The self-assembly phenomena on a special class of poly-hydroxy sugar surfactant have been studied extensively. This class of material is classified as amphitropic liquid crystals since they exhibit both thermotropic and lyotropic liquid crystalline properties. Hence the potential applications of these non-ionic surfactants are more versatile than those from the conventional lyotropic liquid crystals including those from thermotropic phases, but the latters are yet to be realized. Unfortunately, due to the lack of interest (or even awareness), fundamental studies in thermotropic glycolipids are scanty to support application development, and any tangible progress is often mired by the complexity of the sugar stereochemistry. However, some applications may be pursued from these materials by taking the advantage of the sugar chirality and the tilted structure of the lipid organization which implies ferroelectric behavior. Here, we present our studies on the stereochemical diversity of the sugar units in glycosides that form the thermotropic/lyotropic phases. The structure to property relationship compares different chain designs and other popular polyhydroxy compounds, such as monooleins and alkylpolyglucosides. Different structural properties of these glycosides are discussed with respect to their self-assembly organization and potential applications, such as delivery systems and membrane mimetic study.
Water-driven self-assembly of lipids displays a variety of liquid crystalline phases that are crucial for membrane functions. In this work, we characterized the temperature-induced phase transitions in aqueous self-assembly systems using steady-state and time-resolved fluorescence measurements. The polar head group region was investigated using tryptophan (Trp) and two of its ester derivatives, and the hydrophobic tail region was probed using pyrene. The spectral changes in tryptophan and pyrene were used as a benchmark to estimate the polarity of the head group region and the tail region, respectively. A basic medium was detected and estimated for the polar region in the inverse cubic phase of a Guerbet glycolipid and was attributed to the structural effect of the narrow nanochannels. All the studied lipid compositions show completely reversible temperature-induced phase transitions, reflecting the thermodynamic equilibrium structures of their mesophases. The results reveal a large degree of heterogeneity and flexibility of the lipid self-assembly which may be crucial for carrying out different biological functions.