As the packing structure of lipid molecules in the liposomes will vary in the presence of ions, it is expected that the density of lipid and the effective volume of lipid molecules in the dispersions will also vary, albeit minutely. Density measurements of lipid-water dispersions with the addition of Ca(2+) ions were determined accurately. The effect of Ca(2+) ions on the molecular packing structure of the liposomes was elucidated from the results obtained. The results for the density of the lecithin in the dispersions with and without the addition of Ca(2+) ions are, respectively, 1.0782 and 1.0579 g cm(-3) at 25 degrees C; and 1.0048 and 0.9961 g cm(-3) at 50 degrees C. The average values of the effective molecular volume of lecithin in the dispersions with and without the addition of Ca(2+) ions are, respectively, 1.131E-21 and 1.152E-21 cm(3) at 25 degrees C; and 1.213E-21 and 1.224E-21 cm(3) at 50 degrees C.
In this work, we studied whether chondroitin sulfates and dextran sulfates (DXSs) can influence hypochlorite-induced peroxidation of phosphatidylcholine (PC) liposomes. Multilamellar liposomes (2 mg lipid/ml) were prepared in phosphate buffer, pH 7.4, with NaCl or not and exposed to reagent HOCl/ClO- (1mM) at 37 degrees C in the presence of different concentrations of chondroitin 6-sulfate (C6S), chondroitin 4-sulfate (C4S), DXS 8000, DXS 40,000, and DXS 500,000. Lipid peroxidation was assessed by thiobarbituric acid-reactive substance (TBARS) production. DXSs and C6S enhanced TBARS production in a dose-dependent manner. The decline in TBARS production at the relatively high C6S concentrations may be attributed to C4S present in C6S, since in contrast to C6S, C4S is known to react with hypochlorite. Dextrans, nonsulfated analogues of DXS, failed to modulate TBARS production. This fact indicates the important role of negatively charged sulfate groups for DXS to facilitate hypochlorite-induced peroxidation of PC liposomes. The electrostatic nature of the mechanism providing for the pro-oxidative effect of DXS was also supported by the influence of liposome surface charge and solution ionic strength on the extent of liposome peroxidation. The addition of calcium ions to the incubation mixture did not prevent the pro-oxidative action of DXS. The relevance of the results to atherogenesis is discussed.
Phytosterols (PSs) are insoluble in water and poorly soluble in oil, which hampers their potential as cholesterol level regulator in human. To mitigate this problem, monoglycerides (MGs) were used to modulates the crystallization behavior of PSs. Therefore, the understanding on mixing behavior provides the insight into different aspects of crystallization and the resultant effects. The effects on thermal, morphology, diffraction, and spectroscopy behavior were investigated for binary mixtures of 11 different ratios (100:0 to 0:100 MGs:PSs). The phase behavior of binary mixtures of commercial MGs and PSs exhibited complexity with the formation of eutectic mixtures at 90:10 and 80:20 (MGs:PSs) combinations. These combinations revealed a single melting profile and reduced melting enthalpy, though after a month of storage at 5 °C. Conversely, two separate melting regions were observed in others. Furthermore, powder X-ray diffraction (PXRD) analysis of selected combinations revealed a change in crystalline forms with changes in the peaks located between 18-19° (2θ) and 25-26° (2θ). Accordingly, Raman spectroscopy results revealed changes in intensities and peak shape. Therefore, the change in crystalline forms or behavior correlated well to the change in thermal properties. Overall, the characterizations revealed the formation of eutectic mixtures between MGs and PSs at 90:10 and 80:20 (MGs:PSs) in which MGs modified the crystallization of PSs and changed the crystal forms thus, thermal behaviors. This study provides new insight into the mixing behavior of MGs and PSs which supports other research. Therefore, the results of this study are beneficial for the improvement of formulation of phytosterols in food and pharmaceutical products. Nonetheless, this study reveals a simple technique to alter crystal forms of phytosterols through simple complexation with monoglycerides.
Humectants are used widely in topical formulations as they provide cosmetic and health benefits to skin. Of particular interest to our laboratories is the interaction of humectants in phospholipid based topical skin care formulations. This study probed the effects of three exemplary humectants on a fully hydrated lecithin system (DPPC) by use of X-ray scattering and differential scanning calorimetry. While the three humectants affected the nanostructure of 1, 2-dipalmitoyl-sn-glycero-3-phosphocholine, DPPC, bilayers in a similar manner, leading to an increased membrane order, differences in the effect on the thermal behaviour of DPPC suggest that betaine and sarcosine interacted via a different mechanism compared to acetic monoethanolamide, AMEA. At concentrations above 0.4 M, betaine and sarcosine stabilised the gel phase by depletion of the interfacial water via the preferential exclusion mechanism. At the same time, a slight increase in the rigidity of the membrane was observed with an increase in the membrane thickness. Overall, the addition of betaine or sarcosine resulted in an increase in the pre- and main transition temperatures of DPPC. AMEA, on the other hand, decreases both transition temperatures, and although the interlamellar water layer was also decreased, there was evidence from the altered lipid chain packing, that AMEA molecules are present also at the bilayer interface, at least at high concentrations. Above the melting point in the fluid lamellar phase, none of the humectants induced significant structural changes, neither concerning the bilayer stacking order nor its overall membrane fluidity. An humectant-induced increase in the Hamaker constant is the most plausible explanation for the observed reduction of the inter-bilayer distances, both in the gel and fluid phase.
A new synthesis approach towards biantennary lipids of Guerbet glycoside type was developed based on oleic acid as sustainable resource. Functionalization of the double bond provided access to primary alcohols with α-branched C19-skeleton. Formulation studies with corresponding lactosides indicated formation of vesicles with high assembly stability. A relatively narrow bimodal size distribution of the latter, which turns into a narrow unimodal distribution of small vesicles upon addition of an ionic cosurfactant, suggests potential for a vesicular drug delivery system.
Drug delivery through the skin improves solubility, bioavailability, and unwanted systemic side effects of the drug. The selection of a suitable carrier is a challenging process. The conventional lipid vesicles have some limitations. They deliver the drug in the stratum corneum and have poor colloidal stability. Here comes the need for ultra-deformable lipid vesicles to provide the drug beyond the stratum corneum. Transethosomes are novel ultra-deformable vesicles that can deliver drugs into deeper tissues. The composition of transethosomes includes phospholipid, ethanol and surfactants. Each ingredient has a pivotal role in the properties of the carrier. This review covers the design, preparation method, characterisation, and characteristics of the novel vesicle. Also, we cover the impact of surfactants on vesicular properties and the skin permeation behaviour of novel vesicles.
Atorvastatin calcium (ATV) and proanthocyanidins (PAC) have a strong antioxidant activity, that can benefit to reduce the atherosclerotic plaque progression. Unfortunately, the bioavailability of ATV is greatly reduced due to its limited drug solubility while the PAC drug is unstable upon exposure to the atmospheric oxygen. Herein, the lyotropic liquid crystalline nanoparticles (LLCNPs) constructed by a binary mixture of soy phosphatidylcholine (SPC) and citric acid ester of monoglyceride (citrem) at different weight ratios were used to encapsulate the hydrophobic ATV and hydrophilic PAC. The LLCNPs were further characterized by small-angle X-ray scattering and dynamic light scattering. Depending on the lipid composition, the systems have a size range of 140-190 nm and were able to encapsulate both drugs in the range of 90-100%. Upon increasing the citrem content of drug-loaded LLCNPs, the hexosomes (H2) was completely transformed to an emulsified inverse micellar (L2). The optimum encapsulation efficiency (EE) of ATV and PAC were obtained in citrem/SPC weight ratio 4:1 (L2) and 1:1 (H2), respectively. There was a substantial change in the mean size and PDI of the nanoparticles upon 30 days of storage with the ATV-loaded LLCNPs exhibiting greater colloidal instability than PAC-loaded LLCNPs. The biphasic released pattern (burst released at the initial stage followed by the sustained released at the later stage) was perceived in ATV formulation, while the burst drug released pattern was observed in PAC formulations that could be attributed by its internal H2 structure. Interestingly, the cytokine studies showed that the PAC-LLCNPs promisingly up regulate the expressions of tumor necrosis factor-alpha (TNF-α) better than the drug-free and ATV-loaded LLCNPs samples. The structural tunability of citrem/SPC nanoparticles and their effect on physicochemical characteristic, biological activities and potential as an alternative drug delivery platform in the treatment of atherosclerosis are discussed.