katrin Niegelhell ◽  
Thomas Ganner ◽  
Harald Plank ◽  
Evelyn Jantscher-Krenn ◽  
Stefan Spirk
Keyword(s):  
Atomic Force Microscopy ◽  
Surface Plasmon Resonance ◽  
Protein Adsorption ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Resonance Spectroscopy ◽  
Carbohydrate Binding ◽  
Force Microscopy ◽  
Atomic Force ◽  
Slow Kinetics

Lectins are a diverse class of carbohydrate binding proteins with pivotal roles in cell communication and signaling in many (patho)physiologic processes in the human body, making them promising targets in drug development, for instance, in cancer or infectious diseases. Other applications of lectins employ their ability to recognize specific glycan epitopes in biosensors and glycan microarrays. While a lot of research has focused on lectin interaction with specific carbohydrates, the interaction potential of lectins with different types of surfaces has not been addressed extensively. Here, we screen the interaction of two specific plant lectins, Concanavalin A and Ulex Europaeus Agglutinin-I with different nanoscopic thin films. As a control, the same experiments were performed with Bovine Serum Albumin, a widely used marker for non-specific protein adsorption. In order to test the preferred type of interaction during adsorption, hydrophobic, hydrophilic and charged polymer films were explored, such as polystyrene, cellulose, N,-N,-N-trimethylchitosan chloride and gold, and characterized in terms of wettability, surface free energy, zeta potential and morphology. Atomic force microscopy images of surfaces after protein adsorption correlated very well with the observed mass of adsorbed protein. Surface plasmon resonance spectroscopy studies revealed low adsorbed amounts and slow kinetics for all of the investigated proteins for hydrophilic surfaces, making those resistant to non-specific interactions. As a consequence, they may serve as favorable supports for biosensors, since the use of blocking agents is not necessary.

scholarly journals Investigation of the Influence of Liquid Motion in a Flow-based System on an Enzyme Aggregation State with an Atomic Force Microscopy Sensor: The Effect of Water Flow

2020 ◽  
Vol 10 (13) ◽  
pp. 4560 ◽  
Author(s):  
Yuri D. Ivanov ◽  
Tatyana O. Pleshakova ◽  
Ivan D. Shumov ◽  
Andrey F. Kozlov ◽  
Tatyana S. Romanova ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Enzymatic Activity ◽  
Liquid Flow ◽  
Flow Section ◽  
Liquid Motion ◽  
Aggregation State ◽  
Measuring Cell ◽  
Force Microscopy ◽  
Atomic Force ◽  
Solution Studies

The influence of liquid motion in flow-based systems on the aggregation state of an enzyme and on its enzymatic activity was studied, with horseradish peroxidase (HRP) as an example. Our experiments were carried out in a setup modeling the flow section of the biosensor communication with a measuring cell containing a protein solution. Studies were conducted for a biosensor measuring cell located along the axis of a spiral-moving liquid flow. The aggregation state of the protein was determined with an atomic force microscopy-based sensor (AFM sensor). It has been demonstrated that upon flowing of water through silicone biosensor communications, an increased aggregation of HRP protein was observed, but, at the same time, its enzymatic activity did not change. Our results obtained herein are useful in the development of models describing the influence of liquid flow in biosensor communications on the properties of enzymes and other proteins. This is particularly important for the development of serologic protein biosensors, which are beginning to be used for the early diagnosis of oncological diseases (such as brain cancer, prostate cancer, breast cancer etc.). The results obtained herein should also be taken into account when considering possible changes in hemodynamics due to increased protein aggregation.

Characterization of Inversion Domains in GaN by Electric Force Microscopy in Conjunction with Transmission Electron Microscopy and Wet Chemical Etching

2001 ◽  
Vol 680 ◽  
Author(s):  
F. Yun ◽  
P. Visconti ◽  
K. M. Jones ◽  
A. A. Baski ◽  
H. Morkoç ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Control Sample ◽  
Chemical Vapor ◽  
Dark Field ◽  
Electric Force ◽  
Contact Potential ◽  
Force Microscopy ◽  
Transmission Electron ◽  
Electric Force Microscopy

ABSTRACTInversion domains (IDs) in III-nitride semiconductors degrade the performance of such devices, and so their identification and elimination is critical.An inversion domain on a Ga- polarity samples appears as an N-polarity domain, which has a polarization reversed with respect to the rest of the surface and therefore has a different surface potential. Surface-contact-potential electric force microscopy (SCP-EFM) is an extension of atomic force microscopy (AFM) that allows imaging of the surface electrostatic potential. Previously, we established the particular mode of operation necessary to identify inversion domains on III-nitrides using a control sample. We have now studied inversion domains in GaN films grown by metalorganic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE). The existence of inversion domains was also verified by transmission electron microscopy (TEM) using multiple dark field imaging. In MOCVD grown GaN, we found predominant Ga-polarity with very low density of IDs, while in the MBE GaN, a mix polarity feature was identified.

Surface Properties and Cell Response of Bioactive Thermally Grown TiO2 Nanofibers

2014 ◽  
Vol 575 ◽  
pp. 219-222
Author(s):  
A.W. Tan ◽  
Belinda Pingguan-Murphy ◽  
Roslina Ahmad ◽  
Sheikh Akbar
Keyword(s):  
Surface Roughness ◽  
Articular Chondrocytes ◽  
Substrate Surface ◽  
Control Sample ◽  
Degree Of Crystallinity ◽  
Crystallographic Structure ◽  
Cartilage Growth ◽  
Bovine Articular Chondrocytes

Titania nanofiber (TiO2 NFs) arrays were fabricated in situ on a Ti-6Al-4V substrate by an oxidation process. Their surface morphology, crystallographic structure, surface roughness and wettability were characterized, as well as their in vitro interaction with bovine articular chondrocytes at different time points. Results showed that TiO2 NFs possessed greater surface roughness, hydrophilicity and degree of crystallinity. The in vitro cell studies revealed that TiO2 NFs substrate triggers enhanced cell adhesion, proliferation and extracellular matrix (ECM) formation compared to the untreated control sample. These results showed that chondrocytes have an affinity to the nanofibrous substrate surface and thus we suggest that such surfaces are suited to be used as an implant designed for cartilage growth.

scholarly journals Epitaxial Order Driven by Surface Corrugation: Quinquephenyl Crystals on a Cu(110)-(2×1)O Surface

Crystals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 373 ◽  
Author(s):  
Roland Resel ◽  
Markus Koini ◽  
Jiri Novak ◽  
Steven Berkebile ◽  
Georg Koller ◽  
...  
Keyword(s):  
Thin Film ◽  
Crystal Surface ◽  
Substrate Surface ◽  
Lattice Misfit ◽  
Crystallographic Structure ◽  
Initial Growth ◽  
X Ray Diffraction ◽  
Force Microscopy ◽  
Lattice Matching ◽  
Atomic Force

A 30 nm thick quinquephenyl (5P) film was grown by molecular beam deposition on a Cu(110)(2×1)O single crystal surface. The thin film morphology was studied by light microscopy and atomic force microscopy and the crystallographic structure of the thin film was investigated by X-ray diffraction methods. The 5P molecules crystallise epitaxially with (201)5P parallel to the substrate surface (110)Cu and with their long molecular axes parallel to [001]Cu. The observed epitaxial alignment cannot be explained by lattice matching calculations. Although a clear minimum in the lattice misfit exists, it is not adapted by the epitaxial growth of 5P crystals. Instead the formation of epitaxially oriented crystallites is determined by atomic corrugations of the substrate surface, such that the initially adsorbed 5P molecules fill with its rod-like shape the periodic grooves of the substrate. Subsequent crystal growth follows the orientation and alignment of the molecules taken within the initial growth stage.

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