Formation and Properties of a Self-Assembled Nanoparticle-Supported Lipid Bilayer Probed through Molecular Dynamics Simulations

Advancements in nanoscale delivery systems: optimizing intermolecular interactions for superior drug encapsulation and precision release

Nanoscale preparations, such as nanoparticles, micelles, and liposomes, are increasingly recognized in pharmaceutical technology for their high capability in tailoring the pharmacokinetics of the encapsulated drug within the body. These preparations have great potential in extending drug half-life, reducing dosing frequency, mitigating drug side effects, and enhancing drug efficacy. Consequently, nanoscale preparations offer promising prospects for the treatment of metabolic disorders, malignant tumors, and various chronic diseases. Nevertheless, the complete clinical potential of nanoscale preparations remains untapped due to the challenges associated with low drug loading degrees and insufficient control over drug release. In this review, we comprehensively summarize the vital role of intermolecular interactions in enhancing encapsulation and controlling drug release within nanoscale delivery systems. Our analysis critically evaluates the characteristics of common intermolecular interactions and elucidates the techniques employed to assess them. Moreover, we highlight the significant potential of intermolecular interactions in clinical translation, particularly in the screening and optimization of preparation prescriptions. By attaining a deeper understanding of intermolecular interaction properties and mechanisms, we can adopt a more rational approach to designing drug carriers, leading to substantial advancements in the application and clinical transformation of nanoscale preparations. Moving forward, continued research in this field offers exciting prospects for unlocking the full clinical potential of nanoscale preparations and revolutionizing the field of drug delivery.

The Effect of Ethanol on Lipid Nanoparticle Stabilization from a Molecular Dynamics Simulation Perspective

Lipid nanoparticles (LNPs) have emerged as a promising delivery system, particularly for genetic therapies and vaccines. LNP formation requires a specific mixture of nucleic acid in a buffered solution and lipid components in ethanol. Ethanol acts as a lipid solvent, aiding the formation of the nanoparticle's core, but its presence can also affect LNP stability. In this study, we used molecular dynamics (MD) simulations to investigate the physicochemical effect of ethanol on LNPs and gain a dynamic understanding of its impact on the overall structure and stability of LNPs. Our results demonstrate that ethanol destabilizes LNP structure over time, indicated by increased root mean square deviation (RMSD) values. Changes in the solvent-accessible surface area (SASA), electron density, and radial distribution function (RDF) also suggest that ethanol affects LNP stability. Furthermore, our H-bond profile analysis shows that ethanol penetrates the LNP earlier than water. These findings emphasize the importance of immediate ethanol removal in lipid-based systems during LNP production to ensure stability.

Characterizing the Interactions of Cell Membrane-Disrupting Peptides with Lipid-Functionalized Single-Walled Carbon Nanotube Systems for Antimicrobial Screening

Lipid-functionalized single-walled carbon nanotubes (SWNTs) have garnered significant interest for their potential use in a wide range of biomedical applications. In this work, we used molecular dynamics simulations to study the equilibrium properties of SWNTs surrounded by the phosphatidylcholine (POPC) corona phase, and their interactions with three cell membrane disruptor peptides: colistin, TAT peptide, and crotamine-derived peptide. Our results show that SWNTs favor asymmetrical positioning within the POPC corona, so that one side of the SWNT, covered by the thinnest part of the corona, comes in contact with charged and polar functional groups of POPC and water. We also observed that colistin and TAT insert deeply into POPC corona, while crotamine-derived peptide only adsorbs to the corona surface. Compared to crotamine-derived peptide, colistin and TAT also induce larger perturbations in the thinnest region of the corona, by allowing more water molecules to directly contact the SWNT surface. In separate simulations, we show that three examined peptides exhibit similar insertion and adsorption behaviors when interacting with POPC bilayers, confirming that peptide-induced perturbations to POPC in conjugates and bilayers are similar in nature and magnitude. Furthermore, we observed correlations between the peptide-induced structural perturbations and the near-infrared emission of the lipid-functionalized SWNTs, which suggest that the optical signal of the conjugates transduces the morphological changes in the lipid corona. Overall, our findings indicate that lipid-functionalized SWNTs could serve as simplified cell membrane model systems for pre-screening of new antimicrobial compounds that disrupt cell membranes.

Coarse-grained simulation of the self-assembly of lipid vesicles concomitantly with novel block copolymers with multiple tails

We carried out a series of coarse-grained molecular dynamics liposome-copolymer simulations with varying extent of copolymer concentration in an attempt to understand the effect of copolymer structure and concentration on vesicle self-assembly and stability. For one particular case molecular dynamics simulation data was successfully verified against experimental NMR results enhancing the credulity in the simulation methodology. The study focused on a new class of promising copolymers based on ethylene oxide (EO) chains and short blocks of aliphatic double chains that mimic lipid tails. The lipid mimetic units are based on 1,3-didodecyloxy-2-glycidylglycerol (DDGG) and 1,3-didodecyloxy-propane-2-ol (DDP). The conducted simulations indicate that multiple lipid anchor-bearing copolymers lead to stable hybrid liposome formations. Single lipid bearing might incur liposome-stabilizing potential for relatively small ethylene oxide chains but fails dramatically in combination with a longer EO-based moiety. The consistency of the theoretical evidence with experimental NMR observation for certain cases provides confidence for the relevance of the methodology in eliciting the factors governing liposome-polymer stability which is of fundamental and practical significance.

Lipid-polymer hybrid nanoparticles in cancer therapy: current overview and future directions

Cancer remains one of the leading cause of death worldwide. Current therapies are still ineffective in completely eradicating the disease. In the last two decades, the use of nanodelivery systems has emerged as an effective way to potentiate the therapeutic properties of anti-cancer drugs by improving their solubility and stability, prolong drug half-lives in plasma, minimize drug’s toxicity by reducing its off-target distribution, and promote drugs’ accumulation at the desired target site. Liposomes and polymer nanoparticles are the most studied and have demonstrated to be the most effective delivery systems for anti-cancer drugs. However, both liposomes and polymeric nanoparticles suffer from limitations, including high instability, rapid drug release, limited drug loading capacity, low biocompatibility and lack of suitability for large-scale production. To overcome these limitations, lipid-polymer hybrid nanoparticles (LPHNPs) have been developed to merge the advantages of both lipid- and polymer-based nanocarriers, such as high biocompatibility and stability, improved drug loading and controlled release, as well as increased drug half-lives and therapeutic efficacy. This review provides an overview on the synthesis, properties and application of LPHNPs for cancer therapy.

Lipid flip-flop and desorption from supported lipid bilayers is independent of curvature

Flip-flop of lipids of the lipid bilayer (LBL) constituting the plasma membrane (PM) plays a crucial role in a myriad of events ranging from cellular signaling and regulation of cell shapes to cell homeostasis, membrane asymmetry, phagocytosis, and cell apoptosis. While extensive research has been conducted to probe the lipid flip flop of planar lipid bilayers (LBLs), less is known regarding lipid flip-flop for highly curved, nanoscopic LBL systems despite the vast importance of membrane curvature in defining the morphology of cells and organelles and in maintaining a variety of cellular functions, enabling trafficking, and recruiting and localizing shape-responsive proteins. In this paper, we conduct molecular dynamics (MD) simulations to study the energetics, structure, and configuration of a lipid molecule undergoing flip-flop and desorption in a highly curved LBL, represented as a nanoparticle-supported lipid bilayer (NPSLBL) system. We compare our findings against those of a planar substrate supported lipid bilayer (PSSLBL). Our MD simulation results reveal that despite the vast differences in the curvature and other curvature-dictated properties (e.g., lipid packing fraction, difference in the number of lipids between inner and outer leaflets, etc.) between the NPSLBL and the PSSLBL, the energetics of lipid flip-flop and lipid desorption as well as the configuration of the lipid molecule undergoing lipid flip-flop are very similar for the NPSLBL and the PSSLBL. In other words, our results establish that the curvature of the LBL plays an insignificant role in lipid flip-flop and desorption.