Long-Term Stable Liposome Modified by PEG-Lipid in Natural Seawater.

This paper describes the stabilization of liposomes using a PEGylated lipid, N-(methylpolyoxyethylene oxycarbonyl)-1,2-distearoyl-sn-glycero-3-phosphoethanolamine sodium salt (DSPE-PEGs), and the evaluation of the survival rate in natural seawater for future environmental applications. Liposomes in natural seawater were first monitored by confocal microscopy, and the stability was compared among different lengths and the introduction ratio of DSPE-PEGs. The survival rate increased with an increase in the PEG ratio. In addition, the survival rate in different cationic solutions (Na+, K+, Mg2+, and Ca2+ solutions) was studied to estimate the effects of the DSPE-PEG introduction. We propose that these variations in liposome stability are due to the cations, specifically the interaction between the poly(ethylene glycol) (PEG) chains and divalent ions, which contribute to making it difficult for cations to access the lipid membrane. Our studies provide insights into the use of PEG lipids and may offer a promising approach to the fabrication of liposomal molecular robots using different natural environments.

Lipid vesicle-based molecular robots.

A molecular robot, which is a system comprised of one or more molecular machines and computers, can execute sophisticated tasks in many fields that span from nanomedicine to green nanotechnology. The core parts of molecular robots are fairly consistent from system to system and always include (i) a body to encapsulate molecular machines, (ii) sensors to capture signals, (iii) computers to make decisions, and (iv) actuators to perform tasks. This review aims to provide an overview of approaches and considerations to develop molecular robots. We first introduce the basic technologies required for constructing the core parts of molecular robots, describe the recent progress towards achieving higher functionality, and subsequently discuss the current challenges and outlook. We also highlight the applications of molecular robots in sensing biomarkers, signal communications with living cells, and conversion of energy. Although molecular robots are still in their infancy, they will unquestionably initiate massive change in biomedical and environmental technology in the not too distant future.

Liposome Deformation Induced by Membrane-Binding Peptides.

This paper presents an investigation of liposome deformation and shape distortion using four membrane-binding peptides: TAT and C105Y as cell-penetrating peptides (CPPs), and melittin and ovispirin as antimicrobial peptides (AMPs). Liposome deformation was monitored utilizing fluorescent microscopy, while the binding of peptides to the DOPC membrane was estimated through capacitance measurements. The degree of liposome deformation and shape distortion was found to be higher for the CPPs compared to the AMPs. Additionally, it was observed that C105Y did not induce liposome rupture, unlike the other three peptides. We propose that these variations in liposome distortion may be attributed to differences in secondary structure, specifically the presence of an α-helix or random coil. Our studies offer insight into the use of peptides to elicit control of liposome architecture and may offer a promising approach for regulating the bodies of liposomal molecular robots.

Electrophysiological Analysis of Antimicrobial Peptides in Diverse Species.

This study describes a technical platform that allows us to measure the pore-forming activity of antimicrobial peptides (AMPs) in the lipid bilayer and estimate antimicrobial activity. We selected six different AMPs of diverse species from urochordata to vertebrata and measured the channel current signals using a microfabricated lipid bilayer system. As a result of the electrophysiological measurements, we were able to estimate the pore-forming activity and roughly predict the antimicrobial activity although there was not a strong correlation between the pore-forming activity and the variety of species. Our method will be a unique tool for analyzing a wide variety of diverse AMPs.