Synthetic Multifunctional Nanoarchitecture in Lipid Bilayers: Ion Channels, Sensors, and Photosystems

Abstract

The creation of functional materials such as ion channels, porous sensors, or smart photosystems depends critically on our ability to assemble sophisticated, error-free and self-repairing nanoarchitecture in a predictable manner. To address these challenging topics, we often used lipid bilayer membranes as compartmentalizing platform and have introduced rigid-rod molecules as privileged scaffolds that bypass all folding problems because they do not fold. This approach provides access to motifs such as rigid-rod barrels, helices, stacks, slides, and wires that can act as smart, stimuli-responsive photosystems, pores, ion channels, hosts, sensors, and catalysts. The selected examples focus on naphthalenediimides (NDIs), a compact, organizable, colorizable, and functionalizable n-semiconductor. This versatile module is used in rigid-rod molecules to mediate transmembrane anion transport by anion-interactions, as sticky -clamp within pore sensors to catch otherwise elusive analytes by aromatic electron donor-acceptor interactions, or in blue, transmembrane -stack architecture to collect and convert photonic energy. These specific examples with multifunctional NDI nanoarchitecture are of help to outline, on the one hand, possibilities to contribute to advanced functional materials such as multianalyte sensors or solar cells and, on the other hand, to keep on wondering about an enormous structural and functional space waiting to be explored.In biology, highest sophistication on both the structural and functional level is accomplished with membrane proteins. Ion channels and pores, for instance, function as stimuli-responsive multianalyte sensors that assure perception of and communication with the outside world.

Artificial tongues and leaves

“…The objective with synthetic multifunctional nanoarchitecture is to create large suprastructures with interesting functions [1,2]. To address this challenge, we often begin with lipid bilayer membranes or, more recently, conducting surfaces as platforms.…”

“…From this rich collection of rigid-rod molecules, we originally selected p-oligophenyls 2 as model rods [1,2,14]. p-Oligophenyls are not only straightforward to synthesize and derivatize but also nonplanar and fluorescent, and can exhibit a dynamic axial chirality.…”

“…For this purpose, lipid bilayer membranes or conducting surfaces have been used as platforms and rigid-rod molecules as shape-persistent scaffolds. Examples for functions obtained by this approach include pores that can act as multicomponent sensors in complex matrices or rigid-rod π-stack architecture for artificial photosynthesis and photovoltaics.Keywords: nanoarchitecture; sensors; photovoltaics; photosynthesis; lipid bilayer; scaffolds.The objective with synthetic multifunctional nanoarchitecture is to create large suprastructures with interesting functions [1,2]. To address this challenge, we often begin with lipid bilayer membranes or, more recently, conducting surfaces as platforms.…”

“…Rigid oligonaphthalenediimide (O-NDI) rods 5 [9] and oligoperylenediimides (O-PDI) rods 6 [10] are of interest because they are colorizable, π-acidic n-semiconductors. Oligoporphyrins are extensively studied because of their optoelectric properties, the nonplanar rod 7 has been elongated up to l = 1060 Å of the monodisperse 128-mer [11].From this rich collection of rigid-rod molecules, we originally selected p-oligophenyls 2 as model rods [1,2,14]. p-Oligophenyls are not only straightforward to synthesize and derivatize but also nonplanar and fluorescent, and can exhibit a dynamic axial chirality.…”

“…Rigid-rod β-barrels with the general structure 11 are barrel-stave supramolecules composed of rigid-rod staves and β-sheets hoops [1,2]. Rigid-rod β-barrels with p-oligophenyl staves exhibit perfect hoop-stave matching.…”