Glycerosomes: a new tool for effective dermal and transdermal drug delivery

EtoGel for Intra-Articular Drug Delivery: A New Challenge for Joint Diseases Treatment

Ethosomes^® have been proposed as potential intra-articular drug delivery devices, in order to obtain a longer residence time of the delivered drug in the knee joint. To this aim, the conventional composition and preparation method were modified. Ethosomes^® were prepared by using a low ethanol concentration and carrying out a vesicle extrusion during the preparation. The modified composition did not affect the deformability of ethosomes^®, a typical feature of this colloidal vesicular topical carrier. The maintenance of sufficient deformability bodes well for an effective ethosome^® application in the treatment of joint pathologies because they should be able to go beyond the pores of the dense collagen II network. The investigated ethosomes^® were inserted in a three-dimensional network of thermo-sensitive poloxamer gel (EtoGel) to improve the residence time in the joint. Rheological experiments evidenced that EtoGel could allow an easy intra-articular injection at room temperature and hence transform itself in gel form at body temperature into the joint. Furthermore, EtoGel seemed to be able to support the knee joint during walking and running. In vitro studies demonstrated that the amount of used ethanol did not affect the viability of human chondrocytes and nanocarriers were also able to suitably interact with cells.

Nanotechnology for Natural Medicine: Formulation of Neem Oil Loaded Phospholipid Vesicles Modified with Argan Oil as a Strategy to Protect the Skin from Oxidative Stress and Promote Wound Healing

Neem oil, a plant-derived product rich in bioactives, has been incorporated in liposomes and hyalurosomes modified by adding argan oil and so called argan-liposomes and argan-hyalurosomes. Argan oil has also been added to the vesicles because of its regenerative and protective effects on skin. In the light of this, vesicles were specifically tailored to protect the skin from oxidative stress and treat lesions. Argan-liposomes were the smallest vesicles (~113 nm); the addition of sodium hyaluronate led to an increase in vesicle size (~143 nm) but it significantly improved vesicle stability during storage. In vitro studies confirmed the free radical scavenging activity of formulations, irrespective of their composition. Moreover, rheological investigation confirmed the higher viscosity of argan-hyalurosomes, which avoid formulation leakage after application. In vitro studies performed by using the most representative cells of the skin (i.e., keratinocytes and fibroblasts) underlined the ability of vesicles, especially argan-liposomes and argan-hyalurosomes, to counteract oxidative stress induced in these cells by using hydrogen peroxide and to improve the proliferation and migration of cells ensuring the more rapid and even complete closure of the wound (scratch assay).

Characterization of Liposomes Using Quantitative Phase Microscopy (QPM)

The rapid development of nanomedicine and drug delivery systems calls for new and effective characterization techniques that can accurately characterize both the properties and the behavior of nanosystems. Standard methods such as dynamic light scattering (DLS) and fluorescent-based assays present challenges in terms of system's instability, machine sensitivity, and loss of tracking ability, among others. In this study, we explore some of the downsides of batch-mode analyses and fluorescent labeling, while introducing quantitative phase microscopy (QPM) as a label-free complimentary characterization technique. Liposomes were used as a model nanocarrier for their therapeutic relevance and structural versatility. A successful immobilization of liposomes in a non-dried setup allowed for static imaging conditions in an off-axis phase microscope. Image reconstruction was then performed with a phase-shifting algorithm providing high spatial resolution. Our results show the potential of QPM to localize subdiffraction-limited liposomes, estimate their size, and track their integrity over time. Moreover, QPM full-field-of-view images enable the estimation of a single-particle-based size distribution, providing an alternative to the batch mode approach. QPM thus overcomes some of the drawbacks of the conventional methods, serving as a relevant complimentary technique in the characterization of nanosystems.

Skin penetration/permeation success determinants of nanocarriers: Pursuit of a perfect formulation

The advent of nanocarriers in the field of pharmaceutical drug delivery, while exhibiting considerable advantages, has created challenges for researchers. Among the applications of nanocarriers, drug delivery to the skin has attracted increasing attention in recent decades due to its advantages over oral and parenteral administration. Accordingly, this work attempts to discuss the major obstacles surrounding topically applied formulations and different nanocarriers' potential to overcome these barriers to investigate whether their passive penetration through the skin is likely. Therefore, skin anatomical views and transcutaneous pathways are briefly reviewed. Factors commonly thought to influence skin penetration are discussed from the perspective of particularly penetrating nanocarriers. The formulation of these nanocarriers is outlined, and promising constituents are highlighted to help investigators optimize nanocarrier formulations.

Topical Unsaturated Fatty Acid Vesicles Improve Antioxidant Activity of Ammonium Glycyrrhizinate

Linoleic and oleic acids are natural unsaturated fatty acids involved in several biological processes and recently studied as structural components of innovative nanovesicles. The use of natural components in the pharmaceutical field is receiving growing attention from the scientific world. The aim of this research work is to design, to perform physico-chemical characterization and in vitro/in vivo studies of unsaturated fatty acids vesicles containing ammonium glycyrrhizinate, obtaining a new topical drug delivery system. The chosen active substance is well known as an anti-inflammatory compound, but its antioxidant activity is also noteworthy. In this way, the obtained nanocarriers are totally natural vesicles and they have shown to have suitable physico-chemical features for topical administration. Moreover, the proposed nanocarriers have proven their ability to improve the in vitro percutaneous permeation and antioxidant activity of ammonium glycyrrhizinate on human keratinocytes (NCTC 2544 cells). In vivo studies, carried out on human volunteers, have demonstrated the biocompatibility of unsaturated fatty acid vesicles toward skin tissue, indicating a possible clinical application of unsaturated fatty acid vesicles for the treatment of topical diseases.

Nanovesicles Loaded with Origanum onites and Satureja thymbra Essential Oils and Their Activity against Food-Borne Pathogens and Spoilage Microorganisms

Food poisoning is a common cause of illness and death in developing countries. Essential oils (EOs) could be effective and safe natural preservatives to prevent and control bacterial contamination of foods. However, their high sensitivity and strong flavor limit their application and biological effectiveness. The aim of this study was firstly the chemical analysis and the antimicrobial evaluation of the EOs of Origanum onites L. and Satureja thymbra L. obtained from Symi island (Greece), and, secondly, the formulation of propylene glycol-nanovesicles loaded with these EOs to improve their antimicrobial properties. The EOs were analyzed by GC-MS and their chemical contents are presented herein. Different nanovesicles were formulated with small average sizes, high homogeneity, and optimal ζ-potential. Microscopic observation confirmed their small and spherical shape. Antibacterial and antifungal activities of the formulated EOs were evaluated against food-borne pathogens and spoilage microorganisms compared to pure EOs. Propylene glycol-nanovesicles loaded with O. onites EO were found to be the most active formulation against all tested strains. Additionally, in vitro studies on the HaCaT cell line showed that nanovesicles encapsulated with EOs had no toxic effect. The present study revealed that both EOs can be used as alternative sanitizers and preservatives in the food industry, and that their formulation in nanovesicles can provide a suitable approach as food-grade delivery system.

Lipid nanovesicles for biomedical applications: 'What is in a name'?

Vesicles, generally defined as self-assembled structures formed by single or multiple concentric bilayers that surround an aqueous core, have been widely used for biomedical applications. They can either occur naturally (e.g. exosomes) or be produced artificially and range from the micrometric scale to the nanoscale. One the most well-known vesicle is the liposome, largely employed as a drug delivery nanocarrier. Liposomes have been modified along the years to improve physicochemical and biological features, resulting in long-circulating, ligand-targeted and stimuli-responsive liposomes, among others. In this process, new nomenclatures were reported in an extensive literature. In many instances, the new names suggest the emergence of a new nanocarrier, which have caused confusion as to whether the vesicles are indeed new entities or could simply be considered modified liposomes. Herein, we discussed the extensive nomenclature of vesicles based on the suffix "some" that are employed for drug delivery and composed of various types and proportions of lipids and others amphiphilic compounds. New names have most often been selected based on changes of vesicle lipid composition, but the payload, structural complexity (e.g. multicompartment) and new/improved proprieties (e.g. elasticity) have also inspired new vesicle names. Based on this discussion, we suggested a rational classification for vesicles.

Plumbagin-Loaded Glycerosome Gel as Topical Delivery System for Skin Cancer Therapy

Plumbagin (PLM) is a phytochemical which has shown cytotoxicity against of cancer cells both in vitro and in vivo. However, the clinical application of PLM has been hindered due to poor aqueous solubility and low bioavailability. The aim of the present study was to develop, optimize and evaluate PLM-loaded glycerosome (GM) gel and compare with conventional liposome (CL) for therapeutic efficacy against skin cancer. The GM formulations were optimized by employing design expert software by 3-level 3-factor design. The prepared GMs were characterized in vitro for vesicle size, size distribution, zeta potential, vesicle deformability, drug release, skin permeation, retention, texture, antioxidant and cytotoxicity activities. The optimized formulation showed a vesicle size of 119.20 ± 15.67 nm with a polydispersity index (PDI) of 0.145 ± 0.02, the zeta potential of −27 ± 5.12 mV and entrapment efficiency of 76.42 ± 9.98%. The optimized PLM-loaded GM formulation was transformed into a pre-formed gel which was prepared using Carbopol 934 polymer. The drug diffusion fluxes of CL gel and GM-loaded gel were 23.31 ± 6.0 and 79.43 ± 12.43 µg/cm²/h, respectively. The result of texture analysis revealed the adequate hardness, cohesiveness, consistency, and viscosity of the developed GM-loaded gel compared to CL gel. The confocal images showed that glycerosomal gel has deeper skin layer penetration as compared to the control solution. GM-loaded gel treated rat skin showed significantly (p < 0.05) higher drug accumulation in the dermis, higher cytotoxicity and higher antioxidant activity as compared to CL gel and PLM suspension. Thus, findings revealed that novel GM-loaded gel could be potential carriers for therapeutic intervention in skin cancer.

Rosuvastatin calcium-based novel nanocubic vesicles capped with silver nanoparticles-loaded hydrogel for wound healing management: optimization employing Box-Behnken design: in vitro and in vivo assessment

Chronic wounds are a serious problem that could cause severe morbidity and even death. The ability of statins including rosuvastatin calcium (RVS) to enhance wound healing was well reported. However, RVS is poorly soluble and has low bioavailability. Thus, this study aimed to prepare and evaluate RVS-loaded nanocubics to enhance its skin performance. In addition, silver nanoparticles (AgNPs) exhibited potent antimicrobial activity, thus, the optimum RVS-loaded nanocubics was capped with AgNPs to evaluate its effect in wound management. Box-Behnken design was adopted to prepare RVS nanocubics. The design investigated the effect of lecithin, poloxamer 407 concentrations and hydration time on vesicle size, zeta potential (ZP), entrapment efficiency (EE%) and in vitro drug release%. Optimum formulation capped with AgNPs was incorporated into a gel base and examined for wound healing efficiency using different pharmacological tests in rats. Nanocubics have shown a mean diameter between 167.2 ± 7.8 and 408 ± 18.4 nm, ZP values ranging from -20.9 ± 1.9 to -53.5 ± 4 mV, EE% equivocated between 31.6 ± 1.4 and 94.4 ± 8.6 and drug release after 12 h between 17.9 ± 1.9 and 68.0 ± 4.0%. The histopathological studies and serum tumour necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β) levels confirmed the greater efficacy of RVS nanocubics capped with AgNPs gel in wound healing when compared with gentamicin ointment. RVS-loaded nanocubic vesicles and AgNPs-loaded hydrogel could be considered as a promising platform to enhance the wound healing and tissue repair processes.

Development of novel polyglycerol fatty acid ester-based nanoparticles for the dermal delivery of tocopherol acetate

The aim of this study was to develop and evaluate novel polyglycerol fatty acid ester (PGFE)-based nanoparticles (NPs) for the dermal delivery of tocopherol acetate (TA). TA-loaded PGFE-based NPs (PGFE-NPs) were prepared by mixing PGFE, soya phosphatidylcholine, dimyristoylphosphatidylglycerol, and TA with film using the film rehydration and extrusion method. The prepared formulations were analyzed by dynamic light scattering, small-angle X-ray diffraction and polarization microscopy. An in vitro skin accumulation test was performed with TA under occlusive and non-occlusive applications, using Yucatan micropig skin. The size range of the TA-loaded liposome and PGFE-NPs was 107-128 nm, and they were encapsulated in 1.6-2.3 mg/mL TA. All PGFE-NP formulations were negatively charged and stable for 2 weeks. Under occlusive applications, all formulations induced small amounts of TA accumulation in the epidermis but not in the dermis. However, under non-occlusive applications, some of PGFE-NP formulations enhanced TA accumulation in the epidermis. Furthermore, only the polyglycerol 4-laurate (PG4L)-based formulation induced dermal TA accumulation with the change in the formulation from a vesicular to bilayer stacked structure following water evaporation under non-occlusive applications. These results indicated that the novel TA-loaded PG4L formulation enabled the dermal delivery of TA in non-occlusive applications.

A novel nanogel loaded with chitosan decorated bilosomes for transdermal delivery of terbutaline sulfate: artificial neural network optimization, in vitro characterization and in vivo evaluation

The objective of the present work was to formulate, optimize, and evaluate transdermal terbutaline sulfate (TBN)-loaded bilosomes (BLS) in gel, compared to conventional oral TBN solution and transdermal gel loaded with free TBN, aiming at evading the hepatic first-pass metabolism. A face-centered central composite design was adopted to observe the effects of different formulation variables on TBN-BLS, and artificial neural network (ANN) modeling was employed to optimize TBN-BLS. TBN-BLS were prepared by a thin film hydration method integrating soybean phosphatidylcholine and cholesterol as a lipid phase and sodium deoxycholate (SDC) as a surfactant with or without the coating of chitosan (CTS). After being subjected to physicochemical characterization, TBN-BLS were enrolled in a histopathological study and pharmacokinetic investigation in a rat model. The optimized TBN chitosan-coated bilosomes (TBN-CTS-BLS) were spherical vesicles (245.13 ± 10.23 nm) with adequate entrapment efficiency (65.25 ± 5.51%) and good permeation characteristics (340.11 ± 22.34 μg/cm²). The TBN-CTS-BLS gel formulation was well-tolerated with no inflammatory signs manifested upon histopathological evaluation. The pharmacokinetic study revealed that the optimized TBN-CTS-BLS formulation successively enhanced the bioavailability of TBN by about 2.33-fold and increased t_1/2 to about 6.21 ± 0.24 h as compared to the oral solution. These findings support the prospect use of BLS as active and safe transdermal carrier for TBN in the treatment of asthma. Graphical Abstract.

Polyoliposomes: novel polyol-modified lipidic nanovesicles for dermal and transdermal delivery of drugs

Various lipid nanovesicular systems have been developed with the aim to enhance the delivery of drugs via transdermal route. However, their clinical applications are often limited due to the barrier nature of skin and lack of flexibility. Herein, we have modified the conventional nanoliposomes (CLs) prepared by a thin-film hydration method by the addition of a polyol (glycerol) to form novel lipid nanovesicular structures termed 'POLYOLIPOSOMES' (PLs). They were further named as PL-B (before film formation) and PL-A (after film formation), depending on the stage of glycerol addition during production. Optimized CLs, PL-B and PL-A showed spherical nanovesicles and hydrodynamic diameter of 181.3 ± 4.11 nm, 114.2 ± 7.21 nm and 170.2 ± 6.51 nm, respectively. PLs showed significantly higher % entrapment efficiency and deformability index in comparison to CLs, indicating their higher flexibility. Furthermore, DSC and attenuated total relection (ATR)-Fourier transform infrared (FTIR) studies revealed the intercalation of glycerol into the lipid bilayer of PLs and interaction between nanovesicles and skin. Moreover, ex vivo and in vivo skin permeation studies confirmed the enhanced drug delivery of PLs via the transdermal route. Taken together, these results illustrate the potential of PLs as a novel lipid nanovesicular system for drug delivery via the transdermal route for both systematic (PL-B) as well as cutaneous diseases (PL-A).

Innovative strategies to treat skin wounds with mangiferin: fabrication of transfersomes modified with glycols and mucin

Aim: The moisturizing properties of glycerol, the penetration enhancing capability of propylene glycol and the bioadhesive properties of mucin were combined to improve the carrier capabilities of transfersomes and the efficacy of mangiferin in the treatment of skin lesions. Materials & methods: Mangiferin was incorporated in transfersomes and glycoltransfersomes, which were also modified with mucin. The physico-chemical features were assessed, along with the efficacy against oxidative stress and skin wounds in vitro and in vivo. Results: Glycoltransfersomes promoted the deposition of mangiferin in epidermis and dermis, protected fibroblasts from oxidative stress and stimulated their proliferation. The wound healing and anti-inflammatory efficacy of glycoltransfersomes were confirmed in vivo. Conclusion: Results confirmed the potential of glycoltransfersomes in preventing/treating of skin lesions.

Glycerosome of Melissa officinalis L. Essential Oil for Effective Anti-HSV Type 1

Essential oils are complex mixtures of strongly active compounds, very volatile and sensitive to light, oxygen, moisture and temperature. Loading inside nanocarriers can be a strategy to increase their stability and successfully use them in therapy. In the present study, a commercial Melissa officinalis L. (Lamiaceae) essential oil (MEO) was analyzed by gas chromatography-mass spectrometry, loaded inside glycerosomes (MEO-GS) and evaluated for its anti-herpetic activity against HSV type 1. MEO-GS analyses were prepared by the thin layer evaporation method and they were characterized by light scattering techniques, determining average diameter, polydispersity index and ζ-potential. By transmission electron microscopy, MEO-GS appeared as small nano-sized vesicles with a spherical shape. MEO encapsulation efficiency inside glycerosomes, in terms of citral and β-caryophyllene, was found to be ca. 63% and 76% respectively, and MEO release from glycerosomes, performed by dialysis bag method, resulted in less than 10% within 24h. In addition, MEO-GS had high chemical and physical stability during 4 months of storage. Finally, MEO-GS were very active in inhibiting HSV type 1 infection of mammalian cells in vitro, without producing cytotoxic effects. Thus, MEO-GS could be a promising tool in order to provide a suitable anti-herpetic formulation.

Liposomes Entrapped in Biopolymer Hydrogels Can Spontaneously Release into the External Solution

Hydrogels of biopolymers such as agar and gelatin are widely used in many applications, and in many cases, the gels are loaded with nanoparticles. The polymer chains in these gels are cross-linked by physical bonds into three-dimensional networks, with the mesh size of these networks typically being 10-100 nm. One class of "soft" nanoparticles are liposomes, which have an aqueous core surrounded by a lipid bilayer. Solutes encapsulated in the liposomal core can be delivered externally over time. In this paper, we create liposomes with diameters ∼150 nm from an unsaturated phospholipid (lecithin) and embed them in agar gels (the aqueous phase also contains 0-50% of glycerol, which is an active ingredient in cosmetic products). Upon placing this gel in quiescent water, we find that the liposomes release out of the gel into the water over a period of 1-3 days, even though the gel remains intact. This is a surprising result that runs contrary to our expectation that the liposomes would simply remain immobilized in the gel. We show that the release rate of liposomes can be tuned by several variables: for example, the release rate increases as the agar concentration is lowered and the rate increases steadily with temperature. In addition to agar, release of liposomes also occurs out of other physical gels including those of agarose and gelatin. However, liposomes made from a saturated phospholipid do not release out of any gels. We discuss a possible mechanism for liposomal release, which involves intact liposomes deforming and squeezing through transient large pores that arise in physical networks such as agar. Our findings have relevance to transdermal delivery: they suggest the possibility of systematically delivering liposomes loaded with actives out of an intact matrix.

Phospholipid Vesicles for Dermal/Transdermal and Nasal Administration of Active Molecules: The Effect of Surfactants and Alcohols on the Fluidity of Their Lipid Bilayers and Penetration Enhancement Properties

This is a comprehensive review on the use of phospholipid nanovesicles for dermal/transdermal and nasal drug administration. Phospholipid-based vesicular carriers have been widely investigated for enhanced drug delivery via dermal/transdermal routes. Classic phospholipid vesicles, liposomes, do not penetrate the deep layers of the skin, but remain confined to the upper stratum corneum. The literature describes several approaches with the aim of altering the properties of these vesicles to improve their penetration properties. Transfersomes and ethosomes are the most investigated penetration-enhancing phospholipid nanovesicles, obtained by the incorporation of surfactant edge activators and high concentrations of ethanol, respectively. These two types of vesicles differ in terms of their structure, characteristics, mechanism of action and mode of application on the skin. Edge activators contribute to the deformability and elasticity of transfersomes, enabling them to penetrate through pores much smaller than their own size. The ethanol high concentration in ethosomes generates a soft vesicle by fluidizing the phospholipid bilayers, allowing the vesicle to penetrate deeper into the skin. Glycerosomes and transethosomes, phospholipid vesicles containing glycerol or a mixture of ethanol and edge activators, respectively, are also covered. This review discusses the effects of edge activators, ethanol and glycerol on the phospholipid vesicle, emphasizing the differences between a soft and an elastic nanovesicle, and presents their different preparation methods. To date, these differences have not been comparatively discussed. The review presents a large number of active molecules incorporated in these carriers and investigated in vitro, in vivo or in clinical human tests.

Ammonium glycyrrhizate skin delivery from ultradeformable liposomes: A novel use as an anti-inflammatory agent in topical drug delivery

Glycyrrhiza glabra L. is a native plant of Central and South-Western Asia that is also diffused in the Mediterranean area and contains several bioactive compounds such as: flavonoids, sterols, triterpene and saponins. Glycyrrhizin, containing glycyrrhizic and glycyrrhizinic acids has anti-inflammatory and antiallergic effects that are similar to corticosteroids. Ammonium glycyrrhizinate is a derivative salt of glycyrrhizic acid with similar anti-inflammatory activity that cannot pass through the skin due to its physicochemical properties and molecular weight. Although several nanoformulations, such as ethosomes, are designed to provide a systemic effect through a topical application, there are different limitations to the distribution inside the blood stream. For this reason, ultradeformable liposomes, or transfersomes, are selected to improve the topical delivery of drugs and allow the distribution of payloads in the blood stream because they pass intact through the stratum corneum epidermis barrier, due to the presence of sodium cholate, aqueous cutaneous gradient, and the rapid penetration of transfersomes by cutaneous tight junctions, thus allowing the systemic delivery of different therapeutic cargo in non-occlusive conditions. The aim of this work was the synthesis and physicochemical characterization of the ammonium glycyrrhizinate-loaded ultradeformable liposomes, the evaluation of drug release and permeation through stratum corneum and epidermis barrier. The in vivo anti-inflammatory effect of ammonium glycyrrhizinate-loaded ultradeformable liposomes was tested on human healthy volunteers. The results demonstrated that the ammonium glycyrrhizinate-loaded ultradeformable liposomes decreased the skin inflammation on the human volunteers and the resulting nanoformulations can be used as a potential topical drug delivery system for anti-inflammatory therapy. ^☆Parts of these results were presented as a poster communication at the Recent Developments in Pharmaceutical Analysis 2019 (RDPA 2019), Chieti, Italy.

Investigating the potential of utilizing glycerosomes as a novel vesicular platform for enhancing intranasal delivery of lacidipine

Lacidipine is a potent dihydropyridine calcium channel blocker used for management of hypertension and atherosclerosis. The drug has low and fluctuating oral bioavailability owing to its extensive hepatic first-pass metabolism and reduced water solubility. Accordingly, this work aimed at overcoming the aforementioned challenges through the formulation of intranasal nano-sized lacidipine glycerosomes. Box-Behnken was successfully employed for the formulation and in vitro optimization of the glycerosomes. Statistical analysis revealed that cholesterol concentration exhibited a significant effect on the vesicle size, while Phospholipon® 90G and glycerol concentrations exhibited significant effects on both entrapment efficiency and deformability index. The optimized formulation showed spherical shape, good deformability, vesicular size of 220.25 nm, entrapment efficiency of 61.97%, and enhanced ex vivo permeation by 3.65 fold compared to lacidipine suspension. Confocal laser scattering microscope revealed higher penetration depth via nasal mucosa for rhodamine labelled glycerosomes (up to 60 µm) in comparison to rhoadamine dye solution (26 µm). In addition, the optimized lacidipine glycerosomes caused significant reduction in methylprednisolone acetate-induced hypertension in rats for up to 24 h in comparison to oral drug suspension. Histopathological assessment showed intact nasal mucosal epithelial lining with no signs of inflammation or necrosis confirming the safety and tolerability of the proposed glycerosomes. The declared results highlights the potential of utilizing the proposed glycerosomes as safe and effective platform for intranasal delivery of lacidipine.

Preparation and optimization of fisetin loaded glycerol based soft nanovesicles by Box-Behnken design

The present study focused on the development and optimization of glycerosomes for dermal delivery of fisetin. The fisetin loaded glycerosomes formulation was optimized by Box-Behnken design. The independent variables were the lipoid S 100, glycerol, and sonication time, whereas the dependent variables were the vesicles size, entrapment efficiency, and flux. The mechanism of skin penetration of fisetin loaded glycerosomes formulation was determined by the DSC and FTIR studies. Confocal scanning microscopy was used to detect the penetration ability of glycerosomes. The optimized fisetin loaded glycerosomes formulation was converted into a Carbopol® gel matrix, and the latter was analyzed for various parameters. The optimized formulation of glycerosomes presented vesicles size, entrapment efficiency and flux of 138.8 ± 4.09 nm, 86.41 ± 2.95% and 5.04 ± 0.17 µg/cm²/h, respectively. The transmission electron microscopy of optimized fisetin loaded formulation revealed the spherical and sealed structure of glycerosomes vesicles. The confocal study confirmed that the Rhodamine B incorporated glycerosomes penetrated up to deeper layers of skin. The DSC and FTIR studies revealed that the hydration of skin layers and skin lipid fluidization could be the penetration mechanism of fisetin glycerosomes formulation. The optimized fisetin loaded glycerosomes gel formulation presented a flux of 4.24 ± 0.14 μg/cm²/h, and exhibited zero-order release kinetics. The texture analysis of fisetin glycerosomes gel displayed a sufficient hardness, consistency, cohesiveness, and index of viscosity. It was concluded that the prepared fisetin loaded glycerosomes gel was suitable for the dermal application.

Skin permeation and thermodynamic features of curcumin-loaded liposomes

This work describes the development of liposomes encapsulating curcumin (CURC) aiming to provide insights on the influence of CURC on the thermodynamic and skin permeation/penetration features of the vesicles. CURC-loaded liposomes were prepared by hydration of lipid film, in the 0.1-15% CURC:DPPC w/w ratio range. The obtained formulations were characterized for their size distribution, zeta potential and vesicle deformability, along with their thermodynamic properties and ex vivo skin penetration/permeation ability. Liposome size was 110-130 nm for all formulations, with fairly narrow size distribution (polydispersity index was ≤0.20) and a zeta potential mildly decreasing with CURC loading. DSC outcomes indicated that CURC interferes with the packing of DPPC acyl chains in liposome bilayer when CURC percentage was at least 10%, leading to a more fluid state than blank and low-payload vesicles. Consistently, the deformability index of liposomes with 15% CURC:DPPC was strongly increased compared to other formulations. This is congruent with ex vivo skin penetration/permeation results, which showed how more deformable liposomes showed an improved deposition in the epidermis, which acts as a reservoir for the active molecule. Altogether, results hint at a possible application of high payload liposomes for improved topical dermal accumulations of actives.

Encapsulating plant ingredients for dermocosmetic application: an updated review of delivery systems and characterization techniques

Today, there is a rising demand and ongoing search for novel plant-derived phytochemicals in the cosmetic market owing to the growing consumer expectations worldwide for green and natural health products. Various plant ingredients, including polyphenols, oils, volatile oils, vitamins and other herbal extracts, have been extensively used in herbal cosmetics. Recent advances in encapsulation technologies have greatly improved their chemical stability, biocompatibility, skin permeability and dermocosmetic efficiency when applied topically. This comprehensive review summarizes the up-to-date information on encapsulated plant ingredients tailored for dermocosmetic application with a focus on the development of novel delivery systems. An overview of the commonly used techniques for carrier characterization, performance-related properties and toxicological evaluation is also included, which might provide guidance for researchers to select or develop appropriate assay systems.

Stabilization of Deformable Nanovesicles Based on Insulin-Phospholipid Complex by Freeze-Drying

Deformable nanovesicles have been extensively investigated due to their excellent ability to penetrate biological barriers. However, suffering from serious physical and chemical instabilities, the wide use of deformable nanovesicles in medical applications is still limited. Moreover, far less work has been done to pursue the lyophilization of deformable nanovesicles. Here, we aimed to obtain stable deformable nanovesicles via freeze-drying technology and to uncover the underlying protection mechanisms. Firstly, the density of nanovesicles before freeze-drying, the effect of different kinds of cryoprotectants, and the types of different reconstituted solvents after lyophilization were investigated in detail to obtain stable deformable nanovesicles based on insulin-phospholipid complex (IPC-DNVs). To further investigate the underlying protection mechanisms, we performed a variety of analyses. We found that deformable nanovesicles at a low density containing 8% lactose and trehalose in a ratio of 1:4 (8%-L-T) have a spherical shape, smooth surface morphology in the lyophilized state, a whorl-like structure, high entrapment efficiency, and deformability after reconstitution. Importantly, the integrity of IPC, as well as the secondary structure of insulin, were well protected. Accelerated stability studies demonstrated that 8%-L-T remained highly stable during storage for 6 months at 25 °C. Based on in vivo results, lyophilized IPC-DNVs retained their bioactivity and had good efficacy. Given the convenience of preparation and long term stability, the use of combined cryoprotectants in a proper ratio to protect stable nanovesicles indicates strong potential for industrial production.

Eco-scalable baicalin loaded vesicles developed by combining phospholipid with ethanol, glycerol, and propylene glycol to enhance skin permeation and protection

A new class of biocompatible and scalable phospholipid vesicles was developed, aiming at improving the efficacy of baicalin on the skin. Phosphatidylcholine and baicalin (a natural polyphenol) were hydrated in two steps with a mixture of ethanol, glycerol, and propylene glycol at different ratios, and a low amount of water (4%). Hence, water was almost completely replaced by the co-solvents, which were never used before as predominant dispersing medium of phospholipid vesicles. The vesicles appeared three-dimensionally structured, forming a network that conferred a high viscosity to the dispersions. The vesicles were unilamellar, small in size (∼100 nm), and stable during 12 months of storage. They disclosed optimal performances in the transdermal delivery of baicalin, and high biocompatibility with skin cells (i.e., keratinocytes and fibroblasts). Furthermore, the vesicles promoted the efficacy of baicalin in protecting skin cells against oxidative stress in vitro and injured skin in vivo.

The Why, Where, Who, How, and What of the vesicular delivery systems

Though vesicular delivery systems have been widely explored and reviewed, no comprehensive review exists that covers their development from the inception of the concept to its culmination in the form of regulated marketed formulations. With the advancement of scientific research in the field of nanomedicine, certain category of vesicular delivery systems have successfully reached the global market. Despite extensive research and highly encouraging results in a plethora of pathological conditions in the preclinical studies, translation of these nanomedicines from laboratory to market has been very limited. Aim of this review is to describe comprehensively the various colloidal delivery systems, focusing mainly on their conventional and advanced methods of preparation, different characterization techniques and main success stories of their journey from bench to bedside of the patient. The review also touches the finer nuances of the use of modern formulation approach of DoE (Design of Experiments) in their formulation and the status of regulatory guidelines for the approval of these nanomedicines.

Molecular Effects of Glycerol on Lipid Monolayers at the Gas-Liquid Interface: Impact on Microbubble Physical and Mechanical Properties

The production and stability of microbubbles (MBs) is enhanced by increasing the viscosity of both the formation and storage solution, respectively. Glycerol is a good candidate for biomedical applications of MBs, since it is biocompatible, although the exact molecular mechanisms of its action is not fully understood. Here, we investigate the influence glycerol has on lipid-shelled MB properties, using a range of techniques. Population lifetime and single bubble stability were studied using optical microscopy. Bubble stiffness measured by AFM compression is compared with lipid monolayer behavior in a Langmuir-Blodgett trough. We deduce that increasing glycerol concentrations enhances stability of MB populations through a 3-fold mechanism. First, binding of glycerol to lipid headgroups in the interfacial monolayer up to 10% glycerol increases MB stiffness but has limited impact on shell resistance to gas permeation and corresponding MB lifetime. Second, increased solution viscosity above 10% glycerol slows down the kinetics of gas transfer, markedly increasing MB stability. Third, above 10%, glycerol induces water structuring around the lipid monolayer, forming a glassy layer which also increases MB stiffness and resistance to gas loss. At 30% glycerol, the glassy layer is ablated, lowering the MB stiffness, but MB stability is further augmented. Although the molecular interactions of glycerol with the lipid monolayer modulate the MB lipid shell properties, MB lifetime continually increases from 0 to 30% glycerol, indicating that its viscosity is the dominant effect on MB solution stability. This three-fold action and biocompatibility makes glycerol ideal for therapeutic MB formation and storage and gives new insight into the action of glycerol on lipid monolayers at the gas-liquid interface.

Optimization of Innovative Three-Dimensionally-Structured Hybrid Vesicles to Improve the Cutaneous Delivery of Clotrimazole for the Treatment of Topical Candidiasis

New three-dimensionally-structured hybrid phospholipid vesicles, able to load clotrimazole in a high amount (10 mg/mL), were obtained for the first time in this work by significantly reducing the amount of water (≤10%), which was replaced with a mixture of glycerol and ethanol (≈90%). A pre-formulation study was carried out to evaluate the effect of both the composition of the hydrating medium and the concentration of the phospholipid on the physico-chemical properties of hybrid vesicles. Four different three-dimensionally-structured hybrid vesicles were selected as ideal systems for the topical application of clotrimazole. An extensive physico-chemical characterization performed using transmission electron microscopy (TEM), cryogenic transmission electron microscopy (cryo-TEM), ³¹P-NMR, and small-angle X-ray scattering (SAXS) displayed the formation of small, multi-, and unilamellar vesicles very close to each other, and was capable of forming a three-dimensional network, which stabilized the dispersion. Additionally, the dilution of the dispersion with water reduced the interactions between vesicles, leading to the formation of single unilamellar vesicles. The evaluation of the in vitro percutaneous delivery of clotrimazole showed an improved drug deposition in the skin strata provided by the three-dimensionally-structured vesicles with respect to the commercial cream (Canesten^®) used as a reference. Hybrid vesicles were highly biocompatible and showed a significant antifungal activity in vitro, greater than the commercial cream Canesten^®. The antimycotic efficacy of formulations was confirmed by the reduced proliferation of the yeast cells at the site of infection in vivo. In light of these results, clotrimazole-loaded, three-dimensionally-structured hybrid vesicles appear to be one of the most innovative and promising formulations for the treatment of candidiasis infections.

Encapsulation of antioxidant sea fennel (Crithmum maritimum) aqueous and ethanolic extracts in freeze-dried soy phosphatidylcholine liposomes

Soy phosphatidylcholine liposomes encapsulating increasing concentrations of two sea fennel extracts (aqueous and ethanolic) prepared by ultrasonication were freeze-dried, using glycerol as lyoprotectant. Particle properties, water dispersibility, colour, thermal properties and antioxidant capacity (radical scavenging capacity, ferric ion reducing power, Folin-reactive substances) of the liposomal preparations were determined. The freeze-drying process caused an overall increase in particle size and polydispersity index, while the zeta-potential became more electronegative. Both sea fennel extracts were rich in chlorogenic acid (42.61 and 58.48 mg/g for the aqueous and ethanolic extracts, respectively) and showed great antioxidant activity. Vitamin C was identified in the aqueous extract, whereas rutin and rosmarinic acid in the ethanolic one. The entrapment efficiency, determined in the liposomes prepared at the highest extract concentration, was 65.6% and 49.1% for the aqueous extract and the ethanolic extract, respectively. The liposomal antioxidant activity and total phenolic content followed a linear increasing tendency as a result of increasing the extract concentration, irrespective of the type of extract. Higher antioxidant activity was found in the liposomes loaded with the ethanolic extract, in a clear relationship to the greater amount of highly antioxidant phenolic compounds extracted, and also to their lower entrapment efficiency, which caused a greater amount of extract to remain outside the liposome. Both extracts were suitable for producing liposomes with antioxidant properties which could be dried and used to design functional foods.

Citrus limon Extract Loaded in Vesicular Systems for the Protection of Oral Cavity

Background: The nanoincorporation of the extract of Citrus limon (L.) Osbeck var. pompia into liposomes was aimed at improving its antioxidant and antibacterial effects. Methods: The extract of the rind of Citrus limon (L.) Osbeck var. pompia was obtained by maceration in ethanol, evaporation, and freeze-drying. The extract phytochemical fingerprint was obtained by HPLC and mass spectrometry, and it was determined that gallic acid, neohesperidin, eriocitrin, and neoeriocitrin were the most abundant components. The freeze-dried extract was loaded in liposomes, glycerosomes, and penetration-enhancer-containing vesicles prepared with propylene glycol (PG-PEVs). Results: Capability of the vesicles of improving efficacy of the extract in counteracting oxidative stress was studied in vitro in keratinocytes, along with antimicrobial activity against planktonic cultures of Streptococcus mutans, Lactobacillus acidophilus, and Streptococcus sanguinis. Conclusion: Results showed that the vesicles, especially glycerosomes and PG-PEVs, prevented oxidative damage and cell death, and inhibited bacterial proliferation.

Skin-controlled release lipid nanosystems of pranoprofen for the treatment of local inflammation and pain

Aim: The design and development of pranoprofen (PF) nanostructured lipid carriers (NLCs) for topical treatment of local inflammation and pain. Materials & methods: PF-NLCs were designed and optimized by central rotatable composite design. A physicochemical characterization was addressed. Release and skin permeation were performed in Franz diffusion cells. In vivo anti-inflammatory efficacy was assayed in mice and tolerance study in humans. Results: PF-NLCs F7 and F10 provided sustained release, good stability and optimal skin retention avoiding systemic undesired side effects. Anti-inflammatory activity was enhanced, suggesting an improved efficacy as compared with standard formulation. No skin irritancy was detected. Conclusion: Topical PF-NLCs F7 and F10 could be effective and safe new therapeutic tools for the treatment of local inflammation and pain.

[Formula: see text]

The Effect of Alkyl Chain Number in Sucrose Surfactant on the Physical Properties of Quercetin-Loaded Deformable Nanoliposome and Its Effect on In Vitro Human Skin Penetration

Non-invasive skin penetration of a drug is increased by an edge activator, which enhances the nanoliposome deformability. The objective of this study was to investigate the role of the alkyl chain number of sucrose surfactants as an edge activator in elastic nanoliposomes. In addition, the physicochemical properties of the elastic nanoliposomes were characterized and an in vitro human skin permeation study was performed. Elastic nanoliposomes that were composed of sucrose monostearate (MELQ), sucrose distearate (DELQ), and sucrose tristearte (TELQ) were prepared using a thin-film hydration method. Particle size and entrapment efficiency of elastic nanoliposomes increased proportionally with an increase in the amounts and the numbers of the stearate in sucrose surfactant. Deformability of elastic nanoliposomes was indicated as DELQ > MELQ > TELQ and the same pattern was revealed through the in vitro human skin permeability tests. These results suggest that the number of alkyl chains of sucrose surfactant as edge activator affects the physicochemical property, stability, and skin permeability in elastic nanoliposome. Our findings give a valuable platform for the development of elastic nanoliposomes as skin drug delivery systems.

Functional G-Protein-Coupled Receptor (GPCR) Synthesis: The Pharmacological Analysis of Human Histamine H1 Receptor (HRH1) Synthesized by a Wheat Germ Cell-Free Protein Synthesis System Combined with Asolectin Glycerosomes

G-protein-coupled receptors (GPCRs) are membrane proteins distributed on the cell surface, and they may be potential drug targets. However, synthesizing GPCRs in vitro can be challenging. Recently, some cell-free protein synthesis systems have been shown to produce a large amount of membrane protein combined with chemical chaperones that include liposomes and glycerol. Liposomes containing high concentrations of glycerol are known as glycerosomes, which are used in new drug delivery systems. Glycerosomes have greater morphological stability than liposomes. Proteoglycerosomes are defined as glycerosomes that contain membrane proteins. Human histamine H₁ receptor (HRH1) is one of the most studied GPCRs. In this study, we synthesized wild-type HRH1 (WT-HRH1) proteoglycerosomes and D107A-HRH1, (in which Asp107 was replaced by Ala) in a wheat germ cell-free protein synthesis system combined with asolectin glycerosomes. The mutant HRH1 has been reported to have low affinity for the H₁ antagonist. In this study, the amount of synthesized WT-HRH1 in one synthesis reaction was 434 ± 66.6 μg (7.75 ± 1.19 × 10³pmol). The specific binding of [³H]pyrilamine to the WT-HRH1 proteoglycerosomes became saturated as the concentration of the radioligand increased. The dissociation constant (Kd) and maximum density (Bmax) of the synthesized WT-HRH1 were 9.76 ± 1.25 nM and 21.4 ± 0.936 pmol/mg protein, respectively. However, specific binding to D107A-HRH1 was reduced compared with WT-HRH1 and the binding did not become saturated. The findings of this study highlight that HRH1 synthesized using a wheat germ cell-free protein synthesis system combined with glycerosomes has the ability to bind to H₁ antagonists.

Freeze-dried phosphatidylcholine liposomes encapsulating various antioxidant extracts from natural waste as functional ingredients in surimi gels

Three antioxidant extracts (collagen hydrolysate, pomegranate peel extract, shrimp lipid extract) were encapsulated in soy phosphatidylcholine liposomes with the addition of glycerol. The particle size of the fresh liposomes ranged from 75.7 to 81.0 nm and zeta potential from -64.6 to -88.2 mV. Freeze-drying increased particle size (199-283 nm), and slightly decreased zeta potential. The lyophilized liposomes were incorporated in squid surimi gels at 10.5% concentration. An alternative functional formulation was also prepared by adding 2% of non-encapsulated bioactive extract. The gels were characterized in terms of colour, texture and oxidative stability (TBARS) after processing and also after frozen storage. The incorporation of the freeze-dried liposomes caused a slight decrease in gel strength and contributed to maintaining the stability of the gels during long-term frozen storage. The antioxidant properties of the bioactive extracts, liposomes and in vitro digested surimi gels were determined.

Effect of chemical composition and sonication procedure on properties of food-grade soy lecithin liposomes with added glycerol

The effect of two-step and five-step acetone washing of soybean lecithin (SL) on compositional properties of partially purified phosphatidylcholines (PW2 and PW5) was studied. Trace amounts of protein were detected in SL, PW2 and PW5, with a predominance of glutamic acid and aspartic acid. Increasing the number of acetone washing steps significantly reduced the total content of γ-, δ- and α-tocopherol. Similar reductions (≈90%) of neutral lipids were found in both PW2 and PW5, but the removal of free fatty acids was higher in PW5 than in PW2 (78% vs. 71%). Linoleic acid was the main constituent in both the neutral lipids and the phospholipid fractions of SL, PW2 and PW5, accounting for around 53-59% of total fatty acids; however, a considerable amount of it was removed by increasing the number of washing steps. All phospholipid classes were mostly concentrated in the first two-step washing of lecithin. Further washing increased the concentration of phosphatidylcholine (PC) in PW5, as compared to PW2. Glycerol-containing liposomes from PW2 and PW5 were produced using two different-intensity sonication procedures (method A: 120W, 5min; method B: 30W, 2min) using a probe-type sonicator (100mL volume suspension). Liposomes of soy lecithin and liposomes of PW5 without glycerol were also obtained by using strong sonication (method A). The liposomal dispersion with the highest purification and the stronger sonication was clearly distinguished from the others, both in particle size and in zeta potential. DSC results showed noticeable interference of glycerol in the membrane structure, but minimal changes in particle size and surface charge.

Glycerosomes: Investigation of role of 1,2-dimyristoyl-sn-glycero-3-phosphatidycholine (DMPC) on the assembling and skin delivery performances

Glycerosomes were formulated using 1,2-dimyristoyl-sn-glycero-3-phosphatidycholine (DMPC), diclofenac sodium salt and 10, 20 or 30% glycerol in the water phase, while corresponding liposomes were prepared with the same amount of DMPC and diclofenac, without glycerol. The aim of the present work was to evaluate the effect of the used phospholipid on vesicle features and ability to favour diclofenac skin deposition by comparing these results with those found in previous works performed using hydrogenated soy phosphatidylcholine (P90H) and dipalmitoylphosphatidylcholine (DPPC). Liposomes and glycerosomes were multilamellar, liposomes being smaller (72±6nm). Interactions among glycerol, phospholipids and drug led to the formation of a non-rigid bilayer structure and a variation of the main transition temperature, which shifted to lower temperature. The addition of glycerol led to the formation of more viscous systems (from ∼2.5mPa/s for basic liposomes to ∼5mPa/s for glycerosomes), which improved spread ability of the formulations on the skin.Results obtained in vitro were promising using glycerosomes, irrespective of the amount of glycerol used: the amount of drug, which accumulated into and permeated through the different skin strata, was high and comparable with that obtained using P90H, suggesting that glycerosomes may represent an efficient carrier for both local effect or systemic absorption.

Diclofenac Loaded Lipid Nanovesicles Prepared by Double Solvent Displacement for Skin Drug Delivery

PURPOSE

Herein, we detail a promising strategy of nanovesicle preparation based on control of phospholipid self-assembly: the Double Solvent Displacement. A systematic study was conducted and diclofenac as drug model encapsulated. In vitro skin studies were carried out to identify better formulation for dermal/transdermal delivery.

METHODS

This method consists in two solvent displacements. The first one, made in a free water environment, has allowed triggering a phospholipid pre-organization. The second one, based on the diffusion into an aqueous phase has led to liposome formation.

RESULTS

Homogeneous liposomes were obtained with a size close to 100 nm and a negative zeta potential around -40 mV. After incorporation of acid diclofenac, we obtained nanoliposomes with a size between 101 ± 45 and 133 ± 66 nm, a zeta potential between 34 ± 2 and 49 ± 3 mV, and the encapsulation efficiency (EE%) was between 58 ± 3 and 87 ± 5%. In vitro permeation studies showed that formulation with higher EE% dispayed the higher transdermal passage (18,4% of the applied dose) especially targeting dermis and beyond.

CONCLUSIONS

Our results suggest that our diclofenac loaded lipid vesicles have significant potential as transdermal skin drug delivery system. Here, we produced cost effective lipid nanovesicles in a merely manner according to a process easily transposable to industrial scale. Graphical Abstract ᅟ.