Novel methods for liposome preparation

Updates on the use of liposomes for active tumor targeting in cancer therapy

In the development of cancer chemotherapy, besides the discovery of new anticancer drugs, a variety of nanocarrier systems for the delivery of previously developed and new chemotherapeutic drugs have currently been explored. Liposome is one of the most studied nanocarrier systems because of its biodegradability, simple preparation method, high efficacy and low toxicity. To make the best use of this vehicle, a number of multifunctionalized liposomal formulations have been investigated. The objective of this review is to summarize the current development of novel active targeting liposomal formulations, and to give insight into the challenges and future direction of the field. The recent studies in active targeting liposomes suggest the great potential of precise targeted anticancer drug delivery in cancer therapeutics.

Protein delivery by porous cationic maltodextrin-based nanoparticles into nasal mucosal cells: Comparison with cationic or anionic nanoparticles

Different types of biodegradable nanoparticles (NPs) have been studied as delivery systems for proteins into nasal mucosal cells, especially for vaccine applications. Such a nanocarrier must have the ability to be loaded with proteins and to transport this payload into mucosal cells. However, comparative data on nanoparticles' capacity for protein loading, efficiency of subsequent endocytosis and the quantity of nanocarriers used are either lacking or contradictory, making comparisons and the choice of a best candidate difficult. Here we compared 5 types of nanoparticles with different surface charge (anionic or cationic) and various inner compositions as potential vectors: the NPL (cationic maltodextrin NP with an anionic lipid core), cationic and anionic PLGA (Poly Lactic co-Glycolic Acid) NP, and cationic and anionic liposomes. We first quantified the protein association efficiency and NPL associated the largest amount of ovalbumin, used as a model protein. In vitro, the delivery of fluorescently-labeled ovalbumin into mucosal cells (airway epithelial cells, dendritic cells and macrophages) was assessed by flow cytometry and revealed that the NPL delivered protein to the greatest extent in all 3 different cell lines. Taken together, these data underlined the potential of the porous and cationic maltodextrin-based NPL as efficient protein delivery systems to mucosal cells.

Lipid-based Liquid Crystalline Films and Solutions for the Delivery of Cargo to Cells

A major challenge in the delivery of cargo (genes and/or drugs) to cells using nanostructured vehicles is the ability to safely penetrate plasma membranes by escaping the endosome before degradation, later releasing the payload into the cytoplasm or organelle of interest. Lipids are a class of bio-compatible molecules that self-assemble into a variety of liquid crystalline constructs. Most of these materials can be used to encapsulate drugs, proteins, and nucleic acids to deliver them safely into various cell types. Lipid phases offer a plethora of structures capable of forming complexes with biomolecules, most notably nucleic acids. The physichochemical characteristics of the lipid molecular building blocks, one might say the lipid primary structure, dictates how they collectively interact to assemble into various secondary structures. These include bilayers, lamellar stacks of bilayers, two-dimensional (2D) hexagonal arrays of lipid tubes, and even 3D cubic constructs. The liquid crystalline materials can be present in the form of aqueous suspensions, bulk materials or confined to a film configuration depending on the intended application (e.g. bolus vs surface-based delivery). This work compiles recent findings of different lipid-based liquid crystalline constructs both in films and particles for gene and drug delivery applications. We explore how lipid primary and secondary structures endow liquid crystalline materials with the ability to carry biomolecular cargo and interact with cells.

Lipid nanocarriers for microRNA delivery

Non-coding RNAs (ncRNAs) like microRNAs (miRNAs) or small interference RNAs (siRNAs) with their power to selectively silence any gene of interest enable the targeting of so far 'undruggable' proteins and diseases. Such RNA molecules have gained much attention from biotech and pharmaceutical companies, which led to the first Food and Drug Administration (FDA) approved ncRNA therapeutic in 2018. However, the main barrier in clinical practice of ncRNAs is the lack of an effective delivery system that can protect the RNA molecules from nuclease degradation, deliver them to specific tissues and cell types, and release them into the cytoplasm of the targeted cells, all without inducing adverse effects. For that reason, drug delivery approaches, formulations, technologies and systems for transporting pharmacological ncRNA compounds to achieve a diagnostic or therapeutic effect in the human body are in demand. Here, we review the development of therapeutic lipid-based nanoparticles for delivery of miRNAs, one class of endogenous ncRNAs with specific regulatory functions. We outline challenges and opportunities for advanced miRNA-based therapies, and discuss the complexity associated with the delivery of functional miRNAs. Novel strategies are addressed how to deal with the most critical points in miRNA delivery, such as toxicity, specific targeting of disease sites, proper cellular uptake and endosomal escape of miRNAs. Current fields of application and various preclinical settings involving miRNA therapeutics are discussed, providing an outlook to future clinical approaches. Following the current trends and technological developments in nanomedicine exciting new delivery systems for ncRNA-based therapeutics can be expected in upcoming years.

Liposomal Formulations for Nose-to-Brain Delivery: Recent Advances and Future Perspectives

Restricted drug entry to the brain that is closely associated with the existence of the blood brain barrier (BBB) has limited the accessibility of most potential active therapeutic compounds to the brain from the systemic circulation. Recently, evidences for the presence of direct nose-to-brain drug transport pathways have been accumulated by several studies and an intranasal drug administration route has gained attention as a promising way for providing direct access to the brain without the needs to cross to the BBB. Studies aiming for developing nanoparticles as an intranasal drug carrier have shown considerable promise in overcoming the challenges of intranasal drug delivery route. This review gives a comprehensive overview of works having investigated liposomes as a potential vehicle to deliver drugs to the brain through nose-to-brain route while considering the excellent biocompatibility and high potential of liposomes for clinical development. Herein, studies are reviewed with special emphasis on the impact of formulation factors, such as liposome composition and surface modification of liposomes with targeting moieties, in addition to intranasal environmental factors that may affect the extent/site of absorption of intranasally administered, liposome-encapsulated drugs.

Liposome-Enveloped Molecular Nanogels

Novel hydrogel@liposome particles were prepared by pH-triggered molecular gel formation inside of liposomes loaded with a low-molecular weight gelator derived from l-valine (1). Liposome formation was carried out using l-α-phosphatidylcholine (PC) and cholesterol as components of the lipid bilayer. Molecular hydrogelator 1 and pyranine, a ratiometric fluorescent pH probe, were entrapped in the liposomes at pH 9 and posterior acidification with d-glucono-1,5-lactone to pH 5-6 provoked intraliposomal gel formation. Removal of the lipid bilayer with sodium dodecyl sulfate yielded naked nanogel particles. The systems were characterized by transmission electron microscopy and dynamic light scattering. The hydrogel@liposomes were loaded with doxorubicin, showing a similar release than that observed for liposomes. The hybrid particles described here are the first case of nonpolymeric hydrogel@liposome systems reported. This type of nanocarriers merges the benefits of liposomal vehicles with the inherent stimuli responsiveness and enhanced biocompatibility of hydrogels formed by low-molecular weight molecules, foretelling a potential use in environmentally sensitive drug release.

Understanding toward the Biophysical Interaction of Polymeric Proanthocyanidins (Persimmon Condensed Tannins) with Biomembranes: Relevance for Biological Effects

Persimmon condensed tannins (PT) are highly polymerized (mDP = 26) and highly galloylated (72%) proanthocyanidins. Its pleiotropic effects in oxidation resistance, neuroprotection, hypolipidemia, and cardio-protection both in vitro and in vivo were widely reported. Because large proanthocyanidins are unlikely to be absorbed in the gastrointestinal tract, it is believed that the interaction of PT with biological membranes may play a crucial role in its biological activities. In the present study, the capacities of PT adsorbing to membrane, partitioning into membrane, and its influence on the membrane fluidity were investigated by fluorescence quenching, isothermal titration calorimetry (ITC) and fluorescence anisotropy measurements in a biomembrane-mimetic system composed of 1-palmitoyl-2-oleoylphosphatidylcholine (POPC), 1-palmitoyl-2-oleoylphosphatidylethanolamine (POPE), sphingomyelin (SPM), and cholesterol (CHOL). Besides, the effects of PT on the morphology and integrity of the cell membrane were studied by scanning electron microscopy (SEM) and fluorescence staining in the 3T3-L1 cell model. The results suggested that PT could affect cell membrane rafts domains, destroy the cell membrane morphology, and regulate cell membrane fluidity, which might contribute to its biological effects.

Liposomal formulations of photosensitizers

Photodynamic therapy (PDT) is a clinical ablation modality to treat cancers and other diseases. PDT involves administration of a photosensitizer, followed by irradiation of target tissue with light. As many photosensitizers are small and hydrophobic, solubilization approaches and nanoscale delivery vehicles have been extensively explored. Liposomes and lipid-based formulations have been used for the past 30 years, and in some cases have been developed into well-defined commercial PDT products. This review provides an overview of common liposomal formulation strategies for photosensitizers for PDT and also photothermal therapy. Furthermore, research efforts have examined the impact of co-loading therapeutic cargo along with photosensitizers within liposomes. Additional recent approaches including imaging, overcoming hypoxia, upconversion and activatable liposomal formulations are discussed.

A nuclear targeted Dox-aptamer loaded liposome delivery platform for the circumvention of drug resistance in breast cancer

The development of multidrug resistance (MDR) has become an increasingly serious problem in cancer therapy. The cell membrane overexpression of P-glycoprotein (P-gp), which can actively efflux various anticancer drugs in the cytoplasm from the cell, is a major mechanism of MDR. Nuclear-targeted nanoparticle drug delivery system, which enables intranuclear release of anticancer drugs, is expected to address this challenge. In this study, based on nucleolin's active transport property to the nucleus and its affinity with aptamer, we developed a nuclear-targeted delivery system to circumvention of drug resistance in breast cancer (MCF-7/Adr). Dox·HCl inserted in the aptamer AS1411 (Ap-Dox) was encapsulated in the aqueous interior of liposome (Lip(Ap-Dox)). In vitro studies showed that after the Lip(Ap-Dox) diffusing into MCF-7/Adr cells, Ap-Dox complex bound with nucleolin strongly and eventually entered the cell nuclei. By using this drug delivery system, Dox·HCl can efficiently accumulated in the nuclei to effectively kill the cancer cells.

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

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

Didodecyldimethylammonium Bromide Role in Anchoring Gold Nanoparticles onto Liposome Surface for Triggering the Drug Release

Liposomes with their capacity to anchor gold nanoparticles (AuNPs) onto their surface are used in the treatment of several pathologies such as cancer. The objective of this work was the optimization of the vesicle composition by using cationic agents in order to reinforce the anchoring process of AuNPs, and for the study of the influence of local temperature and vesicle size on drug release. A Plackett-Burman design was conducted to determine the optimal composition for the anchoring of AuNPs. A comprehensive study of the influence of lipid bilayer composition on the surface charge, size, and polydispersity index (PdI) of liposomes was carried out. Afterwards, in vitro release studies by dialysis were performed and several release parameters were evaluated as a function of temperature. Cholesterol was fixed as the rigid agent and Didodecyldimethylammonium bromide (DDAB) was selected as the cationic lipid into the liposome bilayer. Photomicrographs revealed that DDAB facilitated the anchoring of AuNPs onto the liposomal surface. The anchoring of AuNPs also enhanced the amount and rate of calcein released, especially in extruded samples, at several incubating temperatures. In addition, it was observed that both the anchoring of AuNPs and the calcein release were improved by increasing the surface of the vesicles. The contributions of liposome composition (DDAB inclusion, incubation temperature, anchoring of AuNPs) and size and surface availability of the vesicles on calcein release could be used to design improved lipid nanostructures for the controlled release of anticancer drugs.

Photoactive Liposomal Formulation of PVP-Conjugated Chlorin e6 for Photodynamic Reduction of Atherosclerotic Plaque

Background: Liposomes serve as delivery systems for biologically active compounds. Existing technologies inefficiently encapsulate large hydrophilic macromolecules, such as PVP-conjugated chlorin e6 (Photolon). This photoactive drug has been widely tested for therapeutic applications, including photodynamic reduction of atherosclerotic plaque. Methods: A novel formulation of Photolon was produced using “gel hydration technology”. Its pharmacokinetics was tested in Sus scrofa f. domestica. Its cellular uptake, cytotoxicity, and ability to induce a phototoxic reaction were demonstrated in J774A.1, RAW264.7 macrophages, and vascular smooth muscle (T/G HA-VSMC) as well as in vascular endothelial (HUVEC) cells. Results: Developed liposomes had an average diameter of 124.7 ± 0.6 nm (polydispersity index (PDI) = 0.055) and contained >80% of Photolon). The half-life of formulation in S. scrofa was 20 min with area under the curve (AUC) equal to 14.7. The formulation was noncytotoxic in vitro and was rapidly (10 min) and efficiently accumulated by macrophages, but not T/G HA-VSMC or HUVEC. The accumulated quantity of photosensitizer was sufficient for induction of phototoxicity in J774A.1, but not in T/G HA-VSMC. Conclusions: Due to the excellent physical and pharmacokinetic properties and selectivity for macrophages, the novel liposomal formulation of Photolon is a promising therapeutic candidate for use in arteriosclerosis treatment when targeting macrophages but not accompanying vascular tissue is critical for effective and safe therapy.

Propolis loaded liposomes: evaluation of antimicrobial and antioxidant activities

Propolis, a natural bee product, has both antimicrobial/antifungal and antioxidant characteristics. Active substances having antimicrobial and antifungal effects are used to avoid infections, which develop during long treatment process of chronic wounds. Antioxidant substances protect wound areas against the effect of free radicals and accelerate the healing process. For this purpose, propolis was used to develop topical liposome formulations for wound treatment. Characterization studies (particle size distribution, polydispersity index, Zeta Potential, morphology pH, loading capacity, encapsulation efficiency, in-vitro release behaviour) as well as stability studies were performed. Then in-vitro antioxidant (free radical scavenging capacity and trolox equivalent antioxidant capacity) and antimicrobial/antifungal activities of formulations have been evaluated. The particle size of formulations was found within the range of 300-750 nm depending on the concentration of lipid and water phase in the formulation. The Zeta Potential and pH values of optimum formulation were -23.0 ± 0.666 and 6.34, respectively. Loading capacity and encapsulation efficiency were 66.535 ± 2.705% and 57.321 ± 2.448%. At the end of 8 h, 48.16% of propolis was released and the formulations were found stable during 3 months at +4 °C. Drug loaded liposome formulations significantly scavenged the ABTS⁺ radical in a dose-dependent manner of propolis when compared with unloaded liposome formulations (p < 0.05). The minimum inhibitory concentration (MIC) values of liposomes ranged from 512 to 128 μg/mL for bacteria and 256 to 128 μg/mL for fungi. Overall results showed that effective and innovative alternative was developed for topical application in wound treatment with propolis loaded liposomal formulations having antioxidant and antimicrobial effects.

Lipid Delivery Systems for Nucleic-Acid-Based-Drugs: From Production to Clinical Applications

In the last years the rapid development of Nucleic Acid Based Drugs (NABDs) to be used in gene therapy has had a great impact in the medical field, holding enormous promise, becoming “the latest generation medicine” with the first ever siRNA-lipid based formulation approved by the United States Food and Drug Administration (FDA) for human use, and currently on the market under the trade name Onpattro™. The growth of such powerful biologic therapeutics has gone hand in hand with the progress in delivery systems technology, which is absolutely required to improve their safety and effectiveness. Lipid carrier systems, particularly liposomes, have been proven to be the most suitable vehicles meeting NABDs requirements in the medical healthcare framework, limiting their toxicity, and ensuring their delivery and expression into the target tissues. In this review, after a description of the several kinds of liposomes structures and formulations used for in vitro or in vivo NABDs delivery, the broad range of siRNA-liposomes production techniques are discussed in the light of the latest technological progresses. Then, the current status of siRNA-lipid delivery systems in clinical trials is addressed, offering an updated overview on the clinical goals and the next challenges of this new class of therapeutics which will soon replace traditional drugs.

Prediction of the size of electroformed giant unilamellar vesicle using response surface methodology

The production of giant unilamellar vesicles (GUVs) with specific size and structure has been a challenge on the design of quantitative biological assays in cell-mimetic micro-compartments. In this study, the effect of electroformation parameters (electric potential, frequency, and temperature) on the size of GUVs was investigated. Using response surface methodology based on Box-Behnken design, GUVs from neutral, positive and negative charges were formulated. The average diameter of GUVs was determined for each formulation. The acquired data of these GUVs were successfully fitted with quadratic regression models. These models were applied to visualize the parameters for ideal GUVs with wanted diameters by the obtained phase diagrams. These results show that response surface methodology can be used to estimate the electroformation parameters for specifically sized GUVs.

Nanoparticles Functionalized with Venom-Derived Peptides and Toxins for Pharmaceutical Applications

Venom-derived peptides display diverse biological and pharmacological activities, making them useful in drug discovery platforms and for a wide range of applications in medicine and pharmaceutical biotechnology. Due to their target specificities, venom peptides have the potential to be developed into biopharmaceuticals to treat various health conditions such as diabetes mellitus, hypertension, and chronic pain. Despite the high potential for drug development, several limitations preclude the direct use of peptides as therapeutics and hamper the process of converting venom peptides into pharmaceuticals. These limitations include, for instance, chemical instability, poor oral absorption, short halflife, and off-target cytotoxicity. One strategy to overcome these disadvantages relies on the formulation of bioactive peptides with nanocarriers. A range of biocompatible materials are now available that can serve as nanocarriers and can improve the bioavailability of therapeutic and venom-derived peptides for clinical and diagnostic application. Examples of isolated venom peptides and crude animal venoms that have been encapsulated and formulated with different types of nanomaterials with promising results are increasingly reported. Based on the current data, a wealth of information can be collected regarding the utilization of nanocarriers to encapsulate venom peptides and render them bioavailable for pharmaceutical use. Overall, nanomaterials arise as essential components in the preparation of biopharmaceuticals that are based on biological and pharmacological active venom-derived peptides.

Delivery of phytochemicals by liposome cargos: recent progress, challenges and opportunities

Bio-availability is a major concern in delivery of dietary phytochemicals for better bio-efficacy. The reduced bio-availability of food bioactive compounds is evident due to degradation during human digestion process which involves liberation, absorption, distribution, metabolism and elimination. The bio-efficacy of any nutrient can be increased by increasing bio-availability. Different technologies are available for engineered efficient delivery systems; still many challenges remain with advancement of delivery systems. The ease of preparedness and adaptability of liposomes has resulted in wide-range of applicability and acceptability in scientific field, especially as delivery vehicles. In view, of properties like biocompatibility and biodegradability, liposomes have been modified with different usable methodologies for delivery of phytochemicals. The aim of this review is to abridge liposomes, methods of preparation, their application as delivery cargo in dietary phytochemicals, result of using different preparation techniques on properties.

Liposomes as models for membrane integrity

Biological membranes form the boundaries to cells. They are integral to cellular function, retaining the valuable components inside and preventing access of unwanted molecules. Many different classes of molecules demonstrate disruptive properties to the plasma membrane. These include alcohols, detergents and antimicrobial agents. Understanding this disruption and the mechanisms by which it can be mitigated is vital for improved therapeutics as well as enhanced industrial processes where the compounds produced can be toxic to the membrane. This mini-review describes the most common molecules that disrupt cell membranes along with a range of in vitro liposome-based techniques that can be used to monitor and delineate these disruptive processes.

Nanoemulsion and Nanoliposome Based Strategies for Improving Anthocyanin Stability and Bioavailability

BACKGROUND

Anthocyanins, a flavonoid class of water-soluble pigments, are reported to possess several biological activities, including antioxidant, anti-inflammatory, and anti-cancer. However, anthocyanins are highly susceptible to degradation in high pH, light, heat, and oxygen during processing and storage. Conventional microencapsulation techniques fail to provide stability to anthocyanins under physiological environments mainly because of their large particle size as well as low zeta potential and encapsulation efficiency.

METHODS

Nanotechnology provides novel strategies for preparing nanoformulations to enhance the physicochemical stability of anthocyanins. Nanoemulsion and nanoliposome are the two most commonly used nanosystems in pharmaceutical and food-related fields. In this review, an overview of various nanoemulsion and nanoliposome systems reported recently for enhancing stability, bioavailability, and bioactivity of anthocyanins is presented.

RESULTS

Anthocyanin nanoemulsions with different oil, water, surfactant, and cosurfactant ratios were prepared from extracts of mangosteen peel, purple sweet potato, cranberry, red cabbage, blueberry, jaboticaba peel, and acai berry and evaluated for their antioxidant activity, enhancement of physicochemical stability, topical skin application, and urinary tract infection. Likewise, unilamellar and multilamellar nanoliposomes were prepared using different types and levels of lecithin without or with cholesterol from anthocyanin standards and extracts of Hibiscus sabdariffa, mulberry, elderberry, black carrot, and pistachio green hull for the evaluation of physicochemical and oxidative stability, in vitro bioaccessibility, and melanogenic activity, as well as protective effects against diabetes mellitus and cataract.

CONCLUSION

This review provides an insight into the current nanotechnology updates on enhancement of anthocyanin stability and biological activity.

Giant Vesicles and Their Use in Assays for Assessing Membrane Phase State, Curvature, Mechanics, and Electrical Properties

Giant unilamellar vesicles represent a promising and extremely useful model biomembrane system for systematic measurements of mechanical, thermodynamic, electrical, and rheological properties of lipid bilayers as a function of membrane composition, surrounding media, and temperature. The most important advantage of giant vesicles over other model membrane systems is that the membrane responses to external factors such as ions, (macro)molecules, hydrodynamic flows, or electromagnetic fields can be directly observed under the microscope. Here, we briefly review approaches for giant vesicle preparation and describe several assays used for deducing the membrane phase state and measuring a number of material properties, with further emphasis on membrane reshaping and curvature.

Preparation, characterization, and in vivo evaluation of cyclosporine cationic liposomes for the treatment of psoriasis

Cyclosporine (CYC), a calcineurin inhibitor acts specifically on T-cells and is one of the most effective treatment options for psoriasis. Systemic administration of the drug has been associated with dose-dependent toxic effects, while its topical delivery is a challenging task due to unfavourable physicochemical properties of drug. The aim of the present study is to develop and evaluate the efficacy of topical liposomal gel containing CYC loaded cationic liposomal nanocarriers in imiquimod induced psoriatic plaque model. Liposomes composed of DOTAP and cholesterol was formulated by different liposomal preparation techniques. Optimized liposomal carriers prepared by ethanol injection method were characterized with respect to size, zeta potential, entrapment efficiency, stability, in vitro drug release and in vivo studies. Cationic liposomes with particle size of 111 ± 1.62 nm, PDI of 0.27 ± 0.08, entrapment efficiency of 93 ± 2.12%, and zeta potential of 41.12 ± 3.56 mV were obtained. Drug loaded liposomal gels showed shear thinning behaviour, which is suitable for topical application. Topical application of CYC liposomal gels on imiquimod induced psoriatic plaque model reduced the symptoms of psoriasis and levels of key psoriatic cytokines such as tumour necrosis factor-α, IL-17, and IL-22. In conclusion, the developed liposomal carrier of CYC was found to be effective and can find application in treatment of psoriasis.

Nanomaterials-Based siRNA Delivery: Routes of Administration, Hurdles and Role of Nanocarriers

Ribonucleic acid interference (RNAi) is a potential alternative therapeutic approach to knock down the overexpression of genes in several disorders especially cancers with underlying genetic dysfunctions. For silencing of specific genes involved in cell cycle, small/short interfering ribonucleic acids (siRNAs) are being used clinically. The siRNA-based RNAi is more efficient, specific and safe antisense technology than other RNAi approaches. The route of siRNA administration for siRNA therapy depends on the targeted site. However, certain hurdles like poor stability of siRNA, saturation, off-target effect, immunogenicity, anatomical barriers and non-targeted delivery restrict the successful siRNA therapy. Thus, advancement of an effective, secure, and long-term delivery system is prerequisite to the medical utilization of siRNA. Polycationic nanocarriers mediated targeted delivery system is an ideal system to remove these hurdles and to increase the blood retention time and rate of intracellular permeability. In this chapter, we will mainly discuss the different biocompatible, biodegradable, non-toxic (organic, inorganic and hybrid) nanocarriers that encapsulate and shield the siRNA from the different harsh environment and provides the increased systemic siRNA delivery.

What Drives Innovation: The Canadian Touch on Liposomal Therapeutics

Liposomes are considered one of the most successful drug delivery systems (DDS) given their established utility and success in the clinic. In the past 40–50 years, Canadian scientists have made ground-breaking discoveries, many of which were successfully translated to the clinic, leading to the formation of biotech companies, the creation of research tools, such as the Lipex Extruder and the NanoAssemblr™, as well as contributing significantly to the development of pharmaceutical products, such as Abelcet^®, MyoCet^®, Marqibo^®, Vyxeos^®, and Onpattro™, which are making positive impacts on patients’ health. This review highlights the Canadian contribution to the development of these and other important liposomal technologies that have touched patients. In this review, we try to address the question of what drives innovation: Is it the individual, the teams, the funding, and/or an entrepreneurial spirit that leads to success? From this perspective, it is possible to define how innovation will translate to meaningful commercial ventures and products with impact in the future. We begin with a brief history followed by descriptions of drug delivery technologies influenced by Canadian researchers. We will discuss recent advances in liposomal technologies, including the Metaplex technology from the author’s lab. The latter exemplifies how a nanotechnology platform can be designed based on multidisciplinary groups with expertise in coordination chemistry, nanomedicines, disease, and business to create new therapeutics that can effect better outcomes in patient populations. We conclude that the team is central to the effort; arguing if the team is entrepreneurial and well positioned, the funds needed will be found, but likely not solely in Canada.

Aptamer-functionalized liposomes for targeted cancer therapy

Accumulation of chemotherapeutic agents in the tumor tissue while reducing adverse effects and drug resistance are among the major goals in cancer therapy. Among nanocarriers, liposomes have been found to be more effective in the passive targeting of cancer cells. A promising recent development in targeted drug delivery is the use of aptamer-functionalized liposomes for cancer therapy. Aptamer-targeted liposomes have enhanced uptake in tumor cells as shown in vitro and in vivo. Here, we discuss the aptamer-functionalized liposome platforms and review functionalization approaches as well as the factors affecting antitumor efficiency of aptamer-targeted liposomal systems. Finally, we provide a comprehensive overview of aptamer-targeted liposomes based on the molecular targets on the surface of cancer cells.

Passive and active targeting in cancer therapy by liposomes and lipid nanoparticles

Considerable development in the application of injectable drug delivery systems for cancer therapy has occurred in the last few decades. These improvements include liposomes, lipid nanoparticles (LNPs), and other nanoparticles with or without macromolecular conjugates. For example, liposomal doxorubicin modified by poly(ethylene glycol) (Doxil) was the first liposome with anti-cancer effects which was approved by the US Food and Drug Administration, whereas Abraxane (modified albumin nanoparticles loaded by paclitaxel) was recently confirmed for the treatment of breast cancer. Recently, drug delivery systems by LNPs are an emerging technology with numerous advantages over conventional liposomes and chemotherapy using free drug treatment of cancer. These properties are biocompatibility, controlled and sustained release of anti-tumor drugs, and lower toxicity. Valuable experiments on these drug delivery systems offer better treatment of multidrug-resistant cancers and lower cardiotoxicity. LNPs have been presented with high functionality in chemotherapeutic targeting of breast and prostate cancer. The basis for this targeting behavior has been shown to be both passive and active targeting. The main objective of this review was an overview of the current position of the liposome-based drug delivery systems in targeted anticancer chemotherapy.

Adapting liposomes for oral drug delivery

Liposomes mimic natural cell membranes and have long been investigated as drug carriers due to excellent entrapment capacity, biocompatibility and safety. Despite the success of parenteral liposomes, oral delivery of liposomes is impeded by various barriers such as instability in the gastrointestinal tract, difficulties in crossing biomembranes, and mass production problems. By modulating the compositions of the lipid bilayers and adding polymers or ligands, both the stability and permeability of liposomes can be greatly improved for oral drug delivery. This review provides an overview of the challenges and current approaches toward the oral delivery of liposomes.

In Vitro Measurement of Sphingolipid Intermembrane Transport Illustrated by GLTP Superfamily Members

Herein, we describe methodological approaches for measuring in vitro transfer of sphingolipids (SLs) between membranes. The approaches rely on direct tracking of the lipid. Typically, direct tracking involves lipid labeling via attachment of fluorophores or introduction of radioactivity. Members of the GlycoLipid Transfer Protein (GLTP) superfamily are used to illustrate two broadly applicable methods for direct lipid tracking. One method relies on Förster resonance energy transfer (FRET) that enables continuous assessment of fluorophore-labeled SL transfer in real time between lipid donor and acceptor vesicles. The second method relies on tracking of radiolabeled SL transfer by separation of lipid donor and acceptor vesicles at discrete time points. The assays are readily adjustable for assessing lipid transfer (1) between various model membrane assemblies (vesicles, micelles, bicelles, nanodiscs), (2) involving other lipid types by other lipid transfer proteins, (3) with protein preparations that are either crudely or highly purified, and (4) that is spontaneous and occurs in the absence of protein.

Magnetoliposomes as model for signal transmission

Liposomes containing magnetic nanoparticles (magnetoliposomes) have been extensively explored for targeted drug delivery. However, the magnetic effect of nanoparticles movement is also an attractive choice for the conduction of signals in communication systems at the nanoscale level because of the simple manipulation and efficient control. Here, we propose a model for the transmission of electrical and luminous signals taking advantage of magnetophoresis. The study involved three steps. Firstly, magnetite was synthesized and incorporated into fusogenic large unilamellar vesicles (LUVs) previously associated with a fluorescent label. Secondly, the fluorescent magnetite-containing LUVs delivered their contents to the giant unilamellar vesicles (GUVs), which were corroborated by magnetophoresis and fluorescence microscopy. In the third step, magnetophoresis of magnetic vesicles was used for the conduction of the luminous signal from a capillary to an optical fibre connected to a fluorescence detector. Also, the magnetophoresis effects on subsequent transmission of the electrochemical signal were demonstrated using magnetite associated with CTAB micelles modified with ferrocene. We glimpse that these magnetic supramolecular systems can be applied in micro- and nanoscale communication systems.

Layer-by-layer adsorption: Factors affecting the choice of substrates and polymers

The electrostatic layer-by-layer technique for fabrication of multi-layered structures of various sizes and shapes using flat and colloidal templates coupled with polyelectrolyte layer-forming materials has attracted significant interest among both academic and industrial researchers due to its versatility and relative simplicity of the procedures involved in its execution. Fabrication of the multi-layered structures using the electrostatic layer-by-layer method involves several distinct stages each of which holds great importance when considering the production of a high-quality product. These stages include selection of materials (both template and a pair of construction polyelectrolytes), adsorption of the first polyelectrolyte layer onto the selected templates, formation of the second layer comprised of the oppositely charged polyelectrolyte and guided by the interactions between the two chosen polyelectrolytes, and multi-layering, where a selected number of layers are produced, and which is conditioned by both intrinsic properties of the involved construction materials and external fabrication conditions such as temperature, pH and ionic strength. The current review summarises the most important aspects of each stage mentioned above and gives examples of the materials suitable for utilization of the technique and describes the underlying physics involved.

Tailoring microstructural, drug release properties, and antichagasic efficacy of biocompatible oil-in-water benznidazol-loaded nanoemulsions

This study explored the transition of lamellar-type liquid crystal (LLC) to biocompatible oil-in-water nanoemulsions able to modify benznidazole (BNZ) release and target the drug to cells infected with the T. cruzi parasite. Three cosolvents (2methylpyrrolidone [NMP], polyethylene glycol [POL], and propylene glycol [PRO] were tested to induce the transition of anisotropic LLC systems to isotropic nanoemulsions. Mixtures of soy phosphatidylcholine with sodium oleate stabilized the dispersions of medium chain triglyceride in water. Rheological measurements, polarized microscopy, and small angle X-ray scattering demonstrated that there is a phase transition from LLC to desired nanoemulsions. These small and narrow droplet-sized nanocarriers exhibited some advantages and promising features, such as the enhanced BNZ aqueous solubility and slow drug release rate. In vitro cell biocompatibility of formulations was assessed in the Vero E6 and SiHa cell lines. Drug-loaded nanoemulsions inhibited the epimastigote growth of the T. cruzi parasite (IC50 0.208 ± 0.052 μg mL^-1) and reduced its infective life form trypomastigote (IC50 0.392 ± 0.107 μg mL^-1). The oil-in-water nanoemulsions were demonstrated as promising biocompatible liquid drug delivery systems capable of improving the BNZ trypanocidal activity for the treatment of Chagas disease.

An Overview of Nanotechnology in Food Science: Preparative Methods, Practical Applications, and Safety

As the researches to utilize nanotechnology in food science are advanced, applications of nanotechnology in various fields of the food industry have increased. Nanotechnology can be applied to the food industry for production, processing, storage, and quality control of foods. Nanomaterials, unlike conventional microscale materials, having novel characteristics can improve sensory quality of foods by imparting novel texture, color, and appearance. Nanotechnology has been used to design nanosensors for detection of harmful components in foods and a smart packaging system enabling to recognize food contamination very rapidly and sensitively. Nanoencapsulation is the most significant technology in food science, especially for bioactive compounds and flavors. Targeted delivery systems designed with nanoencapsulation can enhance bioavailability of bioactive compounds after oral administration. In addition, nanoencapsulation enables to control the release of flavors at the desired time and to protect the degradation of flavors during processing and storage. In this review, current applications of nanotechnology in food science including flavor control, enhancement of bioavailability of bioactive compounds, and detection of deleterious substances in foods are presented. Furthermore, this article overviews classification, preparative methods, and safety issues of nanomaterials for food science. This review will be of help to provide comprehensive information for newcomers utilizing nanotechnology to the food sector.

A Comprehensive Study on the Biological Activity of Elderberry Extract and Cyanidin 3-O-Glucoside and Their Interactions with Membranes and Human Serum Albumin

In our research we used the extract from dietary supplement of elderberry (EE) and its dominant anthocyanin—cyanidin 3-O-glucoside (Cy 3-gluc). By interacting with a model membrane that reflects the main lipid composition of tumor membranes, the extract components, including Cy 3-gluc, caused an increase in packing order, mainly in the hydrophilic region of the membrane. It can thus be stated that EE caused a rigidifying effect, which is fundamental for understanding its anticancer and antioxidant activity. This study represents the first attempt to unravel the mechanism of interaction of elderberry extract with membranes. The results of the interaction with human serum albumin (HSA) proved that the studied substance quenches the fluorescence of HSA through a static mechanism in which the main interaction forces are Van der Waals and hydrogen bonding. The antioxidant activity of EE and Cy 3-gluc on liposomal membranes, antiradical properties and ability to inhibited the activity of the enzymes cyclooxygenase-1 and cyclooxygenase-2 were also demonstrated. Moreover, the anticancer activity of EE and Cy 3-gluc on human breast adenocarcinoma cell line were investigated. In addition, EE also exhibited the ability to form lipid aggregates in the form of liposomal capsules that can be applied as carriers of active biological substances, and the highest efficacy of EE encapsulation was obtained for multilayered liposome formulations.

Large-Scale Preparation of Giant Vesicles by Squeezing a Lipid-Coated Marshmallow-like Silicone Gel in a Buffer

Giant vesicles were efficiently produced by squeezing a lipid (l-α-phosphatidylcholine from egg yolk)-coated marshmallow-like flexible macroporous silicone monolith in a buffer. The mean diameter of the obtained vesicles was 2 μm, showing a wide distribution, up to tens of micrometers, which was similar to that of vesicles formed by a natural swelling method. It was possible to prepare vesicle dispersions on a scale from several microliters to several hundred milliliters. A protein synthesis system (PURE system) contained in vesicles prepared using this method functioned effectively. Our absorbing-squeezing method is expected to help in studies that use giant vesicles such as artificial cells and drug delivery systems.

Liposomal Form of the Echinochrome-Carrageenan Complex

Inclusion of drugs in liposomes offers the potential for localized and sustained delivery to mucosal surfaces. The inclusion of the carrageenan matrix with echinochrome A ((Ech)—the active substance of the drug Histochrome) in liposomes was studied. According to the spectral characteristics, Ech was not oxidized and retained stability after encapsulation in the liposomes and the lyophilization process. Loading the liposomes with negatively charged polysaccharide results in the increase in the zeta potential to more negative values (from −14.6 to −24.4 mV), that together with an increasing in the sizes of liposomes (from 125.6 ± 2.5 nm to 159.3 ± 5.8 nm) propose of the formation of the polymer coating on liposomes. The interactions of liposomes with porcine stomach mucin was determined by the DLS and SEM methods. The changes in the zeta-potential and size of the mucin particles were observed as the result of the interaction of liposomes with mucin. To evaluate the mucoadhesive properties of liposomes and the penetration of Ech in the mucosa, a fresh-frozen inner surface of the small intestine of a pig as a model of mucous tissue was used. Polysaccharide-coated liposomes exhibit very good mucoadhesive properties −50% of Ech remains on the mucosa.

Advancing the Pharmaceutical Potential of Bioinorganic Hybrid Lipid-Based Assemblies

Bioinspired lipid assemblies that mimic the elaborate architecture of natural membranes have fascinated researchers for a long time. These lipid assemblies have gone from being just an imperative platform for biophysical research to a pharmaceutical delivery system for biomedical applications. Despite success, these organized nanosystems are often subject to the mechanical instability and limited theranostic capability without adding any inconvenient modifications. To reach their advanced pharmaceutical potential, various bioinorganic hybrid lipid-based assembles, which provide new opportunities to synergistically complement and improve therapeutic/diagnostic potential of existing lipid-based nanomedicine with distinct mechanisms containing inorganic embedded surfactants, have recently been developed.

Single-Vesicle Assays Using Liposomes and Cell-Derived Vesicles: From Modeling Complex Membrane Processes to Synthetic Biology and Biomedical Applications

The plasma membrane is of central importance for defining the closed volume of cells in contradistinction to the extracellular environment. The plasma membrane not only serves as a boundary, but it also mediates the exchange of physical and chemical information between the cell and its environment in order to maintain intra- and intercellular functions. Artificial lipid- and cell-derived membrane vesicles have been used as closed-volume containers, representing the simplest cell model systems to study transmembrane processes and intracellular biochemistry. Classical examples are studies of membrane translocation processes in plasma membrane vesicles and proteoliposomes mediated by transport proteins and ion channels. Liposomes and native membrane vesicles are widely used as model membranes for investigating the binding and bilayer insertion of proteins, the structure and function of membrane proteins, the intramembrane composition and distribution of lipids and proteins, and the intermembrane interactions during exo- and endocytosis. In addition, natural cell-released microvesicles have gained importance for early detection of diseases and for their use as nanoreactors and minimal protocells. Yet, in most studies, ensembles of vesicles have been employed. More recently, new micro- and nanotechnological tools as well as novel developments in both optical and electron microscopy have allowed the isolation and investigation of individual (sub)micrometer-sized vesicles. Such single-vesicle experiments have revealed large heterogeneities in the structure and function of membrane components of single vesicles, which were hidden in ensemble studies. These results have opened enormous possibilities for bioanalysis and biotechnological applications involving unprecedented miniaturization at the nanometer and attoliter range. This review will cover important developments toward single-vesicle analysis and the central discoveries made in this exciting field of research.

Characterization of self-assembled hybrid siloxane-phosphocholine bilayers

We have synthesized six new hybrid siloxane phosphocholines (SiPCs) and examined their self-assembly behaviour in aqueous dispersions. Employing small angle X-ray scattering we have characterized SiPC bilayers. SiPCs exhibit differential self-assembly behaviour that results from the interplay between the siloxane fatty acid in the sn-2 position and the differing chain length fatty acids in the sn-1 position. SiPCs that possess a fatty acid chain of a C₈-C₁₄ chain length in the sn-1 position form unilamellar vesicles. Extending the fatty acid chain length to C₁₆ and C₁₈ allows for the formation of both unilamellar and multilamellar vesicles. We propose that the preferential formation of unilamellar vesicles is the result of an enhanced hydrophobic effect imparted by siloxane chains at the termini of lipid tails.