In Situ Investigations of the Formation of Mixed Supported Lipid Bilayers Close to the Phase Transition Temperature

Nano Letters ◽  
2004 ◽  
Vol 4 (1) ◽  
pp. 5-10 ◽  
Author(s):  
B. Seantier ◽  
C. Breffa ◽  
O. Félix ◽  
G. Decher
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Lipid Bilayers ◽  
Phase Transition Temperature ◽  
Supported Lipid Bilayers

scholarly journals Variation of thermal conductivity of DPPC lipid bilayer membranes around the phase transition temperature

2017 ◽  
Vol 14 (130) ◽  
pp. 20170127 ◽  
Author(s):  
Sina Youssefian ◽  
Nima Rahbar ◽  
Christopher R. Lambert ◽  
Steven Van Dessel
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Transition Temperature ◽  
Lipid Bilayer ◽  
Lipid Bilayers ◽  
Phase Transition Temperature ◽  
Temperature Gradients ◽  
Phase Behaviour ◽  
Gel Phase

Given their amphiphilic nature and chemical structure, phospholipids exhibit a strong thermotropic and lyotropic phase behaviour in an aqueous environment. Around the phase transition temperature, phospholipids transform from a gel-like state to a fluid crystalline structure. In this transition, many key characteristics of the lipid bilayers such as structure and thermal properties alter. In this study, we employed atomistic simulation techniques to study the structure and underlying mechanisms of heat transfer in dipalmitoylphosphatidylcholine (DPPC) lipid bilayers around the fluid–gel phase transformation. To investigate this phenomenon, we performed non-equilibrium molecular dynamics simulations for a range of different temperature gradients. The results show that the thermal properties of the DPPC bilayer are highly dependent on the temperature gradient. Higher temperature gradients cause an increase in the thermal conductivity of the DPPC lipid bilayer. We also found that the thermal conductivity of DPPC is lowest at the transition temperature whereby one lipid leaflet is in the gel phase and the other is in the liquid crystalline phase. This is essentially related to a growth in thermal resistance between the two leaflets of lipid at the transition temperature. These results provide significant new insights into developing new thermal insulation for engineering applications.

scholarly journals Preparation of a Sustained Release Drug Delivery System for Dexamethasone by a Thermosensitive, In Situ Forming Hydrogel for Use in Differentiation of Dental Pulp

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Elham Khodaverdi ◽  
Fatemeh Kheirandish ◽  
Farnaz Sadat Mirzazadeh Tekie ◽  
Bibi Zahra Khashyarmanesh ◽  
Farzin Hadizadeh ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Delivery System ◽  
In Vitro Release ◽  
In Situ Forming ◽  
Release Study ◽  
Vitro Release

In situ forming delivery systems composed of block copolymers are attracting substantial attention due to their ease of use, biocompatibility, and biodegradability. In this study, the thermoresponsive triblock copolymer PLGA-PEG-PLGA was studied as a dexamethasone delivery system. Dexamethasone, a synthetic glucocorticoid, is used clinically to improve inflammation, pain, and the hyperemesis of chemotherapy, and it is applied experimentally as a differentiation factor in tissue engineering. PLGA-PEG-PLGA was synthesised under microwave irradiation for 5 min. The obtained copolymer was characterised to determine its structure and phase transition temperature. An in vitro release study was conducted for various copolymer structures and drug concentrations. The yield of the reaction and HNMR analysis confirmed the appropriateness of the microwave-assisted method for PLGA-PEG-PLGA synthesis. Phase transition temperature was affected by the drug molecule as well as by the copolymer concentration and structure. An in vitro release study demonstrated that release occurs mainly by diffusion and does not depend on the copolymer structure or dexamethasone concentration.

scholarly journals Morphological Behavior of Lipid Bilayers Induced by Melittin near the Phase Transition Temperature

2005 ◽  
Vol 89 (5) ◽  
pp. 3214-3222 ◽  
Author(s):  
Shuichi Toraya ◽  
Takashi Nagao ◽  
Kazushi Norisada ◽  
Satoru Tuzi ◽  
Hazime Saitô ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Lipid Bilayers ◽  
Phase Transition Temperature ◽  
Morphological Behavior

In situ formed thermogelable hydrogel photonic crystals assembled by thermosensitive IPNs

2021 ◽  
Author(s):  
Xiaoxiao Li ◽  
Di Zhao ◽  
Kenneth J. Shea ◽  
Xueting Li ◽  
Xihua Lu
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Photonic Crystals ◽  
Phase Transition Temperature ◽  
Sol Gel ◽  
Significant Advance ◽  
Sol Gel Transition ◽  
Gel Transition

In this paper, soft thermosensitive photonic crystals are immobilized via a reversible temperature-triggered in situ sol–gel transition above their phase transition temperature (Tp), which may be a significant advance in the field.

Reduction of The Phase Transition Temperature of TiSi2 on Si(111) Using a Ta Interlayer

1999 ◽  
Vol 564 ◽  
Author(s):  
Bokhee Jung ◽  
Young Do Kim ◽  
Woochul Yang ◽  
R. J. Nemanich ◽  
Hyeongtag Jeon
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Analysis Data ◽  
Xrd Analysis ◽  
Titanium Silicide ◽  
Probe Measurements ◽  
Control Samples ◽  
Ti Films

AbstractThe effect of a thin Ta interlayer on the C49 to C54 phase transition of TiSi2 on Si(111) was examined. The Ta interlayered samples were prepared by depositing Ta and Ti films sequentially on Si(111) substrates in a UHV system. As control samples, 100Å Ti films were deposited directly on clean Si(111) substrates. The deposited substrates were annealed for 10 min, in-situ, at temperatures between 500°C and 750°C using 50°C increments. The TiSi2, which formed in this UHV process, was analyzed with XRD, AES, SEM, TEM, and four-point probe measurements. The control samples exhibited the C49 to C54 transition at a temperature of 750°C. However, the TiSi2 samples with 5Å and 10Å Ta interlayers displayed a significant reduction of the phase transition temperature. The XRD analysis indicated that the C49 to C54 transition temperature of TiSi2 was lowered by ∼200°C. The sheet resistance measurement showed a low resistivity characteristic of C54. The SEM and TEM micrographs showed that the Ta interlayer also suppressed the surface agglomeration of the C54 TiSi2 film. The AES analysis data indicated that the composition of the titanium silicide showed the expected Ti:Si stoichiometry of 1:2.

Rapid In Situ Reactive Sintering and Properties of ZrO2-ZrW2O8 Composites

2012 ◽  
Vol 535-537 ◽  
pp. 42-46
Author(s):  
Xiang Yang Guo ◽  
Chun Zhen Fan ◽  
Xian Sheng Liu ◽  
Wen Bo Song ◽  
Chun Xiao Cheng ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
High Density ◽  
Reactive Sintering ◽  
Mass Ratio ◽  
Sintering Additive

ZrO2-ZrW2O8 diphasic composites with controllable coefficients of thermal expansion (CTEs) are synthesized by rapid in-situ reactive sintering with ZrO2 and WO3 as reactants. High density of ZrO2-ZrW2O8 composites without decomposition of ZrW2O8 is obtained with Y2O3 sintering additive. The CTEs of specimen with ZrO2 to ZrW2O8 mass ratio 1:1.0, 1:1.3, 1:1.5 and 1:2.0 are measured to be about 1.20×10−6, 0.31×10−6, -0.78×10−6 and -1.13×10−6 K−1, respectively. Raman mappings demonstrate homogenous dispersions of ZrO2 and ZrW2O8 in the ZrO2-ZrW2O8 composites. In addition to the role as sintering additive, some Y3+ cations enter the lattice to substitute Zr4+ in ZrW2O8, leading to an increase in disorder and a decrease in phase transition temperature of ZrW2O8 in the composites.

The structure of membranes and membrane proteins embedded in amorphous ice

1992 ◽  
Vol 50 (1) ◽  
pp. 432-433
Author(s):  
Uwe Lücken ◽  
Joachim Jäger
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Membrane Proteins ◽  
Phase Transition Temperature ◽  
Lipid Vesicles ◽  
Freezing Stress ◽  
Amorphous Ice ◽  
Different Temperatures ◽  
Band Pass ◽  
Lipid Polymorphism

TEM imaging of frozen-hydrated lipid vesicles has been done by several groups Thermotrophic and lyotrophic polymorphism has been reported. By using image processing, computer simulation and tilt experiments, we tried to learn about the influence of freezing-stress and defocus artifacts on the lipid polymorphism and fine structure of the bilayer profile. We show integrated membrane proteins do modulate the bilayer structure and the morphology of the vesicles.Phase transitions of DMPC vesicles were visualized after freezing under equilibrium conditions at different temperatures in a controlled-environment vitrification system. Below the main phase transition temperature of 24°C (Fig. 1), vesicles show a facetted appearance due to the quasicrystalline areas. A gradual increase in temperature leads to melting processes with different morphology in the bilayer profile. Far above the phase transition temperature the bilayer profile is still present. In the band-pass-filtered images (Fig. 2) no significant change in the width of the bilayer profile is visible.

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