Lipid cubic phases for improved topical drug delivery in photodynamic therapy

Cubic nanoparticles as potential carriers for a natural anticancer drug: development, in vitro and in vivo characterization

Natural compounds that elicit anticancer properties are of great interest for cancer therapy. However, the low solubility and bioavailability of these compounds limit their use as efficient anticancer drugs. To avoid these drawbacks, incorporation of these compounds into cubic nanoparticles (cubosomes) was carried out. Cubosomes containing bergapten which is a natural anticancer compound isolated from Ficus carica were prepared by the homogenization technique using monoolein and poloxamer. These cubosomes were characterized for size, zeta potential, entrapment efficiency, small angle X-ray diffraction, in vitro release, in vitro cytotoxicity, cellular uptake, and antitumor activity. Particle size of cubosomes was 220 ± 3.6 nm with almost neutral zeta potential - 5 ± 1.2 mV and X-ray measurements confirmed the existence of the cubic structure. Additionally, more than 90% of the natural anticancer drug was entrapped within the cubosomes. A sustained release over 30 h was obtained for these cubosomes. Finally, these cubosomes illustrated higher in vitro cytotoxicity and in vivo tumor inhibition compared with the free natural anticancer compound. Thus, cubosomes could be promising carriers for enhancement of antitumor efficiency of this natural compound.

Repurposing levocetirizine hydrochloride loaded into cationic ceramide/phospholipid composite (CCPCs) for management of alopecia: central composite design optimization, in- silico and in-vivo studies

Levocetirizine hydrochloride (LVC) is an antihistaminic drug that is repurposed for the treatment of alopecia. This investigation is targeted for formulating LVC into cationic ceramide/phospholipid composite (CCPCs) for the management of alopecia. CCPCs were fabricated by ethanol-injection approach, through a central composite experiment. CCPCs were evaluated by inspecting their entrapment efficiency (EE%), polydispersity index (PDI), particle size (PS), and zeta potential (ZP). The optimum CCPCs were additionally studied by in-vitro, ex-vivo, in-silico, and in-vivo studies. The fabricated CCPCs had acceptable EE%, PS, PDI, and ZP values. The statistical optimization elected optimum CCPCs composed of 5 mg hyaluronic acid, 10 mg ceramide III, and 5 mg dimethyldidodecylammonium bromide employing phytantriol as a permeation enhancer. The optimum CCPCs had EE%, PS, PDI, and ZP of 88.36 ± 0.34%, 479.00 ± 50.34 nm, 0.377 ± 0.0035, and 20.20 ± 1.13 mV, respectively. The optimum CCPC maintained its stability for up to 90 days. It also viewed vesicles of tube shape via transmission electron microscope. The in-silico assessment resulted in better interaction and stability between LVC and vesicle components in water. The ex-vivo and in-vivo assessments showed satisfactory skin retention of LVC from optimum CCPCs. The histopathological assessment verified the safety of optimum CCPCs to be topically applied. Overall, the optimum CCPCs could be utilized as a potential system for the topical management of alopecia, with a prolonged period of activity, coupled with reduced LVC shortcomings.

Liquid crystalline lipid nanoparticle promotes the photodynamic activity of gallium protoporphyrin against S. aureus biofilms

Antimicrobial photodynamic therapy (aPDT) has emerged as an innovative strategy to combat antibiotic resistant microbes; yet aPDT efficacies against biofilms are sub-optimal due to inability of photosenstizers to reach microbes embedded in biofilm matrix. To overcome this challenge, liquid crystal lipid nanoparticles (LCNP) were employed in this study as a smart, biocompatible and triggerable delivery system for the new photosensitizer gallium protoporphyrin (GaPP), due to their capabilities in promoting efficient antimicrobial delivery to biofilms. The relationship between GaPP loading of LCNP, reactive oxygen species (ROS) production and the in vitro antibacterial activity against two antibiotic resistant Staphylococcus aureus strains was established. LCNP substantially improved the antibacterial activity of GaPP, completely eradicating S. aureus and MRSA planktonic cultures, using a GaPP concentration of 0.8 μM and light dose 1.9 J/cm². At the same concentration and light dose, unformulated GaPP triggered only a 4 log₁₀ and 2 log₁₀ reduction in respective planktonic cultures. Most importantly, the activity of GaPP against biofilms was enhanced by 2-fold compared to unformulated GaPP, reducing the viability of S. aureus and MRSA biofilms by 8 log₁₀ and 5 log₁₀, respectively. The biosafety of photoactivated GaPP-LCNP was evaluated against human fibroblasts, which indicated a high safety profile of the treatment. Therefore, these findings encourage further investigations of GaPP-LCNP as a potential treatment for localized chronic infections.

Recent advances in versatile inverse lyotropic liquid crystals

Owing to the rapid and significant progress in advanced materials and life sciences, nanotechnology is increasingly gaining in popularity. Among numerous bio-mimicking carriers, inverse lyotropic liquid crystals are known for their unique properties. These carriers make accommodation of molecules with varied characteristics achievable due to their complicated topologies. Besides, versatile symmetries of inverse LCNPs (lyotropic crystalline nanoparticles) and their aggregating bulk phases allow them to be applied in a wide range of fields including drug delivery, food, cosmetics, material sciences etc. In this review, in-depth summary, discussion and outlook for inverse lyotropic liquid crystals are provided.

Lyotropic Liquid Crystalline Nanostructures as Drug Delivery Systems and Vaccine Platforms

Lyotropic liquid crystals result from the self-assembly process of amphiphilic molecules, such as lipids, into water, being organized in different mesophases. The non-lamellar formed mesophases, such as bicontinuous cubic (cubosomes) and inverse hexagonal (hexosomes), attract great scientific interest in the field of pharmaceutical nanotechnology. In the present review, an overview of the engineering and characterization of non-lamellar lyotropic liquid crystalline nanosystems (LLCN) is provided, focusing on their advantages as drug delivery nanocarriers and innovative vaccine platforms. It is described that non-lamellar LLCN can be utilized as drug delivery nanosystems, as well as for protein, peptide, and nucleic acid delivery. They exhibit major advantages, including stimuli-responsive properties for the “on demand” drug release delivery and the ability for controlled release by manipulating their internal conformation properties and their administration by different routes. Moreover, non-lamellar LLCN exhibit unique adjuvant properties to activate the immune system, being ideal for the development of novel vaccines. This review outlines the recent advances in lipid-based liquid crystalline technology and highlights the unique features of such systems, with a hopeful scope to contribute to the rational design of future nanosystems.

Hydrogels and Cubic Liquid Crystals for Non-Invasive Sampling of Low-Molecular-Weight Biomarkers-An Explorative In Vivo Study

The molecular composition of human skin is altered due to diseases, which can be utilized for non-invasive sampling of biomarkers and disease diagnostics. For this to succeed, it is crucial to identify a sampling formulation with high extraction efficiency and reproducibility. Highly hydrated skin is expected to be optimal for increased diffusion of low-molecular-weight biomarkers, enabling efficient extraction as well as enhanced reproducibility as full hydration represents a well-defined endpoint. Here, the aim was to explore water-based formulations with high water activities, ensuring satisfactory skin hydration, for non-invasive sampling of four analytes that may serve as potential biomarkers, namely tryptophan, tyrosine, phenylalanine, and kynurenine. The included formulations consisted of two hydrogels (chitosan and agarose) and two different liquid crystalline cubic phases based on the polar lipid glycerol monooleate, which were all topically applied for 2 h on 35 healthy subjects in vivo. The skin status of all sampling sites was assessed by electrical impedance spectroscopy and transepidermal water loss, enabling explorative correlations between biophysical properties and analyte abundancies. Taken together, all formulations resulted in the successful and reproducible collection of the investigated biomarkers. Still, the cubic phases had an extraction capacity that was approximately two times higher compared to the hydrogels.

Lipid Cubic Systems for Sustained and Controlled Delivery of Antihistamine Drugs

Antihistamines are capable of blocking mediator responses in allergic reactions including allergic rhinitis and dermatological reactions. By incorporating various H1 receptor antagonists into a lipid cubic phase network, these active ingredients can be delivered locally over an extended period of time owing to the mucoadhesive nature of the system. Local delivery can avoid inducing unwanted side effects, often observed after systematic delivery. Lipid-based antihistamine delivery systems are shown here to exhibit prolonged release capabilities. In vitro drug dissolution studies investigated the extent and release rate of two model first-generation and two model second-generation H1 antagonist antihistamine drugs from two monoacyglycerol-derived lipid models. To optimize the formulation approach, the systems were characterized macroscopically and microscopically by small-angle X-ray scattering and polarized light to ascertain the mesophase accessed upon an incorporation of antihistamines of varying solubilities and size. The impact of encapsulating the antihistamine molecules on the degree of mucoadhesivity of the lipid cubic systems was investigated using multiparametric surface plasmon resonance. With the ultimate goal of developing therapies for the treatment of allergic reactions, the ability of the formulations to inhibit mediator release utilizing RBL-2H3 mast cells with the propensity to release histamine upon induction was explored, demonstrating no interference from the lipid excipient on the effectiveness of the antihistamine molecules.

Cholesterol and phospholipid-free multilamellar niosomes regulate transdermal permeation of a hydrophobic agent potentially administrated for treating diseases in deep hair follicles

We designed cholesterol- and phospholipid-free multilamellar niosomes (MLNs) structured by glyceryl monooleate (GMO) and poloxamer 407 (F127), and evaluated their capacity for transdermal drug delivery. The optimized MLNs had a mean size of 97.88 ± 63.25 nm and an encapsulation efficiency of 82.68% ± 2.14%. Notably, the MLNs exhibited a remarkable sustained cargo release. Compared with the tincture, lower transdermal flux but higher skin deposition of aconitine in vitro were achieved in the MLN group (p < 0.05). We further found that MLNs improved the permeability of the stratum corneum. Additionally, both water-soluble rhodamine B- and liposoluble coumarin 6-labeled MLNs were found to penetrate deeply into the skin through the hair follicles and could be internalized by fibroblasts (CCC-ESF-1). The MLNs possessed greater wettability, and the study focused on delivery to deeper hair follicles and up to the outer hair sheath, which showed advantages for treating diseases of hair follicles, and was potentially superior to the hydrophobic PLGA nanoparticles (diameter: 637.87 ± 22.77 nm) which mainly accumulated in superficial hair follicles. Hair follicles were therefore demonstrated to be an important way to enhance skin permeability, and MLNs are a promising alternative for topical and transdermal drug delivery.

Cubosomes: Versatile Nanosized Formulation for Efficient Delivery of Therapeutics

Cubosomes are bicontinuous cubic phase nanoparticles with a size range from 10-500 nm. They offer various advantages with some limitations at the production level, e.g., cubosomes have the feature to encapsulate a large amount of the drug due to its large internal area owing to cuboidal shape thus has a larger area but limited in large scale production due to its high viscosity which is associated with the problem in homogenization. This nanoparticulate formulation is compatible for administration by various routes like oral, transdermal, topical, buccal, etc. The drug release mechanism from cubosomes was reported to be dependent on the partition coefficient and diffusion process. Compared with liposomes, cubosomes show many differences in various aspects like shape, size, ingredients, and mode of action. The main ingredients for the preparation of cubosomes include lipids, stabilizer, aqueous phases, and therapeutic agents. Several methods have been reported for cubosomes, including the top-down method, the bottom-up method, and the adopted coarse method. For the optimization of cubosomes, the key factors to be considered, which will affect the cubosomes characteristics include; the concentration of lipid, temperature, and pH. At present, many research groups are exploring the potential of cubosomes as biosensors and nanocarriers. Based on the latest reports and research, this review illuminates the structure of the Cubosomes, mechanism of the drug release, different methods of preparation with factors affecting the cubosomes, application of cubosomes in different sectors, differences from the liposomes, and advantages.

Nanotechnology-based Drug Delivery Systems as Potential for Skin Application: A Review

Administration of substances through the skin represents a promising alternative, in relation to other drug administration routes, due to its large body surface area, in order to offer ideal and multiple sites for drug administration. In addition, the administration of drugs through the skin avoids the first-pass metabolism, allowing an increase in the bioavailability of drugs, as well as reducing their side effects. However, the stratum corneum (SC) comprises the main barrier of protection against external agents, mainly due to its structure, composition and physicochemical properties, becoming the main limitation for the administration of substances through the skin. In view of the above, pharmaceutical technology has allowed the development of multiple drug delivery systems (DDS), which include liquid crystals (LC), cubosomes, liposomes, polymeric nanoparticles (PNP), nanoemulsions (NE), as well as cyclodextrins (CD) and dendrimers (DND). It appears that the DDS circumvents the problems of drug absorption through the SC layer of the skin, ensuring the release of the drug, as well as optimizing the therapeutic effect locally. This review aims to highlight the DDS that include LC, cubosomes, lipid systems, PNP, as well as CD and DND, to optimize topical skin therapies.

Pulmonary route of administration is instrumental in developing therapeutic interventions against respiratory diseases

Pulmonary route of drug delivery has drawn significant attention due to the limitations associated with conventional routes and available treatment options. Drugs administered through pulmonary route has been an important research area that focuses on to developing effective therapeutic interventions for asthma, chronic obstructive pulmonary disease, tuberculosis, lung cancer etc. The intravenous route has been a natural route of delivery of proteins and peptides but associated with several issues including high cost, needle-phobia, pain, sterility issues etc. These issues might be addressed by the pulmonary administration of macromolecules to achieving an effective delivery and efficacious therapeutic impact. Efforts have been made to develop novel drug delivery systems (NDDS) such as nanoparticles, microparticles, liposomes and their engineered versions, polymerosomes, micelles etc to achieving targeted and sustained delivery of drug(s) through pulmonary route. Further, novel approaches such as polymer-drug conjugates, mucoadhesive particles and mucus penetrating particles have attracted significant attention due to their unique features for an effective delivery of drugs. Also, use of semi flourinated alkanes is in use for improvising the pulmonary delivery of lipophilic drugs. Present review focuses on to unravel the mechanism of pulmonary absorption of drugs for major pulmonary diseases. It summarizes the development of interventional approaches using various particulate and vesicular drug delivery systems. In essence, the orchestrated attempt presents an inflammatory narrative on the advancements in the field of pulmonary drug delivery.

Modulating the release of pharmaceuticals from lipid cubic phases using a lipase inhibitor

Lipid cubic phase formulations have gained recognition as potential controlled delivery systems for a range of active pharmaceutical and biological agents on account of their desirable physiochemical properties and ability to encapsulate both hydrophobic and hydrophilic molecules. The most widely studied lipid cubic systems are those of the monoacylglycerol lipid family. These formulations are susceptible to lipolysis by a variety of enzymes, including lipases and esterases, which attack the ester bond present on the lipid chain bridging the oleic acid component to the glycerol backbone. The release of poorly soluble molecules residing in the lipid membrane portions of the phase is limited by the breakdown of the matrix; thus, presenting a potential means for further controlling and sustaining the release of therapeutic agents by targeting the matrix stability and its rate of degradation. The aims of the present study were twofold: to evaluate an approach to regulate the rate of degradation of lipid cubic phase drug delivery systems by targeting the enzyme interactions responsible for their demise; and to study the subsequent drug release profiles from bulk lipid cubic gels using model drugs of contrasting hydrophobicity. Here, hybrid materials consisting of cubic phases with monoacylglycerol lipids of different chain lengths formulated with a potent lipase inhibitor tetrahydrolipstatin were designed. Modulation of the release of a hydrophobic model pharmaceutical, a clofazimine salt, was obtained by exploiting the matrices' enzyme-driven digestion. A stable cubic phase is described, displaying controlled degradation with at least a 4-fold improvement compared to the blank systems shown in inhibitor-containing cubic systems. Sustained release of the model hydrophobic pharmaceutical was studied over 30 days to highlight the advantage of incorporating an inhibitor into the cubic network to achieve tunable lipid release systems. This is done without negatively affecting the structure of the matrix itself, as shown by comprehensive small-angle x-ray scattering experiments.

Theranostic combinatorial drug-loaded coated cubosomes for enhanced targeting and efficacy against cancer cells

Cubosomes, a product of nanobioengineering, are self-structured lipid nanoparticles that act like drug-loaded theranostic probes. Here, we describe a simple method for the preparation of combinatorial drug-loaded cubosomes with, proof-of-principle, therapeutic effect against cancer cells, along with diagnostic capabilities. Anticancer drugs cisplatin and paclitaxel were loaded in the cubosomes in combination. The cubosomes were coated with a layer of poly-Ɛ-lysine, which helped avoid the initial burst release of drug and allowed for a slow and sustained release for better efficacy. Cubosomes were imaged by transmission electron microscope, and their dispersion analyzed in vitro by differential scanning calorimetric and X-ray diffractogram studies. The microscopic images depicted spherical polyangular structures, which are easily distinguishable. The analyses revealed that the drug is uniformly dispersed all through the cubosomes. Further characterization was carried out by zeta-potential measurement, in vitro release, and entrapment efficiency studies. The in vitro studies established that the coating of cubosomes successfully reduced the burst release of drugs initially and confirmed a slow, sustained release over increased time. Comparative cytotoxicity of coated, uncoated, and blank cubosomes was evaluated, using human hepatoma HepG2 cell line, and the formulations were found to be entirely nontoxic, similar to the blank ones. The therapeutic efficiency of the cubosomes against HeLa cells was confirmed by the impedance measurement and fluorescent imaging. Furthermore, the reduction in impedance in cells treated with coated combinatorial cubosomes proved the impairment of HeLa cells, as confirmed by fluorescence microscopy.

Non-Lamellar Lyotropic Liquid Crystalline Lipid Nanoparticles for the Next Generation of Nanomedicine

Nonlamellar lyotropic liquid crystalline (LLC) lipid nanomaterials have emerged as a promising class of advanced materials for the next generation of nanomedicine, comprising mainly of amphiphilic lipids and functional additives self-assembling into two- and three-dimensional, inverse hexagonal, and cubic nanostructures. In particular, the lyotropic liquid crystalline lipid nanoparticles (LCNPs) have received great interest as nanocarriers for a variety of hydrophobic and hydrophilic small molecule drugs, peptides, proteins, siRNAs, DNAs, and imaging agents. Within this space, there has been a tremendous amount of effort over the last two decades elucidating the self-assembly behavior and structure-function relationship of natural and synthetic lipid-based drug delivery vehicles in vitro, yet successful clinical translation remains sparse due to the lack of understanding of these materials in biological bodies. This review provides an overview of (1) the benefits and advantages of using LCNPs as drug delivery nanocarriers, (2) design principles for making LCNPs with desirable functionalities for drug delivery applications, (3) current understanding of the LLC material-biology interface illustrated by more than 50 in vivo, preclinical studies, and (4) current patenting and translation activities in a pharmaceutical context. Together with our perspectives and expert opinions, we anticipate that this review will guide future studies in developing LCNP-based drug delivery nanocarriers with the objective of translating them into a key player among nanoparticle platforms comprising the next generation of nanomedicine for disease therapy and diagnosis.

Liquid crystalline nanoreservoir releasing a highly skin-penetrating berberine oleate complex for psoriasis management

Aim: The current work highlighted preparation of highly penetrating liquid crystalline nanoparticulates (LCNPs) reservoir of a solubility modified berberine oleate (Brb-OL) complex for effective psoriasis management. Materials & methods: Brb-OL-loaded LCNPs (Brb-OL-LCNPs) were prepared using hydrotrope method. Results: The proposed Brb-OL-LCNPs showed a particle size of 137 ± 3.7 nm and negative ζ-potential (-38 ± -5.85 mV). Brb-OL-LCNPs showed a threefold increase in the drug accumulated within rat skin and around tenfold increase in the drug permeation compared with crude Brb. In vivo studies revealed that topical application of Brb-OL-LCNPs hydrogel significantly alleviated psoriasis symptoms and reduced the levels of psoriatic inflammatory cytokines. Conclusion: Formulating Brb-OL in the LCNPs controlled the release, retention and permeation of the drug across skin layers, which are of prime importance for psoriasis management.

Rheology of Ultraswollen Bicontinuous Lipidic Cubic Phases

Rheological studies of liquid crystalline systems based on monopalmitolein and 5 or 8% of 1,2 distearoylphosphatidylglycerol are reported. Such cubic phases have been shown to possess unusually large water channels because of their ability of accommodating up to 80 wt % of water, a feature that renders these systems suitable for crystallizing membrane proteins with large extracellular domains. Their mechanical properties are supposed to be substantially different from those of traditional cubic phases. Rheological measurements were carried out on cubic phases of both Pn3 m and Ia3 d symmetries. It was verified that these ultraswollen cubic phases are less rigid than the normal cubic phases, with the Pn3 m being softer that the Ia3 d ones. Furthermore, for the Pn3 m case, the longest relaxation time is shown to decrease logarithmically with increasing surface area per unit volume, proving the critical role of the density of interfaces in establishing the macroscopic viscoelastic properties of the bicontinuous cubic phases.

Nanostructured Lipid-based Films for Substrate Mediated Applications in Biotechnology

Amphiphilic in nature, lipids spontaneously self-assemble into a range of nanostructures in the presence of water. Among lipid self-assembled structures, liposomes and supported lipid bilayers have long held scientific interest for their main applications in drug delivery and plasma membrane models, respectively. In contrast, lipid-based multi-layered membranes on solid supports only recently begun drawing scientists' attention. New studies on lipid films show that the stacking of multiple bilayers on a solid support yields interestingly complex features to these systems. Namely, multiple layers exhibit cooperative structural and dynamic behavior. In addition, the materials enable compartmentalization, templating, and enhanced release of several molecules of interest. Importantly, supported lipid phases exhibit long-range periodic nano-scale order and orientation that is tunable in response to a changing environment. Herein, we summarize current and pertinent understanding of lipid-based film research focusing on how unique structural characteristics enable the emergence of new applications in biotechnology including label-free biosensors, macroscale drug delivery, and substrate-mediated gene delivery. Our very recent contributions to lipid-based films, focusing on the structural characterization at the meso, nano, and molecular-scale, using Small-Angle X-ray Scattering, Atomic Force Microscopy, Photothermal Induced Resonance, and Solid-State NMR will be also highlighted.

Phytantriol based smart nano-carriers for drug delivery applications

From the last couple of decades, lyotropic liquid crystals have garnered enormous attentions in medical and pharmaceutical sciences. Non-toxic, chemically stable, and biocompatible properties of these liquid crystal systems are contributing to their applications for drug delivery. Among a large variety of liquid crystal phases, inverse bicontinuous cubic and inverse hexagonal mesophases have been extensively investigated for their ability to encapsulate and controlled release of bioactive molecules of various sizes and polarity. The concept of changing the drug release rate in situ by simply changing the mesophase structure is much more fascinating. The encapsulation of bioactive compounds in mesophase systems of desirable features in sub-micron sized particles such as hexosomes and cubosomes, at ambient and high temperature is bringing innovation in the development of new drug applications. This review article outlines unique structural features of cubosomes and hexosomes, their methods of productions, factors affecting their formations and their potential utilization as smart nano-carriers for biopharmaceuticals in drug delivery applications.

Phase behavior, rheology, and release from liquid crystalline phases containing combinations of glycerol monooleate, glyceryl monooleyl ether, propylene glycol, and water

Quaternary phase diagram of the GMO/GME/PG and water system is determined, allowing for controlled phase transitions triggered by temperature or humidity.

Liquid Crystal Systems in Drug Delivery

Liquid crystals have been recently studied as novel drug delivery system. The reason behind this is their similarity to colloidal systems in living organisms. They have proven to be advantageous over Traditional, Dermal, Parentral and Oral Dosage forms. Liquid crystals are thermodynamically stable and possess long shelf life. Liquid crystals show bio adhesive properties and sustained release effects. Objective of this book chapter is to provide in-depth information of Pharmaceutical crystal technology. It shall deal with cubic and hexagonal liquid crystal and their applications in Drug delivery system.

Responsive self-assembled nanostructured lipid systems for drug delivery and diagnostics

While stimuli-responsive polymers have received a huge amount of attention in the literature, responsive lipid-based mesophase systems offer unique opportunities in biomedical applications such as drug delivery and biosensing. The different mesophase equilibrium structures enables dynamic switching between nanostructures to facilitate drug release or as a transducer for recognition events. In drug delivery, this behavior offers researchers the means to deliver a therapeutic payload at a specific rate and time i.e. 'on-demand'. This review summarizes the distinctive features of these multifaceted materials and aggregates the current state of the art research from our groups and others into the use of these materials as bulk gels and nanostructured dispersions for drug delivery, biosensing and diagnostics.

The influence of lung surfactant liquid crystalline nanostructures on respiratory drug delivery

The respiratory route increasingly has been used for both local and systemic drug delivery. Although drug is absorbed rapidly after respiratory delivery, the role of lung surfactant in drug delivery is not well understood. The human lung contains only around 15mL of surface lining fluid spread over ∼100m² surface. The fluid contains lung surfactant at a concentration of 8-24mg/kg/body weight; the lung surfactant which is lipo-protein in nature can form different liquid crystalline nanostructures. After a brief overview of the anatomy of respiratory system, the review has focused on the current understanding of lung surface lining fluid, lung surfactants and their composition and possible self-assembled nanostructures. The role of lung surfactant in drug delivery and drug dissolution has been briefly considered. Lung surfactant may form different liquid crystalline phases which can have an active role in drug delivery. The hypotheses developed in this review focuses on the potential roles of surface epithelial fluid containing liquid crystalline nanostructures in defining the dissolution mechanism and rate. The hypotheses also focus an understanding how liquid crystalline nanostructures can be used to control dissolution rate and how the nanostructures might be changed to influence delivery and induce toxicity.

Liquid crystalline systems containing Vitamin E TPGS for the controlled transdermal nicotine delivery

ABSTRACT Transdermal nicotine patches have been used in smoking cessation therapy, suggested for the treatment of skin disorders with eosinophilic infiltration and have been found to improve attention performance in patients with Alzheimer's disease and age-associated memory impairment. However, skin irritation with extended patch use is still a problem. The aim of this work was to develop a simple to prepare liquid crystalline system containing vitamin E TPGS that would be able to control nicotine delivery and reduce irritation and sensitization problems. The liquid crystalline phases were macroscopically characterized by visual analysis and examined microscopically under a polarized light microscope. Topical and transdermal delivery of nicotine were investigated in vitro using porcine ear skin mounted on a Franz diffusion cell. Nicotine skin permeation from the developed cubic phase followed zero-order kinetics (r = 0.993) and was significantly enhanced after 12 h when compared to the control formulation (nicotine solution) (p < 0.05) (138.86 ± 20.44 and 64.91 ± 4.06 μg/cm2, respectively). Cubic phase was also able to target viable skin layers in comparison to control solution (8.18 ± 1.89 and 2.63 ± 2.51 μg/cm2, respectively). Further studies to evaluate skin sensitization and irritation are now necessary.

Cubosomes: remarkable drug delivery potential

Cubosomes are nanostructured liquid crystalline particles, made of certain amphiphilic lipids in definite proportions, known as biocompatible carriers in drug delivery. Cubosomes comprise curved bicontinuous lipid bilayers that are organized in three dimensions as honeycombed structures and divided into two internal aqueous channels that can be exploited by various bioactive ingredients, such as chemical drugs, peptides and proteins. Owing to unique properties such as thermodynamic stability, bioadhesion, the ability of encapsulating hydrophilic, hydrophobic and amphiphilic substances, and the potential for controlled release through functionalization, cubosomes are regarded as promising vehicles for different routes of administration. Based on the most recent reports, this review introduces cubosomes focusing on their structure, preparation methods, mechanism of release and potential routes of administration.

Self-Assembled Cubic Liquid Crystalline Nanoparticles for Transdermal Delivery of Paeonol

Background

The aim of this study was to optimize the preparation method for self-assembled glyceryl monoolein-based cubosomes containing paeonol and to characterize the properties of this transdermal delivery system to improve the drug penetration ability in the skin.

Material/Methods

In this study, the cubic liquid crystalline nanoparticles loaded with paeonol were prepared by fragmentation of glyceryl monoolein (GMO)/poloxamer 407 bulk cubic gel by high-pressure homogenization. We evaluated the Zeta potential of these promising skin-targeting drug-delivery systems using the Malvern Zeta sizer examination, and various microscopies and differential scanning calorimetry were also used for property investigation. Stimulating studies were evaluated based on the skin irritation reaction score standard and the skin stimulus intensity evaluation standard for paeonol cubosomes when compared with commercial paeonol ointment. In vitro tests were performed on excised rat skins in an improved Franz diffusion apparatus. The amount of paeonol over time in the in vitro penetration and retention experiments both was determined quantitatively by HPLC.

Results

Stimulating studies were compared with the commercial ointment which indicated that the paeonol cubic liquid crystalline nanoparticles could reduce the irritation in the skin stimulating test. Thus, based on the attractive characteristics of the cubic crystal system of paeonol, we will further exploit the cosmetic features in the future studies.

Conclusions

The transdermal delivery system of paeonol with low-irritation based on the self-assembled cubic liquid crystalline nanoparticles prepared in this study might be a promising system of good tropical preparation for skin application.

Docetaxel-Loaded Fluorescent Liquid-Crystalline Nanoparticles for Cancer Theranostics

Here, we describe a novel monoolein-based cubosome formulation engineered for possible theranostic applications in oncology. The Docetaxel-loaded nanoparticles were stabilized in water by a mixture of commercial Pluronic (poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer) F108 (PF108) and rhodamine- and folate-conjugated PF108 so that the nanoparticles possess targeting, therapeutic, and imaging properties. Nanoparticles were investigated by DLS, cryo-TEM, and SAXS to confirm their structural features. The fluorescent emission characterization of the proposed formulation indicated that the rhodamine conjugated to the PF108 experiences an environment less polar than water (similar to chloroform), suggesting that the fluorescent fragment is buried within the poly(ethylene oxide) corona surrounding the nanoparticle. Furthermore, these nanoparticles were successfully used to image living HeLa cells and demonstrated a significant short-term (4 h incubation) cytotoxicity effect against these cancer cells. Furthermore, given their analogy as nanocarriers for molecules of pharmaceutical interest and to better stress the singularities of these bicontinuous cubic nanoparticles, we also quantitatively evaluated the differences between cubosomes and multilamellar liposomes in terms of surface area and hydrophobic volume.

Glycerol prevents dehydration in lipid cubic phases

Lipid cubic phase samples dry out and undergo phase transitions when exposed to air. We demonstrate experimentally and theoretically that adding glycerol controllably lowers the humidity at which cubic phases form. These results broaden the potential applications of cubic phases and open up the potential of a new humidity-responsive nanomaterial.

Characterization of cubosomes as a targeted and sustained transdermal delivery system for capsaicin

Phytantriol- and glycerol monooleate-based cubosomes were produced and characterized as a targeted and sustained transdermal delivery system for capsaicin. The cubosomes were prepared by emulsification and homogenization of phytantriol (F1), glycerol monooleate (F2), and poloxamer dispersions, characterized for morphology and particle size distribution by transmission electron microscope and photon correlation spectroscopy. Their Im3m crystallographic space group was confirmed by small-angle X-ray scattering. An in vitro release study showed that the cubosomes provided a sustained release system for capsaicin. An in vitro diffusion study conducted using Franz diffusion cells indicated that the skin retention of capsaicin from cubosomes in the stratum corneum was much higher (2.75±0.22 μg versus 4.32±0.13 μg, respectively) than that of capsaicin cream (0.72±0.13 μg). The stress testing showed that the cubosome formulations were stable under strong light and high temperature for up to 10 days. After multiapplications on mouse skin, the irritation of capsaicin cubosomes and cream was light with the least amount of side effects. Overall, the present study demonstrated that cubosomes may be a suitable skin-targeted and sustained delivery system for the transdermal administration of capsaicin.

Lipid Liquid-Crystal Phase Change Induced through near-Infrared Irradiation of Entrained Graphene Particles

Lipid packing is intimately related to the geometry of the lipids and the forces that drive self-assembly. Here, the photothermal response of a cubic liquid-crystalline phase formed using phytantriol in the presence of low concentrations of pristine graphene was evaluated. Small-angle X-ray scattering showed the reversible phase changes from cubic to hexagonal to micellar due to localized heating through irradiation with near-infrared (NIR) light and back to cubic after cooling.

Structural studies of the lamellar to bicontinuous gyroid cubic (Q(G)(II)) phase transitions under limited hydration conditions

Non-equilibrium pathways of lyotropic phase transitions such as the lamellar to inverse bicontinuous cubic phase transition are important dynamical processes resembling cellular fusion and fission processes which can be exploited in biotechnological processes such as drug delivery. However, utilising and optimising these structural transformations for applications require a detailed understanding of the energetic pathways which drive the phase transition. We have used the high pressure X-ray diffraction technique to probe the lamellar to Q(G)(II) phase transition in limited hydration monolinolein on the millisecond time scale. Our results show that the phase transition goes via a structural intermediate and once the Q(G)(II) phase initially forms the elastic energy in the bilayer drives this structure to its equilibrium lattice parameter.

Enhancing cubosome functionality by coating with a single layer of poly-ε-lysine

We report the preparation and characterization of monoolein cubosomes that can be easily surface modified through adsorption of a single layer of cationic poly-ε-lysine. Poly-ε-lysine coated cubosomes show remarkable stability in serum solution, are nontoxic and, are readily internalized by HeLa cells. The poly-ε-lysine coating provides chemical handles for further bioconjugation of the cubosome surface. We also demonstrate that the initial release rate of a hydrophilic drug, Naproxen sodium, from the cubosomes is retarded with just a single layer of polymer. Interestingly, cubosomes loaded with Naproxen sodium, recently shown to have anticancer properties, cause more apoptosis in HeLa cells when compared to free unencapsulated drug.

Cubic and hexagonal liquid crystals as drug delivery systems

Lipids have been widely used as main constituents in various drug delivery systems, such as liposomes, solid lipid nanoparticles, nanostructured lipid carriers, and lipid-based lyotropic liquid crystals. Among them, lipid-based lyotropic liquid crystals have highly ordered, thermodynamically stable internal nanostructure, thereby offering the potential as a sustained drug release matrix. The intricate nanostructures of the cubic phase and hexagonal phase have been shown to provide diffusion controlled release of active pharmaceutical ingredients with a wide range of molecular weights and polarities. In addition, the biodegradable and biocompatible nature of lipids demonstrates the minimum toxicity and thus they are used for various routes of administration. Therefore, the research on lipid-based lyotropic liquid crystalline phases has attracted a lot of attention in recent years. This review will provide an overview of the lipids used to prepare cubic phase and hexagonal phase at physiological temperature, as well as the influencing factors on the phase transition of liquid crystals. In particular, the most current research progresses on cubic and hexagonal phases as drug delivery systems will be discussed.

The effects of pressure and temperature on the energetics and pivotal surface in a monoacylglycerol/water gyroid inverse bicontinuous cubic phase

We have studied the effect of pressure and temperature on the location of the pivotal surface in a lipid inverse bicontinuous gyroid cubic phase (Q(G)(II)), described by the area at the pivotal surface (An), the volume between the pivotal surface and the bilayer midplane (Vn), and the molecular volume of the lipid (V). Small angle X-ray scattering (SAXS) was used to measure the swelling behaviour of the lipid, monolinolein, as a function of pressure and temperature, and the data were fitted to two different geometric models: the parallel interface model (PIM), and the constant mean curvature model (CMCM). The results show that an increase in temperature leads to a shift in the location of the pivotal surface towards the bilayer midplane, whilst an increase in pressure causes the pivotal surface to move towards the interfacial region. In addition, we describe the relevance of An, Vn and V for modeling the energetics of curved mesophases with specific reference to the mean curvature at the pivotal surface and discuss the significance of this parameter for modelling the energetics of curved mesophases.

Cubic and sponge phases in ether lipid-solvent-water ternary systems: phase behavior and NMR characterization

The phase behavior of 1-glyceryl monoleyl ether (GME) in mixtures of water and the solvents 1,5-pentanediol (POL) or N-methyl-2-pyrrolidone (NMP) was investigated by ocular inspection, polarization microscopy, and small-angle X-ray diffraction (SAXD). Phase diagrams were constructed based on analyses of more than 200 samples prepared using the two different solvents at 20 °C. The inverse hexagonal phase formed by GME in excess of water was transformed into the cubic and sponge phase with the increasing amount of each solvent. Particularly POL allowed for the formation of an extended sponge phase area in the phase diagram, comprising up to 70% POL-water mixture. The phase behavior using NMP was found to be similar to the earlier investigated solvent propylene glycol. The extended sponge phase for the POL system was attributed to POLs strong surface/interfacial activity with the potential to stabilize the polar/apolar interface of the sponge phase. The cubic and sponge phases formed using POL were further studied by NMR in order to measure the partitioning of POL between the lipid and aqueous domains of the phases. The domain partition coefficient K (lipid domain/aqueous domain) for POL in cubic and sponge phases was found to be 0.78 ± 0.14 and constant for the two phases.