Organic Composomes as Supramolecular Aptamers

Abstract

Information contained in the sequences of biological polymers such as DNA and protein is crucial to determining their function. Lipids are not generally thought of as information-containing molecules. However, from a supramolecular perspective, the number of possible combinations of lipids in a mixture is comparable to the complexity of DNA or proteins. Here, we test the idea that an organic composome can exhibit molecular recognition. We use water/octanol as a model two-phase system and investigate the effect of organic solutes in different combinations in the organic phase on selective partitioning of two water-soluble dyes (Brilliant Blue FCF and Allura Red AC) from the aqueous phase into the organic phase. We found that variation in the concentration of the surfactant cetyltrimethylamonium bromide (CTAB) in the octanol phase alone was sufficient to cause a switch in selectivity, with low CTAB concentrations being selective for the red dye and high CTAB concentrations being selective for the blue dye. Other organic components were added to the organic phase to introduce molecular diversity into the composome and directed evolution was used to optimize the relative concentrations of the solutes. An improvement of selective partitioning in the heterogeneous system over the pure CTAB solution was observed. The results indicate that supramolecular composomes are sufficient for molecular recognition processes in a way analogous to nucleic acid aptamers.

Aptamer Functionalized Lipid Multilayer Gratings for Label-Free Analyte Detection

“…Grating lines in this case are 300 nm, and grating heights are therefore expected to be less than 30 nm, which is more than 30 times thinner than the micrometer-thick multilayers from Figure 2. We hypothesized that the signal could be improved by varying the lipid composition [65]. Since cationic lipids are commonly used to incorporate nucleic acids into liposomes [66], we tested the effect of the cationic lipid DOTAP (Figure 3).…”

Dynamic lipid aptamers: non-polymeric chemical path to early life

“…We draw attention to a possible functional analogy of such lipid molecular configurations to aptamers, combinatorial segments of covalently threaded sequences of folded proteins or RNAs that can perform different molecular recognition tasks. 17 The lipid analogs may behave as non-covalent dynamic aptamers, 18 capable of specific recognition (Fig. 1).…”

“…Additional experimental evidence for small-molecule recognition at lipid surfaces comes from a study 18 in a water/octanol two-phase model system. The authors examine the differential efficacy of transfer of two dyes from the aqueous phase to the organic phase.…”

“…Finally, cellular information is traditionally attributed solely to sequence-based biological polymers such as RNA and proteins, while lipids, with a few exceptions, 5,6,37 are rarely thought of as information carriers. Yet, according to combinatorial analyses, lipid compositional information is comparable to sequence-based information of biopolymers, 18 and appears directly related to molecular recognition functions. 5 Complemented by the reported evidence in this Viewpoint, the Lipid-First scenario appears to share many early evolutionary capabilities with RNA-First, along with several characteristics in which it reveals superiority 38 (Fig.…”

Micellar Composition Affects Lipid Accretion Kinetics in Molecular Dynamics Simulations

“…While lipid-based non-covalent catalysis cases have been presented [16][17][18] , and some reports indicate that specific lipophiles may act as catalysts for the incorporation of new lipid monomers into vesicles 19,20 , limited molecular details have been obtained on the precise mechanism and dynamics of accretion into heterogeneous lipid assemblies. This involves a challenge to investigate the influence of variegated micellar compositions by monitoring picoseconds compositional changes within nanoscopic mixed micelles, so as to be able to track the entire accretion trajectory of multiple assemblies.…”