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Cucurbituril-Based Molecular Recognition.

Fluorescent Dyes and Their Supramolecular Host/Guest Complexes with Macrocycles in Aqueous Solution Roy N. Dsouza, Uwe Pischel,* and Werner M. Nau* School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, D-28759 Bremen, Germany Centro de Investigaci on en Química Sostenible (CIQSO) and Departamento de Ingeniería Química, Química Física y Química Org anica, Universidad de Huelva, Campus de El Carmen s/n, E-21071 Huelva, Spain

Fluorescent dyes and their supramolecular host/guest complexes with macrocycles in aqueous solution.

This review highlights the past six year advances in the blossoming field of cucurbit[n]uril chemistry. Because of their exceptional recognition properties in aqueous medium, these pumpkin-shaped macrocycles have been generating some tremendous interest in the supramolecular community. They have also become key units in various self-organizing and stimulus-controlled assemblies, as well as in advanced materials and drug carriers. The scope of this review is limited to the main family of cucurbit[n]urils (n = 5, 6, 7, 8, 10). The reader will find an overview of their preparation, their physicochemical and biological properties, as well as their recognition abilities towards various organic and inorganic guests. Detailed thermodynamic and kinetic considerations, as well as multiple applications including supramolecular catalysis are also discussed.

Cucurbituril chemistry: a tale of supramolecular success

The rational design of drug delivery approaches leveraging supramolecular chemistry (i.e., “chemistry beyond the molecule”) has garnered significant interest in recent years toward improving therapeutics. By using specific, dynamic, and tunable non-covalent interactions, engineered approaches to drug delivery can be realized. Certain benefits to this approach are molecular-level control of composition, improved routes for incorporating and targeting drugs, and new strategies to create delivery devices that respond to a variety of physiologic indicators. Some of the most recognizable supramolecular motifs – macrocyclic host–guest complexes – afford logical application to drug delivery in using drug as guest. The use of supramolecular motifs may further give rise to materials for the controlled encapsulation and release of therapeutics. Furthermore, given the majority of supramolecular motifs in water are directed by hydrophobic interactions, cooperative delivery strategies can be realized. The modularity of supramolecular interactions also facilitates opportunities to combine multiple drugs within one delivery platform, as well as the facile incorporation of targeting units. In sum, supramolecular design offers ample opportunity to improve the precision of pharmaceutical practice. In the context of clinical translation, features of supramolecular design may prove additionally advantageous, specifically in enabling quantitative drug loading, molecularly discrete delivery devices, and a priori knowledge of carrier degradation and clearance mechanisms. As such, the design opportunities afforded by supramolecular chemistry will play a vital role in the future of the drug delivery field.

Drug delivery by supramolecular design

Lech-Gustav Milroy,† Tom N. Grossmann,‡,§ Sven Hennig,‡ Luc Brunsveld,† and Christian Ottmann*,† †Laboratory of Chemical Biology and Institute of Complex Molecular Systems, Department of Biomedical Engineering, Technische Universiteit Eindhoven, Den Dolech 2, 5612 AZ Eindhoven, The Netherlands ‡Chemical Genomics Centre of the Max Planck Society, Otto-Hahn Straße 15, 44227 Dortmund, Germany Department of Chemistry and Chemical Biology, Technical University Dortmund, Otto-Hahn-Strasse 6, 44227 Dortmund, Germany

/pdf/modulators-of-protein-protein-interactions-ho8upfvoqv.pdf

Modulators of Protein-Protein Interactions

The discovery of molecules that bind tightly and selectively to desired proteins continues to drive innovation at the interface of chemistry and biology. This paper describes the binding of human insulin by the synthetic receptor cucurbit[7]uril (Q7) in vitro. Isothermal titration calorimetry and fluorescence spectroscopy experiments show that Q7 binds to insulin with an equilibrium association constant of 1.5 × 10(6) M(-1) and with 50-100-fold selectivity versus proteins that are much larger but lack an N-terminal aromatic residue, and with >1000-fold selectivity versus an insulin variant lacking the N-terminal phenylalanine (Phe) residue. The crystal structure of the Q7·insulin complex shows that binding occurs at the N-terminal Phe residue and that the N-terminus unfolds to enable binding. These findings suggest that site-selective recognition is based on the properties inherent to a protein terminus, including the unique chemical epitope presented by the terminal residue and the greater freedom of the terminus to unfold, like the end of a ball of string, to accommodate binding. Insulin recognition was predicted accurately from studies on short peptides and exemplifies an approach to protein recognition by targeting the terminus.

/pdf/molecular-recognition-of-insulin-by-a-synthetic-receptor-545mg7vjhb.pdf

Nicholas D. Hargreaves

Papers

Molecular recognition of insulin by a synthetic receptor.