Hydration of surfactant-modified and PEGylated cationic cholesterol-based liposomes and corresponding lipoplexes by monitoring a fluorescent probe and the dielectric relaxation time

Elucidating Structural Configuration of Lipid Assemblies for mRNA Delivery Systems

The development of mRNA delivery systems utilizing lipid-based assemblies holds immense potential for precise control of gene expression and targeted therapeutic interventions. Despite advancements in lipid-based gene delivery systems, a critical knowledge gap remains in understanding how the biophysical characteristics of lipid assemblies and mRNA complexes influence these systems. Herein, we investigate the biophysical properties of cationic liposomes and their role in shaping mRNA lipoplexes by comparing various fabrication methods. Notably, an innovative fabrication technique called the liposome under cryo-assembly (LUCA) cycle, involving a precisely controlled freeze-thaw-vortex process, produces distinctive onion-like concentric multilamellar structures in cationic DOTAP/DOPE liposomes, in contrast to a conventional extrusion method that yields unilamellar liposomes. The inclusion of short-chain DHPC lipids further modulates the structure of cationic liposomes, transforming them from multilamellar to unilamellar structures during the LUCA cycle. Furthermore, the biophysical and biological evaluations of mRNA lipoplexes unveil that the optimal N/P charge ratio in the lipoplex can vary depending on the structure of initial cationic liposomes. Cryo-EM structural analysis demonstrates that multilamellar cationic liposomes induce two distinct interlamellar spacings in cationic lipoplexes, emphasizing the significant impact of the liposome structures on the final structure of mRNA lipoplexes. Taken together, our results provide an intriguing insight into the relationship between lipid assembly structures and the biophysical characteristics of the resulting lipoplexes. These relationships may open the door for advancing lipid-based mRNA delivery systems through more streamlined manufacturing processes.

Physicochemical Factors That Influence the Biocompatibility of Cationic Liposomes and Their Ability to Deliver DNA to the Nuclei of Ovarian Cancer SK-OV-3 Cells

Cationic liposomes composed of 3-[N-(N',N'-dimethylaminoethane)-carbamoyl] cholesterol (DC-chol) and dioleoylphosphatidylethanolamine (DOPE) have previously been shown to have applications in gene delivery. Our study aims to explore the effects of inclusion of polyethylene glycol (PEG) and using different molar ratios of DC-chol/DOPE on size, zeta potential, cytotoxicity and DNA delivery of DC-chol/DOPE liposomes. Our results show that PEGylation reduces the cytotoxicity of DC-chol/DOPE liposomes, and, furthermore, PEGylated liposome-DNA lipoplexes are smaller in size and more uniform in size distribution than those that are not PEGylated. Additionally, toxicity against ovarian cancer SKOV-3 cells decreases with the amount of cationic DC-chol present in the formulation; however, decreased delivery of DNA to cellular nuclei is also observed. Transfection with the PEGylated liposomes was successfully demonstrated using plasmid DNA with a known functional outcome. These results offer further insight into physicochemical properties important for cationic liposomes as vehicles for DNA delivery and demonstrate the potential of PEGylated DC-chol/DOPE liposomes as systemic delivery carriers for DNA-mediated ovarian cancer therapy.

Slp-coated liposomes for drug delivery and biomedical applications: potential and challenges

Slp forms a crystalline array of proteins on the outermost envelope of bacteria and archaea with a molecular weight of 40-200 kDa. Slp can self-assemble on the surface of liposomes in a proper environment via electrostatic interactions, which could be employed to functionalize liposomes by forming Slp-coated liposomes for various applications. Among the molecular characteristics, the stability, adhesion, and immobilization of biomacromolecules are regarded as the most meaningful. Compared to plain liposomes, Slp-coated liposomes show excellent physicochemical and biological stabilities. Recently, Slp-coated liposomes were shown to specifically adhere to the gastrointestinal tract, which was attributed to the "ligand-receptor interaction" effect. Furthermore, Slp as a "bridge" can immobilize functional biomacromol-ecules on the surface of liposomes via protein fusion technology or intermolecular forces, endowing liposomes with beneficial functions. In view of these favorable features, Slp-coated liposomes are highly likely to be an ideal platform for drug delivery and biomedical uses. This review aims to provide a general framework for the structure and characteristics of Slp and the interactions between Slp and liposomes, to highlight the unique properties and drug delivery as well as the biomedical applications of the Slp-coated liposomes, and to discuss the ongoing challenges and perspectives.

Preferential Adsorption of l-Histidine onto DOPC/Sphingomyelin/3β-[N-(N',N'-dimethylaminoethane)carbamoyl]cholesterol Liposomes in the Presence of Chiral Organic Acids

We investigated the effect of organic acids such as mandelic acid (MA) and tartaric acid (TA) on the adsorption behavior of both histidine (His) and propranolol (PPL) onto liposomes. A cationic and heterogeneous liposome prepared using 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/sphingomyelin (SM)/3β-[N-(N',N'-dimethylaminoethane)carbamoyl]cholesterol (DC-Ch) in a ratio of (4/3/3) showed the highest adsorption efficiency of MA and TA independent of chirality, while neutral liposome DOPC/SM/cholesterol = (4/3/3) showed low efficiency. As expected, electrostatic interactions were dominant in MA or TA adsorption onto DOPC/SM/DC-Ch = (4/3/3) liposomes, suggesting that organic acids had adsorbed onto SM/DC-Ch-enriched domains. The adsorption behaviors of organic acids onto DOPC/SM/DC-Ch = (4/3/3) were governed by Langmuir adsorption isotherms. For adsorption, the membrane polarities slightly decreased (i.e., membrane surface was hydrophilic), but no alterations in membrane fluidity were observed. In the presence of organic acids that had been preincubated with DOPC/SM/DC-Ch = (4/3/3), the adsorption of l- and d-His onto those liposomes was examined. Preferential l-His adsorption was dramatically prevented only in the presence of l-MA, suggesting that the adsorption sites for l-His and l-MA on DOPC/SM/DC-Ch = (4/3/3) liposomes are competitive, while those for l-His and d-MA, l-TA, and d-TA are isolated.

Atomic Force Microscopic Analysis of the Effect of Lipid Composition on Liposome Membrane Rigidity

Mechanical rigidity of the liposome membrane is often defined by the membrane bending modulus and is one of the determinants of liposome stability, but the quantitative experimental data are still limited to a few kinds of liposomes. Here, we used atomic force microscopy to investigate the membrane bending moduli of liposomes by immobilizing them on bovine serum albumin-coated glass in aqueous medium. The following lipids were used for liposome preparation: egg yolk phosphatidylcholine, dioleoylphosphatidylcholine, hydrogenated soybean phosphatidylcholine, dipalmitoylphosphatidylcholine, 1,2-dioleoyl-3-trimethylammonium-propane, cholesterol, and N-(carbonylmethoxypoly(ethylene glycol) 2000)-1,2-distearoyl-sn-glycero-3-phosphoethanolamine. By using liposomes of various compositions, we showed that the thermodynamic phase state of the membrane rather than the electric potential or liposome surface modification with poly(ethylene glycol) is the predominant determinant of the bending modulus, which decreased in the following order: solid ordered > liquid ordered > liquid disordered. By using the generalized polarization value of the Laurdan fluorescent probe, we investigated membrane rigidity in terms of membrane fluidity. Atomic force microscopic analysis was superior to the Laurdan method, especially in evaluating the membrane rigidity of liposomes containing hydrogenated soybean phosphatidylcholine and cholesterol. Positively charged liposomes with a large bending modulus were taken up by cells more efficiently than those with a small bending modulus. These findings offer a quantitative method of analyzing the membrane rigidity of nanosized liposomes with different lipid compositions and will contribute to the control of liposome stability and cellular uptake efficiency of liposomal formulations intended for clinical use.

Elucidation of the physicochemical properties and potency of siRNA-loaded small-sized lipid nanoparticles for siRNA delivery

Because nanoparticles with diameters less than 50nm penetrate stromal-rich tumor tissues more efficiently, the synthesis of small-sized nanoparticles encapsulating short interfering RNA (siRNA) is important in terms of realizing novel siRNA medicine for the treatment of various cancers. Lipid nanoparticles (LNPs) are the leading systems for the delivery of siRNA in vivo. Limit size LNPs were successfully synthesized using a microfluidic mixing technique. However, the physicochemical properties and potential for in vivo siRNA delivery of the limit-size LNPs have not been examined in detail. In the present study, we prepared LNPs with different diameters from 32 to 67nm using a microfluidic mixing devise and examined the physicochemical properties of the particles and the potential for their use in delivering siRNA in vitro and in vivo to liver. Reducing the size of the LNPs causes poor-packing and an increased surface area, which result in their instability in serum. Moreover, it was revealed that the ability of endosomal escape (cytosolic siRNA release) of the smaller LNPs is subject to inhibition by serum compared to that of larger counterparts. Taken together, an increase in packing and avoiding the adsorption of serum components are key strategies for the development of next-generation highly potent and small-sized LNPs.

Efficacy of pegylated liposomal etoposide nanoparticles on breast cancer cell lines

BACKGROUND/AIM

This study aimed to investigate the efficacy of pegylated liposomal etoposide nanoparticles (NPs) against T-47D and MCF-7 breast cancer cell lines.

MATERIALS AND METHODS

Pegylated liposomal etoposide NPs were prepared by reverse phase evaporation method. The size, size distribution, and zeta potential of the NPs was measured by a Zetasizer instrument. The cytotoxicity of NPs was inspected by methyl thiazol tetrazolium assay. The release pattern of the drug from the vesicles was studied by the dialysis method. Drug loading and encapsulation efficiency (EE) were also measured.

RESULTS

The mean size, size distribution, and zeta potential of pegylated liposomal etoposide NPs were 491 ± 15.5 nm, 0.504 ± 0.14, and -35.8 ± 2.5 mV, respectively. Drug loading and EE were 10.3 ± 1.6% and 99.1 ± 2.8%, respectively. The etoposide release in the formulation was estimated at about 3.48% after 48 h. The cytotoxicity effect of etoposide NPs on T-47D and MCF-7 cell lines of breast cancer showed higher antitumor activity as compared with those of the free drug.

CONCLUSION

Liposome-based NPs may hold great potential as a drug delivery system.

Hybrid cholesterol-based nanocarriers containing phosphorescent Ir complexes: in vitro imaging on glioblastoma cell line

Recently the use of phosphorescent heavy-metal complexes in bioimaging techniques has been a promising research field and has been attracted increasing interest.

Terpene-containing PEGylated liposomes as transdermal carriers of a hydrophilic compound

We investigated the effect of PEGylated liposomes (PLs) containing a terpene on the penetration of a hydrophilic compound through porcine skin. PLs composed of N-(carbonyl-methoxypolyethyleneglycol-2000)-1,2-distearoyl-sn-glycero-3-phosphoethanolamine (PEG2000-DSPE), the sodium salt of PEG2000-DSPE, phosphatidylcholine (PC), cholesterol (Chol), Tween 20, and d-limonene were prepared as carriers for fluorescein sodium (NaFI). The physicochemical characteristics of PLs and their effects on in vitro skin penetration were evaluated. Tape stripping was used to evaluate NaFI deposition in skin layers, and confocal laser scanning microscopy (CLSM) was used to investigate the depth of skin penetration and the pathways used by NaFI-loaded vesicles. PLs containing d-limonene were smaller and conferred higher entrapment efficiency and skin penetration on NaFI than did PLs and conventional liposomes (CLs). The deposition of NaFI from PLs with d-limonene was greater in epidermis and dermis (6.10±1.74 µg) than stratum corneum (2.06±0.47 µg). CLSM images revealed that NaFI penetrated into the deepest skin layer with maximum fluorescence intensity. NaFI penetrated deeper (180 µm) in follicular than nonfollicular regions (145 µm), suggesting a transfollicular pathway predominates in skin penetration by NaFI-loaded PLs. In conclusion, grafting PEG onto ultra-deformable liposomes may enhance transdermal NaFI delivery and may be used as a carrier to prolong liposome circulation time.

A new class of pegylated plasmonic liposomes: synthesis and characterization

The multifunctional nanoobjects that can be controlled, manipulated and triggered using external stimuli represent very promising candidates for nanoscale therapeutic and diagnostic applications. In this study we report the successful synthesis and characterization of a new class of very stable multifunctional nanoobjects, containing cationic liposomes decorated with PEGylated gold nanoparticles (PEGAuNPs). The multifunctional hybrid nanoobjects (mHyNp) were prepared by taking advantage of the electrostatic interactions between small unilamelar cationic liposomes and negatively charged gold nanoparticles. The mHyNps have been investigated by UV-VIS absorption spectroscopy, Dynamic Light Scattering (DLS), Zeta Potential Measurements and Transmission Electron Microscopy (TEM). The TEM images clearly revealed the attachment of individual gold nanoparticles onto the spherical outer surface of the cationic liposomes which was also confirmed by DLS and UV-VIS data. Furthermore, the plasmonic properties of the hybrid complexes have been evaluated by using the Surface Enhanced Raman Spectroscopy (SERS) technique. It is shown that PEG mediated interaction between the liposomes and the gold nanoparticles enabled the recording of the SER spectra of the liposomes in aqueous environment, thus demonstrating the plasmonic properties of the hybrids.

Recent trends in multifunctional liposomal nanocarriers for enhanced tumor targeting

Liposomes are delivery systems that have been used to formulate a vast variety of therapeutic and imaging agents for the past several decades. They have significant advantages over their free forms in terms of pharmacokinetics, sensitivity for cancer diagnosis and therapeutic efficacy. The multifactorial nature of cancer and the complex physiology of the tumor microenvironment require the development of multifunctional nanocarriers. Multifunctional liposomal nanocarriers should combine long blood circulation to improve pharmacokinetics of the loaded agent and selective distribution to the tumor lesion relative to healthy tissues, remote-controlled or tumor stimuli-sensitive extravasation from blood at the tumor's vicinity, internalization motifs to move from tumor bounds and/or tumor intercellular space to the cytoplasm of cancer cells for effective tumor cell killing. This review will focus on current strategies used for cancer detection and therapy using liposomes with special attention to combination therapies.