Effect of Cholesterol on Nano-Structural Alteration of Light-Activatable Liposomes via Laser Irradiation: Small Angle Neutron Scattering Study

Effect of Solvent and Cholesterol on Liposome Production by the Reverse-Phase Evaporation (RPE) Method

Liposomal drug delivery is a promising approach for delivering therapeutics effectively. While most liposomes are designed to be nanometer-sized for efficient cellular uptake, micron-sized liposomes are gaining interest due to their larger drug-loading capacity. When combined with macroscale structures, such as implants and hydrogels, they offer prolonged therapeutic delivery. This study investigates how solvents affect the production of micron-sized liposomes, with or without cholesterol, using the reverse-phase evaporation (RPE) method. Although the RPE method is established for producing micron-sized liposomes, the influence of solvents on liposome size and uniformity is not well understood. The study explores whether controlling the size of inverse micelles, an intermediate product, through the use of different organic solvents affects the final liposome size. Three solvents─diethyl ether, methanol, and acetone─were tested for their effect on the formation of inverse micelles and liposomes and their sizes. Results showed that without cholesterol, diethyl ether produced uniform inverse micelles, leading to mostly nanosized liposomes. Methanol and acetone resulted in phase separation, preventing uniform liposome formation, although some micron-sized liposomes appeared. The acetone sample yielded mostly oil droplets. The results showed that forming inverse micelles lead to nanosized liposomes. With cholesterol, phase separation was dominant in methanol, but micron-sized liposomes still formed. Across all cases, cholesterol reduced the liposome size. The findings reveal that inverse micelles are not always reliable predictors of the final liposome size and that the RPE method is highly sensitive to solvent polarity and lipid-solvent interactions. Overall, the findings of this study provide valuable insights into how the choice of solvent and lipid composition can influence the production of liposomes via the RPE method. These insights are critical for optimizing liposome production and influencing future designs of liposomal 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.

Development of Robust Cationic Light-Activated Thermosensitive Liposomes: Choosing the Right Lipids

Extensive research has been conducted on cationic light-activated thermosensitive liposomes (CLTSLs) as a means for site-specific and controlled drug release; however, less attention has been given to the stability of these nanoparticles. Selecting the appropriate lipids is crucial for the development of a stable and responsive system. In this study, we investigated the impact of various lipids on the physical properties of cationic light-activated liposomes. Incorporating poly(ethylene glycol) PEG molecules resulted in uniform liposomes with low polydispersity index, while the addition of unsaturated lipid (DOTAP) resulted in extremely leaky liposomes, with almost 80% release in just 10 min of incubation at body temperature. Conversely, the inclusion of cholesterol in the formulation increased liposome stability too much and decreased their sensitivity to stimuli-responsive release, with only 14% release after 2 min of light exposure. To achieve stable and functional CLTSL, we substituted an equivalent amount of unsaturated lipid with a saturated lipid (DPTAP), resulting in stable liposomes at body temperature that were highly responsive to light, releasing 90% of their content in 10 s of light exposure. We also conducted two atomistic molecular dynamics simulations using lipid compositions with saturated and unsaturated lipids to investigate the effect of lipid composition on the dynamical properties of the liposomal lipid bilayer. Our findings suggest that the nature of lipids used to prepare liposomes significantly affects their properties, especially when the drug loading needs to be stable but triggered drug release properties are required at the same time. Selecting the appropriate lipids in the right amount is therefore essential for the preparation of liposomes with desirable properties.

ZnSe@NPSC core-shell nanorods for super sodium ion storage induced from an organic polymer derived N, P, S tri-doped carbon framework

In this work, core-shell structured ZnSe@NPSC nanorods were prepared with a N, P, S hetero-doped carbon shell. The design of the core-shell structure is conducive to facilitating the transport of electrons and buffering the volume expansion during charge/discharge processes, which is favourable for improving the sodium ion storage properties of ZnSe@NPSC. Therefore, it can deliver capacities of 376.67 mA h g-1 after 150 cycles at 0.5 A g-1 and 359.1 mA h g-1 after cycling for 350 cycles at 1.0 A g-1, respectively.

Use of sodium alginate coatings to improve bioavailability of liposomes containing DPP-IV inhibitory collagen peptides

Sodium alginate (SA) was used to coat liposomes containing DPP-IV inhibitory collagen peptides to improve their stability and in vitro absorption for intra-oral delivery. The liposome structure as well as entrapment efficiency and DPP-IV inhibitory activity was characterized. The liposome stability was determined by measuring in vitro release rates and their gastrointestinal stability. Transcellular permeability of liposomes was further tested to characterize their permeability in small intestinal epithelial cells. The results showed that the 0.3% SA coating increased the diameter (166.7 nm to 249.9 nm), absolute value of zeta potential (30.2 mV to 40.1 mV) and entrapment efficiency (61.52% to 70.99%) of liposomes. The SA-coated liposomes containing collagen peptides showed enhanced storage stability within one month, gastrointestinal stability increased by 50% in bioavailability, transcellular permeability increased by 18% in transmission percentage, and in vitro release rates reduced by 34%, compared to uncoated liposomes. SA coating liposomes are promising carriers for transporting hydrophilic molecules, may be beneficial for improving nutrient absorption and can protect bioactive compounds from being inactivated in the gastrointestinal tract.

Lipid-Based Nano-Sized Cargos as a Promising Strategy in Bone Complications: A Review

Bone metastasis has been considered the fatal phase of cancers, which remains incurable and to be a challenge due to the non-availability of the ideal treatment strategy. Unlike bone cancer, bone metastasis involves the spreading of the tumor cells to the bones from different origins. Bone metastasis generally originates from breast and prostate cancers. The possibility of bone metastasis is highly attributable to its physiological milieu susceptible to tumor growth. The treatment of bone-related diseases has multiple complications, including bone breakage, reduced quality of life, spinal cord or nerve compression, and pain. However, anticancer active agents have failed to maintain desired therapeutic concentrations at the target site; hence, uptake of the drug takes place at a non-target site responsible for the toxicity at the cellular level. Interestingly, lipid-based drug delivery systems have become the center of interest for researchers, thanks to their biocompatible and bio-mimetic nature. These systems possess a great potential to improve precise bone targeting without affecting healthy tissues. The lipid nano-sized systems are not only limited to delivering active agents but also genes/peptide sequences/siRNA, bisphosphonates, etc. Additionally, lipid coating of inorganic nanomaterials such as calcium phosphate is an effective approach against uncontrollable rapid precipitation resulting in reduced colloidal stability and dispersity. This review summarizes the numerous aspects, including development, design, possible applications, challenges, and future perspective of lipid nano-transporters, namely liposomes, exosomes, solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC), and lipid nanoparticulate gels to treat bone metastasis and induce bone regeneration. Additionally, the economic suitability of these systems has been discussed and different alternatives have been discussed. All in all, through this review we will try to understand how far nanomedicine is from clinical and industrial applications in bone metastasis.