Triplex formation with alpha-L-LNA (alpha-L-ribo-configured locked nucleic acid)

Using UV melting and CD spectroscopy, we show that alpha-l-LNA-modified oligonucleotides possess the ability to form triplexes at pH 6.8 with significantly increased thermostability relative to DNA triplexes.     

Reduction of primary freeze-drying time by electric field induced ice nucleus formation

The potential of a high electric field was utilized to induce ice nucleus formation in aqueous solutions. Using this technique it was possible to reduce the primary drying time during lyophilization. Samples of 10% (w/v) hydroxyethylstarch (HES) solution were frozen at a constant rate of −1 K/min, while nucleation was initiated at temperatures of −1.5, −4.5 and −8.5°C. In contrast, spontaneous nucleation was observed in a range between −11.5 and −17.1°C. Electrically induced nucleus formation has proved to be a reliable method to start crystallization at a desired temperature. Continuous measurement of the weight allowed to determine the drying rate and to detect at which time primary drying was completed. The drying time and the drying rate were found to be strongly dependent on the nucleation temperature during freezing. A relation between the nucleation temperature, the structure of the frozen samples and the drying times could be established.

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Dihydroazulene-Boron Subphthalocyanine Conjugates with Oligo(phenyleneethynylene) Bridging Unit: Photoswitchable Fluorophores

In this work, we have linked the dihydroazulene (DHA)/vinylheptafulvene (VHF) photo-/thermoswitch and the boron subphthalocyanine (BsubPc) fluorophore via an axial oligo(phenyleneethynylene) bridging unit into new DHA-BsubPc conjugates. The objectives were to elucidate the influence of BsubPc on the DHA/VHF switching reactions and the influence of DHA/VHF on the BsubPc fluorescence in these conjugates for which the entire axial substituent connected to boron comprises one large, conjugated scaffold. We present the synthesis and properties of DHA-BsubPc conjugates with varying peripheral substituents on the BsubPc core, being either unsubstituted (H₁₂BsubPc) or partially fluorinated (F₆BsubPc). Fluorination of the BsubPc core provided a remarkable increase in the reversibility of the DHA-VHF interconversions promoted by light and heat, respectively, and accompanied by on/off switching of the BsubPc fluorescence. Synthetically, the units were connected using Sonogashira coupling reactions of suitable acetylenic building blocks.