Lipoid S100 Research Articles

Effect of composition, hydrogenation of phospholipids and lyophilization on the characteristics of eugenol-loaded liposomes prepared by ethanol injection method

Abstract The effect of composition, hydrogenation of phospholipids and lyophilization on liposomes characteristics was investigated. Liposomes were produced by ethanol injection method, employing hydrogenated (Phospholipon 80H, Phospholipon 90H) or non-hydrogenated soybean phosphatidylcholine (Lipoid S100) with cholesterol. Using Phospholipon 80H, cholesterol addition was crucial for liposomal homogeneity. Phospholipids concentration, stirring rate, and ethanol/water volume ratio were the most determinant factors controlling the vesicles size. Phospholipid assays showed that saturated phospholipids resulted in higher incorporation in vesicles than unsaturated ones. Smaller vesicles were obtained with Phospholipon 80H, due to lower content of phosphatidylcholine and to the presence of phosphatidylethanolamine which might increase repulsion between phospholipids, resulting in an increase in Zeta-potential and a decrease in vesicle size. TEM images revealed nanometric sized and spherical shaped oligo-lamellar vesicles. Although Lipoid S100 liposomes possessed the highest encapsulation efficiency of eugenol (86.6%), they were not stable in aqueous suspension at 4 °C after 2 months of storage, limiting their use in freeze-drying. Among several cryoprotectants, hydroxylpropyl-β-cyclodextrin protected eugenol-loaded Phospholipon 90H liposomes during freeze-drying as the mean vesicle size, polydispersity index, Zeta potential and encapsulation efficiency of eugenol were similar before and after lyophilization. This study demonstrated the possibility of maintaining a volatile essential oil in a suitable lyophilized liposomal formulation despite the very low applied pressures.

Development of a Nonionic Azobenzene Amphiphile for Remote Photocontrol of a Model Biomembrane.

We report the synthesis and characterization of a simple nonionic azoamphiphile, C12OazoE3OH, which behaves as an optically controlled molecule alone and in a biomembrane environment. First, Langmuir monolayer and Brewster angle microscopy (BAM) experiments showed that pure C12OazoE3OH enriched in the (E) isomer was able to form solidlike mesophase even at low surface pressure associated with supramolecular organization of the azobenzene derivative at the interface. On the other hand, pure C12OazoE3OH enriched in the (Z) isomer formed a less solidlike monolayer due to the bent geometry around the azobenzene moiety. Second, C12OazoE3OH is well-mixed in a biological membrane model, Lipoid s75 (up to 20%mol), and photoisomerization among the lipids proceeded smoothly depending on light conditions. It is proposed that the cross-sectional area of the hydroxyl triethylenglycol head of C12OazoE3OH inhibits azobenzenes H-aggregation in the model membrane; thus, the tails conformation change due to photoisomerization is transferred efficiently to the lipid membrane. We showed that the lipid membrane effectively senses the azobenzene geometrical change photomodulating some properties, like compressibility modulus, transition temperature, and morphology. In addition, photomodulation proceeds with a color change from yellow to orange, providing the possibility to externally monitor the system. Finally, Gibbs monolayers showed that C12OazoE3OH is able to penetrate the highly packing biomembrane model; thus, C12OazoE3OH might be used as photoswitchable molecular probe in real systems.

Liposomal buccal mucoadhesive film for improved delivery and permeation of water-soluble vitamins

This study aims at improving the buccal delivery of vitamin B6 (VB6) as a model highly water-soluble, low permeable vitamin. Two main strategies were combined; first VB6 was entrapped in liposomes, which were then formulated as mucoadhesive film. Both plain and VB6-loaded liposomes (LPs) containing Lipoid S100 and propylene glycol (∼200nm) were then incorporated into mucoadhesive film composed of SCMC and HPMC. Results showed prolonged release of VB6 (72.65%, T50% diss 105min) after 6h from LP-film compared to control film containing free VB6 (96.37%, T50% diss 30min). Mucoadhesion was assessed both ex vivo on chicken pouch and in vivo in human. Mucoadhesive force of 0.2N and residence time of 4.4h were recorded. Ex vivo permeation of VB6, across chicken pouch mucosa indicated increased permeation from LP-systems compared to corresponding controls. Interestingly, incorporation of the vesicles in mucoadhesive film reduced the flux by 36.89% relative to LP-dispersion. Meanwhile, both films provided faster initial permeation than the liquid forms. Correlating the cumulative percent permeated ex vivo with the cumulative percent released in vitro indicated that LPs retarded VB6 release but improved permeation. These promising results represent a step forward in the field of buccal delivery of water-soluble vitamins.

Preparation and characterization of clove essential oil-loaded liposomes

In this study, suitable formulations of natural soybean phospholipid vesicles were developed to improve the stability of clove essential oil and its main component, eugenol. Using an ethanol injection method, saturated (Phospholipon 80H, Phospholipon 90H) and unsaturated soybean (Lipoid S100) phospholipids, in combination with cholesterol, were used to prepare liposomes at various eugenol and clove essential oil concentrations. Liposomal batches were characterized and compared for their size, polydispersity index, Zeta potential, loading rate, encapsulation efficiency and morphology. The liposomes were tested for their stability after storing them for 2months at 4°C by monitoring changes in their mean size, polydispersity index and encapsulation efficiency (EE) values. It was found that liposomes exhibited nanometric oligolamellar and spherical shaped vesicles and protected eugenol from degradation induced by UV exposure; they also maintained the DPPH-scavenging activity of free eugenol. Liposomes constitute a suitable system for encapsulation of volatile unstable essential oil constituents.

Influence of different surfactants on the technological properties and in vivo ocular tolerability of lipid nanoparticles.

Addition of one or more surfactant agents is often necessary for the production of nanostructured lipid and polymeric systems. The removal of residual surfactants is a required step for technological and toxicological reasons, especially for peculiar applications, such as the ophthalmic field. This study was planned to assess the technological properties of some surfactants, commonly used for the production of lipid nanoparticles, as well as their ocular safety profile. Stable and small-size solid lipid nanoparticles were obtained using Dynasan(®) 114 as the lipid matrix and all the tested surfactants. However, from a toxicological point of view, the nanocarriers produced using Kolliphor(®) P188 were the most valuable, showing no irritant effect on the ocular surface up to the highest tested surfactant concentration (0.4%, w/v). The SLN produced using Cremophor(®) A25 and Lipoid(®) S100 were tolerated up to a surfactant concentration of 0.2% by weight, while for Tween(®) 80 and Kolliphor(®) HS 15 a maximum concentration of 0.05% can be considered totally not-irritant.

An insight on human skin penetration of diflunisal: lipogel versus hydrogel microemulsion

Diflunisal is a NSAID used in acute and long term management of pain and inflammation associated with osteoarthritis, rheumatoid arthritis and symptoms of primary dysmenorrhea. However, its oral use is associated with side effects such as peptic ulceration, dyspepsia, gastrointestinal disturbances and bleeding. The aim of this work was to develop lecithin organogels (LO) transdermal delivery system for diflunisal and to study its human skin penetration ability in comparison with an optimized microemulsion-based hydrogel. Ternary phase diagrams were constructed using butyl lactate as an organic solvent and two commercial grades of lecithin. The formation of gel phase was lecithin concentration dependent with Phosholipion 85 G being capable of forming organogels at lower lecithin concentration than Lipoid S75. The gels prepared using butyl lactate were able to tolerate higher amounts of water than could be incorporated in the lipogels prepared with other organic solvents. All the investigated gels possessed acceptable physical properties and were able to deliver diflunisal through human skin. The lipogels delivered higher total drug amount through the skin than the hydrogel. The composition of lecithin seemed to have some effect on the skin permeability enhancement ability of the lipogel. Lecithin containing higher amount of phosphatidyl ethanolamine could provide better transdermal delivery. The elaborated lecithin organogels are potential carriers that create a good opportunity for transdermal delivery of diflunisal overcoming the side effects associating its oral route.

Systemic heparin delivery by the pulmonary route using chitosan and glycol chitosan nanoparticles

The aim of this study was to evaluate the performance of chitosan (CS) and glycol chitosan (GCS) nanoparticles containing the surfactant Lipoid S100 for the systemic delivery of low molecular weight heparin (LMWH) upon pulmonary administration. These nanoparticles were prepared in acidic and neutral conditions using the ionotropic gelation technique. The size and zeta potential of the NPs were affected by the pH and also the type of polysaccharide (CS or GCS). The size (between 156 and 385 nm) was smaller and the zeta potential (from +11 mV to +30 mV) higher for CS nanoparticles prepared in acidic conditions. The encapsulation efficiency of LMWH varied between 100% and 43% for the nanoparticles obtained in acidic and neutral conditions, respectively. X-ray photoelectron spectroscopy studies indicated that the surfactant Lipoid S100 was localized on the nanoparticle's surface irrespective of the formulation conditions. In vivo studies showed that systems prepared in acidic conditions did not increase coagulation times when administered to mice by the pulmonary route. In contrast, Lipoid S100-LMWH GCS NPs prepared in neutral conditions showed a pharmacological efficacy. Overall, these results illustrate some promising features of CS-based nanocarriers for pulmonary delivery of LMWH.

Development and characterization of glimepiride nanocrystal formulation and evaluation of its pharmacokinetic in rats

In this paper, orally nanocrystal capsules were produced using nanocrystal formulations in order to optimize dissolution properties of poorly soluble drug glimepiride and improve its bioavailability. The important preparation variables, such as stabilizers, the power input and the time length of ultrasonication on the mean particle size and polydispersity index were investigated systematically, and the optimal values were 0.2% glimepiride (w/v), 1.2% Lipoid S100, 0.6% PEG 6000 (w/v), 0.6% PVPK 30 (w/v), 500 W and 2 min, respectively. Characterization of glimepiride nanocrystal was carried out by X-ray powder diffractometry, differential scanning calorimetry and scanning electron microscopy. In vitro dissolution test, the nanocrystal-loaded capsules of glimepiride showed an evident increase in dissolution rate compared to micronized and market capsules. The in vivo studies demonstrated that a marked enhancement of bioavailability of nanocrystal-loaded capsules was superior compared to the marketed formulation and microcrystal-loaded capsules, which may reduce the risk of side effect by allowing a reduction in either the dose or its frequency of administration.

Formulation, preparation, and stability of intravenous bufadienolides‐loaded lipid microspheres

AbstractThe purpose of this study was to develop a new formulation of intravenous lipid microspheres for bufadienolides (bufadienolides‐loaded lipid microspheres, BU‐LM) and investigate the stability of BU‐LM after dilution and long‐term storage. Photon correlation spectroscopy, electrophoretic light scattering, and light microscopy were used to evaluate the physical characteristics of BU‐LM. The chemical properties of bufadienolides were measured by high‐performance liquid chromatography. The optimum BU‐LM, consisting of 10% MCT, 3.0% Lipoid S75, 0.4% F68, 0.05% sodium oleate and 2.5% glycerol, was prepared by emulsification with a high‐speed shear mixing at 10 000 rpm for 12 min and a high‐pressure homogenization at 800 bar for 8 cycles at 30°C. The BU‐LM at pH 6.48, with the particle size distribution of 175.2 ± 57.3 nm, ζ‐potential of −32.10 mV, entrapment efficiency of 86.9%, 91.7%, 92.9%, and contents of 20.8%, 31.3%, 50.4% for B, C, R, respectively, was stable after sterilization in a 121°C rotating autoclave water steam bath for 10 min. Moreover, BU‐LM had sufficient physicochemical stability after dilution with 5% glucose injection and long‐term storage at 4 ± 2°C for 18 months. BU‐LM has a great potential for clinical applications as a new drug delivery system for bufadienolides.Practical applications: Bufadienolides, mainly composed of bufalin (B), cinobufagin (C), and resibufogenin (R) have poor aqueous solubility and are chemically unstable. Currently the main marketable products of bufadienolides are solution injections, which cause serious venous irritation and in this formulation, the drug is not protected from degradation. Lipid microspheres, with the unique properties of a low cost, low toxicity, good storage stability, easy to scale up production, sustained release and targeting effect, incorporate the drugs into the interior oil phase and the oil‐water interfacial film; thus a direct contact of the drug with body fluids and tissues is prevented, which increases the stability of the drugs and minimizes the possible side effects.

Lecithin/chitosan nanoparticles for transdermal delivery of melatonin

In this study, the potential of lecithin/chitosan nanoparticles (NPs) as colloidal nanosystem for transdermal melatonin delivery was investigated. Mean diameter and zeta-potential of NPs differing in lecithin type (Lipoid S45 and S100) and chitosan content ranged between 113.7 and 331.5 nm and 4.6 and 31.2 mV, respectively. Melatonin loadings were up to 7.2%. The potential of lecithin/chitosan NPs to enhance transdermal melatonin delivery was investigated by determining the drug flux across dermatomed porcine skin and its skin deposition. Lecithin/chitosan NPs provided 1.3–2.3-fold higher flux compared to melatonin solution. The highest flux, 9.0 ± 0.21 µg/cm2/h, was observed for S45 lecithin/chitosan NPs with lecithin/chitosan weight ratio of 20:1. NP possible cytotoxicity in vitro was evaluated using human skin keratinocytes and fibroblasts. It was demonstrated that lecithin/chitosan NPs can be applied to skin cells at concentrations up to 200 µg/mL without inducing plasma membrane damage or cell viability decrease.

Biomolecules in colloid nanocontainers for drug delivery: Entrapment and properties of the delta sleep-inducing peptide

Nanoemulsions of the water in oil type (w/o) composed of nontoxic components, including low concentrations of AOT (5%) and soy-bean lecithin Lipoid S100 (10%) in eucalyptus oil and limonene, were developed and characterized. These nanoemulsions can be used for the incorporation of biomolecules. As shown, AOT based systems possessed the highest solubilization capacity (12% of an aqueous solution); photon-correlation spectroscopy revealed that the size of nanoemulsions of 5% AOT in eucalyptus oil increased linearly with the growth of the water content. The ability of hydrophilic delta sleep-inducing peptide (DSIP), which is a regulatory neuropeptide, to exist in nanoemulsions of the w/o type in the absence and in the presence of additional biopolymers was demonstrated. DSIP entrapment in a nanoemulsion results in its substantial stabilization (80–90% after 2 months of incubation at 22°C versus 28% in an aqueous solution). The kinetics of peptide srelease was studied in in vitro model experiments; a substantial slowing-down of peptide release in nanoemulsions in comparison to aqueous solutions was revealed. DSIP-containing nanoemulsion systems, which can be used in medicine and cosmetology, can serve as a basis for the development of novel stable pharmaceutical dosage forms of prolonged action peptide preparations.

Cytotoxicity studies of Dynasan 114 solid lipid nanoparticles (SLN) on RAW 264.7 macrophages-impact of phagocytosis on viability and cytokine production.

Solid lipid nanoparticles (SLN) based on Dynasan 114 (D114) were tested using RAW 264.7 cells. The influence of different surfactants on the cytotoxicity of this type of SLN was examined, expressed as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) viability and the production of cytokines such as interleukin 6 (IL-6), IL-12 and tumour necrosis factor-alpha (TNF-alpha). Results were compared with previously obtained data when peritoneal mouse macrophages were used. SLN produced with stabilizers/surfactants such as poloxamer 188, sodium cholate, Lipoid S75, Tween 80, Poloxamine 908 and sodium dodecylsulfate were shown to be nontoxic towards RAW 264.7 cells. Cytokine production was reduced and stimulation, expressed in elevated cytokine levels, could not be found. Using cetylpyridinium chloride (CPC) as stabilizing surfactant, SLN became cytotoxic in a concentration-dependent manner. Not only were the viabilities reduced but also cytokine production. Cytotoxic effects of CPC stabilized SLN could be antagonized using cytochalasin B to block phagocytosis. D114-SLN produced with pharmaceutically accepted surfactants for intravenous injection (poloxamer 188, Lipoid S75, sodium cholate, Tween 80) were very well tolerated by the cells. Even sodium dodecylsulfate-stabilized D114-SLN did not exert toxic effects. Comparison of the RAW 264.7 data with previously obtained data from toxicity studies of D114-SLN towards peritoneal mouse macrophages showed similar results. This offers the possibility of using the RAW 264.7 cell line for cytotoxicity studies of colloidal drug carrier systems, rather than using laboratory animals as source of macrophages for these kinds of studies.

Melatonin-loaded lecithin/chitosan nanoparticles: Physicochemical characterisation and permeability through Caco-2 cell monolayers

In this study, the potential of lecithin/chitosan nanoparticles (NPs) as a mucoadhesive colloidal nanosystem for transmucosal delivery of melatonin was investigated. The size, zeta potential and melatonin loading of the lecithin/chitosan NPs were investigated as a function of lecithin type (Lipoid S45, S75 and S100) and chitosan content in the preparation. The NPs were characterised by mean diameter and zeta potential ranging between 121.6 and 347.5 nm, and 7.5 and 32.7 mV, respectively, and increasing with lecithin-negative charge and chitosan content in the preparation. Melatonin loadings were up to 7.1%. All NPs were characterised by prolonged release profiles with an initial burst (approximately 25%), followed by a slow release phase. Approximately 60–70% of melatonin was released in 4 h. The permeability of melatonin was investigated using Caco-2 cells as an in vitro model of the epithelial barrier. Melatonin permeability from an NP suspension prepared with Lipoid S45 lecithin and a lecithin-to-chitosan weight ratio (L/C) of 20:1 (sample C2) was significantly improved compared to the permeability of melatonin from the solution ( P < 0.001) and from all other NPs investigated ( P < 0.05). The results obtained by the cell viability studies (MTT and LDH leakage assays) showed that C2 NP suspension did not induce plasma membrane damage or decrease cell viability and could be safely applied to Caco-2 cells in the concentration range tested (<400 μg/ml).

Influence of emulsifiers on the crystallization of solid lipid nanoparticles

The crystallization temperature and polymorphism of tripalmitin nanoparticles in colloidal dispersions prepared by melt-homogenization and stabilized with different pharmaceutical surfactants (sodium glycocholate, sodium oleate, tyloxapol, Solutol HS 15, Cremophor EL) and their combinations with soybean phospholipid (Lipoid S100) were investigated to establish the influence of the emulsifiers on these parameters. There were no major effects on the crystallization temperature but remarkable differences in the time-course of polymorphic transitions after crystallization of the triglyceride particles indicate interaction between the surfactant layer and the triglyceride matrix. The metastable alpha-modification was most stable in dispersions solely stabilized with glycocholate. Upon fast cooling from the melt, these dispersions form an uncommon type of alpha-modification that displays only a very weak small-angle reflection indicating poor ordering between triglyceride layers. Slow crystallization of these glycocholate-stabilized nanoparticles yields the usual alpha-form. Electron microscopic investigations reveal that, in both cases, the particles in the alpha-modification are less anisometric than those of the stable beta-form. These results indicate that major rearrangements still may take place in solid lipid nanoparticles after recrystallization.

Surfactant, but not the size of solid lipid nanoparticles (SLN) influences viability and cytokine production of macrophages

After intravenous (i.v.) injection, solid lipid nanoparticles (SLN) interact with mononuclear cells. Murine peritoneal macrophages were incubated with SLN formulations consisting of Dynasan 114 coated with different surfactants. The present study was performed to examine the impact of surfactants, which are important surface defining components of SLN, on viability and cytokine production by macrophages. Cytotoxicity, as assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) test, was strongly influenced by the surfactant used being marked with cetylpyridinium chloride- (CPC-) coated SLN at a concentration of 0.001% and further increased at SLN concentrations of 0.01 and 0.1%. All other SLN formulations — containing Poloxamine 908 (P908), Poloxamer 407 (P407), Poloxamer 188 (P188), Solutol HS15 (HS15), Tween 80 (T80), Lipoid S75 (S75), sodium cholate (SC), or sodium dodecylsulfate (SDS) — when used at the same concentrations reduced cell viability only slightly. None of the SLN formulations tested induced cytokine production but a concentration-dependent decrease of IL-6 production was observed, which appeared to be associated with cytotoxic effects. IL-12 and TNF-α were detected neither in supernatants of macrophages treated with SLN at any concentration nor in those of untreated cells. In contrast to the type of surfactant, the size of SLN was found neither to affect cytotoxicity of SLN nor to result in induction or digression of cytokine production by macrophages. In conclusion, testing the effects of surfactants on SLN on activity of macrophages is a prerequisite prior to in vivo use of SLN.