Cubic phase nanoparticles (Cubosome): principles for controlling size, structure, and stability

Hexosomes as Efficient Platforms for Possible Fluoxetine Hydrochloride Repurposing with Improved Cytotoxicity against HepG2 Cells

The aim of this study was to investigate the feasibility of hexosomes (HEXs) as competent platforms for fluoxetine hydrochloride (FH) repurposing against HepG2 hepatocellular carcinoma. Different FH-loaded HEX formulations were prepared and optimized by the hot emulsification method. The HEX features such as particle size, ζ potential, and drug entrapment efficiency (EE%) can be tailored by tuning HEX components and fabrication conditions. The composition of the optimized FH hexosome (OFH-HEX) was composed of 3.1, 1.4, 0.5, 0.2, and 94.8% for glyceryl monooleate, oleic acid, pluronic F127, FH, and deionized water, respectively. The anionic OFH-HEX with a particle size of 145.5 ± 2.5 nm and drug EE% of 45.4 ± 1.2% was able to prolong the in vitro FH release, where only 19.5 ± 2.3% released in phosphate-buffered saline (PBS) pH 7.4 after 24 h. Contrarily, HEX rapidly released FH in acetate buffer pH 5.5 and achieved a 90.5 ± 4.7% release after 24 h. The obtained HEX showed an improved cellular internalization in a time-dependent manner and enhanced the cytotoxicity (2-fold higher than FH solution). The current study suggests the potential of FH-HEX as a possible anticancer agent against hepatocellular carcinoma.

Rapidly dissolving microneedles for the delivery of cubosome-like liquid crystalline nanoparticles with sustained release of rapamycin

In this study, we developed a system for the transdermal delivery and controlled release of the hydrophobic immunosuppressive drug rapamycin, foreseeing an application in psoriasis treatment. To do so, rapamycin was encapsulated in phytantriol-based cubosome-like liquid crystalline nanoparticles stabilized with pluronic F127. The final mass percent composition of the lipid nanoparticles was 0.25% phytantriol, 0.1% pluronic F127, 4.75% ethanol and 94.9% water. These particles showed a rapamycin encapsulation efficiency above 95% and a sustained in vitrodrug release profile throughout 14 days. Subsequently the rapamycin-carrying particles were incorporated into rapidly dissolving microneedle patches composed of a polymeric matrix of poly(vinylpyrrolidone) and poly(vinyl alcohol). Confocal microscopy allowed to infer the preferential distribution of the cubosome-like particles at the tip and baseplate of the microneedles. The fabricated microneedles showed successful piercing and deposition of the loaded cubosome-like particles on a skin-mimicking agarose gel. Finally, the rapamycin-loaded cubosome-like particles showed antiproliferative activity in natural killer cells in vitro. The results here presented show the potential of the developed system to deliver cubosome-like particles into the skin and promote the sustained release of rapamycin in the context of immunomodulation.

Lipid-Based Drug Delivery Nanoplatforms for Colorectal Cancer Therapy

Colorectal cancer (CRC) is a prevalent disease worldwide, and patients at late stages of CRC often suffer from a high mortality rate after surgery. Adjuvant chemotherapeutics (ACs) have been extensively developed to improve the survival rate of such patients, but conventionally formulated ACs inevitably distribute toxic chemotherapeutic drugs to healthy organs and thus often trigger severe side effects. CRC cells may also develop drug resistance following repeat dosing of conventional ACs, limiting their effectiveness. Given these limitations, researchers have sought to use targeted drug delivery systems (DDSs), specifically the nanotechnology-based DDSs, to deliver the ACs. As lipid-based nanoplatforms have shown the potential to improve the efficacy and safety of various cytotoxic drugs (such as paclitaxel and vincristine) in the clinical treatment of gastric cancer and leukemia, the preclinical progress of lipid-based nanoplatforms has attracted increasing interest. The lipid-based nanoplatforms might be the most promising DDSs to succeed in entering a clinical trial for CRC treatment. This review will briefly examine the history of preclinical research on lipid-based nanoplatforms, summarize the current progress, and discuss the challenges and prospects of using such approaches in the treatment of CRC.

Nanomedicines to Treat Skin Pathologies with Natural Molecules

The skin and mucous membranes are subjected to many disorders and pathological conditions. Nature offers a wide range of molecules with antioxidant activity able to neutralize, at least in part, the formation of free radicals and therefore to counteract the phenomena of cellular aging. Since synthetic drugs for the treatment of skin diseases can induce resistance, it is particularly interesting to use compounds of plant origin, transporting them in pharmaceutical forms capable of controlling their release and absorption. This review provides an overview of new findings about the use of lipid-based nanosystems for the delivery of natural molecules useful on the topical treatment of skin disorders. Several natural molecules encapsulated in lipid nanosystems have been considered in the treatment of some skin pathologies or diseases. Particularly, the use of rosemary and eucalyptus essential oil, saffron derivatives, curcumin, eugenol, capsaicin, thymol and lycopene has been reported. The molecules have been alternatively encapsulated in viscous systems, such as the organogels, or in liquid systems, such as ethosomes, transferosomes, solid lipid nanoparticles and monoolein based dispersions thickened by inclusion in carbomer gels. The nanostructured forms have been in vitro and in vivo investigated for the treatment of skin disorders due to dehydration, inflammation, melanoma, wound healing, fungal infections or psoriasis. The data reported in the different studies have suggested that the cutaneous application of lipid nanosystems allows a deep interaction between lipid matrix and skin strata, promoting a prolonged release and efficacy of the loaded natural molecules. This review suggests that the application of natural molecules onto the skin by lipid-based nanosystems can provide numerous clinician benefits in dermatology and cosmetics.

Preparation and characterization of β-casein stabilized lipopeptide lyotropic liquid crystal nanoparticles for delivery of doxorubicin

A kind of lyotropic liquid crystal nanoparticle (LLC NPs) has been designed and prepared. LLC NPs are dSMO/OA/β-casein/water quaternary systems, and their cubic or hexagonal microstructures have been characterized by cryogenic transmission electron microscopy (cryo-TEM) and small angle X-ray scattering (SAXS). The phase transition of LLC NPs takes place with ratio and pH adjustments. The properties, such as cytotoxicity, stability, drug encapsulation and release ability, have been investigated with MTT assay, cryo-TEM and UV-Vis spectroscopy. The results showed that LLC NPs were nontoxic to cells and stable to enzymatic degradation. Hydrophilic drug doxorubicin hydrochloride (DOX·HCl) could be effectively encapsulated in LLC NPs and its release rate could be regulated by pH. It was concluded that LLC NPs are potential nanocarriers in nanomedicine technologies. We hope that this work provides new guidelines for the rational design of LLC NP systems with lipopeptides for biomedical applications.

Stimuli-Responsive Lyotropic Liquid Crystalline Nanosystems with Incorporated Poly(2-Dimethylamino Ethyl Methacrylate)-b-Poly(Lauryl Methacrylate) Amphiphilic Block Copolymer

There is an emerging need to evolve the conventional lyotropic liquid crystalline nanoparticles to advanced stimuli-responsive, therapeutic nanosystems with upgraded functionality. Towards this effort, typically used stabilizers, such as Pluronics^®, can be combined or replaced by smart, stimuli-responsive block copolymers. The aim of this study is to incorporate the stimuli-responsive amphiphilic block copolymer poly(2-(dimethylamino)ethyl methacrylate)-b-poly(lauryl methacrylate) (PDMAEMA-b-PLMA) as a stabilizer in lipidic liquid crystalline nanoparticles, in order to provide steric stabilization and simultaneous stimuli-responsiveness. The physicochemical and morphological characteristics of the prepared nanosystems were investigated by light scattering techniques, cryogenic-transmission electron microscopy (cryo-TEM), X-ray diffraction (XRD) and fluorescence spectroscopy. The PDMAEMA-b-PLMA, either individually or combined with Poloxamer 407, exhibited different modes of stabilization depending on the lipid used. Due to the protonation ability of PDMAEMA blocks in acidic pH, the nanoparticles exhibited high positive charge, as well as pH-responsive charge conversion, which can be exploited towards pharmaceutical applications. The ionic strength, temperature and serum proteins influenced the physicochemical behavior of the nanoparticles, while the polymer concentration differentiated their morphology; their micropolarity and microfluidity were also evaluated. The proposed liquid crystalline nanosystems can be considered as novel and attractive pH-responsive drug and gene delivery nanocarriers due to their polycationic content.

Self-Assembly of a Catalytically Active Lipopeptide and Its Incorporation into Cubosomes

The self-assembly and biocatalytic activity of the proline-functionalized lipopeptide PRW-NH-C₁₆ are examined and compared to that of the related PRW-O-C₁₆ lipopeptide, which differs in having an ester linker between the lipid chain and tripeptide headgroup instead of an amide linker. Lipopeptide PRW-NH-C₁₆ self-assembles into spherical micelles above a critical aggregation concentration, similar to the behavior of PRW-O-C₁₆ reported previously [B. M. Soares et al. Phys. Chem. Chem. Phys., 2017, 19, 1181-1189]. However, PRW-NH-C₁₆ shows an improved catalytic activity in a model aldol reaction. In addition, we explore the incorporation of the biocatalytic lipopeptide into lipid cubosomes. SAXS shows that increasing lipopeptide concentration leads to an expansion of the monoolein cubosome lattice spacing and a loss of long-range cubic order as the lipopeptide is encapsulated in the cubosomes. At higher loadings of lipopeptide, reduced cubosome formation is observed at the expense of vesicle formation. Our results show that the peptide-lipid chain linker does not influence self-assembly but does impart an improved biocatalytic activity. Furthermore, we show that lipopeptides can be incorporated into lipid cubosomes, leading to restructuring into vesicles at high loadings. These findings point the way toward the future development of bioactive lipopeptide assemblies and slow release cubosome-based delivery systems.

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.

Liposomes for delivery of antioxidants in cosmeceuticals: Challenges and development strategies

Antioxidants (AOs) play a crucial role in the protection and maintenance of health and are also integral ingredients in beauty products. Unfortunately, most of them are sensitive due to their instability and insolubility. The use of liposomes to protect AOs and expand their applicability to cosmeceuticals, thereby, is one of the most effective solutions. Notwithstanding their offered advantages for the delivery of AOs, liposomes, in their production and application, present many challenges. Here, we provide a critical review of the major problems complicating the development of liposomes for AO delivery. Along with issues related to preparation techniques and encapsulation efficiency, the loss of protective function and inefficiency of skin permeability are the main disadvantages of liposomes. Corresponding development strategies for resolving these problems, with their respective advantages and drawbacks, are introduced, discussed in some depth, and summarized in these pages as well. Advanced liposomes have a vital role to play in the development and delivery of AOs in practical cosmeceutical product applications.

Cubosomes: The Next Generation of Smart Lipid Nanoparticles?

Cubosomes are highly stable nanoparticles formed from the lipid cubic phase and stabilized by a polymer based outer corona. Bicontinuous lipid cubic phases consist of a single lipid bilayer that forms a continuous periodic membrane lattice structure with pores formed by two interwoven water channels. Cubosome composition can be tuned to engineer pore sizes or include bioactive lipids, the polymer outer corona can be used for targeting and they are highly stable under physiological conditions. Compared to liposomes, the structure provides a significantly higher membrane surface area for loading of membrane proteins and small drug molecules. Owing to recent advances, they can be engineered in vitro in both bulk and nanoparticle formats with applications including drug delivery, membrane bioreactors, artificial cells, and biosensors. This review outlines recent advances in cubosome technology enabling their application and provides guidelines for the rational design of new systems for biomedical applications.

On the advancement of polymeric bicontinuous nanospheres toward biomedical applications

Self-assembled soft nanocarriers that are capable of simultaneous encapsulation of both lipophilic and water soluble payloads have significantly enhanced controlled delivery applications in biomedicine. These nanoarchitectures, such as liposomes, polymersomes and cubosomes, are primarily composed of either amphiphilic polymers or lipids, with the polymeric variants generally possessing greater stability and control over biodistribution and bioresponsive release. Polymersomes have long demonstrated such advantages over their lipid analogs, liposomes, but only recently have bicontinuous nanospheres emerged as a polymeric cubic phase alternative to lipid cubosomes. In this review, we summarize the current state of the field for bicontinuous nanosphere formulation and characterization and suggest future directions for this nascent delivery platform as it is adopted for biomedical applications.

Rapid confocal imaging of vesicle-to-sponge phase droplet transition in dilute dispersions of the C10E3 surfactant

The lamellar-to-sponge phase transition of fluorescently labelled large unilamellar vesicles (LUVs) of the non-ionic surfactant triethylene glycol mono n-decyl ether (C₁₀E₃) was investigated in situ by confocal laser scanning microscopy (CLSM). Stable dispersions of micrometer-sized C₁₀E₃ LUVs were prepared at 20 °C and quickly heated at different temperatures close to the lamellar-to-sponge phase transition temperature. Phase transition of the strongly fluctuating individual vesicles into micrometre-sized sponge phase droplets was observed to occur via manyfold multilamellar morphologies with increasing membrane confinement through inter- and intra- lamellar fusion. The very low bending rigidity and lateral tension of the C₁₀E₃ bilayer were supported by quantitative image analysis of a stable fluctuating membrane using both flicker noise spectroscopy and spatial autocorrelation function.

Metallo-Cubosomes: Zinc-Functionalized Cubic Nanoparticles for Therapeutic Nucleotide Delivery

Development of an effective and potent RNA delivery system remains a challenge for the clinical application of RNA therapeutics. Herein, we describe the development of an RNA delivery platform derived from self-assembled bicontinuous cubic lyotropic liquid crystalline phases, functionalized with zinc coordinated lipids. These metallo-cubosomes were prepared from a series of novel lipidic zinc(II)-bis(dipicolylamine) (Zn₂BDPA)) complexes admixed with glycerol monooleate (GMO). The zinc metallo-cubosomes showed the high affinity to siRNA through interaction between Zn₂BDPA and the phosphate groups of RNA molecules. Using a combination of dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and cryogenic transmission electron microscopy (cryo-TEM), we demonstrated that a variety of Zn₂BDPA lipid derivatives can be loaded into GMO cubosomes and the introduction of Zn₂BDPA lipids effected an internal cubic phase transition of the resulting metallo-cubosomes. The findings of this study lay the foundations for the development of a new class of noncationic lipid-based encapsulation systems, metallo-cubosomes for RNA therapeutic delivery.

Nanostructured cubosomes in an in situ nasal gel system: an alternative approach for the controlled delivery of donepezil HCl to brain

The purpose of this research was to develop cubosomal mucoadhesive in situ nasal gel to enhance the donepezil HCl delivery to the brain. Glycerol mono-oleate (GMO) and surfactant poloxamer 407 were used to prepare cubosomes. The developed formulations were characterized for particle size (PS), poly dispersity index (PDI), zeta potential (ZP), entrapment efficiency (EE), transmission electron microscopy (TEM), in vitro drug release and in vivo bio-distribution study in blood and brain tissue. Central composite design was used for the optimization purpose and the selected formulation (containing GMO 2 g and poloxamer 1.5%) was prepared in presence of gellan gum and konjac gum as gelling agent and mucoadhesive agent respectively. The optimal cubosomal dispersion and optimal cubosomal mucoadhesive in situ nasal gel were subjected to in vivo bio-distribution studies in rat model. It showed significantly higher transnasal permeation and better distribution to the brain, when compared to the drug solution. Thus, the formulated cubosomal mucoadhesive in situ gel could be considered as a promising carrier for brain targeting of CNS acting drugs through the transnasal route.

Polymer cubosomes of block copolymers having cross-linkable soft hydrophobic blocks

Inverse bicontinuous cubic mesophases of block copolymers are an emerging class of mesoporous structures consisting of block copolymer bilayers, in which well-defined reticulated pore networks are intertwined in a long-range crystalline order.

Co-delivery of RNAi and chemokine by polyarginine nanocapsules enables the modulation of myeloid-derived suppressor cells

Myeloid-Derived Suppressor Cells (MDSCs), immunosuppressive cells that promote tumor growth, represent an attractive target in cancer immunotherapy. However, the clinical success of this strategy is limited by the lack of efficient drug delivery vehicles targeting this cell compartment. The objective of this work was to develop a delivery carrier, multilayer polymer nanocapsules, with the capacity to co-encapsulate two types of immunomodulatory drugs, a chemokine and an RNAi sequence, aimed at reverting MDSC-mediated immunosuppression. The chemokine CCL2, intended to attract monocyte-macrophage MDSCs, was encapsulated within the L2 inverse micellar aqueous domains of the lipid core of these nanocapsules. On the other hand, two different RNAi sequences that modulate the CCAAT/enhancer-binding protein beta (C/EBPβ) pathway, shC/EBPβ and miR 142-3p, were successfully associated to their polymer shell. These RNAi sequences were covered by subsequent layers of polyarginine and hyaluronic acid, thereby creating multi-layered assemblies that protected them and facilitated their targeted delivery. The in vitro studies performed in primary MDSCs cultures showed the capacity of miR 142-3p-loaded nanocapsules to reduce the highly immunosuppressive monocyte-macrophage subset. Additionally, the encapsulation of CCL2 within the nanocapsules induced a potent monocyte-macrophage chemoattraction that could be used to direct the therapy to these cell subsets. Finally, in vitro and in vivo studies showed the capacity of shC/EBPβ-loaded nanocapsules to downregulate C/EBPβ levels in MDSCs and to reduce monocyte differentiation into tumor-associated macrophages in an MCA-203 fibrosarcoma mice model. In conclusion, the multilayer polymer nanocapsules described here are efficient vehicles for the co-delivery of proteins and RNA, and are potential candidates as nanomedicines for the modulation of MDSCs.

Development of self-assembled nanocarriers to enhance antitumor efficacy of docetaxel trihydrate in MDA-MB-231 cell line

Self-assembled nanocarriers (SANs) as a novel colloidal controlled delivery for docetaxel trihydrate (DTX) were engineered by high-pressure homogenization method to overcome the several clinical problems. Drug-excipient compatibility was studied using DSC and FTIR spectroscopy. The fabricated SANs was characterized by particle size, zeta potential, and SEM. QbD based central composite design of experiment was employed for formula optimization. The cell viability of DTX-hydroalcoholic solution (DTX-HA) and DTX-loaded SANs has been determined in MDA-MB-231 cell line by MTT assay. The stability study of selected SANs formulations were carried out at various storage conditions as per ICH guidelines. The summary of results obtained shows high drug content with higher entrapment efficiency (91.23 ± 3.41% w/w) of DTX-loaded SANs. It shows diffusion controlled release of DTX over the period of 12 h which is higher than DTX-HA solution, releases the DTX within 4 h. The MTT assay expressed lower cellular viability and improved cell inhibition leads to increase cytotoxicity of formulations towards cells. The stability study reveals stability of DTX-loaded SANs formulations at various storage conditions over a period of three months. The strong experimental evidence confirms the SANs as an effective approach to formulate the controlled delivery system of antineoplastics with improved stability.

Cubosomes for topical delivery of the antimicrobial peptide LL-37

In this study, the use of cubosomes for topical delivery of the antimicrobial peptide (AMP) LL-37 was investigated. Topical delivery of AMPs is of great interest for treatment of skin infections caused by bacteria, such as Staphylococcus aureus. AMP containing cubosomes were produced by three different preparation protocols and compared: (i) pre-loading, where LL-37 was incorporated into a liquid crystalline gel, which thereafter was dispersed into nanoparticles, (ii) post-loading, where LL-37 was let to adsorb onto pre-formed cubosomes, and (iii) hydrotrope-loading, where LL-37 was incorporated during the spontaneously formed cubosomes in an ethanol/glycerol monooleate mixture. Particle size and size distribution were analyzed using dynamic light scattering (DLS), liquid crystalline structure by small angle x-ray scattering (SAXS) and release of LL-37 by a fluorescamine assay. Proteolytic protection of LL-37 as well as bactericidal effect after enzyme exposure was investigated. The skin irritation potential of cubosomes was examined by an in vitro epidermis model. Finally, the bacterial killing property of the cubosomes was examined by an ex vivo pig skin wound infection model with Staphylococcus aureus. Data showed that a high loading of LL-37 induced formation of vesicles in case of cubosomes prepared by sonication (pre-loading). No release of LL-37 was observed from the cubosomes, indicating strong association of the peptide to the particles. Proteolysis studies showed that LL-37 was fully protected against enzymatic attacks while associated with the cubosomes, also denoting strong association of the peptide to the particles. As a consequence, bactericidal effect after enzyme exposure remained, compared to pure LL-37 which was subjected to proteolysis. No skin irritation potential of the cubosomes was found, thus enabling for topical administration. The ex vivo wound infection model showed that LL-37 in pre-loaded cubosomes killed bacteria most efficient.

Nonlamellar liquid crystals: a new paradigm for the delivery of small molecules and bio-macromolecules

The aim of this article is to collate the recent developments in the field of drug delivery, medical therapeutics and diagnostics specifically involving the nonlamellar liquid crystalline (NLC) systems. This review highlights different NLC phases having cubic, hexagonal and sponge internal structures, and their application in the field of drug delivery, such as dose reduction, toxicity reduction and therapeutic efficacy enhancement either in the form of nanoparticles, colloidal dispersion or gels. In addition, application of NLC systems as vehicles for peptides, proteins and as a theranostic system in cancer and other disease conditions is also elaborated, which is a growing platform of interest. Overall, the present review gives us a complete outlook on applications of NLC systems in the field of medicine.

Cubic lyotropic liquid crystals as drug delivery carriers: Physicochemical and morphological studies

The self-assembly process of amphiphilic molecules into solvents results in different mesophases, such as inverse cubic and hexagonal that both belong to the wider category of lyotropic liquid crystals. The above mesophases can be further exploited upon the formation of liquid crystalline nanoparticles, cubosomes and hexosomes respectively, which may be utilized as drug delivery nanosystems, exhibiting major advantages. In the present study, liquid crystalline nanoparticles were prepared and evaluated in terms of morphology and physicochemical behavior. The goal of this study is to examine the effect of the different formulation parameters, as well as the effect of the different microenvironmental factors (temperature, ionic strength, pH, serum proteins presence) on their behavior. The physicochemical behavior and the morphology of the systems were investigated by X-Ray Diffraction (XRD), cryogenic-Transmission Electron Microscopy (cryo-TEM), fluorescence spectroscopy and a gamut of light scattering techniques. The formulation process was proved to influence strictly the physicochemical behavior of the prepared nanosystems. They presented colloidal stability over time and upon ionic strength increase, but they were affected by the presence of proteins and presented reversible structure alterations upon temperature increase. Their morphological structure and internal microenvironment, reflected by micropolarity and microfluidity, were also influenced by the formulation parameters.

Paclitaxel-Loaded Self-Assembled Lipid Nanoparticles as Targeted Drug Delivery Systems for the Treatment of Aggressive Ovarian Cancer

Chemotherapy using cytotoxic agents, such as paclitaxel (PTX), is one of the most effective treatments for advanced ovarian cancer. However, due to nonspecific targeting of the drug and the presence of toxic solvents required for dissolving PTX prior to injection, there are several serious side effects associated with this treatment. In this study, we explored self-assembled lipid-based nanoparticles as PTX carriers, which were able to improve its antitumour efficacy against ovarian cancer. The nanoparticles were also functionalized with epidermal growth factor receptor (EGFR) antibody fragments to explore the benefit of tumor active targeting. The formulated bicontinuous cubic- and sponge-phase nanoparticles, which were stabilized by Pluronic F127 and a lipid poly(ethylene glycol) stabilizer, showed a high capacity of PTX loading. These PTX-loaded nanoparticles also showed significantly higher cytotoxicity than a free drug formulation against HEY ovarian cancer cell lines in vitro. More importantly, the nanoparticle-based PTX treatments, with or without EGFR targeting, reduced the tumor burden by 50% compared to PTX or nondrug control in an ovarian cancer mouse xenograft model. In addition, the PTX-loaded nanoparticles were able to extend the survival of the treatment groups by up to 10 days compared to groups receiving free PTX or nondrug control. This proof-of-concept study has demonstrated the potential of these self-assembled lipid nanomaterials as effective drug delivery nanocarriers for poorly soluble chemotherapeutics, such as PTX.

Reverse Hexosome Dispersions in Alkanes-The Challenge of Inverting Structures

Monoglycerides form lipophilic liquid-crystalline (LC) phases when mixed with water. The corresponding LC nanostructures coexist with excess water, which is a necessary condition for the formation of internally nanostructured dispersed particles. These nanostructures comprise bicontinuous cubic phases, inverted hexagonal phases, and inverted micellar cubic phases. The dispersed particles are therefore named cubosomes, hexosomes, or micellar cubosomes. Such dispersions are usually stabilized by hydrophilic high-molecular-weight triblock (TB) copolymers. Another way to stabilize such dispersions is by forming the so-called Pickering or Ramsden emulsions using nanoparticles as stabilizers. In this contribution, we explore the possibility of forming and stabilizing inverted or reverse systems, that is, dispersions of hydrophilic LC phases in an excess oil phase like tetradecane. Our aim was to change from oil-in-water emulsions to water-in-oil emulsions, where the water phase is a LC phase in equilibrium with excess oil and where the oil is nonpolar, for example, an alkane. This work consists of three parts: (1) to find a hexagonal hydrophilic LC phase that can not only incorporate a certain amount of tetradecane but can also coexist with excess tetradecane in the case of higher oil concentration, (2) to find a suitable stabilizer-either polymeric or nanoparticle type-that can stabilize the emulsion without destroying the hexagonal LC phase, and finally (3) to check the stability of this reverse hexosome emulsion. We discovered that it is possible to create a hexagonal hydrophilic LC phase with short-chain nonionic surfactants such as polyethylene glycol alkyl ethers or with high-molecular-weight TB copolymers of type A-B-A. Furthermore, it is possible to successfully stabilize the reverse hexosomes with low hydrophilic-lipophilic balance TB copolymers-either synthesized in our laboratory or commercially available ones-as well as with hydrophobized, commercially available silica nanoparticles.

Heat Treatment of Poloxamer-Stabilized Triglyceride Nanodispersions: Effects and Underlying Mechanism

Lipid nanoemulsions are being investigated for the parenteral administration of poorly soluble drugs. A narrow particle size distribution in these formulations is a prerequisite for meaningful research and safe administration to patients. Autoclaving a poloxamer-stabilized trimyristin nanoemulsion resulted in moderate particle growth and a strong decrease in particle size distribution width ( Göke , K. ; Roese , E. ; Arnold , A. ; Kuntsche , J. ; Bunjes , H. Mol. Pharmaceutics 2016 , 13 , 3187 . ). In this work, the critical parameters for such a change upon autoclaving poloxamer 188-stabilized lipid nanodispersions were investigated to elucidate the underlying mechanism. Nanodispersions of triglycerides with esterified fatty acid chain lengths from C8 to C18 were treated at different temperatures and for varying durations. The influence of a decrease in poloxamer 188's cloud point was tested by adding potassium chloride to the dispersions prior to autoclaving. The influence of poloxamer 188 concentration and of the type of emulsifier was investigated. The change in particle size and particle size distribution width upon heat treatment was analyzed by dynamic or static light scattering or differential scanning calorimetry. A short esterified fatty acid chain length of the triglycerides, high temperatures, and the addition of potassium chloride were key factors for particle growth up to emulsion break up, whereas the cloud point of poloxamer 188 was irrelevant. Sodium dodecyl sulfate and sucrose laurate had negative effects on emulsion stability during autoclaving. It was concluded that the increase in particle size and the decrease in particle size distribution widths upon heat treatment resulted from heat-accelerated Ostwald ripening and not from a coalescence-based process.

Lipidated polymers for the stabilization of cubosomes: nanostructured drug delivery vehicles

Lipidated polymers, like their protein counterparts, may be useful in fields as diverse as biochemistry and drug delivery. As such, strategies for preparing lipidated polymers with defined molecular architecture are clearly warranted. Herein, we describe a broadly-applicable methodology for synthesizing such lipidated materials, and demonstrate how they can be applied to the preparation of nanostructured drug delivery vehicles.

Freeze-dried and re-hydrated liquid crystalline nanoparticles stabilized with disaccharides for drug-delivery of the plectasin derivative AP114 antimicrobial peptide

Liquid crystalline nanoparticles (LCNPs), e.g. cubosomes and hexosomes, are receiving more and more attraction as drug delivery vehicles. Dry powder formulation that forms LCNPs upon hydration can be advantageous to make new routes of administration accessible. In this work, we investigate use of three disaccharides (lactose, trehalose and sucrose) as protective matrices for glycerol monooleate based LCNP forming powders produced by freeze-drying. Phase behavior, particle size and size distributions at the different preparation steps were monitored by small angle x-ray scattering (SAXS) and dynamic light scattering (DLS). Particle appearance was imaged by cryogenic transmission electron microscopy (cryo-TEM). Moreover, the therapeutic relevant antimicrobial peptide AP114 (plectasin derivative) was incorporated in the formulations. Peptide encapsulation and release as well as in vitro antibacterial effect were investigated. Results showed that all freeze-dried powders did form particles with liquid crystalline structure upon hydration. However, a phase transition from the bicontinuous cubic Pn3m to the reversed hexagonal was observed, as a consequence of sugar addition and the freeze-drying procedure. Data indicates that trehalose is the preferred choice of lyo-protectant in order to maintain a mono-modal particle size distribution. In addition, antimicrobial activity of AP114-containing formulations was found to be highest for the formulation containing trehalose. The release kinetics of AP114 from the nanoparticles was strongly affected by the dimensions of the hexagonal phase. Larger dimension of the hexagonal phase, significantly improved the release of AP114 and antimicrobial activity of the formulation.

Lyotropic liquid crystal engineering moving beyond binary compositional space - ordered nanostructured amphiphile self-assembly materials by design

Ordered amphiphile self-assembly materials with a tunable three-dimensional (3D) nanostructure are of fundamental interest, and crucial for progressing several biological and biomedical applications, including in meso membrane protein crystallization, as drug and medical contrast agent delivery vehicles, and as biosensors and biofuel cells. In binary systems consisting of an amphiphile and a solvent, the ability to tune the 3D cubic phase nanostructure, lipid bilayer properties and the lipid mesophase is limited. A move beyond the binary compositional space is therefore required for efficient engineering of the required material properties. In this critical review, the phase transitions upon encapsulation of more than 130 amphiphilic and soluble additives into the bicontinuous lipidic cubic phase under excess hydration are summarized. The data are interpreted using geometric considerations, interfacial curvature, electrostatic interactions, partition coefficients and miscibility of the alkyl chains. The obtained lyotropic liquid crystal engineering design rules can be used to enhance the formulation of self-assembly materials and provides a large library of these materials for use in biomedical applications (242 references).

Non-lamellar lyotropic liquid crystalline nanoparticles enhance the antibacterial effects of rifampicin against Staphylococcus aureus

The fight against infection in an era of emerging antibiotic resistant bacteria is one of the grandest scientific challenges facing society today. Nano-carriers show great promise in improving the antibacterial activity of antibiotics as they are able to enhance their solubility, provide sustained release and reduce toxic side effects via specifically targeting infection sites. Here, we investigate the antibacterial effect of two lipidic nano-carriers that contain the poorly soluble antibiotic rifampicin in their bilayers. One nanoparticle is assembled solely from the lipid monoolein, thus is neutral at physiological pH and the other contains a mixture of monoolein and the cationic lipid N-[1-(2,3-Dioleoyloxy)propyl]-N,N,N-trimethylammonium methyl-sulfate (DOTAP), thus is positively charged. Our results show that rifampicin-loaded nanoparticles reduce the minimum inhibitory concentration against Staphylococcus aureus compared to rifampicin alone, however this reduction was most pronounced for the positively charged nanoparticles. Fluorescent microscopy revealed binding of all nanoparticles to the bacteria and enhanced binding was observed for the charged nanoparticles. This suggests that the cationic lipids promote electrostatic interactions with the negatively charged bacterial membrane. Förster resonance energy transfer demonstrated that the cationic charged nanoparticles were able to fuse with bacterial membranes whilst atomic force microscopy and transmission electron microscopy revealed structural damage to the bacterial membranes caused by the nanoparticles. Significantly, we identified a concentration window in which the nanoparticles exhibited antibacterial activity while not affecting HeLa and CHO cell viability. This ability to improve the efficacy of antibiotics without affecting their eukaryotic cytotoxicity is of significant importance for future development of nanomedicine based strategies to combat infections.

Gel-Phase-like Ordered Membrane Properties Observed in Dispersed Oleic Acid/1-Oleoylglycerol Self-Assemblies: Systematic Characterization Using Raman Spectroscopy and a Laurdan Fluorescent Probe

Aqueous dispersions of oleic acid (OA) and those modified with 1-oleoylglycerol (monoolein, MO) form various kinds of self-assembled structures: micelles, vesicles, oil-in-water (O/W) emulsions, hexagonal phases, and dispersed cubic phases. Conventionally, these self-assembled structures have been characterized using cryogenic transmission electron microscopy or X-ray diffraction spectroscopy. However, these methodologies require specialized treatment before they can be used, which may lead to the self-assemblies not adopting their true equilibrium state. Herein, we systematically characterized the self-assemblies composed of OA and MO in aqueous solution using Raman spectroscopy and fluorescent probe 6-dodecanoyl-2-dimethylaminonaphthalene (Laurdan). The OA/MO dispersions at pH 5.0 showed increased chain packing in comparison to the OA micelle at pH 11 or OA vesicle at pH 9.0, which were characterized by the intensity ratio of the Raman peaks at 2850 and 2890 cm^-1, R = I₂₈₉₀/I₂₈₅₀. In the Laurdan fluorescence measurements, the obtained spectra were deconvoluted to two peak fractions (A₁: λ_em= 490 nm; A₂: λ_em = 440 nm), and the peak area ratio, A₁/(A₁ + A₂), was defined as the membrane hydrophilicity Ø_m. The Ø_m value of the OA/MO dispersion at pH 5.0 was similar to that of the OA O/W emulsion, indicating that the membrane surfaces of these self-assemblies were relatively dehydrated compared to the OA micelle or OA vesicle. To categorize the type of self-assembly dispersion, a Cartesian diagram plot was systematically drawn: R on the x axis and Ø_m on the y axis, with the cross point at x = 1, y = 0.5. By comparing the membrane properties of the OA-based micelles, O/W emulsions, and dispersed cubic phases, we determined that the OA/MO dispersion at pH 5.0 possessed higher chain packing (R > 1) and a dehydrated membrane surface (Ø_m < 0.5), which is similar to that of the ordered membranes in gel phases. This characterization method can be useful in evaluating the ordered membrane properties in dispersed self-assemblies in aqueous media.

Evaluation of toxicity of glycerol monooleate nanoparticles on PC12 cell line

An innovative approach to improve drug delivery is the use of glycerol monooleate nanoparticles. Numerous studies describe their high versatility, low toxicity and ability to carry relatively high loads of conjugated compounds including scarcely soluble ones, providing sustained drug release and increasing drug diffusion and half-life. Despite a growing interest in their potential use for therapeutic applications, there are surprisingly few literature data concerning the toxic effects of these nanoparticles at high concentrations in vitro and in vivo, and their effects on cell metabolism. We produced and characterized from a physical-chemical point of view glycerol monooleate nanoparticles and tested them on the PC12 cell line, a rat model of neuronal differentiation. The toxicity of these nanoparticles was evaluated by molecular methods on cell viability, cell cycle, nanoparticle uptake and induction of apoptosis. The results showed that glycerol monooleate nanoparticles up to 100 μg/mL had no toxic effects on PC12 cells, did not induce significant changes in the cell cycle nor cause apoptosis. The nanoparticles entered PC12 cells 8 h after treatment, successfully delivering the conjugate compound inside cells. Overall, glycerol monooleate nanoparticles did not exhibit significant toxicity on PC12 cell line in concentrations up to 100 µg/mL, supporting their therapeutic use as drug delivery systems.

Liquid crystalline drug delivery vehicles for oral and IV/subcutaneous administration of poorly soluble (and soluble) drugs

Poorly soluble drug molecules often have low bioavailability issues and absorption problems in the clinical setting. As the number of poorly soluble drugs increases from discovery, developing technologies to enhance their solubility, while also controlling their release is one of the many challenges facing the pharmaceutical industry today. Liquid crystalline systems, nanoparticulate or macro-matrix, self-assemble in the presence of an aqueous environment and can provide a solubility enhancement, while also controlling the drug release rate. This review examines the fundamentals of liquid crystalline systems through the representative literature, concluding with examples of liquid crystalline systems in clinical trials development. The review focus is on the potential of utilizing liquid crystalline systems for poorly soluble drugs, in the areas of oral delivery and IV/subcutaneous, followed by water soluble molecules. Key considerations in utilizing liquid crystalline systems advantages while also discussing potential areas of key research that may be needed will be highlighted.

Box-like gel capsules from heterostructures based on a core–shell MOF as a template of crystal crosslinking

Cubic polymer capsules (PCs) were obtained using a crystal crosslinking (CC) method on core–shell MOF crystals, with a well-defined hollow cubic shape reflecting the heterostructure of the template.

Cubosomes post-loaded with antimicrobial peptides: characterization, bactericidal effect and proteolytic stability

Novel antibiotics, such as antimicrobial peptides (AMPs), have recently attended more and more attraction. In this work, dispersed cubic liquid crystalline gel (cubosomes) was used as drug delivery vehicles for three AMPs (AP114, DPK-060 and LL-37). Association of peptides onto cubosomes was studied at two cubosome/peptide ratios using high performance liquid chromatography, ζ-potential and circular dichroism measurements. AMPs impact on the cubosome structure was investigated using small angle x-ray scattering and cryogenic transmission electron microscopy. The antimicrobial effect of the AMP loaded cubosomes was studied in vitro by minimum inhibitory concentration and time-kill assays. Proteolytic protection was investigated by incubating the formulations with two elastases and the antimicrobial effect after proteolysis was studied using radial diffusion assay. Different association efficacy onto the cubosomes was observed among the AMPs, with LL-37 showing greatest association (>60%). AP114 loaded cubosomes displayed a preserved antimicrobial effect, whereas for LL-37 the broad spectrum bacterial killing was reduced to only comprise Gram-negative bacteria. Interestingly, DPK-060 loaded cubosomes showed a slight enhanced effect against S. aureus and E. coli strains. Moreover, the cubosomes were found to protect LL-37 from proteolytic degradation, resulting in a significantly better bactericidal effect after being subjected to elastase, compared to unformulated peptide.

Enhancing the Solubility and Oral Bioavailability of Poorly Water-Soluble Drugs Using Monoolein Cubosomes

Monoolein cubosomes containing either spironolactone (SPI) or nifedipine (NI) were prepared using a high-pressure homogenization technique and characterized in terms of their solubility and oral bioavailability. The mean particle size, polydispersity index (PDI), zeta potential, solubility and encapsulation efficiency (EE) values of the SPI- and NI-loaded cubosomes were determined to be 90.4 nm, 0.187, -13.4 mV, 163 µg/mL and 90.2%, and 91.3 nm, 0.168, -12.8 mV, 189 µg/mL and 93.0%, respectively, which were almost identical to those of the blank cubosome. Small-angle X-ray scattering analyses confirmed that the SPI-loaded, NI-loaded and blank cubosomes existed in the cubic space group Im3̄m. The lattice parameters of the SPI- and NI-loaded cubosomes were 147.6 and 151.6 Å, respectively, making them almost identical to that of blank cubosome (151.0 Å). The in vitro release profiles of the SPI- and NI-loaded cubosomes showed that they released less than 5% of the drugs into various media over 12-48 h, indicating that most of the drug remained encapsulated within the cubic phase of their lipid bilayer. Furthermore, the in vivo pharmacokinetic results suggested that these cubosomes led to a considerable increase in the systemic oral bioavailability of the drugs compared with pure dispersions of the same materials. Notably, the stability results indicated that the mean particle size and PDI values of these cubosomes were stable for at least 4 weeks. Taken together, these results demonstrate that monoolein cubosomes represent promising drug carriers for enhancing the solubility and oral bioavailability of poorly water-soluble drugs.

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.

Cubosomes from hierarchical self-assembly of poly(ionic liquid) block copolymers

Cubosomes are micro- and nanoparticles with a bicontinuous cubic two-phase structure, reported for the self-assembly of low molecular weight surfactants, for example, lipids, but rarely formed by polymers. These objects are characterized by a maximum continuous interface and high interface to volume ratio, which makes them promising candidates for efficient adsorbents and host-guest applications. Here we demonstrate self-assembly to nanoscale cuboidal particles with a bicontinuous cubic structure by amphiphilic poly(ionic liquid) diblock copolymers, poly(acrylic acid)-block-poly(4-vinylbenzyl)-3-butyl imidazolium bis(trifluoromethylsulfonyl)imide, in a mixture of tetrahydrofuran and water under optimized conditions. Structure determining parameters include polymer composition and concentration, temperature, and the variation of the solvent mixture. The formation of the cubosomes can be explained by the hierarchical interactions of the constituent components. The lattice structure of the block copolymers can be transferred to the shape of the particle as it is common for atomic and molecular faceted crystals.

In Vitro Modulation of TrkB Receptor Signaling upon Sequential Delivery of Curcumin-DHA Loaded Carriers Towards Promoting Neuronal Survival

PURPOSE

To in vitro investigate the capacity of carrier-free and lipid-nanoparticle (NP)-encapsulated phytochemical compounds to prevent neuronal damage through neurotrophin potentiating activities. Delivery of molecules promoting the neurotrophin receptor signaling in the central nervous system (CNS) present ongoing interest for combination therapy development.

METHODS

Super-resolution Stimulated Emission Depletion (STED) microscopy imaging and flow cytometry analysis were employed to study the expression of the neurotrophin TrkB receptor in a neuronal cell model, which is highly responsive to binding of brain-derived neurotrophic factor (BDNF). Dual drug-loaded nanoparticle formulations, prepared by self-assembly of lyotropic lipids and PEGylated amphiphile derivatives, were delivered to differentiated human neuroblastoma SH-SY5Y cells subjected to degenerative conditions.

RESULTS

The expression of BDNF in the intra and extracellular domains was quantified by ELISA and flow cytometry after sequential treatment of the degenerating SH-SY5Y cells by neurotherapeutic formulations. Flow cytometry was also used to assess the phosphorylation of the transcription factor cAMP response element-binding protein (CREB) in the intracellular domain as a result of the treatment by nanoformulations.

CONCLUSION

Over time, dual drug formulations (curcumin and docosahexaenoic acid (DHA)) promoted the neuronal survival and repair processes through enhanced BDNF secretion and increased phosphorylation of CREB as compared to untreated degenerating cells.

Characterization of Lipid-Based Hexosomes as Versatile Vaccine Carriers

Subunit vaccines typically show insufficient immunogenicity. To address this issue, we developed a novel self-adjuvanting particulate carrier system based upon the lipids phytantriol (Phy) and mannide monooleate (MaMo). Phy is a lipid known to form nonlamellar phases in fully hydrated systems, whereas MaMo has been found to promote immune responses in emulsion form. A bulk phase composition of Phy/MaMo (14 wt %) showed hexagonal (HII) phase behavior over a practical temperature range (including room and body temperature), and was therefore used for particle development. Hexosomes stabilized with different concentrations of either poloxamer 407, Myrj 59, or Pluronic F108 were successfully prepared. To demonstrate the versatile nature of these systems, the particles were further modified with either positively or negatively charged lipids and loaded with model antigens, while maintaining the HII structure. These hexosomes are structurally robust and amenable to customization, rendering them suitable as antigen delivery carriers.

Incorporation of an Endogenous Neuromodulatory Lipid, Oleoylethanolamide, into Cubosomes: Nanostructural Characterization

Oleoylethanolamide (OEA) is an endogenous lipid with neuroprotective properties and the fortification of its concentration in the brain can be beneficial in the treatment of many neurodegenerative disorders. However, OEA is rapidly eliminated by hydrolysis in vivo, limiting its therapeutic potential. We hypothesize that packing OEA within a nanoparticulate system such as cubosomes, which can be used to target the blood-brain barrier (BBB), will protect it against hydrolysis and enable therapeutic concentrations to reach the brain. Cubosomes are lipid-based nanoparticles with a unique bicontinuous cubic phase internal structure. In the present study, the incorporation and chemical stability of OEA in cubosomes was investigated. Cubosomes containing OEA had a mean particle size of less than 200 nm with low polydispersity (polydispersity index <0.25). Infrared spectroscopy and high-performance liquid chromatography showed chemical stability and the encapsulation of OEA within cubosomes. Cryo-TEM and SAXS measurements were used to probe the influence of the addition of OEA on the internal structure of the cubosomes. Up to 30% w/w OEA (relative to phytantriol) could be incorporated into phytantriol cubosomes without any significant disruption of the nanostructure of the cubosomes. Combined, the results indicate that OEA-loaded cubosomes have the potential for application as a colloidal carrier for OEA, potentially preventing hydrolysis in vivo.