Liquid crystal character controlled by complementary discotic molecules mixtures： Columnar stacking type and mesophase temperature range

In this work, the mesophase properties were tuned via mixing two discotic molecules with structural complementarity. Compared with the liquid crystalline hexakis（n-hexyloxy）triphenylene（H6TP）materials（columnar hexagonal phase from 53 ℃ to 91 ℃）, mesophase types as well as phase transition temperatures varied with the introduction of crystalline hexaazatriphenylene derivative（PBH）molecules. The introduction of less than 33% amount of PBH disrupted the columnar hexagonal phase formed by H6 TP remarkably, followed by the decreased clearing temperatures of liquid crystals. As the PBH amount was further increased, the destroyed columnar hexagonal phase was turned into the columnar rectangular phase, in which H6 TP and PBH molecules together formed the columnar mesophase. The formation of new mesophase contributed to the enlarged mesophase temperature（from44 ℃ to 144 ℃）. We speculated that the alkyl chains interaction induced by the PBH component competed with the strong p–p stacking between H6 TP molecules, thus altering the liquid crystalline properties including mesophase types and phase transition temperatures.

Tailoring active compounds across biological membranes by cubosomal technology: an updated review

It is challenging for many drugs to be transported across various biological membranes. Furthermore, development of many drugs gets thwarted owing to their hydrophilic nature. The bioavailability of such drugs, which is the function of their ability to cross the membrane, tends to be low and exhibit high intra and inter subject variability. At present, formulation scientists are pursuing many projects for transdermal, nasal, target delivery of many active compounds, and it is prudent to explore alternative possibilities. Cubosomes offer transportation and tailoring of active compounds intended for both systemic and dermal delivery. Cubosomes are dispersed, self-assembled nanoparticles of bicontinuous cubic liquid crystalline phase formed from lipid and surfactant systems. Monoolein, poloxamer 407 and polyvinyl alcohol are the mostly used ingredients in the formulation of cubosomes. The adjustment in lipid composition can control the internal and structural changes of cubosomes. Based on the nodal surfaces, three structures of cubosomes proposed are Pn3m, Ia3d and Im3m. Top-down and bottom-up techniques are widely considered in the formulation process of extreme viscous bulk phase and aggregate from a precursor respectively. This article gives a bird's eye view about the engineering, characterization and evaluation of cubosomes, covering researches and applications of cubosomes done till date.