Bicontinuous cubic phases in biological and artificial self-assembled systems

Abstract

Nature has created innumerable life forms with miraculous hierarchical structures and morphologies that are optimized for different life events through evolution over billions of years. Bicontinuous cubic structures, which are often described by triply periodic minimal surfaces (TPMSs) and their constant mean curvature (CMC)/parallel surface companions, are of special interest to various research fields because of their complex form with unique physical functionalities. This has prompted the scientific community to fully understand the formation, structure, and properties of these materials. In this review, we summarize and discuss the formation mechanism and relationships of the relevant biological structures and the artificial self-assembly systems. These structures can be formed through biological processes with amazing regulation across a great length scales; nevertheless, artificial construction normally produces the structure corresponding to the molecular size and shape. Notably, the block copolymeric system is considered to be an applicable and attractive model system for the study of biological systems due to their versatile design and rich phase behavior. Some of the phenomena found in these two systems are compared and discussed, and this information may provide new ideas for a comprehensive understanding of the relationship between molecular shape and resulting interface curvature and the selfassembly process in living organisms. We argue that the copolymeric system may serve as a model to understand these biological systems and could encourage additional studies of artificial self-assembly and the creation of new functional materials.

Structural responses of model biomembranes to Mars-relevant salts

“…For example, they are used as slow drug release systems in pharmacology. 60,61 Remarkably, such structures have also been discovered in biological systems, such as in chloroplasts (thylakoid membranes) and the inner mitochondrial membrane, and planar biological membranes have been found to fold into cubic membranes in response to external stresses such as starvation. 60,61 Interestingly, even in 1 M concentrations of sodium perchlorate salt lipid vesicles were still preserved with only some fluidizing effect.…”

“…60,61 Remarkably, such structures have also been discovered in biological systems, such as in chloroplasts (thylakoid membranes) and the inner mitochondrial membrane, and planar biological membranes have been found to fold into cubic membranes in response to external stresses such as starvation. 60,61 Interestingly, even in 1 M concentrations of sodium perchlorate salt lipid vesicles were still preserved with only some fluidizing effect. Vesicular structures are well preserved for the all-fluid phospholipid bilayer DOPC and the bacterial model membrane DOPE : DOPG (70 : 30) owing to the high conformational disorder of their cis-unsaturated acyl chains (e.g., T m (1 bar) E À22 1C, dT m /dp E 10 1C kbar À1 for DOPC bilayers).…”

Electroanalytical Biosensors for Circulating Tumor DNA Detection—A Brief Review

“…The biomolecular recognition elements of ctDNA biosensor can be categorized into enzymes, nucleic acids, simulated enzymes, immune substances, etc [11] . Biomolecular probes can be fixed on the surface of biosensor by physical adsorption [17] , covalent bonding [18][19][20] , embedding [21][22][23] , self-assembled membrane [24][25][26] , affinity [27,28] and other methods, as shown in Fig. 2.…”

Cell mechanics and signalisation: SARS-CoV-2 hijacks membrane liquid crystals and cytoskeletal fractal topology

“…In a planar membrane, as the cell membrane, the two are equal, as is also roughly the case for the viral membrane, at the cost of dissymmetry between the inner and outer sides. The infection mechanism involves the development of a tube (or tunnel) between the two membranes, in the form of a hyperboloid, figure 1 (i.e., with negative Gaussian curvature of surface) which is only stable if the polar heads occupy more lateral space than the hydrophobic chains [58]. This is a classic mechanism in phase transition from lamellar structures to "cubic" or "hexagonal" phases (see this book [59] and in particular the chapter by Charvolin et al).…”