Calorimetric Study On The Interactions Of 5-n-Heptadec(en)Yiresolcinols From Cereal Grains With Zwitterionic Phospholipid (DPPC)

1991 ◽  
Vol 46 (5-6) ◽  
pp. 423-427 ◽  
Author(s):  
Andrzej B. Hendrich ◽  
Arkadiusz Kozubek
Keyword(s):  
Transition Temperature ◽  
Heat Content ◽  
Half Width ◽  
Cereal Grains ◽  
Aliphatic Chain ◽  
Calorimetric Study ◽  
Main Transition ◽  
Resorcinol Derivative ◽  
Thermotropic Properties ◽  
Transition Heat

The effect of two 5-n-alk(en)ylresorcinol* (17:1 and 17:0) homologs at the concentrations of 5 - 20% on the thermotropic properties of dipalmitoylphosphatidylcholine in hydrated bilayers has been studied. The effect is different, depending on unsaturation of the aliphatic chain of resorcinol derivative. Saturated homologue ( 5 - 2 0 m ol% ) induces disappearance of the pretransition , increase of the main transition temperature and a half-width of the sition peak. Unsaturated homologue shifts pretransition towards higher temperatures, and similarly to the saturated one increases transition half-width but decreases the transition temperature, decreases the transition heat content and induces some phase separation

scholarly journals The Effect of Selected Anions on Dipalmitoylphosphatidylcholine Phase Transitions

2002 ◽  
Vol 57 (7-8) ◽  
pp. 712-716 ◽  
Author(s):  
Adriana Przyczyna ◽  
Bożenna Różycka-Roszk ◽  
Marek Langner
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Salt Concentration ◽  
Half Width ◽  
Main Phase ◽  
Interface Properties ◽  
Transition Enthalpy ◽  
Peak Half Width

The effect of three anions, Cl-, Br- and I-, on the phase transitions of dipalmitoylphosphatidylcholine (DPPC) was measured. Main phase transition was modestly affected by these anions in the salt concentration range 0.2 M. For Cl- and Br- the temperature of main phase transition was lower (by about 0.5 °C), its half-width modestly larger and enthalpy practically unchanged, all three parameters were altered to a much larger degree. Main phase transition temperature was 1.5 °C lower and the peak half-width significantly smaller. These changes were not accompanied by any alteration in main phase transition enthalpy. Iodide shifted the pretransition temperature toward lower values and increased its half-width to such an extent that at concentrations above 100 mm it was practically undetectable. Besides cations, the presence of anions also has a distinct effect on lipid bilayer interface properties.

Bismaleimide/Allylnadic-Imide Blends Yield Low Dielectric Constant And Low Water Uptake

1991 ◽  
Vol 227 ◽  
Author(s):  
J-PH Ansermet ◽  
A. Kramer
Keyword(s):  
Dielectric Constant ◽  
Glass Transition ◽  
Transition Temperature ◽  
Dielectric Properties ◽  
Water Uptake ◽  
Water Saturation ◽  
Low Dielectric Constant ◽  
Aliphatic Chain ◽  
Bismaleimide Resin ◽  
Low Dielectric

ABSTRACTThe bismaleimide resin Matrimid 5292A (I) was cocured with an allylnadic-imide resin (EP 433) which contained a long aliphatic chain as backbone (II). Water uptake, swelling, and the dielectric properties (up to 300 MHz) were studied in cast plates. The dielectric constant varied from 5.4 in (I) to 3.2 in (II) at water saturation, compared to 3.1 in (I) to 2.7 in (II) in the dry state. The glass transition temperature stayed above 200 °C at less than 80 mol% of (II).

Synthesis and Characterization of Biphenylnate Liquid Crystalline Polyurethanes

2010 ◽  
Vol 428-429 ◽  
pp. 158-161 ◽  
Author(s):  
Jian Feng Ban ◽  
Shao Rong Lu ◽  
Chen Xi Zhang
Keyword(s):  
Transition Temperature ◽  
Melting Point ◽  
Diethylene Glycol ◽  
Liquid Crystalline ◽  
Molar Ratio ◽  
Synthesis And Characterization ◽  
Flexible Chain ◽  
Ft Ir ◽  
Thermotropic Properties

A series of novel biphenylnate liquid crystalline polyurethanes (BLCPs) were synthesized by polyaddition reaction of 4,4’-dihydroxybiphenyl with 2,4-TDI(2,4-toluenediisocyanate) and diethylene glycol through changing the molar ratio of diphenol and diol. The thermotropic properties, the melting point (Tm) and the isotropization temperature (Ti) of the synthesized polyurethanes were characterized by FT-IR, DSC, POM and WXRD. The results of experiments showed that all of the polyurethane polymers exhibited thermotropic liquid crystalline properties between 130°C and 230°C. The transition temperature (Tm and Ti) decreased with an increase in the length of the flexible chain.

scholarly journals Divergent interaction profiles of gabapentin and levetiracetam with dipalmitoylphosphatidylcholine lipids

2017 ◽  
Vol 04 (02) ◽  
pp. 150-158
Author(s):  
Sevgi Türker-Kaya ◽  
Aygül Kına ◽  
Selen Alın
Keyword(s):  
Transition Temperature ◽  
Binding Capacity ◽  
Lipid Solubility ◽  
Hydrogen Binding ◽  
Biophysical Parameters ◽  
Scanning Calorimetry ◽  
System Availability ◽  
Lipid Order ◽  
Acyl Chains ◽  
Main Transition

Abstract Background/Objectives The lipid solubility of antiepileptic drugs directly affects central nervous system availability. In relation to this, the interactions of gabapentin and levetiracetam with dipalmitoylphosphatidylcholine lipids depending on concentrations were comparatively investigated in the present study. Methods The effects of gabapentin and levetricetam as a function of concentration (1–5–10–20 mol%) on biophysical parameters of dipalmitoylphosphatidylcholine multilammelar vesicles were studied by differential scanning calorimetry and fourier transform infrared spectroscopy. Results The data revealed that gabapentin at all concentrations and levetiracetam at 1–5 mol% lowered main transition temperature, enthalpy, cooperativity, lipid fluidity, lipid order, and increased hydrogen binding capacity of glycerol and phosphate groups. However, 10–20 mol% of levetiracetam tend to show different effect on transition temperature, which could also reflect its opposing effect on lipid order and glycerol and phosphate group’s hydrations. Conclusions According to the corresponding findings depending on concentrations both drugs incorporate into phosphatidylcholines, perturbing the packing of lipids and affecting their thermotropic properties. Their binding affinity to acyl chains and hydrophilic parts of lipids was found to highly correlate with lipid-water partition and their solubility degree in water. Hence, the obtained results may offer evaluation of partition profile of the drugs into biological membranes depending on concentration.

Influence of Lipid’s Main Transition Temperature on the Stability of Chimeric Liposomal Systems

2019 ◽  
Vol 9 (2) ◽  
pp. 158-165
Author(s):  
Konstantina Zouliati ◽  
Christina Massala ◽  
Natassa Pippa ◽  
Nikolaos Naziris ◽  
Stergios Pispas ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Physicochemical Properties ◽  
Lipid Bilayers ◽  
Structural Characteristics ◽  
Physical Stability ◽  
Structural Rearrangement ◽  
Physicochemical Characteristics ◽  
Polymeric Compounds ◽  
Main Transition ◽  
The Stability

Background: The incorporation of polymeric components into liposomes promotes structural rearrangement of the lipid bilayers that could affect their properties and their behavior. Therefore, by mixing phospholipids with polymeric compounds the, socalled chimeric liposomal nanosystems are produced and could be advantageous, compared with conventional (e.g. composed of pure phospholipids) liposomal nanostructures. Objective: In this work, we used lipids with different main transition temperature (Tm) i.e 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC, Tm=55°C), L-α-phosphatidylcholine, hydrogenated (Soy) (HSPC, Tm=52 °C) and egg phosphatidylcholine (EggPC, Tm=23 °C) and we studied and compared the physicochemical characteristics and the stability of conventional with that of chimeric liposomes. Methods: Thin-film hydration method (TFH) was used as the preparation protocol for all systems. Dynamic and electrophoretic light scattering (DLS and ELS) were utilized in order to elucidate the physicochemical characteristics of all systems. All liposomal systems exhibited sizes below 100nm while the ζ-potential was around zero, indicating the absence of surface charge. Results: The results revealed that the Tm of each phospholipid influences the biophysical behavior of the lipidic membrane, which contributes to the physicochemical characteristics and affects the physical stability of the liposomal nanosystems. The nature and physicochemical properties of each phospholipid seem to play a key role, regarding the structural characteristics and the formation process of the liposomal nanosystems. Conclusion: : Comparing the physicochemical properties of the conventional liposomes with those of the chimeric liposomal systems, we conclude that the complexity of the latter, due to the incorporation of the polymeric guest into the lipidic bilayer, revealed new properties, which correspond to increased physical stability.

Calorimetric Study of the Interaction of Local Anesthetics [2-(Alkyloxy)phenyl]-2-(1-piperidinyl)ethyl Carbamates with Model Dipalmitoylphosphatidylcholine Membranes

1995 ◽  
Vol 60 (5) ◽  
pp. 763-780 ◽  
Author(s):  
Jana Gallová ◽  
Jaroslava Bágeľová ◽  
Jozef Čižmárik ◽  
Pavol Balgavý
Keyword(s):  
Computer Simulation ◽  
Phase Transitions ◽  
Aqueous Phase ◽  
Homologous Series ◽  
Local Anesthetics ◽  
Partition Coefficients ◽  
Ethyl Esters ◽  
Carbamic Acid ◽  
Calorimetric Study ◽  
Main Transition

Local anesthetics of the homologous series of monohydrochlorides of [2-(alkoxy)phenyl]-2-(1-piperidinyl)ethyl esters of carbamic acid decrease the temperature of phase transitions Lβ' → Pβ (pretransition) and Pβ → Lα (main transition) of 1,2-dipalmitoyl-sn-phosphatidylcholine in aqueous phase at pH 6.2. The efficiency of the anesthetics in decreasing the pretransition temperature increases with the number of carbon atoms n of the alkoxy substituent up to n = 6. For n > 6 no pretransition could be detected. The efficiency in decreasing the temperature of the main transition increases up to n = 8 - 9 while it starts decreasing at n = 10. Computer simulation of the thermograms has shown that the decrease of efficiency at n = 10 is caused by the dependence of the partition coefficients of the anesthetics KP,G and KP,LC between the aqueous phase and the Pβ and Lα phases, respectively, on the length of the alkoxy substituent, thus: log KP,LC = ALC + BLC n and log KP,G = AG + BG n, where BLC < BG.

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