Cuboplexes: Topologically Active siRNA Delivery

Design of thermo-responsive self-assembly of PEGylated fatty acids: Switching reversibly from tubes or vesicles to micelles at physiological temperature

HYPOTHESIS

The mixing of end-capped poly(ethylene glycol) (PEG) chains with 12-hydroxy stearic acid (12-HSA) molecules is a simple one-pot strategy to design thermo-responsive PEGylated self-assemblies of fatty acids with various morphology types at room temperature (multi-lamellar tubes or vesicles) that transit reversibly upon heating into small micelles around physiological temperature.

EXPERIMENTAL

4 types of 4k end-capped poly(ethylene glycol) (PEG) chains, capped respectively at one end or at both ends with either 12-HSA or stearic acid (SA), were mixed with 12-hydroxy stearic acid molecules, at a low constant ratio of end capped fatty acid moieties brought by the chains to that of free 12-HSA molecules. The detailed structure of the self-assemblies of mixtures was obtained using Small Angle Neutron Scattering with contrast variation at both 20 °C and 45 °C, and their temperature-dependent rheological behavior was characterized.

FINDINGS

For both types of mono-functionalized PEG, the chains insert homogenously in the multi-lamellar tubes formed by 12-HSA molecules. The mixtures of di-functionalized chains by 12-HSA with 12-HSA molecules produce PEGylated vesicles, since the change of packing parameter induced by insertion of the telechelic chains no longer allows the formation of tubes. Conversely, mixtures of di-functionalized chains by SA with 12-HSA molecules enable to keep multi-lamellar tubes, a specific behavior that likely comes from the fact that they only insert by one end within the 12-HSA bilayers. All systems transit reversibly into small PEGylated ellipsoidal micelles. The morphological transitions enable to tune the rheological properties of suspensions, that are gelled at low temperature and turn Newtonian liquid at around 37 °C.

Multiparametric functional characterization of individual lipid nanoparticles using surface-sensitive light-scattering microscopy

The most efficient lipid nanoparticles (LNPs) for gene therapeutics rely on specific lipids that protect the oligonucleotide cargo and aid cellular uptake and subsequent endosomal escape. Yet, the efficacy of current state-of-the-art LNP formulations remains low, a few percent at best. A deeper understanding of how LNP cargo, lipid composition, stoichiometry, size, structure, and pH-induced conformational changes influence their efficiency is therefore necessary for improved design. Given the variability of these properties, preferred screening methods should offer single-particle-resolved multiparametric characterization. In this work, we employ combined surface-sensitive fluorescence and label-free scattering microscopy with single LNP resolution, which when integrated with microfluidics for liquid exchange between media of varying refractive index, enables quantification of LNP size, refractive index, and cargo content. We investigate two LNP formulations that, while similar in size and mRNA content, exhibit differences in functional mRNA delivery. Correlating size with the content of Cy5-labeled mRNA revealed that the cargo scaled with LNP volume for both types of LNPs, while the refractive index varied marginally across LNP size. While this multiparametric fingerprinting alone could not distinguish the two LNP formulations, we use the same experimental platform to show that their difference in fusogenicity to a supporting lipid bilayer under early endosomal conditions (drop in pH from 7.4 to 6.0) correlates with observed differences in in vitro cellular data. This highlights a limitation of the current state-of-the-art toolbox for in situ LNP characterization, which generally focuses on structural properties of suspended LNPs, which may not adequately capture functional performance.

Direct Surface Modification of the Epidermis Using Mussel-Inspired Polydopamine with Multiple Anti-Biofouling Functions

The surface properties of the epidermis are crucial in pathogen adhesion and proliferation. Moreover, damage to the epidermis caused by various physical and chemical attacks provides a favorable environment for pathogen penetration and proliferation through the exposed internal living tissue. Surface modification of the epidermis to impart anti-biofouling properties can provide effective protection against infections. In this study, a facile method of imparting multiple anti-biofouling functions by directly modifying the epidermal surface of an organism using dopamine, which is a mussel-inspired substance, is introduced. Biocompatible polydopamine (PDA) is uniformly applied to organic surfaces with diverse morphological features and surface energies, indicating its versatility. In addition, the reliability of epidermal modification with PDA is confirmed via the PDA-induced prevention of chronic changes in the impedance of the epidermis. Critically, the PDA-modified epidermis exhibited various anti-biofouling functions, including antibacterial and anti-adsorption properties against bacteria and cellular/noncellular microorganisms, respectively. Improved antibacterial properties are successfully realized via integration with tobramycin, which is a representative antibiotic. Direct surface modification using PDA offers an innovative approach to safeguard biological surfaces, particularly the human epidermis, against various pathogens, with potential for application in medical patches and skin-attached devices.

Fusogenic lipid nanoparticles for rapid delivery of large therapeutic molecules to exosomes

Exosomes, as cell-derived lipid nanoparticles, are promising drug carriers because they can traverse challenging physiological barriers such as the blood-brain barrier (BBB). However, a major obstacle in utilizing exosomes as drug carriers is loading large therapeutic molecules without compromising the structural integrity of embedded biomolecules. Here, we introduce a membrane fusion method utilizing fusogenic lipid nanoparticles, cubosomes, to load large molecules into exosomes in a non-destructive manner. When the drug-loaded cubosome and exosome solutions are simply mixed, membrane fusion is completed in just 10 min. Our method effectively loads doxorubicin and immunoglobulin G into exosomes. Moreover, even the most challenging molecule-mRNA-is loaded with nearly 100% efficiency, demonstrating the versatility of our approach. In terms of biological behavior, the resulting hybrid exosomes preserve the functional behavior of exosomes in BBB uptake and penetration. Surprisingly, controlling exosome-to-cubosome ratios allows precise control over BBB uptake and transport. Furthermore, these hybrid exosomes retain cell-specific delivery properties, preserving the targeted delivery functions dictated by their exosomal origin. This study demonstrates the feasibility of a mix-and-load method for rapid and efficient drug loading into exosomes, with significant potential for the treatment of neurological diseases.

The Internal Nanostructure of Lipid Nanoparticles Influences Their Diverse Cellular Uptake Pathways

Lipid nanoparticles have emerged as critical platforms for bioactive agent delivery, with their success in COVID-19 vaccines highlighting the urgent need to address gaps in understanding their biological interactions. Lyotropic liquid crystalline nanoparticles (LLCNPs) represent promising nanocarriers for bioactive agent delivery. In this study, it is revealed for the first time how internal nanostructures of LLCNPs - liposomes, cubosomes, hexosomes, and micellar cubosomes - influence their cellular uptake pathways. By isolating the effects of mesophase while maintaining consistent particle size, charge, and surface coating, it is demonstrated that non-lamellar LLCNPs, particularly cubosomes, significantly enhance cellular uptake via distinct endocytic and non-endocytic mechanisms. These nanoparticles predominantly utilize passive non-endocytic pathways, such as membrane fusion, bypassing endocytic recycling challenges faced by most nanomaterials, including lamellar liposomes. Among active endocytic pathways, macropinocytosis emerges as the dominant route for non-lamellar particles. The findings establish a direct link between LLCNP internal nanostructure and cellular internalization mechanisms, highlighting the critical role of mesophase design in optimizing nanocarrier performance. This knowledge enables the rational engineering of LLCNPs tailored to target specific uptake pathways, facilitating precision delivery for diverse therapeutic applications and addressing key barriers in intracellular drug transport.

Inverse Bicontinuous and Discontinuous Phases of Lipids, and Membrane Curvature

In this review article I briefly describe lipid self-assembly, interfacial curvature, and lyotropic phase diagrams. I then go on to describe how the phase behaviour can be controlled, and the structure of lyotropic phases can be tuned, by various parameters such as temperature, hydrostatic pressure, or the addition of amphiphilic molecules such as fatty acids, diacylglycerols, and cholesterol. I then give a few illustrations of how such structures/phases may play roles in lipid-based biotechnologies, and in biomembrane systems.

Click Lipid Nanoparticles for the Delivery of mRNA to Metabolically Labeled Cancer Cells

Lipid nanoparticle (LNP)-based mRNA delivery has a lot of potential in combating a wide range of diseases, but delivering mRNA to specific cell types continues to be challenging. Despite recent advances in organ and cell specificity, the majority of clinical LNP systems cannot fully release their payload to a targeted site. Incorporating active targeting moieties into LNPs is highly desired to expand nanomedicine applications. In this Letter, we developed LNPs that harness the power of bioorthogonal "click" azide-alkyne chemical reactions. We show that the plasma membranes of cancer cells can be labeled with azide groups by metabolic sugar labeling, and these azide groups can react with dibenzocyclooctyne (DBCO) on LNPs to achieve specific binding. To achieve this, we synthesized new and versatile lipids by functionalizing DBCO groups to phospholipids with or without a poly(ethylene glycol) (PEG) linker. The DBCO lipids were successfully formulated into DBCO-LNPs comprising other standard lipid compounds. When using these DBCO-LNPs to deliver mRNA to metabolically labeled cells, DBCO-LNPs showed a remarkable ability to preferentially deliver mRNA to azide-labeled cells. Removing PEG linkers from DBCO lipids enables better integration and retention in the LNP, and the higher the amount of DBCO lipid, the stronger the targeting effect. This work demonstrates that cell-specific targeting can be achieved utilizing azide-alkyne ″click″ chemistry and could inspire the development of the next generation of LNPs for active cyto-tropic nanomedicines.

Exosome-Inspired Lipid Nanoparticles for Enhanced Tissue Penetration

The extracellular matrix (ECM) is a complex network of biomolecules with varying pore sizes, posing a challenge for the effective penetration of lipid nanoparticles. In contrast, cell-derived lipid nanoparticles, such as exosomes, have demonstrated the ability to travel to distant organs, indicating their capacity to penetrate the ECM. Here, we designed exosome-like vesicles (ELVs) inspired by exosomes' distinct transport phenomena. Specifically, we integrated three exosomal components (anionic lipid, cholesterol, and aquaporin-1) associated with transport into our ELVs to mimic the superior diffusion behavior of exosomes over synthetic lipid nanoparticles. Surprisingly, both bulk- and single-particle-diffusion studies revealed a more than 33 times increase in the effective diffusion coefficient within model ECM compared to conventional lipid nanoparticles. Furthermore, ELVs show an 80% increase in the effective diffusion coefficient within biological tissues. The excellent transport behavior of ELVs was further validated in vivo, where intratumoral injection showcased their superior transport. These findings provide insights into lipid nanoparticle design for improved tissue penetration.

Topological and Morphological Membrane Dynamics in Giant Lipid Vesicles Driven by Monoolein Cubosomes

Lipid nanoparticles have important applications as biomedical delivery platforms and broader engineering biology applications in artificial cell technologies. These emerging technologies often require changes in the shape and topology of biological or biomimetic membranes. Here we show that topologically-active lyotropic liquid crystal nanoparticles (LCNPs) can trigger such transformations in the membranes of giant unilamellar vesicles (GUVs). Monoolein (MO) LCNPs, cubosomes with an internal nanostructure of space groupI m 3 m ${Im3m}$ incorporate into 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) GUVs creating excess membrane area with stored curvature stress. Using time-resolved fluorescence confocal and lattice light sheet microscopy, we observe and characterise various life-like dynamic events in these GUVs, including growth, division, tubulation, membrane budding and fusion. Our results shed new light on the interactions of LCNPs with bilayer lipid membranes, providing insights relevant to how these nanoparticles might interact with cellular membranes during drug delivery and highlighting their potential as minimal triggers of topological transitions in artificial cells.

Nanostructure Formation in Glycerolipid Films during Enzymatic Hydrolysis: A GISAXS Study

Responsive nanostructured films from food-grade lipids can be valuable for food, pharmaceutical, and biotechnological science. Lyotropic liquid crystalline structures that respond to enzymes in their environment can, for instance, be innovated as drug delivery platforms or biosensors. However, the structural changes that such films undergo during enzymatic reactions with lipase are not yet understood. This work demonstrates the preparation of mesostructured lipid films from the food-grade lipids glycerol monooleate (GMO) and triolein on silicon wafers and their digestion with pancreatic lipase using time-resolved synchrotron grazing incidence small-angle X-ray scattering (GISAXS). The film structure is compared with the corresponding GMO/triolein bulk phases in excess water. Increasing the GMO/triolein ratio in the film makes it possible to modulate the structure of the films from oil coatings to inverse hexagonal and inverse bicontinuous cubic films. Pancreatic lipase triggered swelling of the internal film nanostructure and eventually structural transformation inside the film. Orientation and reorientation of the internal film structure relative to the silicon wafer surface were observed during the preparation of the films and their digestion. The findings contribute to the understanding of self-assembly in thin films and guide the development of enzyme-responsive coatings for the functional modification of various substrates.

Mixtures of Intrinsically Disordered Neuronal Protein Tau and Anionic Liposomes Reveal Distinct Anionic Liposome-Tau Complexes Coexisting with Tau Liquid-Liquid Phase-Separated Coacervates

Tau, an intrinsically disordered neuronal protein and polyampholyte with an overall positive charge, is a microtubule (MT) associated protein that binds to anionic domains of MTs and suppresses their dynamic instability. Aberrant tau-MT interactions are implicated in Alzheimer's and other neurodegenerative diseases. Here, we studied the interactions between full-length human protein tau and other negatively charged binding substrates, as revealed by differential interference contrast (DIC) and fluorescence microscopy. As a binding substrate, we chose anionic liposomes (ALs) containing either 1,2-dioleoyl-sn-glycero-3-phosphatidylserine (DOPS, -1e) or 1,2-dioleoyl-sn-glycero-3-phosphatidylglycerol (DOPG, -1e) mixed with zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) to mimic anionic plasma membranes of axons where tau resides. At low salt concentrations (0 to 10 mM KCl or NaCl) with minimal charge screening, reaction mixtures of tau and ALs resulted in the formation of distinct states of AL-tau complexes coexisting with liquid-liquid phase-separated tau self-coacervates arising from the polyampholytic nature of tau containing cationic and anionic domains. AL-tau complexes (i.e. tau-lipoplexes) exhibited distinct types of morphologies. This included large ∼20-30 μm tau-decorated giant vesicles with additional smaller liposomes with bound tau attached to the giant vesicles and tau-mediated finite-size assemblies of small liposomes. As the salt concentration was increased to near and above 150 mM for 1:1 electrolytes, AL-tau complexes remained stable, while tau self-coacervate droplets were found to dissolve, indicative of the breaking of (anionic/cationic) electrostatic bonds between tau chains due to increased charge screening. The findings are consistent with the hypothesis that distinct cationic domains of tau may interact with anionic lipid domains of the lumen-facing monolayer of the axon's plasma membrane, suggesting the possibility of transient yet robust interactions near relevant ionic strengths found in neurons.

Preparation and characterization of macrophage membrane camouflaged cubosomes as a stabilized and immune evasive biomimetic nano-DDS

This study aims to develop a biomimetic nano-drug delivery system (nano-DDS) by employing a macrophage cell membrane camouflaging strategy to modify lyotropic liquid crystal nanoparticles (LLC-NPs). The cubic-structured LLC-NPs (Cubosomes, CBs) were prepared via a top-down approach (ultra-sonification) using monoolein (MO) and doped with the cationic lipid, DOTAP. The cell membrane camouflaging procedure induced changes in the cubic lipid phase from primitive cubic phase (QIIP) to a coexistence of QIIP and diamond cubic phase (QIID). The macrophage membrane camouflaging strategy protected CB cores from the destabilization by blood plasma and enhanced the stability of CBs. The in vitro experiment results revealed that the macrophage cell membrane coating significantly reduced macrophage uptake efficacy within 8 h of incubation compared to the non-camouflaged CBs, while it had minimal impact on cancer cell uptake efficacy. The macrophage membrane coated CBs showed lower accumulation in the heart, kidney and lungs in vivo. This study demonstrated the feasibility of employing cell membrane camouflaging on CBs and confirmed that the bio-functionalities of the CBs-based biomimetic nano-DDS were retained from the membrane source cells, and opened up promising possibilities for developing an efficient and safe drug delivery system based on the biomimetic approach.

Mixtures of Intrinsically Disordered Neuronal Protein Tau and Anionic Liposomes Reveal Distinct Anionic Liposome-Tau Complexes Coexisting with Tau Liquid-Liquid Phase Separated Coacervates

Tau, an intrinsically disordered neuronal protein and polyampholyte with an overall positive charge, is a microtubule (MT) associated protein, which binds to anionic domains of MTs and suppresses their dynamic instability. Aberrant tau-MT interactions are implicated in Alzheimer's and other neurodegenerative diseases. Here, we studied the interactions between full length human protein tau and other negatively charged binding substrates, as revealed by differential-interference-contrast (DIC) and fluorescence microscopy. As a binding substrate, we chose anionic liposomes (ALs) containing either 1,2-dioleoyl-sn-glycero-3-phosphatidylserine (DOPS, -1e) or 1,2-dioleoyl-sn-glycero-3-phosphatidylglycerol (DOPG, -1e) mixed with zwitterionic 1,2dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) to mimic anionic plasma membranes of axons where tau resides. At low salt concentrations (0 to 10 mM KCl or NaCl) with minimal charge screening, reaction mixtures of tau and ALs resulted in the formation of distinct states of AL-tau complexes coexisting with liquid-liquid phase separated tau self-coacervates arising from the polyampholytic nature of tau containing cationic and anionic domains. AL-tau complexes exhibited distinct types of morphologies. This included, large ≈20-30 micron tau-decorated giant vesicles with additional smaller liposomes with bound tau attached to the giant vesicles, and tau-mediated finite-size assemblies of small liposomes. As the ionic strength of the solution was increased to near and above physiological salt concentrations for 1:1 electrolytes (≈150 mM), AL-tau complexes remained stable while tau self-coacervate droplets were found to dissolve indicative of breaking of (anionic/cationic) electrostatic bonds between tau chains due to increased charge screening. The findings are consistent with the hypothesis that distinct cationic domains of tau may interact with anionic lipid domains of the lumen facing monolayer of the axon plasma membrane suggesting the possibility of transient yet robust interactions at physiologically relevant ionic strengths.

Recent Advances in the Use of Cubosomes as Drug Carriers with Special Emphasis on Topical Applications

Topical drug delivery employing drug nanocarriers has shown prominent results in treating topical ailments, especially those confined to the skin and eyes. Conventional topical formulations persist with drug and disease-related challenges during treatment. Various nanotechnology-driven approaches have been adopted to mitigate the issues associated with conventional formulations. Among these, cubosomes have shown potential applications owing to their liquid crystalline structure, which aids in bioadhesion, retention, sustained release, and loading hydrophilic and hydrophobic moieties. The phase transition behavior of glyceryl monooleate, the concentration of stabilizers, and critical packing parameters are crucial parameters that affect the formation of cubosomes. Microfluidics-based approaches constitute a recent advance in technologies for generating stable cubosomes. This review covers the recent topical applications of cubosomes for treating skin (psoriasis, skin cancer, cutaneous candidiasis, acne, and alopecia) and eye (fungal keratitis, glaucoma, conjunctivitis, and uveitis) diseases. The article summarizes the manufacturing and biological challenges (skin and ocular barriers) that must be considered and encountered for successful clinical outcomes. The patented products are successful examples of technological advancements within cosmeceuticals that support various topical applications with cubosomes in the pharmaceutical field.

Liposomes to Cubosomes: The Evolution of Lipidic Nanocarriers and Their Cutting-Edge Biomedical Applications

Lipidic nanoparticles have undergone extensive research toward the exploration of their diverse therapeutic applications. Although several liposomal formulations are in the clinic (e.g., DOXIL) for cancer therapy, there are many challenges associated with traditional liposomes. To address these issues, modifications in liposomal structure and further functionalization are desirable, leading to the emergence of solid lipid nanoparticles and the more recent liquid lipid nanoparticles. In this context, "cubosomes", third-generation lipidic nanocarriers, have attracted significant attention due to their numerous advantages, including their porous structure, structural adaptability, high encapsulation efficiency resulting from their extensive internal surface area, enhanced stability, and biocompatibility. Cubosomes offer the potential for both enhanced cellular uptake and controlled release of encapsulated payloads. Beyond cancer therapy, cubosomes have demonstrated effectiveness in wound healing, antibacterial treatments, and various dermatological applications. In this review, the authors provide an overview of the evolution of lipidic nanocarriers, spanning from conventional liposomes to solid lipid nanoparticles, with a special emphasis on the development and application of cubosomes. Additionally, it delves into recent applications and preclinical trials associated with cubosome formulations, which could be of significant interest to readers from backgrounds in nanomedicine and clinicians.

Revolutionizing transdermal drug delivery: unveiling the potential of cubosomes and ethosomes

The area of drug delivery systems has witnessed significant advancements in recent years, with a particular focus on improving efficacy, stability, and patient compliance. Transdermal drug delivery offers numerous benefits compared to conventional methods of drug administration through the skin. It helps in avoiding gastric irritation, hepatic first-pass metabolism, and gastric degradation of the drug. It bypasses the gastrointestinal tract, eliminating the risk of first-pass metabolism and allowing drugs to be administered without being affected by pH, enzymes, or intestinal bacteria. Additionally, it allows for sustained release of the drug, is noninvasive, and enhances patient adherence to the treatment regimen. The transdermal drug delivery system (TDDS) can serve as an alternative route for drug administration in individuals who cannot tolerate oral medications, experience nausea, or are unconscious. When compared to intravenous, hypodermic, and other parenteral routes, TDDS stands out due to its ability to eliminate pain, reduce the risk of infection, and prevent disease transmission associated with needle reuse. Consequently, the overall patient compliance is significantly improved with the utilization of TDDS. Among the noteworthy developments are cubosomes and ethosomes, two distinct yet promising carriers that have garnered attention for their unique properties. In conclusion, this review synthesizes the current knowledge on cubosomes and ethosomes, shedding light on their individual strengths and potential synergies. The exploration of their application in various therapeutic areas underscores their versatility and establishes them as key players in the evolving landscape of drug delivery systems.

Small-angle X-ray and neutron scattering applied to lipid-based nanoparticles: Recent advancements across different length scales

Lipid-based nanoparticles (LNPs), ranging from nanovesicles to non-lamellar assemblies, have gained significant attention in recent years, as versatile carriers for delivering drugs, vaccines, and nutrients. Small-angle scattering methods, employing X-rays (SAXS) or neutrons (SANS), represent unique tools to unveil structure, dynamics, and interactions of such particles on different length scales, spanning from the nano to the molecular scale. This review explores the state-of-the-art on scattering methods applied to unveil the structure of lipid-based nanoparticles and their interactions with drugs and bioactive molecules, to inform their rational design and formulation for medical applications. We will focus on complementary information accessible with X-rays or neutrons, ranging from insights on the structure and colloidal processes at a nanoscale level (SAXS) to details on the lipid organization and molecular interactions of LNPs (SANS). In addition, we will review new opportunities offered by Time-resolved (TR)-SAXS and -SANS for the investigation of dynamic processes involving LNPs. These span from real-time monitoring of LNPs structural evolution in response to endogenous or external stimuli (TR-SANS), to the investigation of the kinetics of lipid diffusion and exchange upon interaction with biomolecules (TR-SANS). Finally, we will spotlight novel combinations of SAXS and SANS with complementary on-line techniques, recently enabled at Large Scale Facilities for X-rays and neutrons. This emerging technology enables synchronized multi-method investigation, offering exciting opportunities for the simultaneous characterization of the structure and chemical or mechanical properties of LNPs.

Lipid nanoparticles for RNA delivery: Self-assembling vs driven-assembling strategies

Among non-viral vectors, lipid nanovectors are considered the gold standard for the delivery of RNA therapeutics. The success of lipid nanoparticles for RNA delivery, with three products approved for human use, has stimulated further investigation into RNA therapeutics for different pathologies. This requires decoding the pathological intracellular processes and tailoring the delivery system to the target tissue and cells. The complexity of the lipid nanovectors morphology originates from the assembling of the lipidic components, which can be elicited by various methods able to drive the formation of nanoparticles with the desired organization. In other cases, pre-formed nanoparticles can be mixed with RNA to induce self-assembly and structural reorganization into RNA-loaded nanoparticles. In this review, the most relevant lipid nanovectors and their potentialities for RNA delivery are described on the basis of the assembling mechanism and of the particle architecture.

Nanotechnology strategies to address challenges in topical and cellular delivery of siRNAs in skin disease therapy

Gene therapy is one of the most advanced therapies in current medicine. In particular, interference RNA-based therapy by small interfering RNA (siRNA) has gained attention in recent years as it is a highly versatile, selective and specific therapy. In dermatological conditions, topical delivery of siRNA offers numerous therapeutic advantages, mainly by inhibiting the expression of target transcripts directly in the skin. However, crossing the stratum corneum and overcoming intracellular barriers is an inherent challenge. Substantial efforts by scientists have moved towards the use of multimodal and multifunctional nanoparticles to overcome these barriers and achieve greater bioavailability in their site of action, the cytoplasm. In this review the most innovative strategies based on nanoparticle and physical methods are presented, as well as the design principles and the main factors that contribute to the performance of these systems. This review also highlights the synergistic contributions of medicine, nanotechnology, and molecular biology to advancing translational research into siRNA-based therapeutics for skin diseases.

Regulating the structural polymorphism and protein corona composition of phytantriol-based lipid nanoparticles using choline ionic liquids

Lipid-based lyotropic liquid crystalline nanoparticles (LCNPs) face stability challenges in biological fluids during clinical translation. Ionic Liquids (ILs) have emerged as effective solvent additives for tuning the structure of LCNP's and enhancing their stability. We investigated the effect of a library of 21 choline-based biocompatible ILs with 9 amino acid anions as well as 10 other organic/inorganic anions during the preparation of phytantriol (PHY)-based LCNPs, followed by incubation in human serum and serum proteins. Small angle X-ray scattering (SAXS) results show that the phase behaviour of the LCNPs depends on the IL concentration and anion structure. Incubation with human serum led to a phase transition from the inverse bicontinuous cubic (Q2) to the inverse hexagonal (H2) mesophase, influenced by the specific IL present. Liquid chromatography-mass spectrometry (LC-MS) and proteomics analysis of selected samples, including PHY control and those with choline glutamate, choline hexanoate, and choline geranate, identified abundant proteins in the protein corona, including albumin, apolipoproteins, and serotransferrin. The composition of the protein corona varied among samples, shedding light on the intricate interplay between ILs, internal structure and surface chemistry of LCNPs, and biological fluids.

EZH2 as a potential therapeutic target for gastrointestinal cancers

Gastrointestinal (GI) cancers continue to be a major cause of mortality and morbidity globally. Understanding the molecular pathways associated with cancer progression and severity is essential for creating effective cancer treatments. In cancer research, there is a notable emphasis on Enhancer of zeste homolog 2 (EZH2), a key player in gene expression influenced by its irregular expression and capacity to attach to promoters and alter methylation status. This review explores the impact of EZH2 signaling on various GI cancers, such as colorectal, gastric, pancreatic, hepatocellular, esophageal, and cholangiocarcinoma. The primary function of EZH2 signaling is to facilitate the accelerated progression of cancer cells. Additionally, EZH2 has the capacity to modulate the reaction of GI cancers to chemotherapy and radiotherapy. Numerous pathways, including long non-coding RNAs and microRNAs, serve as upstream regulators of EZH2 in these types of cancer. EZH2's enzymatic activity enables it to attach to target gene promoters, resulting in methylation that modifies their expression. EZH2 could be considered as an independent prognostic factor, with increased expression correlating with a worse disease prognosis. Additionally, a range of gene therapies including small interfering RNA, and anti-tumor agents are being explored to target EZH2 for cancer treatment. This comprehensive review underscores the current insights into EZH2 signaling in gastrointestinal cancers and examines the prospect of therapies targeting EZH2 to enhance patient outcomes.

How Cell-Penetrating Peptides Behave Differently from Pore-Forming Peptides: Structure and Stability of Induced Transmembrane Pores

Peptide-induced transmembrane pore formation is commonplace in biology. Examples of transmembrane pores include pores formed by antimicrobial peptides (AMPs) and cell-penetrating peptides (CPPs) in bacterial membranes and eukaryotic membranes, respectively. In general, however, transmembrane pore formation depends on peptide sequences, lipid compositions, and intensive thermodynamic variables and is difficult to observe directly under realistic solution conditions, with structures that are challenging to measure directly. In contrast, the structure and phase behavior of peptide-lipid systems are relatively straightforward to map out experimentally for a broad range of conditions. Cubic phases are often observed in systems involving pore-forming peptides; however, it is not clear how the structural tendency to induce negative Gaussian curvature (NGC) in such phases is quantitatively related to the geometry of biological pores. Here, we leverage the theory of anisotropic inclusions and devise a facile method to estimate transmembrane pore sizes from geometric parameters of cubic phases measured from small-angle X-ray scattering (SAXS) and show that such estimates compare well with known pore sizes. Moreover, our model suggests that although AMPs can induce stable transmembrane pores for membranes with a broad range of conditions, pores formed by CPPs are highly labile, consistent with atomistic simulations.

Overcoming biological barriers by virus-like drug particles for drug delivery

Virus-like particles (VLPs) have natural structural antigens similar to those found in viruses, making them valuable in vaccine immunization. Furthermore, VLPs have demonstrated significant potential in drug delivery, and emerged as promising vectors for transporting chemical drug, genetic drug, peptide/protein, and even nanoparticle drug. With virus-like permeability and strong retention, they can effectively target specific organs, tissues or cells, facilitating efficient intracellular drug release. Further modifications allow VLPs to transfer across various physiological barriers, thus acting the purpose of efficient drug delivery and accurate therapy. This article provides an overview of VLPs, covering their structural classifications, deliverable drugs, potential physiological barriers in drug delivery, strategies for overcoming these barriers, and future prospects.

Lyotropic liquid crystalline 2D and 3D mesophases: Advanced materials for multifunctional anticancer nanosystems

Cancer remains a leading cause of mortality. Despite significant breakthroughs in conventional therapies, treatment is still far from ideal due to high toxicity in normal tissues and therapeutic inefficiency caused by short drug lifetime in the body and resistance mechanisms. Current research moves towards the development of multifunctional nanosystems for delivery of chemotherapeutic drugs, bioactives and/or radionuclides that can be combined with other therapeutic modalities, like gene therapy, or imaging to use in therapeutic screening and diagnosis. The preparation and characterization of Lyotropic Liquid Crystalline (LLC) mesophases self-assembled as 2D and 3D structures are addressed, with an emphasis on the unique properties of these nanoassemblies. A comprehensive review of LLC nanoassemblies is also presented, highlighting the most recent advances and their outstanding advantages as drug delivery systems, including tailoring strategies that can be used to overcome cancer challenges. Therapeutic agents loaded in LLC nanoassemblies offer qualitative and quantitative enhancements that are superior to conventional chemotherapy, particularly in terms of preferential accumulation at tumor sites and promoting enhanced cancer cell uptake, lowering tumor volume and weight, improving survival rates, and increasing the cytotoxicity of their loaded therapeutic agents. In terms of quantitative anticancer efficacy, loaded LLC nanoassemblies reduced the IC50 values from 1.4-fold against lung cancer cells to 125-fold against ovarian cancer cells.

How cell penetrating peptides behave differently from pore forming peptides: structure and stability of induced transmembrane pores

Peptide induced trans-membrane pore formation is commonplace in biology. Examples of transmembrane pores include pores formed by antimicrobial peptides (AMPs) and cell penetrating peptides (CPPs) in bacterial membranes and eukaryotic membranes, respectively. In general, however, transmembrane pore formation depends on peptide sequences, lipid compositions and intensive thermodynamic variables and is difficult to observe directly under realistic solution conditions, with structures that are challenging to measure directly. In contrast, the structure and phase behavior of peptide-lipid systems are relatively straightforward to map out experimentally for a broad range of conditions. Cubic phases are often observed in systems involving pore forming peptides; however, it is not clear how the structural tendency to induce negative Gaussian curvature (NGC) in such phases is quantitatively related to the geometry of biological pores. Here, we leverage the theory of anisotropic inclusions and devise a facile method to estimate transmembrane pore sizes from geometric parameters of cubic phases measured from small angle X-ray scattering (SAXS) and show that such estimates compare well with known pore sizes. Moreover, our model suggests that whereas AMPs can induce stable transmembrane pores for membranes with a broad range of conditions, pores formed by CPPs are highly labile, consistent with atomistic simulations.

Lipid nanoparticle topology regulates endosomal escape and delivery of RNA to the cytoplasm

RNA therapeutics have the potential to resolve a myriad of genetic diseases. Lipid nanoparticles (LNPs) are among the most successful RNA delivery systems. Expanding their use for the treatment of more genetic diseases hinges on our ability to continuously evolve the design of LNPs with high potency, cellular-specific targeting, and low side effects. Overcoming the difficulty of releasing cargo from endocytosed LNPs remains a significant hurdle. Here, we investigate the fundamental properties of nonviral RNA nanoparticles pertaining to the activation of topological transformations of endosomal membranes and RNA translocation into the cytosol. We show that, beyond composition, LNP fusogenicity can be prescribed by designing LNP nanostructures that lower the energetic cost of fusion and fusion-pore formation with a target membrane. The inclusion of structurally active lipids leads to enhanced LNP endosomal fusion, fast evasion of endosomal entrapment, and efficacious RNA delivery. For example, conserving the lipid make-up, RNA-LNPs having cuboplex nanostructures are significantly more efficacious at endosomal escape than traditional lipoplex constructs.

Prospective Subunit Nanovaccine against Mycobacterium tuberculosis Infection─Cubosome Lipid Nanocarriers of Cord Factor, Trehalose 6,6' Dimycolate

An improved vaccine is urgently needed to replace the now more than 100-year-old Bacillus Calmette-Guérin (BCG) vaccine against tuberculosis (TB) disease, which represents a significant burden on global public health. Mycolic acid, or cord factor trehalose 6,6' dimycolate (TDM), a lipid component abundant in the cell wall of the pathogen Mycobacterium tuberculosis (MTB), has been shown to have strong immunostimulatory activity but remains underexplored due to its high toxicity and poor solubility. Herein, we employed a novel strategy to encapsulate TDM within a cubosome lipid nanocarrier as a potential subunit nanovaccine candidate against TB. This strategy not only increased the solubility and reduced the toxicity of TDM but also elicited a protective immune response to control MTB growth in macrophages. Both pre-treatment and concurrent treatment of the TDM encapsulated in lipid monoolein (MO) cubosomes (MO-TDM) (1 mol %) induced a strong proinflammatory cytokine response in MTB-infected macrophages, due to epigenetic changes at the promoters of tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) in comparison to the untreated control. Furthermore, treatment with MO-TDM (1 mol %) cubosomes significantly improved antigen processing and presentation capabilities of MTB-infected macrophages to CD4 T cells. The ability of MO-TDM (1 mol %) cubosomes to induce a robust innate and adaptive response in vitro was further supported by a mathematical modeling study predicting the vaccine efficacy in vivo. Overall, these results indicate a strong immunostimulatory effect of TDM when delivered through the lipid nanocarrier, suggesting its potential as a novel TB vaccine.

Liquid crystalline nanoparticles enable a multifunctional approach for topical psoriasis therapy by co-delivering triptolide and siRNAs

Liquid crystalline nanoparticles (LCNs) are an attractive drugs topical delivery system due to the great internal ordering, wide interfacial area and structural similarities with the skin. In this work, LCNs were designed to encapsulate triptolide (TP) and to complex on its surface small interfering RNAs (siRNA) targeting TNF-α and IL-6, aiming at topical co-delivery and regulating multi-targets in psoriasis. These multifunctional LCNs showed appropriate physicochemical properties for topical application, such as a mean size of 150 nm, low polydispersion, TP encapsulation greater than 90% and efficient complexation with siRNA. The internal reverse hexagonal mesostructure of LCNs was confirmed by SAXS while their morphology was assessed by cryo-TEM. In vitro permeation studies revealed an increase of more than 20-fold in the distribution of TP through the porcine epidermis/dermis was achieved after the application of LCN-TP or LCN TP in hydrogel. In cell culture, LCNs showed good compatibility and rapid internalization, which was attributed to macropinocytosis and caveolin-mediated endocytosis. Anti-inflammatory potential of multifunctional LCNs was assessed by reducing of TNF-α, IL-6, IL-1β and TGF-β1 levels in LPS-stimulated macrophages. These results support the hypothesis that the co-delivery of TP and siRNAs by LCNs may be a new strategy for psoriasis topical therapy.

Microfluidic synthesis of multilayered lipid-polymer hybrid nanoparticles for the formulation of low solubility drugs

Hybrid phospholipid/block copolymer membranes where polymers and lipids are molecularly mixed or phase-separated into polymer-rich and lipid-rich domains are promising drug delivery materials. Harnessing the chemical diversity of polymers and the biocompatability of lipids is a compelling approach to design the next generation of drug carriers. Here, we report on the development of a microfluidics-based strategy analogous to produce lipid nanoparticles (LNPs) for the nanomanufacturing of multilayered hybrid nanoparticles (HNPs). Using X-ray scattering, Cryo-electron, and polarized microscopy we show that phosphatidylcholine (PC) and PBD-b-PEO (poly(butadiene-block-ethylene oxide)) hybrid membranes can be nanomanufactured by microfluidics into HNPs with dense and multilayered cores which are ideal carriers of low-solubility drugs of the Biopharmaceutical Classification System (BCS) II and IV such as antimalarial DSM265 and Paclitaxel, respectively.

Enhancing the photoluminescence and cellular uptake of fluorescent carbon nanodots via cubosome lipid nanocarriers

Carbon nanodots (C-dots) have attracted much attention for their use in the fields of bioimaging, drug delivery, and sensing due to their excellent fluorescent and photoluminescent properties, photostability, biocompatibility, and amenability to surface modification. Herein, we report a nanocomposite formulation of C-dots (<5 nm) encapsulated in lipid-based lyotropic liquid crystalline nanoparticles (∼250 nm) via either passive diffusion or electrostatic mechanisms. The physicochemical properties of the nanocomposite formulation including particle size, surface charge, internal cubic nanostructures, and pH-dependent fluorescent properties were characterised. Upon loading of C-dots into lipid nanoparticles, the highly ordered inverse bicontinuous cubic mesophase existed in the internal phase of the nanoparticles, demonstrated by synchrotron small angle X-ray scattering, molecular dynamic simulation and cryogenic transmission electron microscopy. The pH-dependent fluorescent property of the C-dots was modified via electrostatic interaction between the C-dots and cationic lipid nanoparticles, which further enhanced the brightness of C-dots through self-quenching prevention. The cytotoxicity and cellular uptake efficiency of the developed nanocomposites were also examined in an epithelial gastric adenocarcinoma cell line (AGS) and a macrophage cell line (stimulated THP-1). Compared to free C-dots, the uptake and cell imaging potential of the C-dot nanocomposites was significantly improved, by several orders of magnitude as demonstrated by cytoplasmic fluorescent intensities using confocal microscopy. Loading C-dots into mesoporous lipid nanocarriers presents a new way of modifying C-dot physicochemical and fluorescent properties, alternative to direct chemical surface modification, and advances the bioimaging potential of C-dots by enhancing cellular uptake efficiency and converging C-dot light emission.

A Versatile Nanocarrier-Cubosomes, Characterization, and Applications

The impact of nanotechnology on the exponential growth of several research areas, particularly nanomedicine, is undeniable. The ability to deliver active molecules to the desired site could significantly improve the efficiency of medical treatments. One of the nanocarriers developed which has drawn researchers' attention are cubosomes, which are nanosized dispersions of lipid bicontinuous cubic phases in water, consisting of a lipidic interior and aqueous domains folded in a cubic lattice. They stand out due to their ability to incorporate hydrophobic, hydrophilic, and amphiphilic compounds, their tortuous internal configuration that provides a sustained release, and the capacity to protect and safely deliver molecules. Several approaches can be taken to prepare this structure, as well as different lipids like monoolein or phytantriol. This review paper describes the different methods to prepare nanocarriers. As it is known, the physicochemical properties of nanocarriers are very important, as they influence their pharmacokinetics and their ability to incorporate and deliver active molecules. Therefore, an extensive characterization is essential to obtain the desired effect. As a result, we have extensively described the most common techniques to characterize cubosomes, particularly nanocarriers. The exceptional properties of the cubosomes make them suitable to be used in several applications in the biomedical field, from cancer therapeutics to imaging, which will be described. Taking in consideration the outstanding properties of cubosomes, their application in several research fields is envisaged.

Stabilizing a Double Gyroid Network Phase with 2 nm Feature Size by Blending of Lamellar and Cylindrical Forming Block Oligomers

Molecular dynamics simulations are used to study binary blends of an AB-type diblock and an AB₂-type miktoarm triblock amphiphiles (also known as high-χ block oligomers) consisting of sugar-based (A) and hydrocarbon (B) blocks. In their pure form, the AB diblock and AB₂ triblock amphiphiles self-assemble into ordered lamellar (LAM) and cylindrical (CYL) structures, respectively. At intermediate compositions, however, the AB₂-rich blend (0.2 ≤ x _AB ≤ 0.4) forms a double gyroid (DG) network, whereas perforated lamellae (PL) are observed in the AB-rich blend (0.5 ≤ x _AB ≤ 0.8). All of the ordered mesophases present domain pitches under 3 nm, with 1 nm feature sizes for the polar domains. Structural analyses reveal that the nonuniform interfacial curvatures of DG and PL structures are supported by local composition variations of the LAM- and CYL-forming amphiphiles. Self-consistent mean field theory calculations for blends of related AB and AB₂ block polymers also show the DG network at intermediate compositions, when A is the minority block, but PL is not stable. This work provides molecular-level insights into how blending of shape-filling molecular architectures enables network phase formation with extremely small feature sizes over a wide composition range.

Recent advances in versatile inverse lyotropic liquid crystals

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

A vibrational in vitro approach to evaluate the potential of monoolein nanoparticles as isofuranodiene carrier in MDA-MB 231 breast cancer cell line: New insights from Infrared and Raman microspectroscopies

Isofuranodiene (IFD) is a sesquiterpene occurring in several plant species, which proved to have multiple anticancer activities. IFD has a lipophilic nature and, hence, a very low water solubility and a poor bioavailability; moreover, it is not stable, undergoing the "Cope rearrangement" to the less active curzerene. The use of appropriate delivery systems can thus be considered as a valid tool to enhance IFD bioavailability, solubility, stability and at the same time also to improve its intracellular uptake and pharmacological activity. Within this frame, monoolein (GMO) nanoparticles loaded with IFD were prepared and their enhanced anticancer activity, compared to pristine IFD, was assessed. In this study, for the first time, an in vitro Fourier Transform Infrared and Raman Microspectroscopy approaches were exploited to evaluate the effects of IFD, alone and loaded in GMO nanoparticles, on MDA-MB 231 breast cancer cell line. The anti-cancer effects of IFD were evidenced by both the spectroscopic techniques and discriminated from the GMO-induced changes in the culture environment; moreover, a synergistic effect of IFD and GMO administration can be envisaged by the experimental results.

Affimer Tagged Cubosomes: Targeting of Carcinoembryonic Antigen Expressing Colorectal Cancer Cells Using In Vitro and In Vivo Models

Nanomedicines, while having been approved for cancer therapy, present many challenges such as low stability, rapid clearance, and nonspecificity leading to off-target toxicity. Cubosomes are porous lyotropic liquid crystalline nanoparticles that have shown great premise as drug delivery vehicles; however, their behavior in vivo is largely underexplored, hindering clinical translation. Here, we have engineered cubosomes based on the space group Im3m that are loaded with copper acetylacetonate as a model drug, and their surfaces are functionalized for the first time with Affimer proteins via copper-free click chemistry to actively target overexpressed carcinoembryonic antigens on LS174T colorectal cancer cells. Unlike nontargeted cubosomes, Affimer tagged cubosomes showed preferential accumulation in cancer cells compared to normal cells not only in vitro (2D monolayer cell culture and 3D spheroid models) but also in vivo in colorectal cancer mouse xenografts, while exhibiting low nonspecific absorption and toxicity in other vital organs. Cancerous spheroids had maximum cell death compared to noncancerous cells upon targeted delivery. Xenografts subjected to targeted drug-loaded cubosomes showed a 5-7-fold higher drug accumulation in the tumor tissue compared to the liver, kidneys, and other vital organs, a significant decrease in tumor growth, and an increased survival rate compared to the nontargeted group. This work encompasses the first thorough preclinical investigation of Affimer targeted cubosomes as a cancer therapeutic.

Use of cubic structure with primitive nanochannels for fabrication of free standing 3D nanowire network of Pt withPm3msymmetry

In this work, we developed a lipid mixture based on phytantriol / polyoxyethylene surfactant (Brij-56) that forms aIm3msymmetry bicontinuous cubic phase based on the Schwartz primitive surface (Q_II^P), from which we templated highly ordered 3D nanoporous platinum with a novel 'single primitive' morphology (Pm3msymmetry). TheQ_II^Ptemplate phase is obtained by incorporation of 17.5% w/w Brij-56 (C₁₆EO₁₀) (a type-I surfactant) into phytantriol under excess hydration conditions. Phytantriol alone forms the double diamondQ_II^D(Pn3m) phase, and in previous studies incorporating Brij-56 at different compositions the cubic phase maintained this morphology, but increased its lattice parameter; mesoporous metals templated from theseQ_II^Dlipid templates all exhibited the 'single diamond' (Fd3m) morphology. In contrast, the current paper presents the availability of ourQ_II^Pcubic phases to template nanoporous materials of single primitivePm3mmorphology via chemical and electrochemical methods. To explore the structure porosity and morphological features of the templated Pt material, x-ray scattering and transmission electron microscopy are used. The resulting 3D nanoporous Pt materials are found to exhibit a regular network of Pt nanowires of ∼4 nm in diameter with a unit cell dimension of 14.8 ± 0.8 nm, reflecting the aqueous network within theQ_II^Ptemplate.

A pressure-jump study on the interaction of osmolytes and crowders with cubic monoolein structures

Many vital processes that take place in biological cells involve remodeling of lipid membranes. These processes take place in a milieu that is packed with various solutes, ranging from ions and small organic osmolytes to proteins and other macromolecules, occupying about 30% of the available volume. In this work, we investigated how molecular crowding, simulated with the polymer polyethylene glycol (PEG), and the osmolytes urea and trimethylamine-N-oxide (TMAO) affect the equilibration of cubic monoolein structures after a phase transition from a lamellar state induced by an abrupt pressure reduction. In absence of additives, swollen cubic crystallites form after the transition, releasing excess water over several hours. This process is reflected in a decreasing lattice constant and was monitored with small angle X-ray scattering. We found that the osmotic pressure exerted by PEG and TMAO, which are displaced from narrow inter-bilayer spaces, accelerates the equilibration. When the radius of gyration of the added PEG was smaller than the radius of the water channels of the cubic phase, the effect became more pronounced with increasing molecular weight of the polymers. As the release of hydration water from the cubic structures is accompanied by an increasing membrane curvature and a reduction of the interface between lipids and aqueous phase, urea, which has a slight affinity to reside near membrane surfaces, stabilized the swollen crystallites and slowed down the equilibration dynamics. Our results support the view that cellular solutes are important contributors to dynamic membrane processes, as they can accelerate dehydration of inter-bilayer spaces and promote or counteract membrane curvature.

Near-Infrared-Triggered Reversible Transformations of Gold Nanorod-Laden Lipid Assemblies: Implications for Cellular Delivery

Robust drug and gene delivery systems require innovative methods to control payload release and tune delivery efficiency. The most promising delivery materials are lipid-based and their efficiency often hinges on structural transformations activated by endogenous pH changes. Exogenously driving phase transitions in lipid assemblies is a tantalizing idea that could lead to better control of cargo release dynamics. Multiple reports have demonstrated phase transitions induced in lipid systems, achieved via plasmonic heating of entrained gold nanorods. However, undesirable nonlocalized heating is common due to the size mismatch between the nanorods and the lipid architecture in these systems. Lipid assemblies often exhibit lattice dimensions of just a few nanometers, rendering gold particles challenging to integrate due to their incommensurate sizes, especially in lipid nanoparticle or colloidal forms. We investigate these processes using a judiciously chosen ternary lipid system with entrained small gold nanorods that undergoes transitions between bicontinuous cubic and inverse hexagonal phases on exposure to near-infrared light. Utilizing small-angle X-ray scattering alongside electron reconstruction, we show that gold nanorods integrate into the lipid assembly core lattice by colocalizing in the water nanochannels. We also found that plasmonically activated transformations occur in a couple of minutes and are reversible.

A polytherapy based approach to combat antimicrobial resistance using cubosomes

A depleted antimicrobial drug pipeline combined with an increasing prevalence of Gram-negative ‘superbugs’ has increased interest in nano therapies to treat antibiotic resistance. As cubosomes and polymyxins disrupt the outer membrane of Gram-negative bacteria via different mechanisms, we herein examine the antimicrobial activity of polymyxin-loaded cubosomes and explore an alternative strategy via the polytherapy treatment of pathogens with cubosomes in combination with polymyxin. The polytherapy treatment substantially increases antimicrobial activity compared to polymyxin B-loaded cubosomes or polymyxin and cubosomes alone. Confocal microscopy and neutron reflectometry suggest the superior polytherapy activity is achieved via a two-step process. Firstly, electrostatic interactions between polymyxin and lipid A initially destabilize the outer membrane. Subsequently, an influx of cubosomes results in further membrane disruption via a lipid exchange process. These findings demonstrate that nanoparticle-based polytherapy treatments may potentially serve as improved alternatives to the conventional use of drug-loaded lipid nanoparticles for the treatment of “superbugs”.

An increasing prevalence of Gram-negative bacteria increases the interest in nanotherapies to treat antibiotic resistance. Here, the authors examine the antimicrobial activity of polymyxin-loaded cubosomes and explore a polytherapy treatment of pathogens with cubosomes in combination with polymyxin.

Chemistry of Lipid Nanoparticles for RNA Delivery

Lipid nanoparticles (LNPs) are a type of lipid vesicles that possess a homogeneous lipid core. These vesicles are widely used in small-molecule drug and nucleic acid delivery and recently gained much attention because of their remarkable success as a delivery platform for COVID-19 mRNA vaccines. Nonetheless, the utility of transient protein expression induced by mRNA extends far beyond vaccines against infectious diseases─they also hold promise as cancer vaccines, protein replacement therapies, and gene editing components for rare genetic diseases. However, naked mRNA is inherently unstable and prone to rapid degradation by nucleases and self-hydrolysis. Encapsulation of mRNA within LNPs protects mRNA from extracellular ribonucleases and assists with intracellular mRNA delivery.In this Account, we discuss the core features of LNPs for RNA delivery. We focus our attention on LNPs designed to deliver mRNA; however, we also include examples of siRNA-LNP delivery where appropriate to highlight the commonalities and the dissimilarities due to the nucleic acid structure. First, we introduce the concept of LNPs, the advantages and disadvantages of utilizing nucleic acids as therapeutic agents, and the general reasoning behind the molecular makeup of LNPs. We also briefly highlight the most recent clinical successes of LNP-based nucleic acid therapies. Second, we describe the theory and methods of LNP self-assembly. The common idea behind all of the preparation methods is inducing electrostatic interactions between the nucleic acid and charged lipids and promoting nanoparticle growth via hydrophobic interactions. Third, we break down the LNP composition with special attention to the fundamental properties and purposes of each component. This includes the identified molecular design criteria, commercial sourcing, impact on intracellular trafficking, and contribution to the properties of LNPs. One of the key components of LNPs is ionizable lipids, which initiate electrostatic binding with endosomal membranes and facilitate cytosolic release; however, the roles of other lipid components should not be disregarded, as they are associated with stability, clearance, and distribution of LNPs. Fourth, we review the attributes of LNP constructs as a whole that can heavily influence RNA delivery. These attributes are LNP size, charge, internal structure, lipid packing, lipid membrane hydration, stability, and affinity toward biomacromolecules. We also discuss the specific techniques used to examine these attributes and how they can be adjusted. Finally, we offer our perspective on the future of RNA therapies and some questions that remain in the realm of LNP formulation and optimization.

Electroformation of Particulate Emulsions Using Lamellar and Nonlamellar Lipid Self-Assemblies

We report on the development of an electroformation technique for the preparation of particulate (particle-based) emulsions. These oil-in-water (here, lipid phase acts as an "oil") emulsions were prepared using nonlamellar lipid phases. Such emulsion particles offer high hydrophobic volumes compared to conventional lipid particles based on lamellar phases (vesicles/liposomes). In addition, the tortuous internal nanostructure contributes through greater surface area per volume of lipid particles allowing an enhanced loading of payloads. The electroformation method makes use of a capacitor formed from two indium tin oxide coated conductive glass surfaces separated by a dielectric aqueous medium. This capacitor setup is enclosed in a custom-designed 3D-printed unit. Lipid molecules, deposited on conductive surfaces, self-assemble into a nanostructure in the presence of an aqueous medium, which when subjected to an alternating current electric field forms nano- and/or microparticles. Optical microscopy, dynamic light scattering, and small-angle X-ray scattering techniques were employed for micro- and nanostructural analyses of electroformed particles. With this method, it is possible to produce particulate emulsions at a very low (e.g., 0.0005 wt % or 0.5 mg/mL) lipid concentration. We demonstrate an applicability of the electroformation method for drug delivery by preparing lipid particles with curcumin, which is a highly important but water-insoluble medicinal compound. As the method employs gentle conditions, it is potentially noninvasive for the delivery of delicate biomolecules and certain drugs, which are prone to decomposition or denaturation due to the high thermomechanical energy input and/or nonaqueous solvents required for existing methods.

Polymer-Lipid Hybrid Materials

Hierarchic self-assembly underpins much of the form and function seen in synthetic or biological soft materials. Lipids are paramount examples, building themselves in nature or synthetically in a variety of meso/nanostructures. Synthetic block copolymers capture many of lipid's structural and functional properties. Lipids are typically biocompatible and high molecular weight polymers are mechanically robust and chemically versatile. The development of new materials for applications like controlled drug/gene/protein delivery, biosensors, and artificial cells often requires the combination of lipids and polymers. The emergent composite material, a "polymer-lipid hybrid membrane", displays synergistic properties not seen in pure components. Specific examples include the observation that hybrid membranes undergo lateral phase separation that can correlate in registry across multiple layers into a three-dimensional phase-separated system with enhanced permeability of encapsulated drugs. It is timely to underpin these emergent properties in several categories of hybrid systems ranging from colloidal suspensions to supported hybrid films. In this review, we discuss the form and function of a vast number of polymer-lipid hybrid systems published to date. We rationalize the results to raise new fundamental understanding of hybrid self-assembling soft materials as well as to enable the design of new supramolecular systems and applications.

Uptake Dynamics of Cubosome Nanocarriers at Bacterial Surfaces and the Routes for Cargo Internalization

Antibiotic-resistant bacteria pose a significant threat to humanity. Gram-negative strains have demonstrated resistance to last resort antibiotics, partially due to their outer membrane, which hinders transport of antimicrobials into the bacterium. Nanocarrier (NC)-mediated drug delivery is one proposed strategy for combating this emerging issue. Here, the uptake of self-assembled lipid nanocarriers of cubic symmetry (cubosomes) into bacteria revealed fundamental differences in the uptake mechanism between Gram-positive and Gram-negative bacteria. For Gram-positive bacteria, the NCs adhere to the outer peptidoglycan layers and slowly internalize to the bacterium. For Gram-negative bacteria, the NCs interact in two stages, fusion with the outer lipid membrane and then diffusion through the inner wall. The self-assembled nature of the cubosomes imparts a unique ability to transfer payloads via membrane fusion. Remarkably, the fusion uptake mechanism allowed rapid NC internalization by the Gram-negative bacteria, overcoming the outer membrane responsible for their heightened resilience. Here this is demonstrated by the marked reduction in the minimal inhibition concentration required for antibiotics against a pathogenic strain of Gram-negative bacteria, Escherichia coli. These results provide mechanistic insight for the development of lipid NCs as a new tool to combat bacteria.

Breaking Isolation to Form New Networks: pH-Triggered Changes in Connectivity inside Lipid Nanoparticles

There is a growing demand to develop smart nanomaterials that are structure-responsive as they have the potential to offer enhanced dose, temporal and spatial control of compounds and chemical processes. The naturally occurring pH gradients found throughout the body make pH an attractive stimulus for guiding the response of a nanocarrier to specific locations or (sub)cellular compartments in the body. Here we have engineered highly sensitive lyotropic liquid crystalline nanoparticles that reversibly respond to changes in pH by altering the connectivity within their structure at physiological temperatures. At pH 7.4, the nanoparticles have an internal structure consisting of discontinuous inverse micellar "aqueous pockets" based on space group Fd3m. When the pH is ≤6, the nanoparticles change from a compartmentalized to an accessible porous internal structure based on a 2D inverse hexagonal phase (plane group p6mm). We validate the internal symmetry of the nanoparticles using small-angle X-ray scattering and cryogenic transmission electron microscopy. The high-resolution electron microscopy images obtained have allowed us for the first time to directly visualize the internal structure of the Fd3m nanoparticles and resolve the two different-sized inverse micelles that make up the structural motif within the Fd3m unit cell, which upon structural analysis reveal excellent agreement with theoretical geometrical models.

Cationic Liposomes as Vectors for Nucleic Acid and Hydrophobic Drug Therapeutics

Cationic liposomes (CLs) are effective carriers of a variety of therapeutics. Their applications as vectors of nucleic acids (NAs), from long DNA and mRNA to short interfering RNA (siRNA), have been pursued for decades to realize the promise of gene therapy, with approvals of the siRNA therapeutic patisiran and two mRNA vaccines against COVID-19 as recent milestones. The long-term goal of developing optimized CL-based NA carriers for a broad range of medical applications requires a comprehensive understanding of the structure of these vectors and their interactions with cell membranes and components that lead to the release and activity of the NAs within the cell. Structure-activity relationships of lipids for CL-based NA and drug delivery must take into account that these lipids act not individually but as components of an assembly of many molecules. This review summarizes our current understanding of how the choice of the constituting lipids governs the structure of their CL-NA self-assemblies, which constitute distinct liquid crystalline phases, and the relation of these structures to their efficacy for delivery. In addition, we review progress toward CL-NA nanoparticles for targeted NA delivery in vivo and close with an outlook on CL-based carriers of hydrophobic drugs, which may eventually lead to combination therapies with NAs and drugs for cancer and other diseases.

Calcium mediated DNA binding in non-lamellar structures formed by DOPG/glycerol monooleate

In order to test an encapsulation method of short fragmented DNA (∼ 20-300 bp), we study the solubilisation in 150 mM solution of NaCl of a cubic phase formed by glycerol monooleate (GMO) with negatively charged dioleoylphosphatidylglycerol (DOPG) up to the level of unilamellar vesicles and, subsequently, the restoration of the cubic phase using Ca²⁺ cations. We performed small angle X-ray and neutron scattering (SAXS and SANS) to follow structural changes in DOPG/GMO mixtures induced by increasing DOPG content. The cubic phase (Pn3m space group) is preserved up to ∼ 11 mol% of DOPG in DOPG/GMO. Above 20 mol%, the SANS curves are typical of unilamellar vesicles. The thickness of the DOPG/GMO lipid bilayer (d_L) decreases slightly with increasing fraction of DOPG. The addition of 15 mM of CaCl₂ solution shields the electrostatic repulsions of DOPG molecules, increases slightly d_L and restores the cubic structures in the mixtures up to ∼ 37 mol% of DOPG. Zeta potential shows negative surface charge. The analysis of the data provides the radius of the water nano-channels of the formed non-lamellar structures. We discuss their dimensions with respect to DNA binding. In addition, Ca²⁺ mediates DNA - DOPG/GMO binding. The formed hexagonal phase, H_II, binds less of DNA in comparison with cubic phases (∼ 6 wt% and ∼ 20 wt% of the total amount, respectively). The studied system can be utilized as anionic Q_II delivery vector for genetic material.

Dynamics in supramolecular nanomaterials

Self-assembly of amphiphilic small molecules in water leads to nanostructures with customizable structure-property relationships arising from their tunable chemistries. Characterization of these assemblies is generally limited to their static structures -e.g. their geometries and dimensions - but the implementation of tools that provide a deeper understanding of molecular motions has recently emerged. Here, we summarize recent reports showcasing dynamics characterization tools and their application to small molecule assemblies, and we go on to highlight supramolecular systems whose properties are substantially affected by their conformational, exchange, and water dynamics. This review illustrates the importance of considering dynamics in rational amphiphile design.