Physicochemical Properties Of Liposomes Research Articles

Preparation of pectin-coated and chitosan-coated phenylethanoside liposomes: Studies on characterization, stability, digestion and release behavior

In this paper, the effects of extrusion, ultrasound on physicochemical properties of liposomes were studied, and the liposomes were prepared by ethanol injection combined with extrusion-ultrasound. In addition, the quality of PhGs lips, pectin-coated PhGs lips (P-lips) and chitosan-coated PhGs lips (C-lips) was evaluated by the average particle size, encapsulation efficiency (EE) and other indicators, which indicated that the nanoparticles had been successfully prepared. Compared with extrusion or ultrasonic operation alone, the EEs of ethanol injection combined with extrusion-ultrasonic increased by 8 % and 18 % respectively. Subsequently, transmission electron microscopy, Fourier transform infrared spectroscopy and DSC thermal analysis showed that PhGs in PhGs lips may produce hydrogen bonding forces with phospholipids, and pectin and chitosan in P-lips and C-lips were not only coated on the surface of PhGs lips, but also might have some interaction between them. Cell experiments showed that PhGs lips, P-lips and C-lips can effectively improve the bioavailability of PhGs. In addition, the storage stability of P-lips and C-lips was not significantly improved compared to PhGs lips, but their digestive stability was significantly improved, and the final retention rate in simulated intestinal fluid was about 25 % higher than that of PhGs lips.

To Assess Drug Delivery System Nanocarrier at Industrial Production: Establishment of Liposomal Surface Using Physicochemical Properties

Liposomes have been reported to be useful nanocarrier, however, there are number of challenges to resolve before they can be optimized for drug delivery. Liposomes are taken up by cell in the reticuloendothelial system (RES). Polyethyleneglycol (PEG) modification on the liposomal membrane forms a fixed aqueous layer and thus prevents uptake by the RES. The physicochemical properties of liposomes that are most commonly evaluated particle size and zeta potential are not sufficient indicator of the passive targeting effect by PEG modification. In contrast, the fixed aqueous layer thickness (FALT) around liposomal surface was clear to be regulated to be the utilized action in the body. It was showed that the FALT value of PEG-modified liposomes containing doxorubicin increased with the increase in the molecular weight of PEG. Furthermore, PEG modification with a combination of high- and low- molecular weight PEGs on liposomal membranes showed in optimal results with respect to FALT and a higher antitumor effect. In addition, we designed and synthesized a novel PEG-lipid, different double arms PEG (DDA-PEG), which consisted of two PEG chains of 500 and 2000 in one molecule to develop more useful PEG-modified liposomes. DDA-PEG was found to have superior antitumor activity and was associated with the prevention of tumor metastasis. Furthermore, we sought to (-)-epigallocatechin-3-O-gallate (EGCG) functions as a target ligand of the 67-kDa laminin receptor (67LR), which is expressed on high-grade tumor cells. EGCG-PEG-modified liposome appear to have superior antitumor activity against high 67LR-expressing tumor cells, as the liposomes had dual effects.

Layer-by-layer self-assembled liposomes prepared using sodium alginate and chitosan: Insights into vesicle characteristics and physicochemical stability

In this study, layer-by-layer self-assembled liposomes were prepared with different mixing ratios (3:7, 1:1, and 7:3) of sodium alginate (SA) and chitosan (CS), and the morphology, structure, and physicochemical properties of liposomes after layer-by-layer coating were investigated. After coating the liposomes with SA-CS layer-by-layer (S–C-L), the particle size of liposomes increased from 244.50 to 423.33 nm, the potential changed from negative to positive to 21.20 mV, and the PDI was only 0.393. In the S–C-L 7:3 formulation, the liposomes were uniformly distributed and spherical in size with a clear fingerprint structure. In addition, S–C-L reduced the number of hydrophobic regions within the molecule, allowing the phospholipid molecules to bind tightly into stacks, thus making the liposomes more stable. The S–C-L 7:3 formulation effectively improved the tolerance of liposomes to strong acids and bases, high-salt environments, and UV exposure, and maintained a constant particle size of 400 nm after 28 days of storage. The findings of this study might contribute to the development of polysaccharide layer-by-layer modification of liposomes for a more stable liposomal transport system.

Liposomes as Carriers of GHK-Cu Tripeptide for Cosmetic Application.

Liposomes are self-assembled spherical systems composed of amphiphilic phospholipids. They can be used as carriers of both hydrophobic and hydrophilic substances, such as the anti-aging and wound-healing copper-binding peptide, GHK-Cu (glycyl-L-histidyl-L-lysine). Anionic (AL) and cationic (CL) hydrogenated lecithin-based liposomes were obtained as GHK-Cu skin delivery systems using the thin-film hydration method combined with freeze-thaw cycles and the extrusion process. The influence of total lipid content, lipid composition and GHK-Cu concentration on the physicochemical properties of liposomes was studied. The lipid bilayer fluidity and the peptide encapsulation efficiency (EE) were also determined. Moreover, in vitro assays of tyrosinase and elastase inhibition were performed. Stable GHK-Cu-loaded liposome systems of small sizes (approx. 100 nm) were obtained. The bilayer fluidity was higher in the case of cationic liposomes. As the best carriers, 25 mg/cm3 CL and AL hydrated with 0.5 mg/cm3 GHK-Cu were selected with EE of 31.7 ± 0.9% and 20.0 ± 2.8%, respectively. The obtained results confirmed that the liposomes can be used as carriers for biomimetic peptides such as copper-binding peptide and that the GHK-Cu did not significantly affect the tyrosinase activity but led to 48.90 ± 2.50% elastase inhibition, thus reducing the rate of elastin degeneration and supporting the structural integrity of the skin.

Transferrin-Targeted Liposomes in Glioblastoma Therapy: A Review.

Glioblastoma (GBM) is a highly aggressive brain tumor, and its treatment is further complicated by the high selectivity of the blood-brain barrier (BBB). The scientific community is urgently seeking innovative and effective therapeutic solutions. Liposomes are a promising new tool that has shown potential in addressing the limitations of chemotherapy, such as poor bioavailability and toxicity to healthy cells. However, passive targeting strategies based solely on the physicochemical properties of liposomes have proven ineffective due to a lack of tissue specificity. Accordingly, the upregulation of transferrin receptors (TfRs) in brain tissue has led to the development of TfR-targeted anticancer therapeutics. Currently, one of the most widely adopted methods for improving drug delivery in the treatment of GBM and other neurological disorders is the utilization of active targeting strategies that specifically target this receptor. In this review, we discuss the role of Tf-conjugated liposomes in GBM therapy and present some recent studies investigating the drug delivery efficiency of Tf-liposomes; in addition, we address some challenges currently facing this approach to treatment and present some potential improvement possibilities.

Rosehip Extract-Loaded Liposomes for Potential Skin Application: Physicochemical Properties of Non- and UV-Irradiated Liposomes.

In the present study, rosehip (Rosa canina L.) extract was successfully encapsulated in phospholipid liposomes using a single-step procedure named the proliposome method. Part of the obtained liposomes was subjected to UV irradiation and non-treated (native) and UV-irradiated liposomes were further characterized in terms of encapsulation efficiency, chemical composition (HPLC analysis), antioxidant capacity, particle size, PDI, zeta potential, conductivity, mobility, and antioxidant capacity. Raman spectroscopy as well as DSC analysis were applied to evaluate the influence of UV irradiation on the physicochemical properties of liposomes. The encapsulation efficiency of extract-loaded liposomes was higher than 90%; the average size was 251.5 nm; the zeta potential was -22.4 mV; and the conductivity was found to be 0.007 mS/cm. UV irradiation did not cause a change in the mentioned parameters. In addition, irradiation did not affect the antioxidant potential of the liposome-extract system. Raman spectroscopy indicated that the extract was completely covered by the lipid membrane during liposome entrapment, and the peroxidation process was minimized by the presence of rosehip extract in liposomes. These results may guide the potential application of rosehip extract-loaded liposomes in the food, pharmaceutical, or cosmetic industries, particularly when liposomal sterilization is needed.

The effect of antifibrotic and antibacterial drugs on the physicochemical properties of liposomes: A spectral study

The effect of antifibrotic and antibacterial drugs on the physicochemical properties of liposomes: A spectral study

Acylglycerols of Myristic Acid as New Candidates for Effective Stigmasterol Delivery-Design, Synthesis, and the Influence on Physicochemical Properties of Liposomes.

New carriers of phytosterols; acylglycerols containing natural myristic acid at sn-1 and sn-3 positions and stigmasterol residue linked to sn-2 position by carbonate and succinate linker have been designed and synthesized in three-step synthesis from dihydroxyacetone (DHA). The synthetic pathway involved Steglich esterification of DHA with myristic acid; reduction of carbonyl group of 1,3-dimyristoylpropanone and esterification of 1,3-dimyristoylglicerol with stigmasterol chloroformate or stigmasterol hemisuccinate. The structure of the obtained hybrids was established by the spectroscopic methods (NMR; IR; HRMS). Obtained hybrid molecules were used to form new liposomes in the mixture with model phospholipid and their effect on their physicochemical properties was determined, including the polarity, fluidity, and main phase transition of liposomes using differential scanning calorimetry and fluorimetric methods. The results confirm the significant effect of both stigmasterol-containing acylglycerols on the hydrophilic and hydrophobic region of liposome membranes. They significantly increase the order in the polar heads of the lipid bilayer and increase the rigidity in the hydrophobic region. Moreover, the presence of both acylglycerols in the membranes shifts the temperature of the main phase transition towards higher temperatures. Our results indicate stabilization of the bilayer over a wide temperature range (above and below the phase transition temperature), which in addition to the beneficial effects of phytosterols on human health makes them more attractive components of novel lipid nanocarriers compared to cholesterol.

Liposomal-Based Formulations: A Path from Basic Research to Temozolomide Delivery Inside Glioblastoma Tissue.

Glioblastoma (GBM) is a lethal brain cancer with a very difficult therapeutic approach and ultimately frustrating results. Currently, therapeutic success is mainly limited by the high degree of genetic and phenotypic heterogeneity, the blood brain barrier (BBB), as well as increased drug resistance. Temozolomide (TMZ), a monofunctional alkylating agent, is the first line chemotherapeutic drug for GBM treatment. Yet, the therapeutic efficacy of TMZ suffers from its inability to cross the BBB and very short half-life (~2 h), which requires high doses of this drug for a proper therapeutic effect. Encapsulation in a (nano)carrier is a promising strategy to effectively improve the therapeutic effect of TMZ against GBM. Although research on liposomes as carriers for therapeutic agents is still at an early stage, their integration in GBM treatment has a great potential to advance understanding and treating this disease. In this review, we provide a critical discussion on the preparation methods and physico-chemical properties of liposomes, with a particular emphasis on TMZ-liposomal formulations targeting GBM developed within the last decade. Furthermore, an overview on liposome-based formulations applied to translational oncology and clinical trials formulations in GBM treatment is provided. We emphasize that despite many years of intense research, more careful investigations are still needed to solve the main issues related to the manufacture of reproducible liposomal TMZ formulations for guaranteed translation to the market.

The Physico-Chemical Properties of Liposomes Made from Lipids of the Liver and Brain of Mice Receiving Nanolipid Complexes

The Physico-Chemical Properties of Liposomes Made from Lipids of the Liver and Brain of Mice Receiving Nanolipid Complexes

The effect of the polyethylene glycol chain length of a lipopolymer (DSPE-PEGn) on the properties of DPPC monolayers and bilayers

Due to the growing importance of controlled drug delivery systems (DDS), the main task of nanotechnology is to develop stable, effective and non-toxic nanocarriers in which the drug can be encapsulated and delivered to a specific diseased site in the patient's body. Currently, one of the most popular ways to improve the pharmacokinetic and physicochemical properties of liposomes is introducing into their structure poly(ethylene glycol) chains conjugated with 1,2-disteroil-sn-glycero-3-phosphoethanolamine (DSPE) molecules. Because the research so far does not give an unequivocal answer which length of PEG chains is more beneficial for liposomes properties, the aim of this work was to investigate the influence of this parameter (DSPE-PEG350, DSPE-PEG750 and DSPE-PEG2000) on model DPPC membrane. The studies were performed on monolayer and bilayer systems and were related to the surface pressure measurements, Brewster angle microscopy experiments, Grazing Incidence X-ray Diffraction studies, dynamic light scattering and zeta potential measurements and the experiments with the calcein release and steady-state fluorescence anisotropy of DPH. The obtained results proved that the molecular organization of the DPPC membrane strongly depends on the length of poly(ethylene glycol) chains conjugated with DSPE. Moreover, the addition of different lengths of polymer chains changes the properties of formulated liposomes, especially their stability, permeability, size and surface charge.

Recent Advancements in Liposome-Targeting Strategies for the Treatment of Gliomas: A Systematic Review.

Malignant tumors represent some of the most intractable diseases that endanger human health. A glioma is a tumor of the central nervous system that is characterized by severe invasiveness, blurred boundaries between the tumor and surrounding normal tissue, difficult surgical removal, and high recurrence. Moreover, the blood-brain barrier (BBB) and multidrug resistance (MDR) are important factors that contribute to the lack of efficacy of chemotherapy in treating gliomas. A liposome is a biofilm-like drug delivery system with a unique phospholipid bilayer that exhibits high affinities with human tissues/organs (e.g., BBB). After more than five decades of development, classical and engineered liposomes consist of four distinct generations, each with different characteristics: (i) traditional liposomes, (ii) stealth liposomes, (iii) targeting liposomes, and (iv) biomimetic liposomes, which offer a promising approach to promote drugs across the BBB and to reverse MDR. Here, we review the history, preparatory methods, and physicochemical properties of liposomes. Furthermore, we discuss the mechanisms by which liposomes have assisted in the diagnosis and treatment of gliomas, including drug transport across the BBB, inhibition of efflux transporters, reversal of MDR, and induction of immune responses. Finally, we highlight ongoing and future clinical trials and applications toward further developing and testing the efficacies of liposomes in treating gliomas.

Box Behnken design of siRNA-loaded liposomes for the treatment of a murine model of ocular keratitis caused by Acanthamoeba.

Acanthamoeba keratitis is an ophthalmic disease with no specific treatment that specially affects contact lens users. The silencing of serine phosphatase (SP) and glycogen phosphorylase (GP) proteins produced by Acanthamoeba has been shown to significantly reduce the cytopathic effect, although no vehicle was proposed yet to deliver the siRNA sequences to the trophozoites. In this study, PEGylated cationic liposomes were proposed and optimized using Box-Behnken design. The influence of DOTAP:DOPE ratio, DSPE-PEG concentration, and siRNA/DOTAP charge ratio were evaluated over both biological response and physicochemical properties of liposomes. The ratio of DOTAP:DOPE had an effect in the trophozoite activity whereas the charge ratio influenced both size and protease activity. The predicted values were very close to the observed values, yielding a formulation with good activity and toxicity profile, which was used in the following experiments. A murine model of ocular keratitis was treated with siGP + siSP-loaded liposomes, as well as their respective controls, and combined treatment of liposomes and chlorhexidine. After 15 days of eight daily administrations, the liposomal complex combined with chlorhexidine was the only treatment able to reverse the more severe lesions associated with keratitis. There was 60% complete regression in corneal damage, with histological sections demonstrating the presence of an integral epithelium, without lymphocytic infiltrate. The set of results demonstrate the efficacy of a combined therapy based on siRNA with classical drugs for a better prognosis of keratitis caused by Acanthamoeba.

Labrasol-Enriched Nanoliposomal Formulation: Novel Approach to Improve Oral Absorption of Water-Insoluble Drug, Carvedilol

The purpose of the current study was to develop a novel liposomal formulation to improve the oral bioavailability of carvedilol, a Biopharmaceutics Classification System class II with poor aqueous solubility and extensive presystemic metabolism. Conventional and various surfactant-enriched carvedilol-loaded liposomes were prepared by thin film hydration technique and physicochemical properties of liposomes (including size, encapsulation efficiency, release behavior, and morphology) were evaluated. To assess the oral bioavailability, in vivo studies were carried out in eight groups of male Wistar rats (n = 6) and the drug plasma concentration was determined. Conventional and surfactant containing liposomes showed average particle size of 76-104nm with a narrow size distribution, high encapsulation efficiency (80%≤) and a sustained release profile in simulated intestinal fluid. Compared to the suspension, conventional and Labrasol containing liposomes significantly improved the oral bioavailability and peak plasma concentration of carvedilol. Biocompatibility studies (cell cytotoxicity and histopathological analyses) showed that the enhancing effect might be achieved without any apparent toxicity in the intestine. Decreased oral absorption of carvedilol nanovesicles by using a chylomicron flow blocker indicated contribution of lymphatic transport in nanocapsules absorption. The results reported the successful development of biocompatible Labrasol-enriched carvedilol nanoliposomal formulation with a significant oral enhancement capability. Graphical Abstract ᅟ.

Influence of Lipid Composition, pH, and Temperature on Physicochemical Properties of Liposomes with Curcumin as Model Drug.

The physicochemical properties of large unilamellar vesicles (LUVs) were assessed with respect to lipid composition, pH, time, and temperature by monitoring their size, zeta potential, drug payload, and thermal behavior. A conventional thin film hydration technique was employed to prepare liposomes from soy phosphatidylcholine (SPC), dipalmitoylphosphatidylcholine (DPPC), dipalmitoylphosphatidylglycerol (DPPG), and a 7:3 (M/M) mixture of DPPC+DPPG along with 30 mole% cholesterol in each combination. While the size of liposomes depended on lipid composition, pH and temperature, the zeta potential was found to be independent of the pH of the medium, although it varied with liposome type. Spherical morphology and bilayer were observed by electron microscopy. The phase transition temperature increased with decreasing pH. Membrane micro-viscosity showed the highest value for SPC, and membrane rigidity increased with increasing pH. The entrapment efficiency of liposomes with reference to curcumin was as follows: DPPC>DPPC+DPPG>DPPG>SPC. Sustained release of curcumin was observed for all liposomes. Curcumin-loaded liposomes exhibited substantial antibacterial activity against the gram-positive bacteria Bacillus amyloliquefaciens. Additional studies are needed to improve the understanding of the effect of formulation variables on the physicochemical stability of liposomes.

Physical Characterization of Synthetic Phosphatidylinositol Dimannosides and Analogues in Binary Systems with Phosphatidylcholine

Native phosphatidylinositol mannosides (PIMs) from the cell wall of Mycobacterium bovis (M. bovis) and synthetic analogues have been identified to exert immunostimulatory activities. These activities have been investigated using particulate delivery systems containing native mannosylated lipids or total lipid extracts. Limited work has been carried out examining the incorporation of individual PIM lipids into suitable particulate formulations such as liposomes. The present study explored the possibility of constructing phosphatidylcholine (PC)-based liposomes containing synthetic PIM analogues. A series of six phosphatidylinositol dimannosides (PIM(2)s) and phosphatidylglycerol dimannosides (PGM(2)s) was characterized in this study. Binary Langmuir monolayers are a useful approach for establishing pharmaceutical properties, such as lipid-lipid interactions in mixed monolayers, to facilitate the design of liposome-based delivery systems. In mixed films the phosphoglycolipids were found to be miscible with PC based on evaluation of collapse pressures and deviations of experimental molecular areas from calculated ideal values. Concanavalin A (ConA) agglutination confirmed the presence of mannosylated lipids on the surface of the liposomes. Physicochemical properties of liposomes were affected by the presence of 2% (w/w) of phosphoglycolipids with liposome stability being increased by incorporation of long-chain PIM(2) and PGM2. Overall, while membrane stability of the liposomes was found to be dependent on incorporation of the phosphoglycolipids, all formulations retained proteins in amounts making them suitable for delivery.

Physicochemical properties of liposomes as potential anticancer drugs carriers. Interaction of etoposide and cytarabine with the membrane: Spectroscopic studies

The interactions between etoposide, cytarabine and 1,2-dihexadecanoyl-sn-glycerol-3-phosphocholine bilayers were studied using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR). These techniques have proven to be a very powerful tool in studying the structure and dynamics of phospholipid bilayers. In particular, DSC can provide information on the phase transition temperature and cooperativity of the lipid molecules in the absence and presence of the drug. Vibrational spectroscopy is well suited to the study of drug–lipid interactions, since it allows for an investigation of the conformation of phospholipid molecules at different levels in lipid bilayers and follows structural changes that occur during the gel to liquid–crystalline phase transition. NMR supported the determination of the main phase transition temperatures (TC) of 1,2-dihexadecanoyl-sn-glycerol-3-phosphocholine (DPPC). The main phase transition temperature (TC) determined by 1H NMR is comparable with values obtained by DSC for all studied liposomes. The location of cytarabine and etoposide in liposomes was also determined by NMR. Atomic force microscopy (AFM) images, acquired immediately after sample deposition on a mica surface, revealed the spherical shape of lipid vesicles.

Observation of Inhomogeneity in the Lipid Composition of Individual Nanoscale Liposomes

Liposomes are one of the most extensively used model systems for studying the physical and chemical properties of membranes and the majority of these studies have implicitly assumed that all liposomes in an ensemble are identical. However recent measurements performed at the level of single liposomes revealed the existence of intrinsic intra-sample heterogeneities that were otherwise averaged out in ensemble experiments. By employing fluorescently labeled lipids and measuring at the single liposome level we examined the compositional inhomogeneity between individual liposomes within an ensemble. In a recent publication we demonstrated an up to ten-fold variation in the relative lipid composition of individual liposomes with diameters between 50 nm and 15 μm.1 This observation is made for both a variety of different lipid-labels and compositions, which suggest that compositional inhomogeneity is a general phenomenon present in liposome systems. As a result, bulk measurement of physical and chemical properties that depend on bilayer composition, e.g. phase-transition temperature, will produce results representing the ensemble average, which will be a convolution of the properties arising from many different bilayer compositions of the individual liposomes. Furthermore, we saw that the choice of liposome preparation method greatly influences the degree of compositional inhomogeneity. This could be particularly important when using liposomes as drug delivery carriers where the monodispersity of, and control over, bilayer properties is instrumental. Since the physicochemical properties of liposomes are directly linked to their composition a direct consequence of compositional inhomogeneities is a polydispersity in the properties of the individual liposomes in an ensemble. (1) Larsen, J.; Hatzakis, N. S.; Stamou, D. J. Am. Chem. Soc. 2011, 133, 10685-10687.

Observation of Inhomogeneity in the Lipid Composition of Individual Nanoscale Liposomes

Liposomes, or vesicles, have been studied extensively both as models of biological membranes and as drug delivery vehicles. Typically it is assumed that all liposomes within the same preparation are identical. Here by employing pairs of fluorescently labeled lipids we demonstrated an up to 10-fold variation in the relative lipid composition of individual liposomes with diameters between 50 nm and 15 μm. Since the physicochemical properties of liposomes are directly linked to their composition, a direct consequence of compositional inhomogeneities is a polydispersity in the properties of the individual liposomes in an ensemble.

Nanovesicle encapsulation of antimicrobial peptide P34: physicochemical characterization and mode of action on Listeria monocytogenes

Antimicrobial peptide P34, a substance showing antibacterial activity against pathogenic and food spoilage bacteria, was encapsulated in liposomes prepared from partially purified soybean phosphatidylcholine, and their physicochemical characteristics were evaluated. The antimicrobial activity was estimated by agar diffusion assay using Listeria monocytogenes ATCC 7644 as indicator strain. A concentration of 3,200 AU/mL of P34 was encapsulated in nanovesicles and stocked at 4 °C. No significant difference (p > 0.05) in the biological activity of free and encapsulated P34 was observed through 24 days. Size and PDI of liposomes, investigated by light scattering analysis, were on average 150 nm and 0.22 respectively. Zeta potential was −27.42 mV. There was no significant change (p > 0.05) in the physicochemical properties of liposomes during the time of evaluation. The liposomes presented closed spherical morphology as visualized by transmission electron microscopy (TEM). The mode of action of liposome-encapsulated P34 under L. monocytogenes cells was investigated by TEM. Liposomes appeared to adhere but not fuse with the bacterial cell wall, suggesting that the antimicrobial is released from nanovesicles to act against the microorganism. The effect of free and encapsulated P34 was tested against L. monocytogenes, showing that free bacteriocin inhibited the pathogen more quickly than the encapsulated P34. Liposomes prepared with low-cost lipid showed high encapsulation efficiency for a new antimicrobial peptide and were stable during storage. The mode of action against the pathogen L. monocytogenes was characterized.