Ion probes: A potassium‐sensing oligonucleotide with terminal pyrene moieties can be used as a fluorescent probe for the real‐time monitoring of the extracellular concentration of K+ ions under physiological conditions. The excimer emission intensity (b) of the chair‐type quadruplex structure formed depends on the K+ ion concentration (0–200 mm), and differs significantly from that in the absence of potassium (a).

A microreactor array was developed which enables high-throughput cell-free protein synthesis. The microreactor array is composed of a temperature control chip and a reaction chamber chip. The temperature control chip is a glass-made chip on which temperature control devices, heaters and temperature sensors, are fabricated with an ITO (indium tin oxide) resistive material. The reaction chamber chip is fabricated by micromolding of PDMS (polydimethylsiloxane), and is designed to have an array of reaction chambers and flow channels for liquid introduction. The microreactor array is assembled by placing the reaction chamber chip on the temperature control chip. The small thermal mass of the reaction chamber resulted in a short thermal time constant of 170 ms for heating and 3 s for cooling. The performance of the microreactor array was examined through the experiments of cell-free protein synthesis. By measuring the fluorescence emission from the products, it was confirmed that GFP (Green Fluorescent Protein) and BFP (Blue Fluorescent Protein) were successfully synthesized using Escherichia coli extract.

The dual-labeled oligonucleotide derivative, FAT-0, carrying 6- carboxyfluorescein (FAM) and 6-carboxytetramethylrhodamine (TAMRA) labels at the 5' and 3' termini of the thrombin-binding aptamer (TBA) sequence 5'-GGT TGG TGT GGT TGG-3', and its derivatives, FAT-n (n=3, 5, and 7) with a spacer at the 5'-end of a TBA sequence of T(m)A (m=2, 4, and 6) have been designed and synthesized. These fluorescent probes were developed for monitoring K(+) concentrations in living organisms. Circular dichroism, UV-visible absorption, and fluorescence studies revealed that all FAT-n probes could form intramolecular tetraplex structures after binding K(+). Fluorescence resonance energy transfer and quenching results are discussed taking into account dye-dye contact interactions. The relationship between the fluorescence behavior of the probes and the spacer length in FAT-n was studied in detail and is discussed.

Ionensonde: Ein Kalium‐empfindliches Oligonucleotid mit terminalen Pyreneinheiten kann als Fluoreszenzsonde für die Verfolgung der extrazellulären Konzentration von K+‐Ionen in Echtzeit unter physiologischen Bedingungen genutzt werden. Die Intensität der Excimer‐Emission (b) der gebildeten stuhlförmigen Quadruplexstruktur hängt von der K+‐Ionenkonzentration (0–200 mM) ab und unterscheidet sich deutlich von der ohne Kalium gemessenen Intensität (a).

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