Supramolecular analytical chemistry
Molecular sensors for small molecules (NO, CO, sugars and anions):
Receptors – Transition metal complexes and boronic acids
Indicators – Fluorescent dyes, fluorine decorated ligands (19F NMR)
Indicator displacement assays
Indicator displacement assays (IDAs) represent an elegant approach in supramolecular analytical chemistry.[1] We use the Singaram/Wessling type sensing probe (boronic acid appended viologen BBV together with fluorescent dyes) as allosteric indicator displacement assay (AIDA).[2-4]
Sugar sensors in enzyme assays. In-vitro fluorescent enzyme assays have been developed for sucrose phosphorylase (SPO) and phosphogluco-mutase (PGM). These assays make use of a selective carbohydrate sensing system that detects the unlabeled enzymatic products fructose and glucose-6-phosphate. The system comprises 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) as the reporter unit and boronic acid appended viologens as selective receptors with working ranges from 70 μM to 1.0 mM for fructose (SPO) and 190 μM to 2.0 mM for glucose-6-phosphate (PGM).[3]
Cyanide sensor. A new hybrid sensor consists of the enzyme β-glucosidase and a boronic acid appended viologen together with a fluorescent reporter dye.[1-4] β-Glucosidase degrades the amygdalin into hydrogen cyanide, glucose, and benzaldehyde. Only the released cyanide binds at the allosteric site of the boronic acid receptor thereby inducing changes in the affinity of a formerly bound fluorescent indicator dye at the other side of the receptor. Thus, the sensing probe performed as allosteric indicator displacement assay (AIDA) for cyanide in water. [4]
References
[1] E. V. Anslyn, J. Org. Chem. 2007, 72, 687. [2] D. A. Jose, A. Ghosh, A. Schiller, in Discovering the future of molecular sciences (Ed.: B. Pignataro), Wiley-VCH, Weinheim, 2014, p. 3-30. [3] A. Schiller, R. A. Wessling, B. Singaram, Angew. Chem., Int. Ed. 2007, 46, 6457. [3] B. Vilozny, A. Schiller, R. A. Wessling, B. Singaram, Anal. Chim. Acta 2009, 649, 246-251. [4] D. A. Jose, M. Elstner, A. Schiller, Chem. Eur. J. 2013, 19, 14451.