Using small molecules to facilitate exchange of bicarbonate and chloride anions across liposomal membranes

Davis, Jeffery T.; Gale, Philip A.; Okunola, Oluyomi A.; Prados, Pilar; Iglesias-Sánchez, José Carlos; Torroba, Tomás; Quesada, Roberto

doi:10.1038/nchem.178

Cited by 189 publications

(176 citation statements)

References 42 publications

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“…Transmembrane anion channels80 have been made, as well as transporter systems, largely led by Gale and co‐workers 81, 82, 83. In these studies, an anion host (typically an uncharged small molecule) is added to a buffered aqueous solution containing liposomes with an anion concentration gradient imposed across the membrane.…”

Section: Macromolecular Recognition Of Anions In Watermentioning

confidence: 99%

Anion Recognition in Water: Recent Advances from a Supramolecular and Macromolecular Perspective

2015

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The recognition of anions in water remains a key challenge in modern supramolecular chemistry, and is essential if proposed applications in biological, medical, and environmental arenas that typically require aqueous conditions are to be achieved. However, synthetic anion receptors that operate in water have, in general, been the exception rather than the norm to date. Nevertheless, a significant step change towards routinely conducting anion recognition in water has been achieved in the past few years, and this Review highlights these approaches, with particular focus on controlling and using the hydrophobic effect, as well as more exotic interactions such as C−H hydrogen bonding and halogen bonding. We also look beyond the field of small‐molecule recognition into the macromolecular domain, covering recent advances in anion recognition based on biomolecules, polymers, and nanoparticles.

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Section: Macromolecular Recognition Of Anions In Watermentioning

confidence: 99%

Anion Recognition in Water: Recent Advances from a Supramolecular and Macromolecular Perspective

2015

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“…3 The results clearly show that in these simple tren-based systems, the thioureas are significantly 90 better at transporting bicarbonate anions than are the corresponding ureas (A.P. Davis and B.D.…”

Section: Discussionmentioning

confidence: 92%

“…Further studies in POPC/cholesterol 70:30 vesicles showed a reduction in chloride transport rate consistent with the compounds 1-4 functioning as discrete molecular carriers and not as channels. 2 We also repeated the Cl -/NO 3 -experiments in the presence of a pH gradient and saw little change in the rate of transport of chloride which suggests that Cl -/NO 3 -antiport is the predominant mechanism 5 repsonsible for the release of chloride from the vesicles. We used an HPTS fluorescence assay to study whether the compounds function as HCl co-transporters with nitrate as the external anion.…”

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confidence: 85%

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Tripodal transmembrane transporters for bicarbonate

et al. 2010

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Easy-to-make tripodal tris-thiourea receptors based upon tris(2-aminoethyl)amine are capable of chloride/bicarbonate transport and as such represent a new class of bicarbonate transport agent.The key roles that anions play in a whole range of biological 10 processes has lead to much recent interest in the design of transporters and channels capable of carrying guests 1 such as chloride 2 or bicarbonate 3 across lipid bilayer membranes. Compounds based on tris(2-aminoethyl)amine (tren) have proven to be effective receptors for a variety of anionic 15 species. 4 Recently tren-based tris-ureas have been employed by Custelcean as agents to selectively crystallise strongly solvated tetrahedral oxo-anions such as sulfate. 5 In the anion transport arena, D.K. Smith and co-workers have shown that tren-based tris amides are capable of HCl co-transport through The results show that the thiourea derivatives are capable of both chloride/nitrate and more significanly of transporting the more hydrophilic bicarbonate anion via a chloride/bicarbonate antiport mechanism. 3 35Compounds 1-4 were synthesised by modifications of literature procedures (see ESI). 9 Proton NMR titration techniques were used to assess the stability of the receptor:anion complexes. Stability constants for the ligand-anion complexes were determined using the 40 EQNMR computer programme. 10 NMR titrations were conducted in DMSO-d 6 /0.5% water solutions with tetrabutylammonium anion salts (except for bicarbonate which was added as the tetraethylammonium salt). The results show that in all cases the receptors bind sulfate strongly with K a > bicarbonate. ¶ The X-ray crystal structure revealed that two equivalents of receptor 4 bind to a single carbonate anion in the solid state via twelve hydrogen bonds in the range 2.824(6)-3.070(7)Å with several other longer range NH … O interactions ( Figure 1a). We have previously observed that 60 anion receptors that form multiple hydrogen bond to oxoanions can perturb the pKa of the guest to the extent that the guest anion is deprotonated by free anion in solution. 11 This process may also occur here and account for the difficulty in fitting the bicarbonate NMR titration results to a simple 65 binding model. The structure itself shows the carbonate anion encapsulated between two receptors effectively shielded from the environent external to the complex. The sulfur atoms of the thiourea groups decorate the surface of the capsule-like complex (Figure 1b). 70In order to study the chloride transport properties of compounds 1-4 we prepared a series of unilamellar 1-palmitoyl-2-oleoylphophatidylcholine (POPC) vesicles loaded with sodium chloride (489 mM) and suspended them in an external NaNO 3 (489 mM) solution. A sample of receptor 1-4 75 or control compound trihexylamine (2% molar carrier to lipid) was added as a DMSO solution and the resultant Cl -efflux monitored using a chloride selective electrode. 12 After 300 s, the vesicles were lysed by addition of detergent and the final reading of the electrode was used to cali...

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“…that can be formed in few synthetic steps using inexpensive starting materials). [6][7][8][9][10][11][12][13] For practical applications, these sensors also need to satisfy strict photophysical criteria, such as being able to absorb and emit at long wavelengths to facilitate the use of naked eye detection or the use of inexpensive optics, posses relatively long lived excited states, 12 and have high quantum yields.…”

Section: Introductionmentioning

confidence: 99%

Colorimetric and fluorescent anion sensors: an overview of recent developments in the use of 1,8-naphthalimide-based chemosensors

et al. 2010

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This critical review focuses on the development of anion sensors, being either fluorescent and/or colorimetric, based on the use of the 1,8-naphthalimide structure; a highly versatile building unit that absorbs and emits at long wavelengths. The review commences with a short description of the most commonly used design principles employed in chemosensors, followed by a discussion on the photophysical properties of the 4-amino-1,8-naphthalimide structure which has been most commonly employed in both cation and anion sensing to date. This is followed by a review of the current state of the art in naphthalimide-based anion sensing, where systems using ureas, thioureas and amides as hydrogen-bonding receptors, as well as charged receptors have been used for anion sensing in both organic and aqueous solutions, or within various polymeric networks, such as hydrogels. The review concludes with some current and future perspectives including the use of the naphthalimides for sensing small biomolecules, such as amino acids, as well as probes for incorporation and binding to proteins; and for the recognition/sensing of polyanions such as DNA, and their potential use as novel therapeutic and diagnostic agents (95 references).

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Using small molecules to facilitate exchange of bicarbonate and chloride anions across liposomal membranes

Cited by 189 publications

References 42 publications

Anion Recognition in Water: Recent Advances from a Supramolecular and Macromolecular Perspective

Anion Recognition in Water: Recent Advances from a Supramolecular and Macromolecular Perspective

Tripodal transmembrane transporters for bicarbonate

Colorimetric and fluorescent anion sensors: an overview of recent developments in the use of 1,8-naphthalimide-based chemosensors

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