Condensed Supramolecular Helices: The Twisted Sisters of DNA

Abstract

Condensation of DNAh elices into hexagonally packed bundles and toroids represents an intriguing example of functional organization of biological macromolecules at the nanoscale.T he condensation models are based on the unique polyelectrolyte features of DNA, however here we could reproduce aD NA-like condensation with supramolecular helices of small chiral molecules,t hereby demonstrating that it is am ore general phenomenon. We showt hat the bile salt sodium deoxycholate can form supramolecular helices upon interaction with oppositely charged polyelectrolytes of homopolymer or blockc opolymers.A th igher order,acontrolled hexagonal packing of the helices into DNA-like bundles and toroids could be accomplished. The results disclose unknown similarities between covalent and supramolecular non-covalent helical polyelectrolytes,w hich inspire visionary ideas of constructing supramolecular versions of biological macromolecules.A sd rug nanocarriers the polymer-bile salt superstructures would get advantage of ac omplex chirality at molecular and supramolecular levels,w hose effect on the nanocarrier assisted drug efficiency is as till unexplored fascinating issue.

Interactions in Aqueous Mixtures of Cationic Hydroxyethyl Cellulose and Different Anionic Bile Salts

“…The findings from this work have provided a more detailed insight of the origin and characteristics of the interactions between bile salts of similar chemical structures and catHEC, which may be advantageous in the design of supplements and functional foods that can diminish the levels of blood cholesterol. As a comparison, it is interesting to note that NaDC is able to form long supramolecular helical structures upon the interaction with oppositely charged diblock copolymers . Based on these previous results, we could speculate whether the long thread-like connections between the large aggregates found in the catHEC/NaDC system (Figure b) have a helical structure.…”

“…In this study, we consider the interactions between a charged polymer (catHEC) and an oppositely charged surfactant (NaC or NaDC); this situation usually leads to strong association behavior in water. This is a complex process where features from both the surfactant and polyelectrolyte (e.g., surfactant structure and chirality, the charge density, chain conformation, hydrophobicity, and molecular weight of the polymer) can affect the associative interactions and lead to the formation of polyelectrolyte complexes. − At compositions near the charge neutralization point between the polyelectrolyte and the oppositely charged bile salt, associative macroscopic phase separation or coacervation is promoted. , This intricate process is often driven by both electrostatic attraction and hydrophobic interactions . However, macroscopic phase separation can be avoided by using instead of homopolyelectrolytes diblock copolymers composed of one polyelectrolyte and one nonionic block .…”

“…The bile salt micelles of the bile salts are formed through hydrophobic interactions followed by hydrogen bonding . The presence of one additional −OH group in NaC compared to NaDC makes NaC easier to dissolve in aqueous media, and the critical micelle concentrations of NaC and NaDC are ∼16 and ∼6 mM, respectively. , In this study, it is demonstrated that this minor difference in the chemical structure between NaC and NaDC has a vital impact on the strength of interaction between catHEC and the type of bile salt. A principle aim of this work was to investigate how minor variances in the chemical structure of the bile salt can give rise to fundamental differences in the rheological and structural behavior in aqueous mixtures of catHEC and bile salt.…”

“…However, macroscopic phase separation can be avoided by using instead of homopolyelectrolytes diblock copolymers composed of one polyelectrolyte and one nonionic block . We have previously investigated the complex formation between NaDC and different types of cationic diblock copolymers in aqueous media. ,, In one study, the results showed that it is possible to build supramolecular helices, based on self-assembled DC molecules as the result of the interaction with the diblock copolymer. These supramolecular helices were able to condense, without exhibiting macroscopic phase separation, into higher-order supramolecular structures upon increasing the NaDC concentration, in a DNA-like condensation process.…”

Noncovalent Bile Acid Oligomers as Facial Amphiphilic Antimicrobials

“…It is known that the micellization of sodium salts of bile acids upon increasing concentration is a stepwise process. The formation of premicelles is hypothesized in the first step below CMC and further associate with each other at a larger concentration, above CMC. − The CMC values of sodium cholate and sodium deoxycholate are 11.0 mM and 4.0 mM, respectively, and their surface tension values at CMC (expressed as γ CMC ) are all >46 mN·m –1 . , When the polyamines are added, surface tension values are reduced and all γ CMC values become stable in the range of 40–45 mN·m –1 , although some curves decrease first to thereafter reach this range. The final surface tension is dictated by the molecular packing of the unbound and bound bile acids with the polyamines at the air/water interface.…”