Svetlana Litvinchuk

Analyte Sensing Across Membranes with Artificial Pores

This review covers synthetic pores as sensors, an interdisciplinary topic that may appeal not only to bioorganic and supramolecular but also to analytical, organic, or physical chemists. In the introduction, fundamental concepts and methods are briefly reiterated. The next section introduces synthetic pores as multifunctional supramolecules that are created from abiotic scaffolds and act in lipid bilayer membranes. Then follows the introduction of the concept of synthetic multifunctional pores as general optical transducers of chemical reactions. For this purpose, synthetic pores that recognize small changes in bulk and/or charge of as many substrates and products as possible are best, and internal π-clamps are added to catch elusive analytes. For multicomponent sensing in complex matrixes, synthetic pores as general transducers are combined with enzymes as specific signal generators. Realized examples of practical applications to samples from the supermarket describe synthetic pores as sensors of sugar in soft drinks. Section 3 focuses on sensing with biological and bioengineered pores. Selected topics, such as general electrical transduction in planar and supported lipid bilayer membranes, the concept of stochastic sensing of single analytes, immunosensing, covalent polynucleotide amplifiers, and single gene sequencing, are briefly spotlighted to also outline future perspectives with synthetic pore sensors. Section 4 briefly covers initial breakthroughs on sensing with synthetic pores in membranes other than lipid bilayers, such as functionalized conical gold and cylindrical carbon nanotubes.

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.

Blockage of Rigid-rod β-Barrel Pores with Rigid-rod α-Helix Mimics*

We report the completion of a series of biological β-barrel pores blocked by an α-helix (Oomen et al., EMBO J. 2004, 23, 1257) and rigid-rod β-barrel pores blocked by an α-helix (Sordé and Matile, J. Supramol. Chem. 2002, 2, 191) with experimental evidence for a rigid-rod β-barrel pore blocked by a rigid-rod α-helix mimic. These presumably dimeric, shape-persistent p-oligophenyl α-helix mimics are of interest to address the functional-group density of full α-helix surfaces and to obtain insights into α-helix folding and recognition.