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Lipid molecules such as glycolipids that are modified with hydrophilic biopolymers participate in the biochemical reactions occurring on cell membranes. Their functions and efficiency are determined by the formation of microdomains and their physical properties. We investigated the morphology and properties of domains induced by the hydrophilic-polymer-modified lipid applying a polyethylene glycol (PEG)-modified lipid as a model modified lipid. We formed supported lipid bilayers (SLBs) using a 0–10 mol % range of PEG-modified lipid concentration (CPEG). We studied their morphology and fluidity by fluorescence microscopy, the fluorescence recovery after photobleaching method, and atomic force microscopy (AFM). Fluorescence images showed that domains rich in the PEG-modified lipid appeared and SLB fluidity decreased when CPEG ≥ 5%. AFM topographies showed that clusters of the PEG-modified lipid appeared prior to domain formation and the PEG-lipid-rich domains were observed as depressions. Frequency-modulati...

Formation of supported lipid bilayer (SLB) and additional structures of Escherichia coli (E. coli) lipids were investigated with fluorescence microscopy and atomic force microscopy. Ca2+ in the aqueous phase with concentration above 2 mM was necessary for the formation of SLB. Additional lipid structures, string-like structures, the second lipid bilayer, and multilayer stacking appeared on the first layer SLB depending on Ca2+ concentration. The bridging effect of Ca2+ between the negatively charged E. coli lipid bilayers and substrate is the dominant factor determining the two-dimensional and three-dimensional morphology of the E. coli lipid bilayer membranes.

Ferulic acid dimers with phenylindane skeletons were obtained from ferulic acid 1 in an acidic ethanol solution. The reaction conditions used to prepare the dimers or the ester were examined in detail, and the stereochemistries of the dimers were determined. The structural features of the dimers and the diastereoselective formation mechanisms involved in forming the two types of dimers (the racemic diastereomer 8α, which was a major product, and the racemic diastereomer 8γ, which was a minor product) were characterized.

As a bacterial model cell system, a reconstituted Escherichia coli (E. coli) cell membrane has been studied. The chemically extracted E. coli lipid mixture such as polar lipid extract (PLE) is widely used in the previous studies. These lipid extracts contain three main phospholipid classes, phosphatidylethanolamine (PE), phosphatidylglycerol (PG) and cardiolipin (CA). These lipids have different electrical and physical properties. However, the characters of the lipid bilayer membrane composed of each component have not been investigated. Understanding the behaviors of each lipid extract component leads to fabricating bacterial model membrane platforms, and to further understanding of roles of lipids in bacterial membrane reactions. In this study, we examined supported lipid bilayers of E. coli extracted PE, PG and CA on thermally oxidized SiO2/Si and mica substrates with fluorescence microscopy and atomic force microscopy.