Preparation of Giant Unilamellar Vesicles and Solid Supported Bilayer from Large Unilamellar Vesicles: Model Biological Membranes

2017 ◽  
Vol 32 (3-4) ◽  
pp. 85 ◽  
Author(s):  
Amrita Basu ◽  
Pabitra Maity ◽  
Prasanta Karmakar ◽  
Sanat Karmakar
Keyword(s):  
Chemical Properties ◽  
Giant Unilamellar Vesicles ◽  
Unilamellar Vesicles ◽  
Force Microscopy ◽  
Atomic Force ◽  
Large Unilamellar Vesicles ◽  
Physico Chemical ◽  
Micron Size ◽  
Planar Membranes ◽  
Extrusion Method

Giant Unilamellar Vesicles (GUV) and supported planar membranes are excellent model biological systems for studying the structure and functions of membranes. We have prepared GUV from Large Unilamellar Vesicles (LUV) using electroformation and Supported planar Lipid Bilayer (SLB) by vesicle fusion method. LUV was prepared using an extrusion method and was characterized using Dynamic Light Scattering (DLS) and zeta potential measurements. The techniques for obtaining GUV as well as SLB from LUV have been demonstrated. We have directly observed the formation of GUV under phase contrast microscopy. This study will provide some insights into the physico-chemical properties of both nano and micron size vesicles. We believe that this method could be extremely useful for reconstituting various bio-molecules in GUV. We have presented one example where an antimicrobial peptide NK-2 was reconstituted in GUV prepared from LUV. SLB formation was monitored and characterized using Atomic Force Microscopy (AFM).

scholarly journals LIPSS Structures Induced on Graphene-Polystyrene Composite

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3460 ◽  
Author(s):  
Dominik Fajstavr ◽  
Klára Neznalová ◽  
Václav Švorčík ◽  
Petr Slepička
Keyword(s):  
Chemical Properties ◽  
Laser Pulses ◽  
Periodic Pattern ◽  
Krypton Fluoride ◽  
Periodic Surface ◽  
Laser Modification ◽  
Force Microscopy ◽  
Periodic Surface Structure ◽  
Atomic Force ◽  
Physico Chemical

A laser induced periodic surface structure (LIPSS) on graphene doped polystyrene was prepared by the means of a krypton fluoride (KrF) laser with the wavelength of 248 nm and precisely desired physico-chemical properties were obtained for the structure. Surface morphology after laser modification of polystyrene (PS) doped with graphene nanoplatelets (GNP) was studied. Laser fluence values of modifying laser light varied between 0–40 mJ·cm−2 and were used on polymeric PS substrates doped with 10, 20, 30, and 40 wt. % of GNP. GNP were incorporated into PS substrate with the solvent casting method and further laser modification was achieved with the same amount of laser pulses of 6000. Formed nanostructures with a periodic pattern were examined by atomic force microscopy (AFM). The morphology was also studied with scanning electron microscopy SEM. Laser irradiation resulted in changes of chemical composition on the PS surface, such as growth of oxygen concentration. This was confirmed with energy-dispersive X-ray spectroscopy (EDS).

scholarly journals Atomic force microscopy of phase separation on ruptured, giant unilamellar vesicles

2018 ◽  
Author(s):  
Yanfei Jiang ◽  
Guy M. Genin ◽  
Kenneth M. Pryse ◽  
Elliot L. Elson
Keyword(s):  
Atomic Force Microscopy ◽  
Phase Separation ◽  
Model Systems ◽  
Study Phase ◽  
Dark Phase ◽  
Giant Unilamellar Vesicles ◽  
Unilamellar Vesicles ◽  
Force Microscopy ◽  
Atomic Force ◽  
Lipid Species

AbstractGiant unilamellar vesicles (GUVs) and supported lipid bilayers (SLBs) are synthetic model systems widely used in biophysical studies of lipid membranes. Phase separation behaviors of lipid species in these two model systems differ due to the lipid-substrate interactions that are present only for SLBs. Therefore, GUVs are believed to resemble natural cell membranes more closely, and a very large body of literature focuses on applying nano-characterization techniques to quantify phase separation on GUVs. However, one important technique, atomic force microscopy (AFM), has not yet been used successfully to study phase separation on GUVs. In the present study, we report that in binary systems, certain phase domains on GUVs retain their original shapes and patterns after the GUVs rupture on glass surfaces. This enabled AFM experiments on phase domains from binary GUVs containing 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) and either 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC). These DLPC/DSPC and DLPC/DPPC GUVs both presented two different gel phases, one of which (bright phase) included a relatively high concentration of DiI-C20 but excluded Bodipy-HPC, and the other of which (dark phase) excluded both probes. The bright phases are of interest because they seem to stabilize dark phases against coalescence. Results suggested that the gel phases labeled by DiI-C20 in the DLPC/DSPC membrane, which surround the dark gel phase, is an extra layer of membrane, indicating a highly curved structure that might stabilize the interior dark domains. This phenomenon was not found in the DLPC/DPPC membrane. These results show the utility of AFM on collapsed GUVs, and suggest a possible mechanism for stabilization of lipid domains.

scholarly journals Atomic Force Microscopy of Phase Separation on Ruptured, Giant Unilamellar Vesicles, and a Mechanical Pathway for the Co-Existence of Lipid Gel Phases

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Yanfei Jiang ◽  
Kenneth M. Pryse ◽  
Srikanth Singamaneni ◽  
Guy M. Genin ◽  
Elliot L. Elson
Keyword(s):  
Atomic Force Microscopy ◽  
Phase Separation ◽  
Lipid Vesicles ◽  
Giant Unilamellar Vesicles ◽  
Unilamellar Vesicles ◽  
Surface Receptors ◽  
Force Microscopy ◽  
Atomic Force ◽  
Lipid Species ◽  
Surface Domains

Phase separation of lipid species is believed to underlie formation of lipid rafts that enable the concentration of certain surface receptors. However, the dynamics and stabilization of the resulting surface domains are unclear. We developed a methodology for collapsing giant unilamellar vesicles (GUVs) into supported bilayers in a way that keeps membrane nanodomains stable and enables their imaging. We used a combination of fluorescence and atomic force microscopy (AFM) of this system to uncover how a surprising phase separation occurs on lipid vesicles, in which two different gel phases of the same lipid co-exist. This unusual phase behavior was evident in binary GUVs containing 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) and either 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC). The approach showed that one of the phases is stabilized by lipid patches that become ejected from the membrane, thereby enabling the stabilization of what would otherwise be a thermodynamically impossible coexistence. These results show the utility of AFM on collapsed GUVs, and suggest a possible mechanical mechanism for stabilization of lipid domains.

scholarly journals Electrospun Combination of Peppermint Oil and Copper Sulphate with Conducive Physico-Chemical properties for Wound Dressing Applications

Polymers ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 586 ◽  
Author(s):  
Saravana Jaganathan ◽  
Mohan Mani ◽  
Ahmad Khudzari
Keyword(s):  
Surface Roughness ◽  
Copper Sulphate ◽  
Wound Dressing ◽  
Fiber Diameter ◽  
Blood Compatibility ◽  
Chemical Properties ◽  
Force Microscopy ◽  
Atomic Force ◽  
Physico Chemical ◽  
Afm Analysis

The ultimate goal in tissue engineering is to fabricate a scaffold which could mimic the native tissue structure. In this work, the physicochemical and biocompatibility properties of electrospun composites based on polyurethane (PU) with added pepper mint (PM) oil and copper sulphate (CuSO4) were investigated. Field Emission Electron microscope (FESEM) study depicted the increase in mean fiber diameter for PU/PM and decrease in fiber diameter for PU/PM/CuSO4 compared to the pristine PU. Fourier transform infrared spectroscopy (FTIR) analysis revealed the formation of a hydrogen bond for the fabricated composites as identified by an alteration in PU peak intensity. Contact angle analysis presented the hydrophobic nature of pristine PU and PU/PM while the PU/PM/CuSO4 showed hydrophilic behavior. Atomic force microscopy (AFM) analysis revealed the increase in the surface roughness for the PU/PM while PU/PM/CuSO4 showed a decrease in surface roughness compared to the pristine PU. Blood compatibility studies showed improved blood clotting time and less toxic behavior for the developed composites than the pristine PU. Finally, the cell viability of the fabricated composite was higher than the pristine PU as indicated in the MTS assay. Hence, the fabricated wound dressing composite based on PU with added PM and CuSO4 rendered a better physicochemical and biocompatible nature, making it suitable for wound healing applications.

Anodized Aluminum Oxide Films as Nanostructured Template for the Grow of Carbon Nanotubes

2000 ◽  
Vol 633 ◽  
Author(s):  
Y.C. Sui ◽  
J.A. González-León ◽  
A. Bermùdez ◽  
D.R. Acosta ◽  
J. Feuchtwanger ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Properties ◽  
Wall Structure ◽  
Anodized Aluminum ◽  
Anodized Aluminum Oxide ◽  
Force Microscopy ◽  
Work Related ◽  
Atomic Force ◽  
Physico Chemical ◽  
Alumina Oxide

AbstractA summary of our recent work related to the growth of carbon nanotubes (CNTs) inside the pores of anodized alumina oxide (AAO) films is presented. The surface topography of the AAO film was studied by atomic force microscopy, while the internal pore structure of the AOO templates was concluded from the shape of the CNTs obtained. The effect of the different experimental approaches and of the anodization voltage value on the features of the pores and CNTs is also discussed, as well as the catalytic effect in the acetylene pyrolysis of the Co particles and internal alumina walls. The CNTs wall structure observed by HRTEM and its implication on some physico-chemical properties of the CNTs are also presented.

Infrared Characterization of PMMA-SiO2 Hybrid Glasses Obtained by Sol-Gel Process

2010 ◽  
Vol 1278 ◽  
Author(s):  
L.L. Díaz-Flores ◽  
A. S. López Rodríguez ◽  
P. SifuentesGallardo ◽  
M.A. Hernàndez Rivera ◽  
M.a Garnica Romo ◽  
...  
Keyword(s):  
Sol Gel ◽  
Chemical Properties ◽  
Hybrid Coatings ◽  
Force Microscopy ◽  
Air Atmosphere ◽  
Atomic Force ◽  
Sol Gel Process ◽  
Traditional Process ◽  
And Chemical Properties

AbstractThis work is about the production of hybrid coatings of the system SiO2-PMMA (PMMA, polymethylmethacrylate). These materials have interesting mechanical and chemical properties useful for anticorrosive and wear resistance applications. SiO2-PMMA hybrids were obtained by the sol-gel traditional process, using tetraethylorthosilicate (TEOS) and methylmethacrylate (MMA) by Aldrich Co, as starting reagents. The SiO2:PMMA ratio was varied from 0:1 to about 1:1 at air atmosphere deposition. The coatings were obtained on acrylic sheets and silicon wafers. A diversity of coatings with chemical composition ranging from SiO2 and PMMA to obtain the SiO2-PMMA hybrids were obtained. Infrared (IR) and atomic force microscopy (AFM), were performed to determinate structural and morphological behavior.

scholarly journals Optimization of Innovative Three-Dimensionally-Structured Hybrid Vesicles to Improve the Cutaneous Delivery of Clotrimazole for the Treatment of Topical Candidiasis

Pharmaceutics ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 263 ◽  
Author(s):  
Maria Letizia Manca ◽  
Iris Usach ◽  
José Esteban Peris ◽  
Antonella Ibba ◽  
Germano Orrù ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chemical Properties ◽  
Chemical Characterization ◽  
Yeast Cells ◽  
Unilamellar Vesicles ◽  
Transmission Electron ◽  
Physico Chemical

New three-dimensionally-structured hybrid phospholipid vesicles, able to load clotrimazole in a high amount (10 mg/mL), were obtained for the first time in this work by significantly reducing the amount of water (≤10%), which was replaced with a mixture of glycerol and ethanol (≈90%). A pre-formulation study was carried out to evaluate the effect of both the composition of the hydrating medium and the concentration of the phospholipid on the physico-chemical properties of hybrid vesicles. Four different three-dimensionally-structured hybrid vesicles were selected as ideal systems for the topical application of clotrimazole. An extensive physico-chemical characterization performed using transmission electron microscopy (TEM), cryogenic transmission electron microscopy (cryo-TEM), 31P-NMR, and small-angle X-ray scattering (SAXS) displayed the formation of small, multi-, and unilamellar vesicles very close to each other, and was capable of forming a three-dimensional network, which stabilized the dispersion. Additionally, the dilution of the dispersion with water reduced the interactions between vesicles, leading to the formation of single unilamellar vesicles. The evaluation of the in vitro percutaneous delivery of clotrimazole showed an improved drug deposition in the skin strata provided by the three-dimensionally-structured vesicles with respect to the commercial cream (Canesten®) used as a reference. Hybrid vesicles were highly biocompatible and showed a significant antifungal activity in vitro, greater than the commercial cream Canesten®. The antimycotic efficacy of formulations was confirmed by the reduced proliferation of the yeast cells at the site of infection in vivo. In light of these results, clotrimazole-loaded, three-dimensionally-structured hybrid vesicles appear to be one of the most innovative and promising formulations for the treatment of candidiasis infections.

Stereocomplex electrospun fibers from high molecular weight of poly(L-lactic acid) and poly(D-lactic acid)

2020 ◽  
Vol 40 (2) ◽  
pp. 136-142 ◽  
Author(s):  
Homa Maleki ◽  
Hossein Barani
Keyword(s):  
Molecular Weight ◽  
Lactic Acid ◽  
Thermal Properties ◽  
High Molecular Weight ◽  
Chemical Properties ◽  
Electrospun Fibers ◽  
Scanning Calorimetry ◽  
Force Microscopy ◽  
Atomic Force ◽  
Electrospinning Method

AbstractThe stereocomplex formation is a promising method to improve the properties of poly(lactide) (PLA)-based products due to the strong interaction of the side-by-side arrangement of the molecular chains. Recently, electrospinning method has been applied to prepare PLA stereocomplex, which is more convenient. The objective of the current study is to make stereocomplexed PLA nanofibers using electrospinning method and compare their properties and structures with pure poly(l-lactide) (PLLA) fibers. The stereocomplexed fibers were electrospun from a blend solution of high molecular weight PLLA and poly(d-lactide) (1:1 ratio). The morphology of the obtained electrospun fibers was examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Differential scanning calorimetry was applied to study their thermal properties and crystallinity. Fourier transform infrared spectroscopy (FTIR) test was conducted on the samples to characterize their chemical properties. The SEM and AFM images indicated that smooth uniform fibers with a cylindrical structure were produced. Besides, the FTIR results and thermal properties confirmed that only stereocomplex crystallites formed in the resulting fibers via the electrospinning method.

Carbon Fiber Surface Modification by Plasma Treatment for Interface Adhesion Improvements of Aerospace Composites

2016 ◽  
Vol 1135 ◽  
pp. 75-87 ◽  
Author(s):  
Alberto Lima Santos ◽  
Edson Cocchieri Botelho ◽  
Konstantin Georgiev Kostov ◽  
Mario Ueda ◽  
Leide Lili G. da Silva
Keyword(s):  
Carbon Fibers ◽  
Photoelectron Spectroscopy ◽  
Fiber Surface ◽  
Polyphenylene Sulfide ◽  
Thermoplastic Composite ◽  
Force Microscopy ◽  
Atomic Force ◽  
Physico Chemical ◽  
Plasma Immersion Ion Implantation ◽  
Interlaminar Shear

This paper is focused on the processing of thermoplastic composite materials obtained from carbon fibers (CFs) treated by plasma assisted techniques. The treatments employed in this work were the Dielectric Barrier Discharge (DBD), which is done at atmospheric pressure, involving lower energies and the Plasma Immersion Ion Implantation (PIII), which is performed at low pressure, involving higher energies. After the treatments, samples characterizations were performed to determine which treatment is most effective to get better physico-chemical CF surface properties. The techniques employed in this work in order to evaluate the surface treatment were: scanning electron microscopy (SEM); atomic force microscopy (AFM) Raman spectroscopy and x-ray photoelectron spectroscopy (XPS). Treated and untreated CFs/Polyphenylene sulfide (PPS) composites were processed by hot-compression molding technique. These composites were evaluated by interlaminar shear tests (ILSS). After analyzing the results, it was found that the treatments increased the CF roughness and caused slight changes in the CF structure. In addition, there was an increase in the shear strength of the composites obtained from treated fibers by both plasma processes. In conclusion, DBD and PIII treatments are effective tools for improving adhesion between CF and the polymeric matrix.

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