Super‐Resolution Imaging of the Golgi in Live Cells with a Bioorthogonal Ceramide Probe

We report a lipid‐based strategy to visualize Golgi structure and dynamics at super‐resolution in live cells. The method is based on two novel reagents: a trans‐cyclooctene‐containing ceramide lipid (Cer‐TCO) and a highly reactive, tetrazine‐tagged near‐IR dye (SiR‐Tz). These reagents assemble via an extremely rapid “tetrazine‐click” reaction into Cer‐SiR, a highly photostable “vital dye” that enables prolonged live‐cell imaging of the Golgi apparatus by 3D confocal and STED microscopy. Cer‐SiR is nontoxic at concentrations as high as 2 μM and does not perturb the mobility of Golgi‐resident enzymes or the traffic of cargo from the endoplasmic reticulum through the Golgi and to the plasma membrane.     

High-Affinity Ratiometric Fluorescence Probe Based on 6-Amino-2,2′-Bipyridine Scaffold for Endogenous Zn2+ and Its Application to Living Cells

Zinc is an essential trace element involved in many biological activities; however, its functions are not fully understood. To elucidate the role of endogenous labile Zn²⁺, we developed a novel ratiometric fluorescence probe, 5-(4-methoxyphenyl)-4-(methylsulfanyl)-[2,2′-bipyridin]-6-amine (6 (rBpyZ)) based on the 6-amino-2,2′-bipyridine scaffold, which acts as both the chelating agent for Zn²⁺ and the fluorescent moiety. The methoxy group acted as an electron donor, enabling the intramolecular charge transfer state of 6 (rBpyZ), and a ratiometric fluorescence response consisting of a decrease at the emission wavelength of 438 nm and a corresponding increase at the emission wavelength of 465 nm was observed. The ratiometric probe 6 (rBpyZ) exhibited a nanomolar-level dissociation constant (K_d = 0.77 nM), a large Stokes shift (139 nm), and an excellent detection limit (0.10 nM) under physiological conditions. Moreover, fluorescence imaging using A549 human lung adenocarcinoma cells revealed that 6 (rBpyZ) had good cell membrane permeability and could clearly visualize endogenous labile Zn²⁺. These results suggest that the ratiometric fluorescence probe 6 (rBpyZ) has considerable potential as a valuable tool for understanding the role of Zn²⁺ in living systems.     

Thermal change of Alq3, tris(8-hydroxyquinolinato) aluminum(III) studied by TG and XRD-DSC

The thermal change of the tris(8-hydroxyquinolinato)aluminum (Alq₃) is currently investigated by XRD-DSC and TG. The phase transition of Alq₃ from α-phase to γ-phase takes place at 643–669 K. A very sharp peak with the peak temperature at approx. 709 K is ascribed to the melting of the Alq₃. The decomposition of the Alq₃ was observed accompanied with the melting and evaporation at >703K. The effect of the atmospheres on the mass loss procedure was studied by TG. It was found that thermal process of Alq₃ was strongly influenced by the partial pressure of water vapor in the atmosphere instead of oxygen.     

Electroreduction of tetra-coordinate phosphonium derivatives; one-pot transformation of triphenylphosphine oxide into triphenylphosphine

Electroreduction of triphenylphosphine dichloride in acetonitrile was performed successfully in an undivided cell fitted with an aluminium sacrificial anode and a platinum cathode, wherein Al³⁺, which was electrogenerated at the anode would react as a Lewis acid with triphenylphosphine dichloride to afford tetra-coordinate chlorotriphenylphosphonium species and subsequent two-electron reduction at the cathode would give triphenylphosphine. One-pot transformation of triphenylphosphine oxide to triphenylphosphine was achieved successfully by the treatment of triphenylphosphine oxide with oxalyl chloride and subsequent electroreduction. In a similar manner, some tetra-coordinate triphenylphosphonium species derived from triphenylphosphine oxide were reduced electrochemically to triphenylphosphine in moderate yields.