Hydrogenated Phosphatidylcholine Research Articles

Size- and Shape-Dependent Interactions of Lipid-Coated Silver Nanoparticles: An Improved Mechanistic Understanding through Model Cell Membranes and In Vivo Toxicity.

The widespread use of silver nanoparticles (AgNPs) in various applications and industries has brought to light the need for understanding the complex relationship between the physicochemical properties (shape, size, charge, and surface chemistry) of AgNPs that affect their ability to enter cells and cause toxicity. To evaluate their toxicological outcomes, this study systematically analyzed a series of homogeneous hybrid lipid-coated AgNPs spanning sizes from 5 to 100 nm with diverse shapes (spheres, triangles, and cubes). The hybrid lipid membrane comprises hydrogenated phosphatidylcholine (HPC), sodium oleate (SOA), and hexanethiol (HT), which shield the AgNP surface from surface oxidation and toxic Ag+ ion release to minimize its contribution to toxicity. To reduce any significant effects by surface chemistry, the HPC, SOA, and HT membrane composition ratio was kept constant, and the AgNPs were assessed using embryonic zebrafish (Danio rerio). While a direct comparison cannot be drawn due to the lack of complementary sizes below 40 nm for triangular plates and cubes due to synthetic challenges, significant mortality was observed for spherical AgNPs (AgNSs) of 5, 20, 40, and 60 nm at 120 h postfertilization at concentrations ≥6 mg Ag/L. In contrast, the 10, 80, and 100 nm AgNSs, 40, 70, and 100 nm triangular plate AgNPs (AgNPLs), and 55, 75, and 100 nm cubic AgNPs (AgNCs) showed no significant mortality at 5 days postfertilization following exposure to AgNPs at concentrations up to 12 mg Ag/L. With constant surface chemistry on the AgNPs, size is the dominant factor driving toxicological responses, with smaller nanoparticles (5 to 60 nm) being the most toxic. Larger AgNSs, AgNCs, and AgNPLs from 75 to 100 nm do not show any evidence of toxicity. However, when closely examining sizes between 40 and 60 nm for AgNSs, AgNCs, and AgNPLs, there is evidence that discriminates shape as a driver of toxicity since sublethal responses generally were observed to follow a pattern, suggesting toxicity is most significant for AgNSs followed by AgNPLs and then AgNCs, which is the least toxic. Sum frequency generation vibrational spectroscopy showed that irrespective of size or shape, all hybrid lipid-coated AgNPs interact with membrane surfaces and "snorkel" between phases into the lipid monolayer with minimal energetic cost. These findings decisively demonstrate that not only smaller AgNPs but also the shape of the AgNPs influences their biological compatibility.

Oxidation-resistant nanoliposomes loaded with osteogenic peptides: Characteristics, stability and bioaccessibility

Phosphatidylcholine (PC) oxidation leads to the fusion of nanoliposomes and leakage of containment compounds during the storage period. This study aims to improve the oxidation resistance by partially substituting PC in the osteogenic peptides (OPs) loaded nanoliposomes with hydrogenated phosphatidylcholine (HPC). The investigation assessed the characteristics, stability, and bioaccessibility of these novel nanoliposomes. By altering the PC/HPC mass ratio from 1:0 to 0:1, an increase in the encapsulation efficiency (EE), loading capacity (LC), polydispersity index (PDI), and bioaccessibility of OPs-loaded nanoliposomes was observed. Additionally, there was a decrease in thiobarbituric acid reactive substances (TBARS), peroxide value (POV), non-volatile aldehyde, and ketone. The stability of salt decreased when using HPC alone (0:1). The performance of OPs-loaded nanoliposomes with a PC/HPC mass ratio of 1:3 was found to be satisfactory in terms of storage and pH stability. Fluorescence spectroscopy, Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared spectroscopy (FTIR) revealed a tighter lipid aggregation, enhanced intermolecular van der Waals forces, and hydrogen bond formation in membranes of nanoliposomes containing HPC. The addition of HPC to the nanoliposomes delayed the release of peptides in simulated without affecting osteogenic activity. These results provide guidance for the development of oxidation-resistant nanoliposomes loaded with OPs products.

Assessment of Amentoflavone Loaded Sub-Micron Particle Preparation using Supercritical Antisolvent for its Antitumor Activity.

The amentoflavone (AMF) loaded polymeric sub-micron particles were prepared using supercritical antisolvent (SAS) technology with the aim of improving the anticancer activity of AMF. Zein and phospholipid mixtures composed of Hydrogenated Phosphatidylcholine (HPC) and egg lecithin (EPC) were used as carrier materials and, the effects of carrier composition on the product morphology and drug release behavior were investigated. When the mass ratio of Zein/HPC/ EPC was 7/2/1, the AMF loaded particles were spherical shape and sub-micron sized around 400 nm, with a drug load of 4.3±0.3 w% and entrapment efficacy of 87.8±1.8%. The in vitro drug release assay showed that adding EPC in the wall materials could improve the dispersion stability of the released AMF in an aqueous medium, and the introduction of HPC could accelerate the drug release speed. MTT assay demonstrated that AMF-loaded micron particles have an improved inhibitory effect on A375 cells, whose IC50 was 37.39μg/ml, compared with that of free AMF(130.2μg/ml). It proved that the AMF loaded sub-micron particles prepared by SAS were a prospective strategy to improve the antitumor activity of AMF, and possibly promote the clinical use of AMF preparations.

Development of curcumin-loaded composite phospholipid ethosomes for enhanced skin permeability and vesicle stability.

Ethosomes are widely applied as the carriers for the transdermal delivery of hydrophobic and hydrophilic drugs. Herein, curcumin-loaded ethosomes (CE) with different phospholipid composition were formulated and thoroughly compared. A significant interaction between the unsaturated phosphatidylcholine (PC) and saturated hydrogenated phosphatidylcholine (HPC) was found by molecular simulation and differential scanning calorimetry (DSC), which led to the reduction of PC peroxidation with the presence of HPC. Subsequently, the composite phospholipid ethosomes containing curcumin were prepared for the first time to evaluate their properties in comparison with the conventional ethosomes composed of PC (CE-P) or HPC (CE-H). CE with PC/HPC ratio of 1:1 (CE-P1H1) with the best vesicle stability and flexibility significantly decreased the uptake by HaCaT cells compared to CE-H and free curcumin, indicating reduced skin cell toxicity. Compared with free curcumin, CE-P1H1 had the highest transdermal efficiency (p<0.001), followed by CE-P (p<0.05), partly due to the fact that CE-P1H1 could disturb lipid domain of stratum corneum (SC). Moreover, CE-P1H1 was found to promote curcumin for deep penetration of the skin via the hair follicles route. Our study has shown that using composite phospholipid ethosomes as lipid vesicular carriers could enhance transdermal penetration of drugs and increase in the vesicle stability.

An in vitro digestion study of encapsulated lactoferrin in rapeseed phospholipid–based liposomes

Effectiveness of liposomes elaborated with rapeseed phospholipid (RP) extracted from a residue of oil processing, stigmasterol (ST) and/or hydrogenated phosphatidylcholine (HPC) for the encapsulation lactoferrin (LF) was studied; lipid membrane of liposomes was characterized (bilayer size, chain conformational order, lateral packing, lipid phase, and morphology) and the protection offered to the encapsulated LF during in vitro digestion was determined. Liposomes composed of RP+STLC(low concentration) showed spherical and irregular vesicles without perforations. Lamellar structure was organized in a liquid–ordered phase with a potential orthorhombic packing. Stability and size of the liposomes were more affected by gastric digestion than intestinal digestion; 67–80% of the initially encapsulated LF remained intact after gastric digestion whereas the percentage was reduced to 16–35% after intestinal digestion. Our results shows that liposomes elaborated with RP, properly combined with other lipids, can be a useful oral delivery system of molecules sensitive to digestive enzymes.

Preparation, characterization and in vivo studies of amorphous solid dispersion of berberine with hydrogenated phosphatidylcholine

Berberine, a pure crystalline quaternary ammonium salt with the basic structure of isoquinoline alkaloid, has multiple pharmacological bioactivities. But the poor bioavailability of berberine limited its wide clinical applications. In the present study, we aimed to develop an amorphous solid dispersion of berberine with hydrogenated phosphatidylcholine (HPC) in order to improve its bioavailability. The physical characterization studies such as differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD), Fourier transform infrared spectrophotometry (FT-IR) and scanning electron microscopy (SEM) were conducted to characterize the formation of amorphous berberine HPC solid dispersion (BHPC-SD). The everted intestinal sac and single-pass intestinal perfusion study proved that permeability and intestinal absorption of amorphous BHPC-SD was improved compared with that of pure crystalline berberine, and the pharmacokinetic study results demonstrated that the extent of bioavailability was significantly increased as well. However, the dissolution study indicated that the aqueous cumulative dissolution percentages of berberine remained unchanged or even lower by means of preparation into solid dispersion with HPC. Therefore, according to the previous mechanistic studies, the present results supported that it is the enhanced molecularly dissolved concentration (supersaturation) of berberine by transformation from crystalline structure into amorphous solid dispersions that triggers the enhanced permeability, and consequently results in the improved intestinal absorption and bioavailability.

Predicting the in vivo release from a liposomal formulation by IVIVC and non-invasive positron emission tomography imaging

This study aimed to predict the in vivo performance from the in vitro release of a low-molecular weight model compound, [18F]-2-fluoro-2-deoxy-d-glucose ([18F]FDG), from liposomes and by means of positron emission tomography (PET). Liposomes composed of hydrogenated phosphatidylcholine (HPC) were prepared by a freeze–thaw method. Particle size distribution was measured by dynamic light scattering (DLS). In vitro release was examined with a dispersion method detecting the radioactivity of [18F]FDG. In vivo release of [18F]FDG, following i.p. injection of the liposomes in rats, was determined by using a Micro-PET scanner. Convolution was performed to predict the in vivo profiles from the in vitro data and to establish an in vitro–in vivo correlation (IVIVC). The in vivo predictions slightly underestimated the experimentally determined values. The magnitude of the prediction errors (13% and 19%) displayed a satisfactory IVIV relationship leaving yet room for further improvement. This study demonstrated for the first time the use of PET in attaining an IVIVC for a parenterally administered modified release dosage form. It is therefore possible to predict target tissue concentrations, e.g., in the brain, from in vitro release experiments. IVIVC using non-invasive PET imaging could thus be a valuable tool in drug formulation development, resulting in reduced animal testing.

Development of liposomal capreomycin sulfate formulations: Effects of formulation variables on peptide encapsulation

Purpose The aim of this work was the investigation of the effects of preparation variables on drug content for the development of capreomycin sulfate (CS) liposomal formulations as potential aerosol antitubercular agents. Methods Dipalmitoylphosphatidylcholine (DPPC), hydrogenated phosphatidylcholine (HPC) and distearoylphosphatidylcholine (DSPC) were used for liposome preparation. A freeze–thawing method was chosen for CS encapsulation. Peptide entrapment, size and morphology were evaluated by UV spectrophotometry, photocorrelation spectroscopy (PCS) and transmission electron microscopy (TEM), respectively. A 2 3 full factorial protocol was designed to evaluate the conditions for CS encapsulation improvement. Results Peptide content ranged between 1 and 8%. Vesicles showed a narrow size distribution, with average diameters around 1 μm and a good morphology. A mathematical model was generated for each liposomal system and check point analyses revealed good agreement between experimental and predicted values. DPPC liposomes were found to provide the highest CS content. Conclusions Peptide content was successfully increased by assessing formulation variable effects using a 2 3 factorial design that proved to be a time saving method helpful in developing new CS liposomal formulations for a possible application in aerosol antitubercular therapies.

Biodistribution Study of Doxorubicin Encapsulated in Liposomes: Influence of Peptide Coating and Lipid Composition

In this paper we describe the biodistribution of doxorubicin (DXR) encapsulated in three different types of liposomes. Common composition was hydrogenated phosphatidylcholine (HPC)/phosphatidylglycerol (PG) cholesterol (Chol)/X, X being either 10% N‐glutaryl phosphatidylethanolamine (NGPE), 10% NGPE + 6% distearoyl‐phosphatidylethanolamine‐polyethyleneglycol 2000 (DSPE‐PEG), or 10% NGPE + 6% DSPE‐PEG‐COOH. These series of vesicles were coated with an active or an inactive sequence of laminin (laminin receptors, integrins, are over‐expressed in tumor cells). Single doses of these preparations were injected, i.v., into healthy mice. For biodistribution experiments, mice were sacrificed at three different time‐points post‐treatment. Doxorubicin and doxorubicinol (DXOH) levels were determined in plasma, heart, lung, kidney, spleen, and liver using HPLC with daunorubicin (DNR) as internal standard. The results obtained indicate that compositions containing DSPE‐PEG have the longest half‐lives in plasma, as was to be expected according to the data in the literature. However, the presence of the peptides on the surface of liposomes reduces concentration values in this tissue. Distribution in other organs reveals high differences, among the liposomal samples studied, depending mainly on the presence of active or inactive peptide on the surface of vesicles. Liposomes coated with the laminin active sequence show lower accumulation in studied tissues than free DXR. This indicates that heart toxicity, associated to DXR treatments, could be diminished, and open promising perspectives for its future study in tumor‐bearing animals.

Enhancement of skin permeation of miconazole by phospholipid and dodecyl 2-( N, N-dimethyl amino)propionate (DDAIP)

Miconazole (MCZ) has very low solubility in both water and oil. Permeation rates through shed snakeskin from an aqueous suspension and a mineral oil suspension were 0.5 μg/cm 2/h and almost none, respectively. When hydrogenated phosphatidylcholine (HPC) was added to mineral oil and heated to 95 °C, the solubility of MCZ increased in proportion to the HPC concentration. DSC measurements also indicated an interaction between them. Thus, a gel formed by hydrogenated phospholipid and mineral oil, as vehicle was prepared. The solubility of MCZ in the gel was around 1% and the permeation rate was 1.3 μg/cm 2/h, which was about 2.5 times that from an aqueous suspension. As an alternative approach, a skin permeation enhancer, dodecyl 2-( N, N-dimethyl amino)propionate (DDAIP) was applied 2 h before a skin permeation study. The permeation from an aqueous suspension became 11 times that of the suspension without DDAIP pretreatment. The concentration of MCZ in the skin increased 8-fold, indicating that the enhancement effect involved high partition of MCZ into the skin. On the other hand, when a gel formulation was used, pretreatment with DDAIP was not as effective as incorporation of DDAIP in the gel formulation. Following pretreatment, permeation was only two times that of the gel without DDAIP pretreatment, and half that of the water suspension with DDAIP pretreatment. This suggested that release from the gel was the rate-limiting step with the gel formulation. When DDAIP was added to the gel, the permeation rate of MCZ was 3.3 μg/cm 2/h. It was also a release limited type permeation. The gel with DDAIP is potentially a useful formulation, because of relatively high permeation while possibly avoiding overdosing.

Paramagnetic liposomes as MRI contrast agents: influence of liposomal physicochemical properties on the in vitro relaxivity.

The in vitro contrast efficacy of liposome encapsulated gadolinium-[10-(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane-1, 4,7-triacetic acid] (GdHPDO3A) has been assessed by relaxometry. The internal concentrations were 150 and 250 mM Gd. Two types of liposome compositions were investigated: a phospholipid blend consisting of both hydrogenated phosphatidylcholine (HPC) and phosphatidylserine (HPS) with a gel-to-liquid crystalline phase transition temperature (Tm) of 50 degrees C, and a mixture of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG) with a Tm of 41 degrees C. The investigated liposome size range was 70-400 nm. The T1 and T2 relaxivities (r1 and r2) of liposome encapsulated GdHPDO3A were significantly reduced at 37 degrees C and 0.47 T, compared to those of non-liposomal metal chelate, due to an exchange limitation of the dipolar relaxation process. The highest relaxivity values were obtained for the DPPC/DPPG liposomes, and were attributed to a higher liposome water permeability and to a more efficient water exchange across the membrane. A reduction in liposome size increased the r1, confirming the exchange limited dipolar relaxation. The increased r1 with increasing temperature demonstrated the prerequisite of rapid water exchange between the interior and exterior of the liposome for efficient dipolar relaxation enhancement. Susceptibility effects were present in the liposome systems as the r2/r1 ratio increased with increasing liposome size and internal Gd concentration. In summary, the current work has shown the influence of key physicochemical properties, such as liposome size, membrane composition and permeability, on the in vitro relaxivity of liposome encapsulated GdHPDO3A.

Paramagnetic liposomes as magnetic resonance imaging contrast agents. Assessment of contrast efficacy in various liver models.

Liposomal gadolinium (Gd)-HP-DO3A has been evaluated as a contrast agent for liver magnetic resonance imaging. The influence of various liposomal physicochemical properties on the liver uptake and contrast efficacy was investigated in various ex vivo and in vivo liver models. Liposomes of different size and membrane properties were prepared. The liposome size ranged from 74 to 304 nm. Two types of phospholipid compositions were studied; a mixture of hydrogenated phosphatidylcholine (HPC) and hydrogenated phosphatidylserine (HPS) with a phase transition temperature (Tm) of 51 degrees C and, a blend composed of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG) displaying a Tm of 41 degrees C. Ex vivo tissue relaxometry and in vivo liver imaging were used to study the influence of liposome composition on the liver uptake and contrast efficacy of intravenously injected liposomes. The influence of liposome size and composition on the kinetics of liver uptake and imaging effect was assessed ex vivo in the perfused rat liver. The HPC/HPS preparations showed generally a higher and faster liver uptake than the DPPC/DPPG preparations due to a higher stability in blood/perfusate (high Tm) and to the HPS component. The liposome size modulated the extent and kinetics of liver uptake; the larger the size, the faster and more extensive was the liver uptake. Both types of liposome preparations were shown to be efficient liver susceptibility agents both ex vivo and in vivo due to their uptake by the Kupffer cells of liver. The lack of full correlation between the extent of liver uptake and degree of contrast enhancement might be attributed to different regimes of susceptibility-based relaxation. The present study has demonstrated the influence of key liposomal physicochemical properties on the liver uptake and contrast efficacy of liposome-encapsulated Gd chelates, exemplified by Gd-HP-DO3A.