Dendritic Domains with Hexagonal Symmetry Formed by X-Shaped Bolapolyphiles in Lipid Membranes

• Published in: Chemistry : a European journal Vol. 21; no. 24; pp. 8840 - 8850
• Main Authors: Werner, Stefan, Ebert, Helgard, Lechner, Bob-Dan, Lange, Frank, Achilles, Anja, Bärenwald, Ruth, Poppe, Silvio, Blume, Alfred, Saalwächter, Kay, Tschierske, Carsten, Bacia, Kirsten
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 08-06-2015; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: bolapolyphiles; Chemistry; Corrugating; Corrugation; Lipids; Membranes; Nanostructure; Phospholipids; pi interactions; self-assembly; Stacking; Symmetry; membranes; self-assembly; lipids; pi interactions; bolapolyphiles
• ISSN: 0947-6539; 1521-3765; 1521-3765
• DOI: 10.1002/chem.201405994

A novel class of bolapolyphile (BP) molecules are shown to integrate into phospholipid bilayers and self‐assemble into unique sixfold symmetric domains of snowflake‐like dendritic shapes. The BPs comprise three philicities: a lipophilic, rigid, π–π stacking core; two flexible lipophilic side chains; and two hydrophilic, hydrogen‐bonding head groups. Confocal microscopy, differential scanning calorimetry, XRD, and solid‐state NMR spectroscopy confirm BP‐rich domains with transmembrane‐oriented BPs and three to four lipid molecules per BP. Both species remain well organized even above the main 1,2‐dipalmitoyl‐sn‐glycero‐3‐phosphocholine transition. The BP molecules only dissolve in the fluid membrane above 70 °C. Structural variations of the BP demonstrate that head‐group hydrogen bonding is a prerequisite for domain formation. Independent of the head group, the BPs reduce membrane corrugation. In conclusion, the BPs form nanofilaments by π stacking of aromatic cores, which reduce membrane corrugation and possibly fuse into a hexagonal network in the dendritic domains.
Coming together: Bolapolyphile (BP) molecules integrate into phospholipid bilayers and self‐assemble into unique sixfold symmetric domains of snowflake‐like dendritic shapes (see figure; DPPC=1,2‐dipalmitoyl‐sn‐glycero‐3‐phosphocholine). In these domains the BPs are transmembrane oriented and organized in π ‐stacked nano‐filaments.