Experimental and Theoretical Studies on Cobalt-Catalyzed Regioselective Hydrosilylation of Tetrafluorinated Cyclohexa-1,3-dienes.

Cyclohexa-1,3-dienes bearing a tetrafluoroethylene group underwent highly regioselective hydrosilylation in the presence of 1-10 mol % Co2(CO)8 in 1,2-dichloroethane under mild conditions (reflux, 3 h), which led to an abundant yield of homoallylsilanes. Mechanistic studies proved that the reaction proceeds as per the modified Chalk-Harrod mechanism; via DFT calculation, the reason for homoallylsilanes being exclusively obtained was demonstrated. The formal synthesis of a tetrafluorinated negative-type liquid crystal demonstrated the synthetic utility of such hydrosilylation.

Synthesis of a Dual-Color Fluorescent Dendrimer for Diagnosis of Cancer Metastasis in Lymph Nodes.

Detection of cancer metastasis spread in lymph nodes is important in cancer diagnosis. In this study, a fluorescence imaging probe was designed for the detection of both lymph node and tumor cells using always-ON and activatable fluorescence probes with different colors. Rhodamine B (Rho), a matrix metalloproteinase-2 (MMP-2)-responsive green fluorescence probe, and a tumor-homing peptide were conjugated to a carboxy-terminal dendrimer that readily accumulates in lymph nodes. The activatable green fluorescence signal increased in the presence of MMP-2, which is secreted by tumor cells. Both the always-ON Rho signal and the activatable green fluorescence signal were observed from tumor cells, but only the weak always-ON Rho signal was from immune cells. Thus, this type of dendrimer may be useful for non-invasive imaging to diagnose cancer metastasis in lymph nodes.

Design of a dendrimer with a matrix metalloproteinase-responsive fluorescence probe and a tumor-homing peptide for metastatic tumor cell imaging in the lymph node.

Fluorescence imaging is a noninvasive technique for cancer diagnosis. Dendrimers are regularly branched macromolecules with highly controllable size and structure that are a potent multifunctional nanoparticle. Anionic-terminal polyamidoamine (PAMAM) dendrimers were previously found to be accumulated in the lymph node, which is one of the main routes of tumor metastasis. In this study, we designed and synthesized a dendrimeric imaging probe for lymph node-resident tumor cell imaging. A matrix metalloproteinase-2 (MMP-2)-responsive fluorescence peptide probe and a tumor-homing peptide were conjugated to the carboxy-terminal dendrimer. The dendrimeric imaging probe treatment showed fluorescence signals inside some tumor cells (e.g., human fibrosarcoma HT-1080 and breast cancer 4T1 cells), depending on the MMP activity, but not in macrophage-like RAW264 cells.