Hydroxypropyl-ß-cyclodextrin as a membrane protectant during freeze-drying of hydrogenated and non-hydrogenated liposomes and molecule-in-cyclodextrin-in- liposomes: Application to trans-anethole

Sugar-based Cryoprotectants Stabilize Liposomal Vesicles by Exhibiting a Cholesterol-like Effect

Liposomal vesicles tend to fuse and aggregate during lyophilization. To avoid these events, cryoprotectants are added to the dispersion before lyophilization. Herein, we have compared the effect of three commonly used cryoprotectants (mannitol, MTL; trehalose, THL; and β-cyclodextrin, β-CD) upon structural characteristics of liposomes. The formulation was prepared using ethanol injection method, and cryoprotectants were tested at three dose levels (2, 6, and 10 mM). We have elucidated their effect on soy lecithin (SL) liposomes formulated with and without cholesterol (CHL). Characterizations were performed using scattering, thermal, and spectroscopic techniques. CHL molecules interacted hydrophobically with the SL bilayer. In spite of triggering a noticeable increase in the hydrodynamic diameter (about 30 nm), CHL promoted the stabilization of vesicles. Hydrogen bonding interactions were verified by the shift in -OH stretching over 3300-3500 cm-1. This manifested in an increased phase transition temperature (Tm) of SL liposomes. Tm increased further upon incorporation of cryoprotectants, particularly with β-CD. Enthalpic changes were indicative of an affinity interaction between phospholipids and cryoprotectants, regardless of the presence of CHL. β-CD showed concentration-dependent changes in the energetics of this interaction. The affinity of cryoprotectant-liposome interaction has been ranked as β-CD ≫ THL > MNT.

Effect of oligosaccharides as lyoprotectants on the stability of curcumin-loaded nanoliposomes during lyophilization

Nanoliposome is a promising delivery system, whereas its commercial application is limited by the structural instability, cargo leakage and particles aggregation during the processing such as freeze-drying. In this study, the effect of four oligosaccharides, fructo-oligosaccharides, lactose, inulin and sucrose (control), on the physicochemical properties, structural stability, and in vitro semi-dynamic digestion behavior of curcumin-loaded nanoliposomes were investigated before and after lyophilization. The results showed that the addition of the oligosaccharides inhibited the changes in particle size and reduced curcumin leakage from lyophilized nanoliposomes. Oligosaccharides significantly improved the physical stability of lyophilized nanoliposomes and delayed curcumin release during in vitro digestion. In addition, oligosaccharides could decrease the hydrophobicity of liposomal membrane and the tightness of phospholipid molecule arrangement, with the increase in micropolarity and fluidity of the bilayer membranes. These results suggested that fructo-oligosaccharides, lactose and inulin could be effective lyoprotectants for lyophilized nanoliposomes.

Comparative study of cyclosporine A liposomes and emulsions for ophthalmic drug delivery: Process optimization through response surface methodology (RSM) and biocompatibility evaluation

Herein, cyclosporine A loaded liposomes (CsA-Lips) were fabricated aimed at improving the biocompatibility of the ophthalmic formulation and getting rid of the direct contact of ocular tissues with irritant excipients. Response surface methodology was exploited in order to investigate the influence of miscellaneous factors on the key characteristics of CsA-Lips. Ratio of EPC:CsA, ratio of EPC:Chol, and stirring speed were selected as the independent variables, while size, drug-loading content (DL), and drug-loading content (DL) loss rate were applied as the response variables. In case of the maximal lack-of-fit p-value and minimum sequential p-value, quadratic model was regarded as the fittest model to analyze the data. The correlation of independent variables with response variables was described by three-dimension surface figures. Optimized formulation for CsA-Lips was obtained with ratio of EPC:CsA set as 15, ratio of EPC:Chol set as 2, and stirring speed set as 800 rpm. The particle size of CsA-Lips was 129.2 nm after optimalization while their TEM images exhibited spherical unilamellar vesicles with clearly shell-core structure. CsA released more rapidly from CsA-Lips in comparison with self-made emulsion and Restasis®. Besides, minimum cytotoxicity of CsA-Lips was perceived via both MTT method and LDH method, indicating the excellent compatibility of the ophthalmic formulation. Simultaneously, CsA-Lips showed enhanced nonspecific internalization in the cytoplasm with a time-dose-dependent manner. In conclusion, CsA-Lips could be adhibited as the hopeful ophthalmic drug delivery system clinically for dry eye syndrome (DES).

Budesonide-Loaded Bilosomes as a Targeted Delivery Therapeutic Approach Against Acute Lung Injury in Rats

Budesonide (BUD), a glucocorticoids drug, inhibits all steps in the inflammatory response. It can reduce and treat inflammation and other symptoms associated with acute lung injury such as COVID-19. Loading BUD into bilosomes could boost its therapeutic activity, and lessen its frequent administration and side effects. Different bilosomal formulations were prepared where the independent variables were lipid type (Cholesterol, Phospholipon 80H, L-alpha phosphatidylcholine, and Lipoid S45), bile salt type (Na cholate and Na deoxycholate), and drug concentration (10, 20 mg). The measured responses were: vesicle size, entrapment efficiency, and release efficiency. One optimum formulation (composed of cholesterol, Na cholate, and 10 mg of BUD) was selected and investigated for its anti-inflammatory efficacy in vivo using Wistar albino male rats. Randomly allocated rats were distributed into four groups: The first: normal control group and received intranasal saline, the second one acted as the acute lung injury model received intranasal single dose of 2 mg/kg potassium dichromate (PD). Whereas the third and fourth groups received the market product (Pulmicort® nebulising suspension 0.5 mg/ml) and the optimized formulation (0.5 mg/kg; intranasal) for 7 days after PD instillation, respectively. Results showed that the optimized formulation decreased the pro-inflammatory cytokines TNF-α, and TGF-β contents as well as reduced PKC content in lung. These findings suggest the potentiality of BUD-loaded bilosomes for the treatment of acute lung injury with the ability of inhibiting the pro-inflammatory cytokines induced COVID-19.

Effect of cysteamine hydrochloride-loaded liposomes on skin depigmenting and penetration

Skin hyperpigmentation is caused by an excessive production of melanin. Cysteamine, an aminothiol compound physiologically synthetized in human body cells, is known as depigmenting agent. The aim of this study was to evaluate the depigmenting activity and skin penetration of liposome formulations encapsulating cysteamine hydrochloride. First, cysteamine hydrochloride-loaded liposomes were prepared and characterized for their size, polydispersity index, zeta potential and the encapsulation efficiency of the active molecule. The stability of cysteamine hydrochloride in the prepared liposome formulations in suspension and freeze-dried forms was then assessed. The in vitro cytotoxicity of cysteamine and cysteamine-loaded liposome suspensions (either original or freeze-dried) was evaluated in B16 murine melanoma cells. The measurement of melanin and tyrosinase activities was assessed after cells treatment with free and encapsulated cysteamine. The antioxidant activity of the free and encapsulated cysteamine was evaluated by the measurement of ROS formation in treated cells. The ex vivo human skin penetration study was also performed using Franz diffusion cell. The stability of cysteamine hydrochloride was improved after encapsulation in liposomal suspension. In addition, for the liposome re-suspended after freeze-drying, a significant increase of vesicle stability was observed. The free and the encapsulated cysteamine in suspension (either original or freeze-dried) did not show any cytotoxic effect, inhibited the melanin synthesis as well as the tyrosinase activity. An antioxidant activity was observed for the free and the encapsulated cysteamine hydrochloride. The encapsulation enhanced the skin penetration of cysteamine hydrochloride. The penetration of this molecule was better for the re-suspended freeze-dried form than the original liposomal suspension where the drug was found retained in the epidermis layer of the skin.

Encapsulation of α-Pinene in Delivery Systems Based on Liposomes and Cyclodextrins

The essential oil component α-pinene has multiple biological activities. However, its application is limited owing to its volatility, low aqueous solubility, and chemical instability. For the aim of improving its physicochemical properties, α-pinene was encapsulated in conventional liposomes (CLs) and drug-in-cyclodextrin-in-liposomes (DCLs). Hydroxypropyl-β-cyclodextrin/α-pinene (HP-β-CD/α-pinene) inclusion complexes were prepared in aqueous solution, and the optimal solubilization of α-pinene occurred at HP-β-CD:α-pinene molar ratio of 7.5:1. The ethanol-injection method was applied to produce different formulations using saturated (Phospholipon 90H) or unsaturated (Lipoid S100) phospholipids in combination with cholesterol. The size, the phospholipid and cholesterol incorporation rates, the encapsulation efficiency (EE), and the loading rate (LR) of α-pinene were determined, and the storage stability of liposomes was assessed. The results showed that α-pinene was efficiently entrapped in CLs and DCLs with high EE values. Moreover, Lipoid S100 CLs displayed the highest LR (22.9 ± 2.2%) of α-pinene compared to the other formulations. Both carrier systems HP-β-CD/α-pinene inclusion complex and Lipoid S100 CLs presented a gradual release of α-pinene. Furthermore, the DPPH radical scavenging activity of α-pinene was maintained upon encapsulation in Lipoid S100 CLs. Finally, it was found that all formulations were stable after three months of storage at 4 °C.

Nanocarriers for Biomedicine: From Lipid Formulations to Inorganic and Hybrid Nanoparticles

Encapsulation of cargoes in nanocontainers is widely used in different fields to solve the problems of their solubility, homogeneity, stability, protection from unwanted chemical and biological destructive effects, and functional activity improvement. This approach is of special importance in biomedicine, since this makes it possible to reduce the limitations of drug delivery related to the toxicity and side effects of therapeutics, their low bioavailability and biocompatibility. This review highlights current progress in the use of lipid systems to deliver active substances to the human body. Various lipid compositions modified with amphiphilic open-chain and macrocyclic compounds, peptide molecules and alternative target ligands are discussed. Liposome modification also evolves by creating new hybrid structures consisting of organic and inorganic parts. Such nanohybrid platforms include cerasomes, which are considered as alternative nanocarriers allowing to reduce inherent limitations of lipid nanoparticles. Compositions based on mesoporous silica are beginning to acquire no less relevance due to their unique features, such as advanced porous properties, well-proven drug delivery efficiency and their versatility for creating highly efficient nanomaterials. The types of silica nanoparticles, their efficacy in biomedical applications and hybrid inorganic-polymer platforms are the subject of discussion in this review, with current challenges emphasized.

Biopolymer-liposome hybrid systems for controlled delivery of bioactive compounds: Recent advances

Conventional liposomes still face many challenges associated with the poor physical and chemical stability, considerable loss of encapsulated cargo, lack of stimulus responsiveness, and rapid elimination from blood circulation. Integration of versatile functional biopolymers has emerged as an attractive strategy to overcome the limitation of usage of liposomes. This review comprehensively summarizes the most recent studies (2015-2020) and their challenges aiming at the exploration of biopolymer-liposome hybrid systems, including surface-modified liposomes, biopolymer-incorporated liposomes, guest-in-cyclodextrin-in-liposome, liposome-in-hydrogel, liposome-in-film, and liposome-in-nanofiber. The physicochemical principles and key technical information underlying the combined strategies for the fabrication of polymeric liposomes, the advantages and limitations of each of the systems, and the stabilization mechanisms are discussed through various case studies. Special emphasis is directed toward the synergistic efficiencies of biopolymers and phospholipid bilayers on encapsulation, protection, and controlled delivery of bioactives (e.g., vitamins, carotenoids, phenolics, peptides, and other health-related compounds) for the biomedical, pharmaceutical, cosmetic, and functional food applications. The major challenges, opportunities, and possible further developments for future studies are also highlighted.

Enhancing the preservation of liposomes: The role of cryoprotectants, lipid formulations and freezing approaches

In the last decades, liposomes acquired a striking success in the biomedical field thanks to their biocompatibility and drug delivery ability. Many liposomal drug formulations have been already approved by the Food and Drug Administration (FDA) and used for the treatment of a wide range of pathologies with or without further engineering. Their clinical application requires strict compliance with high standard quality rules, and it is crucial to employ storage methods that do not affect the integrity of the vesicles and preventing the leakage of their cargo. In this work, the design of a suitable formulation for freeze-drying had been investigated for two different liposomes, DOPC-DOTAP and the PEGylated counterpart, DOPC-DOTAP-DSPE-PEG. The role of various cryoprotectants was evaluated paying attention to their ability to preserve the structural integrity of liposomes. At first, the study was focused on freezing and two methodologies were investigated, quenching in liquid nitrogen and shelf-ramped freezing. This analysis showed that the disaccharides (cellobiose, glucose, lactose, sucrose, and trehalose) and the polyol (mannitol) protected successfully the integrity of liposomes, while during the process, in the presence of a surfactant, liposomes were strongly damaged and fragmented by the ice crystals. Furthermore, the choice of the rate of freezing depended on the different compositions of the lipid bilayer. Finally, the effects of lyophilization on liposomes with and without additives were studied; cellobiose, lactose and trehalose showed encouraging results for the maintenance of the morpho-functional parameters of liposomes during the entire freeze-drying process.

Brain Delivery of Nanomedicines: Trojan Horse Liposomes for Plasmid DNA Gene Therapy of the Brain

Non-viral gene therapy of the brain is enabled by the development of plasmid DNA brain delivery technology, which requires the engineering and manufacturing of nanomedicines that cross the blood-brain barrier (BBB). The development of such nanomedicines is a multi-faceted problem that requires progress at multiple levels. First, the type of nanocontainer, e.g., nanoparticle or liposome, which encapsulates the plasmid DNA, must be developed. Second, the type of molecular Trojan horse, e.g., peptide or receptor-specific monoclonal antibody (MAb), must be selected for incorporation on the surface of the nanomedicine, as this Trojan horse engages specific receptors expressed on the BBB, and the brain cell membrane, to trigger transport of the nanomedicine from blood into brain cells beyond the BBB. Third, the plasmid DNA must be engineered without bacterial elements, such as antibiotic resistance genes, to enable administration to humans; the plasmid DNA must also be engineered with tissue-specific gene promoters upstream of the therapeutic gene, to insure gene expression in the target organ with minimal off-target expression. Fourth, upstream manufacturing of the nanomedicine must be developed and scalable so as to meet market demand for the target disease, e.g., annual long-term treatment of 1,000 patients with an orphan disease, short term treatment of 10,000 patients with malignant glioma, or 100,000 patients with new onset Parkinson's disease. Fifth, downstream manufacturing problems, such as nanomedicine lyophilization, must be solved to ensure the nanomedicine has a commercially viable shelf-life for treatment of CNS disease in humans.

Development of cysteamine loaded liposomes in liquid and dried forms for improvement of cysteamine stability

Despite the high aqueous solubility of cysteamine, its unpleasant organoleptic properties, hygroscopicity, instability in solutions, and poor pharmacokinetic profile are the main drawbacks that limit its use for medical and cosmetic purposes. In this study, cysteamine-loaded liposomes were prepared using the ethanol injection method. Liposomes were characterized for their size, homogeneity, surface charge, and morphology. The incorporation ratios of cholesterol and phospholipids, the encapsulation efficiency and the loading ratio of cysteamine in liposomes were determined. Moreover, the stability of free and encapsulated cysteamine was assessed at different temperatures (4, 25, and 37 °C) in the presence and absence of light. Cysteamine-loaded liposomes were freeze-dried and reconstituted liposomes were characterized. Finally, the storage stability of the freeze-dried cysteamine-loaded liposomes was studied. Liposomes were nanometric, oligolamellar, and spherical. The encapsulation efficiency and the loading ratio of cysteamine varied between 12 and 40% in the different formulations. The encapsulation improved the stability of cysteamine in the various storage conditions. The dried form of cysteamine-loaded liposomes conserved the size of the vesicles and retained 33% of cysteamine present in the liposomal suspension before lyophilization. The freeze-dried liposomes formulations were stable after four months of storage at 4 °C.

Lyoprotectant Optimization for the Freeze-Drying of Receptor-Targeted Trojan Horse Liposomes for Plasmid DNA Delivery

Trojan horse liposomes (THLs) are a form of ligand-targeted nanomedicine, where a plasmid DNA is encapsulated in the interior of a 100-150 nm pegylated liposome, and the tips of a fraction of the surface pegylated strands are covalently linked to a receptor-specific monoclonal antibody (MAb) via a thio-ether linkage. The goal of this work was to develop a lyophilization methodology that enables retention of the structure and function of the THLs following the freeze-drying/hydration process. THL fusion and leakage of plasmid DNA were observed with several lyoprotectants, including trehalose, hyaluronic acid, γ-cyclodextrin, or sulfobutylether-β-cyclodextrin. However, the use of hydroxypropyl-γ-cyclodextrin, at a 40:1 wt/wt ratio relative to the THL phospholipid, eliminated liposome fusion and produced high retention of encapsulated plasmid DNA and THL-mediated gene expression after lyophilization followed by hydration. The freeze-dried THL cake was amorphous without cavitation, and the diameters and functional properties of the THLs were preserved following hydration of cakes stored for at least six months. Intravenous administration of the hydrated freeze-dried THLs in the Rhesus monkey demonstrated the safety of the formulation. Blood plasmid DNA was measured with a quantitative polymerase chain reaction method, which enabled a pharmacokinetics analysis of the blood clearance of the THL-encapsulated plasmid DNA in the primate. The work shows that optimization of the lyoprotectant enables long-term storage of the MAb-targeted DNA encapsulated liposomes in the freeze-dried state.

Liposomal membrane permeability assessment by fluorescence techniques: Main permeabilizing agents, applications and challenges

Liposomes are lipid vesicles made of one or multiple lipid bilayers surrounding an internal aqueous core. They are broadly employed as models to study membrane structure and properties. Among these properties, liposome membrane permeability is crucial and widely assessed by fluorescence techniques. The first part of this review is devoted to describe the various techniques used for membrane permeability assessment. Attention is paid to fluorescence techniques based on vesicle leakage of self-quenching probes, dye/quencher pair or cation/ligand pair. Secondly, the membrane-active agents inducing membrane permeabilization is presented and details on their mechanisms of action are given. Emphasis is also laid on the intrinsic and extrinsic factors that can modulate the membrane permeability. Hence, a suitable liposomal membrane should be formulated according to the aim of the study and its application.

Lyophilized liposome-based parenteral drug development: Reviewing complex product design strategies and current regulatory environments

Given the successful entry of several liposomal drug products into market, and some with decades of clinical efficacy, liposomal drug delivery systems have proven capabilities to overcome certain limitations of traditional drug delivery, especially for toxic and biologic drugs. This experience has helped promote new liposomal approaches to emerging drug classes and current therapeutic challenges. All approved liposomal dosage forms are parenteral formulations, a pathway demonstrating greatest safety and efficacy to date. Due to the intrinsic instability of aqueous liposomal dispersions, lyophilization is commonly applied as an important solution to improve liposomal drug stability, and facilitate transportation, storage and improve product shelf-life. While lyophilization is a mature pharmaceutical technology, liposome-specific lyophilization platforms must be developed using particular lyophilization experience and strategies. This review provides an overview of liposome formulation-specific lyophilization approaches for parenteral use, excipients used exclusively in liposomal parenteral products, lyophilized liposome formulation design and process development, long-term storage, and current regulatory guidance for liposome drug products. Readers should capture a comprehensive understanding of formulation and process variables and strategies for developing parenterally administered liposomal drugs.

Use of free and encapsulated nerolidol to inhibit the survival of Lactobacillus fermentum in fresh orange juice

Lactobacillus fermentum is commonly responsible for fruit juice fermentation and spoilage. The aim of this study was to investigate the potential use of nerolidol to control the spoilage of fresh orange juice by L. fermentum. Nerolidol was incorporated into hydroxypropyl-β-cyclodextrin inclusion complex, conventional liposome, and drug-in-cyclodextrin-in liposome systems. The systems were lyophilized and characterized with respect to their nerolidol content, size, and morphology. The effects of the acidity and cold storage of orange juice on the survival of L. fermentum were evaluated. Subsequently, the antibacterial activity of nerolidol in refrigerated orange juice was assessed at pH 3.3. Nerolidol showed a faster antibacterial activity at 4 000 μM (5 days) compared to 2 000 μM (8 days). Under the same conditions, the inclusion complex completely killed bacteria within 6 days of incubation at 4 000 μM, suggesting its potential application in fruit juices. Nerolidol-loaded liposomes did not exhibit an antibacterial activity and altered the appearance of juice.

Effect of the Incorporation of Functionalized Cyclodextrins in the Liposomal Bilayer

Liposomes loaded with drug–cyclodextrin complexes are widely used as drug delivery systems, especially for species with low aqueous solubility and stability. Investigation of the intimate interactions of macrocycles with liposomes are essential for formulation of efficient and stable drug-in-cyclodextrin-in-liposome carriers. In this work, we reported the preparation of unilamellar vesicles of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) embedded with native β-cyclodextrin and two synthetic derivatives: heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TMCD) and heptakis(2,3-di-O-acetyl)-β-cyclodextrin (DACD). We then studied the effect of these macrocycles on the liposomal size, membrane viscosity, and liposomal stability at different temperatures and concentrations. We observed that TMCD and DACD affected vesicle size and the change of size was related to CD concentration. Irrespective of its nature, the macrocycle established interactions with the phospholipidic head groups, preventing cyclodextrins to diffuse into the lipid bilayer, as confirmed by molecular dynamics simulations. Such supramolecular structuring improves liposome stability making these colloid systems promising carriers for biologically active compounds.