Dynamic hybrid materials for constitutional self-instructed membranes

Abstract

Constitutional self-instructed membranes were developed and used for mimicking the adaptive structural functionality of natural ionchannel systems. These membranes are based on dynamic hybrid materials in which the functional self-organized macrocycles are reversibly connected with the inorganic silica through hydrophobic noncovalent interactions. Supramolecular columnar ion-channel architectures can be generated by reversible confinement within scaffolding hydrophobic silica mesopores. They can be structurally determined by using X-ray diffraction and morphologically tuned by alkali-salts templating. From the conceptual point of view, these membranes express a synergistic adaptive behavior: the simultaneous binding of the fittest cation and its anion would be a case of ''homotropic allosteric interactions,'' because in time it increases the transport efficiency of the pore-contained superstructures by a selective evolving process toward the fittest ion channel. The hybrid membranes presented here represent dynamic constitutional systems evolving over time to form the fittest ion channels from a library of molecular and supramolecular components, or selecting the fittest ion pairs from a mixture of salts demonstrating flexible adaptation.crown-ethers ͉ ion channels ͉ self-assembly

Highly Selective Artificial Cholesteryl Crown Ether K+‐Channels

“…[25] Thetransport activity of 1a decreased in the following order: (Table 1), corresponding to the Eisenman sequence IV or V. [26] We know from previously reported X-ray single-crystal structures,t hat lipophilic ureido-benzo-15-crown-5-ether and ureido-benzo-18-crown-6-ether bind Na + (Figure 3a)a nd K + (Figure 3b) cations,r espectively,t hrough one macrocycle,w hile as andwich-type geometry has been determined for complexation of the bigger K + cations by two 15-crown-5-ethers moieties (Figure 3c). [27] Theh ighly selective transport rate of K + cations is in part due to its sandwich-type recognition by the crown-ethers as observed in the crystal structure,completely surrounding the K + cations in as imilar manner to the water molecules around the hydrated cation (Figure 3c,b ottom).…”

“…cations (middle and right, black spheres) in the presented X-ray crystal structures. [27] Angewandte Chemie degree of supramolecular order within bilayers.The transport experiments show that these superstructures form membrane spanning structures with clear cation-conductance behaviors. Themacrocycles pointing toward the hydrophylic part of the channel certainly facilitate the transport of the cations, allowing the control of K + -transport selectivity,w hich is rarely observed with self-assembled artificial systems.A s observed in crystal structures,t he dimensional fit of Na + cations induce an incomplete coordination ability,w hich leads,a fter cation entrance,t oapartial dehydration and correspondingly to low transport rate.I nc ontrast, the sandwich-type recognition surrounding the K + cations in asimilar manner to the water molecules around the hydrated cation in water, has important consequences for the highly selective K + translocation along the channel, which totally compensates the energetic cost of their dehydration.…”

Real‐Time Optical Detection of Stabilized Artificial G‐Quadruplexes Under Confined Conditions

“…[6] Liposomes, [7] surfaces, [8] dynamers, [9] hybrid materials, [10,11] and mesoporous silica [12] have been used as scaffolding matrices to stabilize and to orient the anisotropic directional G-mesophases. They are reminiscent of other supramolecular pore-confined systems [13,14] or DNA-modified surfaces. [15,16] Among confining matrices, single-layer thin films of mesoporous silicon (pSi), multilayer Bragg reflectors, or Rugate filters can be easily obtained by electrochemical etching (Supporting Information, Figure S1 a).…”

Dynamic Nanoplatforms in Biosensor and Membrane Constitutional Systems

“…The result is a selfassembled bilayer which exhibits a closer approximation of true cell membrane fluidity [93]. Such a construction also allows for the accommodation of proteins [94], incorporated synthetic ion-channels [95] and sugar lectin systems [96]. Taylor et al has reported on SPR detection of cholera toxin using a tethered bilayer [97].…”