A coumarin-based two-photon probe for hydrogen peroxide.

A new fluorescence probe was developed for hydrogen peroxide (H2O2) detection based on donor-excited photo induced electron transfer (D-PET) mechanism, together with the benzil as a quenching and recognizing moiety. The benzil could convert to benzoic anhydride via a Baeyer-Villiger type reaction in the presence of H2O2, followed by hydrolysis of benzoicanhydride to give benzoic acid, and the fluorophore released. The probe was synthesized by a 6-step procedure starting from 4-(diethylamino)salicylaldehyde. A density functional theory (DFT) calculation was performed to demonstrate that the benzil was a fluorescence quencher. The probe was evaluated in both one-photon and two-photon mode, and it exhibited high selectivity toward H2O2 over other reactive oxygen species and high sensitivity with a detection limit of 0.09 µM. Furthermore, the probe was successfully applied to cell imaging of intracellular H2O2 levels with one-photon microscopy and two-photon microscopy. The superior properties of the probe made it of great potential use in more chemical and biological researches.

[Expression of vascular endothelial growth factor A and C in human breast cancer and their significance].

BACKGROUND & OBJECTIVE: Vascular endothelial growth factor (VEGF) family is related to angiogenesis. VEGF-A and VEGF-C are closely related to tumorigenesis and lymphatic metastasis. This study was to detect the expression of VEGF-A and VEGF-C in breast cancer, and explore their correlation to cell proliferation, microvessel density (MVD), and lymphatic metastasis of breast cancer. METHODS: The expression of VEGF-A, VEGF-C, proliferating cell nuclear antigen (PCNA), and CD34 in 98 samples of breast cancer were detected by SP immunohistochemistry. RESULTS: The positive rate of VEGF-A was 85.7%; that of VEGF-C was 90.8%. The positive rates of VEGF-A and VEGF-C were significantly higher in cancers with lymph node metastasis than in cancers without lymph node metastasis (P<0.05). The positive rate of PCNA was 98.0%; its expression level was increased with the expression levels of VEGF-A and VEGF-C (r=0.432, P=0.000; r=0.294, P=0.001). MVD was significantly higher in cancers with lymph node metastasis than in cancers without lymph node metastasis(64.26+/-26.40 vs. 50.29+/-29.35, P<0.05). MVD was positively correlated to the expression of VEGF-A (r=0.327, P<0.001), but had no correlation to VEGF-C (r=0.123, P>0.05). CONCLUSIONS: VEGF-A mainly mediates angiogenesis, cell proliferation, and metastasis of human breast cancer. VEGF-C promotes cell proliferation of human breast cancer; it is correlated to lymph node metastasis, but has no correlation to MVD.