Duy-Hien Tran

Fluorometric Detection of Inositol Phosphates and the Activity of Their Enzymes with Synthetic Pores: Discrimination of IP7 and IP6 and Phytate Sensing in Complex Matrices

We report the fluorometric and noninvasive detection of inositol phosphates, which act as privileged blockers of synthetic pores. Phytate (IP6) and IP7 recognition in the pore occurs substoichiometrically in the low nanomolar range, with more than 2 orders of magnitude higher sensitivity than the best available alternative. Zn2+-mediated fluorometric discrimination between IP6 and IP7 demonstrates that significant pore discrimination challenges can be solved with judiciously selected additives. The detectability of inositol phosphate enzyme activity was exemplified with phytase. Phytate sensing was accomplished in complex matrices such as extracts from almonds, soybeans, or lentils, using phytase as a specific signal generator. These results are important because they not only add essential evidence in support of the usefulness of synthetic pores as multianalyte sensors in complex matrices but also reveal the existence of privileged analytes that can provide access to submicromolar sensitivity without the...

Synthetic pores with sticky π-clamps

In this report, we describe design, synthesis, evaluation and molecular dynamics simulations of synthetic multifunctional pores with pi-acidic naphthalenediimide clamps. Experimental evidence is provided for the formation of unstable but inert, heterogeneous and acid-insensitive dynamic tetrameric pores that are sensitive to base and ionic strength. Blockage experiments reveal that the introduction of aromatic electron donor-acceptor interactions provides access to the selective recognition of pi-basic intercalators within the pore. This breakthrough is important for the application of synthetic pores as multianalyte sensors.

Asymmetric Synthesis and Configurational Stability of C2-Symmetric Hexacoordinated Phosphate Anions (TARPHATs) with Predetermined Chirality from Tartrate Esters

C2-Symmetric TARPHAT anions 5 made of a central PV atom, one tartrato (=dialkyl 2,3-di(hydroxy-KO)butanedioato(2-)), and two tetrachloropyrocatecholato (=3,4,5,6-tetrachlorobenzene-1,2-diolato(2-)-KO,KO) ligands can be easily prepared in decent to high yields (50-86%) as their dimethylammonium salt by using a one-pot process and simple commercially available starting materials. The presence of the chiral tartrato ligands (usually (2R,3R)) leads to the formation of diastereoisomeric anions ((?,2R,3R)/(?,2R,3R)). Decent to good control by the chiral ligands - under equilibration conditions - over the ? or ? configuration of the adducts was observed (d.r. 84 : 16 in CHCl3 for the di(tert-butyl) tartrate derivative), the selectivity depending on the nature of the ester chains as well as on the solvent.

Recent Progress with Functional Biosupramolecular Systems

The objective of this account is to summarize our recent progress with functional biosupramolecular systems concisely. The functions covered are artificial photosynthesis, anion transport, and sensing in lipid bilayer membranes. With artificial photosynthesis, the current emphasis is on the construction of ordered and oriented architectures on solid surfaces. Recent examples include the zipper assembly of photosystems with supramolecular n/p-heterojunctions and oriented antiparallel redox gradients. Current transport systems in lipid bilayers reveal new interactions at work. Examples include anion-macrodipole or anion-π interactions. Current attention with membrane-based sensing systems shifts from biosensor approaches with enzymatic signal generation to aptamers (i.e., the DNA version of immunosensing) and differential sensing with dynamic polyion-counterion transporters. The functional diversity accessible with biosupramolecular systems is highlighted, as is the critical importance of cross-fertilization at intertopical convergence zones.

Artificial tongues and leaves

The objective with synthetic multifunctional nanoarchitecture is to create large suprastructures with interesting functions. 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.