Conformational Behavior, Topographical Features, and Antioxidant Activity of Partly De-Esterified Arabinoxylans

This study aimed to investigate the effect of arabinoxylans (AX) partial de-esterification with feruloyl esterase on the polysaccharide conformational behavior, topographical features, and antioxidant activity. After enzyme treatment, the ferulic acid (FA) content in AX was reduced from 7.30 to 5.48 µg FA/mg polysaccharide, and the molecule registered a small reduction in radius of gyration (RG), hydrodynamic radius (Rh), characteristic ratio (C∞), and persistence length (q). A slight decrease in α and a small increase in K constants in the Mark–Houwink–Sakurada equation for partially de-esterified AX (FAX) suggested a reduction in molecule structural rigidity and a more expanded coil conformation, respectively, in relation to AX. Fourier transform infrared spectroscopy spectra of AX and FAX presented a pattern characteristic for this polysaccharide. Atomic force microscopy topographic analysis of FAX showed a more regular surface without larger hollows in relation to AX. The antioxidant activity of FAX, compared to AX, was reduced by 30 and 41% using both 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS+) and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) methods, respectively. These results suggest that feruloyl esterase treatment of AX could offer a strategy to tailor AX chains conformation, morphological features, and antioxidant activity, impacting the development of advanced biomaterials for biomedical and pharmaceutical applications.

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The Reactive Formation of Diblock Copolymer at a Polymer/Polymer Interface and its Effect on Interfacial Structure

MRS Proceedings ◽

10.1557/proc-629-ff2.2 ◽

2000 ◽

Vol 629 ◽

Cited By ~ 1

Author(s):

Jonathan S. Schulze ◽

Timothy P. Lodge ◽

Christopher W. Macosko

Keyword(s):

Molecular Weight ◽

Interfacial Structure ◽

Root Mean Square Roughness ◽

Radius Of Gyration ◽

Interfacial Region ◽

Force Microscopy ◽

Amino Terminal ◽

Polymer Interface ◽

Atomic Force ◽

Time Required

ABSTRACTThe reaction of perdeuterated amino-terminal polystyrene (dPS-NH2) with anhydrideterminal poly(methyl methacrylate) (PMMA-anh) at a PS/PMMA interface has been observed with forward recoil spectrometry (FRES). Bilayer samples were constructed by placing thin films of PS containing ∼8.5 wt % dPS-NH2 on a PMMA-anh layer. Significant reaction was observed only after annealing the samples at 174°C for several hours, a time scale at least two orders of magnitude greater than the time required for the dPS-NH2 chains to diffuse through the bulk PS layer. The topography of the interfacial region as copolymer formed was measured using atomic force microscopy (AFM). Roughening of the PS/PMMA interface was observed to varying degrees in all annealed samples. Furthermore, the extent of this roughening was found to depend on the PS matrix molecular weight. Reaction in the samples with a high molecular weight PS matrix resulted in a root mean square roughness approximately equal to the radius of gyration Rg of the copolymer. However, approximately twice as much roughening was observed in the low molecular weight PS matrix. This study reveals how the molecular weight of one of the phases can affect the rate of reaction at a polymer/polymer interface.

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The Statistical Segment Length of DNA: Opportunities for Biomechanical Modeling in Polymer Physics and Next-Generation Genomics

Journal of Biomechanical Engineering ◽

10.1115/1.4037790 ◽

2018 ◽

Vol 140 (2) ◽

Cited By ~ 6

Author(s):

Kevin D. Dorfman

Keyword(s):

Genome Mapping ◽

Persistence Length ◽

Magnetic Tweezers ◽

Polymer Physics ◽

Polymer Dynamics ◽

Segment Length ◽

Next Generation ◽

Bending Energy ◽

Force Microscopy ◽

Statistical Segment

The development of bright bisintercalating dyes for deoxyribonucleic acid (DNA) in the 1990s, most notably YOYO-1, revolutionized the field of polymer physics in the ensuing years. These dyes, in conjunction with modern molecular biology techniques, permit the facile observation of polymer dynamics via fluorescence microscopy and thus direct tests of different theories of polymer dynamics. At the same time, they have played a key role in advancing an emerging next-generation method known as genome mapping in nanochannels. The effect of intercalation on the bending energy of DNA as embodied by a change in its statistical segment length (or, alternatively, its persistence length) has been the subject of significant controversy. The precise value of the statistical segment length is critical for the proper interpretation of polymer physics experiments and controls the phenomena underlying the aforementioned genomics technology. In this perspective, we briefly review the model of DNA as a wormlike chain and a trio of methods (light scattering, optical or magnetic tweezers, and atomic force microscopy (AFM)) that have been used to determine the statistical segment length of DNA. We then outline the disagreement in the literature over the role of bisintercalation on the bending energy of DNA, and how a multiscale biomechanical approach could provide an important model for this scientifically and technologically relevant problem.

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Atomic force microscopy of the morphology and mechanical behaviour of barnacle cyprid footprint proteins at the nanoscale

Journal of The Royal Society Interface ◽

10.1098/rsif.2009.0127 ◽

2009 ◽

Vol 7 (43) ◽

pp. 285-296 ◽

Cited By ~ 20

Author(s):

In Yee Phang ◽

Nick Aldred ◽

Xing Yi Ling ◽

Jurriaan Huskens ◽

Anthony S. Clare ◽

...

Keyword(s):

Atomic Force Microscopy ◽

Sea Water ◽

Persistence Length ◽

Force Microscopy ◽

Bond Model ◽

Atomic Force ◽

Extension Force ◽

Force Curves ◽

High Elongation ◽

Glass Surfaces

Barnacles are a major biofouler of man-made underwater structures. Prior to settlement, cypris larvae explore surfaces by reversible attachment effected by a ‘temporary adhesive’. During this exploratory behaviour, cyprids deposit proteinaceous ‘footprints’ of a putatively adhesive material. In this study, footprints deposited by Balanus amphitrite cyprids were probed by atomic force microscopy (AFM) in artificial sea water (ASW) on silane-modified glass surfaces. AFM images obtained in air yielded better resolution than in ASW and revealed the fibrillar nature of the secretion, suggesting that the deposits were composed of single proteinaceous nanofibrils, or bundles of fibrils. The force curves generated in pull-off force experiments in sea water consisted of regions of gradually increasing force, separated by sharp drops in extension force manifesting a characteristic saw-tooth appearance. Following the relaxation of fibrils stretched to high strains, force–distance curves in reverse stretching experiments could be described by the entropic elasticity model of a polymer chain. When subjected to relaxation exceeding 500 ms, extended footprint proteins refolded, and again showed saw-tooth unfolding peaks in subsequent force cycles. Observed rupture and hysteresis behaviour were explained by the ‘sacrificial bond’ model. Longer durations of relaxation (>5 s) allowed more sacrificial bond reformation and contributed to enhanced energy dissipation (higher toughness). The persistence length for the protein chains ( L P ) was obtained. At high elongation, following repeated stretching up to increasing upper strain limits, footprint proteins detached at total stretched length of 10 µm.

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Antioxidant activity of enzyme-assisted extract derived from round kumquat peel (Fortunella japonica)

Can Tho University Journal of Science ◽

10.22144/ctu.jen.2021.032 ◽

2021 ◽

Vol 13 (2) ◽

pp. 69-76

Author(s):

Tam Vo Dinh Le ◽

Dinh Duyen Hai Nguyen

Keyword(s):

Antioxidant Activity ◽

Dry Matter ◽

Cation Radical ◽

Pharmaceutical Products ◽

Extraction Time ◽

Enzyme Treatment ◽

Total Phenolic ◽

Extraction Temperature ◽

Antioxidant Power ◽

Peel Extract

This study intends to apply enzyme-assisted extraction method to determine the antioxidant activity of round kumquat peel extract. Firstly, chemical composition of the kumquat peel was determined. Then, single factor test was employed to evaluate the effects of enzyme treatment conditions (enzyme amount and extraction time, ethanol concentration, material:ethanol ratio, extraction time and extraction temperature) on total phenolic content (TPC) and antioxidant activity of the kumquat peel extract. The result showed that the content of phenolic compounds in the kumquat peel achieved 1.3%. The peel extract exhibited the maximum TPC of 335.96±16.79 milligrams of gallic acid equivalents (mg GAE)/g dry matter, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) cation radical (ABTS●+) scavenging activity of 1993.26±99.66 μmol Trolox Equivalent (TE)/g dry matter and ferric reducing antioxidant power (FRAP) value of 3202.86±160.14 μmol TE/g dry matter. This extract was obtained under enzyme treatment condition including enzyme content of 9 U/g dry matter, enzyme-treating time of 90 min and the extraction condition comprising of kumquat peel: 96% ethanol ratio of 1:40 (w/v), extraction time of 150 min and temperature of 50°C. The results revealed that the kumquat peel extract could be used as a potential natural antioxidant in food and/or pharmaceutical products.

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Astaxanthin-Loaded Nanostructured Lipid Carriers for Preservation of Antioxidant Activity

Molecules ◽

10.3390/molecules23102601 ◽

2018 ◽

Vol 23 (10) ◽

pp. 2601 ◽

Cited By ~ 16

Author(s):

Violeta Rodriguez-Ruiz ◽

José Salatti-Dorado ◽

Abolfazl Barzegari ◽

Alba Nicolas-Boluda ◽

Amel Houaoui ◽

...

Keyword(s):

Oxidative Stress ◽

Electron Microscopy ◽

Antioxidant Activity ◽

Charged Particles ◽

Nanostructured Lipid Carriers ◽

Green Process ◽

Force Microscopy ◽

Atomic Force ◽

Interesting Candidate ◽

Microscopy Techniques

Astaxanthin is a xanthophyll carotenoid showing efficient scavenging ability and represents an interesting candidate in the development of new therapies for preventing and treating oxidative stress-related pathologies. However, its high lipophilicity and thermolability often limits its antioxidant efficacy in human applications. Here, we developed a formulation of lipid carriers to protect astaxanthin’s antioxidant activity. The synthesis of natural astaxanthin-loaded nanostructured lipid carriers using a green process with sunflower oil as liquid lipid is presented. Their antioxidant activity was measured by α-Tocopherol Equivalent Antioxidant Capacity assay and was compared to those of both natural astaxanthin and α-tocopherol. Characterizations by dynamic light scattering, atomic force microscopy, and scattering electron microscopy techniques were carried out and showed spherical and surface negative charged particles with z-average and polydispersity values of ~60 nm and ~0.3, respectively. Astaxanthin loading was also investigated showing an astaxanthin recovery of more than 90% after synthesis of nanostructured lipid carriers. These results demonstrate the capability of the formulation to stabilize astaxanthin molecule and preserve and enhance the antioxidant activity.

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Concentration Dependent Structural Ordering of Poloxamine 908 on Polystyrene Nanoparticles and Their Modulatory Role on Complement Consumption

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2006.406 ◽

2006 ◽

Vol 6 (9) ◽

pp. 3126-3133 ◽

Cited By ~ 48

Author(s):

O. Al-Hanbali ◽

K. J. Rutt ◽

D. K. Sarker ◽

A. C. Hunter ◽

S. M. Moghimi

Keyword(s):

Adsorption Isotherm ◽

Conformational Changes ◽

Adsorbed Layer ◽

Surface Characteristics ◽

Radius Of Gyration ◽

Phase Lag ◽

Ambient Conditions ◽

Polystyrene Nanoparticles ◽

Force Microscopy

Adsorption of poloxamine 908, a tetrafunctional polyethylene oxide (PEO)-polypropylene oxide ethylenediamine block copolymer, onto the surface of monodispersed polystyrene nanoparticles (232±0.33 nm) follows a bimodal pattern. Initially, the isotherm follows a Langmuir profile with a plateau observable over a very narrow equilibrium poloxamine concentration (0.0018–0.0031 mM). The isotherm then begins to rise again, reaching a final plateau at equilibrium poloxamine concentrations above 0.0089 mM. Similarly, the profile of the adsorbed layer thickness of poloxamine on the surface of nanoparticles is bimodal. The first plateau corresponds to a thickness of 4.6±0.07 nm, which occurs over the same range of poloxamine concentrations as in the initial plateau of the adsorption isotherm. The second plateau corresponds to a thickness of 9.53±0.32nm, observable at a minimum poloxamine concentration of 0.0067 mM. By using a calculated radius of gyration of a PEO chain in poloxamine as 3.1 nm, these observations reflect dynamic changes in the arrangement of surface projected PEO chains; a mushroom-like conformation at the first plateau region of the adsorption isotherm, followed by a transition into a brush-like conformation. These conformational changes are also reflected in rheological studies; the apparent viscosity of nanoparticles in which the PEO chains are in mushroom conformation is considerably higher than particles displaying the brush conformation. Further, atomic force microscopy studies (height profile and phase lag measurements) corroborated that the proposed poloxamine concentration dependent transition of surface associated PEO chains from mushroom to brush appearance is conserved when nanoparticles are dried under ambient conditions. Finally, we compared the influence of the surface PEO characteristics on complement consumption in human serum. Our results show complement-activating nature of all poloxamine-coated nanoparticles. However, complement consumption is reduced substantially with particles bearing a minimum of 11448 poloxamine molecules on their surface, thus demonstrating the importance of PEO surface density as well as brush conformation in suppressing complement consumption. This relationship between surface characteristics of poloxamine nanoparticles and their in vivo performance is discussed.

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Persistence Length of Cylindrical Brush Molecules Measured by Atomic Force Microscopy

Macromolecules ◽

10.1021/ma0516081 ◽

2006 ◽

Vol 39 (6) ◽

pp. 2219-2224 ◽

Cited By ~ 40

Author(s):

Nikhil Gunari ◽

Manfred Schmidt ◽

Andreas Janshoff

Keyword(s):

Atomic Force Microscopy ◽

Persistence Length ◽

Force Microscopy ◽

Atomic Force

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Protein O-Fucosyltransferase 1 Undergoes Interdomain Flexibility in Solution

Molecules ◽

10.3390/molecules26082105 ◽

2021 ◽

Vol 26 (8) ◽

pp. 2105

Author(s):

Erandi Lira-Navarrete ◽

María Carmen Pallarés ◽

Fabio Castello ◽

Maria J. Ruedas-Rama ◽

Angel Orte ◽

...

Keyword(s):

Atomic Force Microscopy ◽

Single Molecule ◽

Resonance Energy Transfer ◽

Resonance Energy ◽

Catalytic Cycle ◽

Conformational Behavior ◽

Single Molecule Fluorescence ◽

Force Microscopy ◽

Atomic Force ◽

Dynamic Population

Protein O-fucosyltransferase 1 (PoFUT1) is a GT-B fold enzyme that fucosylates proteins containing EGF-like repeats. GT-B glycosyltransferases have shown a remarkable grade of plasticity adopting closed and open conformations as a way of tuning their catalytic cycle, a feature that has not been observed for PoFUT1. Here, we analyzed Caenorhabditis elegans PoFUT1 (CePoFUT1) conformational behavior in solution by atomic force microscopy (AFM) and single-molecule fluorescence resonance energy transfer (SMF-FRET). Our results show that this enzyme is very flexible and adopts mainly compact conformations and to a lesser extend a highly dynamic population that oscillates between compact and highly extended conformations. Overall, our experiments illustrate the inherent complexity of CePoFUT1 dynamics, which might play a role during its catalytic cycle.

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Antioxidant Property and Bactericidal Activity of Linum usitatissimum Seed Essential Oil Nanoemulsion (LSEO-NE) on Staphylococcus aureus

International Journal of Infection ◽

10.5812/iji.101639 ◽

2020 ◽

Vol 7 (2) ◽

Cited By ~ 1

Author(s):

Roghaye Keykhasalar ◽

Masoud Homayouni Tabrizi ◽

Pouran Ardalan

Keyword(s):

Staphylococcus Aureus ◽

Antioxidant Activity ◽

Essential Oil ◽

Bactericidal Activity ◽

Linum Usitatissimum ◽

Bacterial Infections ◽

Antioxidant Property ◽

In Vivo Studies ◽

Force Microscopy

Background: Linum usitatissimum Seed Essential Oil (LSEO) as an efficient antimicrobial compound contains various types of phytochemicals, such as lignans and phenols. Objectives: In the current study, we produced LSEO nanoemulsion (LSEO-NE) to study its antioxidant capacity and bactericidal activity against Staphylococcus aureus. Methods: The LSEO-NE was produced using the ultrasonication method and characterized by Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS), and Scanning Electron Microscopy (SEM). Then, we measured its antioxidant activity utilizing both ABTS and DPPH tests at four different LSEO-NE concentrations (200, 600, 800, and 1000 µg/mL) compared to glutathione. Finally, we evaluated its bactericidal activity on S. aureus by studying Antibiotic Susceptibility Testing (AST) using LSEO-NE-smeared discs compared to non-smeared and kanamycin discs. Results: The 67.3 nm droplets of LSEO-NE with PDI of 0.452 exhibited strong antioxidant activity, similar to glutathione, in both ABTS (IC50 = 350 µg/mL) and DPPH (IC50 = 235 µg/mL) tests. Moreover, the AST results revealed the significant sensitivity of S. aureus to LSEO-NE-smeared discs when compared to non-smeared and kanamycin discs. Conclusions: According to the results, LSEO-NE can be applied as a safe, natural, and effective antibiotic for bacterial infections caused by S. aureus in most organs, such as the respiratory system and skin. However, further in vivo studies are required to evaluate the LSEO-NE antibacterial efficiency against other pathogenic S. aureus strains.

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