Molecular Engineering of Perylene Diimide Polymers with a Robust Built-in Electric Field for Enhanced Solar-Driven Water Splitting.

The built-in electric field of the polymer semiconductors could be regulated by the dipole moment of its building blocks, thereby promoting the separation of photogenerated carriers and achieving efficient solar-driven water splitting. Herein, three perylene diimide (PDI) polymers, namely oPDI, mPDI and pPDI, are synthesized with different phenylenediamine linkers. Notably, the energy level structure, light-harvesting efficiency, and photogenerated carrier separation and migration of polymers are regulated by the orientation of PDI unit. Among them, oPDI enables a large dipole moment and robust built-in electric field, resulting in enhanced solar-driven water splitting performance. Under simulated sunlight irradiation, oPDI exhibits the highest photocurrent of 115.1 µA cm-2 for photoelectrochemical oxygen evolution, which is 11.5 times that of mPDI, 26.8 times that of pPDI and 104.6 times that of its counterparts PDI monomer at the same conditions. This work provides a strategy for designing polymers by regulating the orientation of structural units to construct efficient solar energy conversion systems.

[Clinical features of coronavirus disease 2019 in children aged <18 years in Jiangxi, China: an analysis of 23 cases].

OBJECTIVE: To study the clinical features of coronavirus disease 2019 (COVID-19) in children aged <18 years. METHODS: A retrospective analysis was performed from the medical data of 23 children, aged from 3 months to 17 years and 8 months, who were diagnosed with COVID-19 in Jiangxi, China from January 21 to February 29, 2020. RESULTS: Of the 23 children with COVID-19, 17 had family aggregation. Three children (13%) had asymptomatic infection, 6 (26%) had mild type, and 14 (61%) had common type. Among these 23 children, 16 (70%) had fever, 11 (48%) had cough, 8 (35%) had fever and cough, and 8 (35%) had wet rales in the lungs. The period from disease onset or the first nucleic acid-positive detection of SARS-CoV-2 to the virus nucleic acid negative conversion was 6-24 days (median 12 days). Of the 23 children, 3 had a reduction in total leukocyte count, 2 had a reduction in lymphocytes, 2 had an increase in C-reactive protein, and 2 had an increase in D-dimer. Abnormal pulmonary CT findings were observed in 12 children, among whom 9 had patchy ground-glass opacities in both lungs. All 23 children received antiviral therapy and were recovered. CONCLUSIONS: COVID-19 in children aged <18 years often occurs with family aggregation, with no specific clinical manifestation and laboratory examination results. Most of these children have mild symptoms and a good prognosis. Epidemiological history is of particular importance in the diagnosis of COVID-19 in children aged <18 years.

Expression and purification of the catalytic domain of human vascular endothelial growth factor receptor 2 for inhibitor screening.

Vascular endothelial growth factor (VEGF), an endothelial cell-specific mitogen, can act in tumor-induced angiogenesis by binding to specific receptors on the surface of endothelial cells. One such receptor, VEGFR-2/KDR, plays a key role in VEGF-induced angiogenesis. Here, we expressed the catalytic domain of VEGFR-2 as a soluble active kinase using Bac-to-Bac expression system, and investigated correlations between VEGFR-2 activity and enzyme concentration, ATP concentration, substrate concentration and divalent cation type. We used these data to establish a convenient, effective and non-radioactive ELISA screening technique for the identification and evaluation of potential inhibitors for VEGFR-2 kinase. We screened 200 RTK target-based compounds and identified one (TKI-31) that potently inhibited VEGFR-2 kinase activity (IC50=0.596 microM). Treatment of NIH3T3/KDR cells with TKI-31 blocked VEGF-induced phosphorylation of KDR in a dose-dependent manner. Moreover, TKI-31 dose-dependently suppressed HUVEC tube formation. Thus, we herein report a novel, efficient method for identifying VEGFR-2 kinase inhibitors and introduce one, TKI-31, that may prove to be a useful new angiogenesis inhibitor.

TKI-31 inhibits angiogenesis by combined suppression signaling pathway of VEGFR2 and PDGFRbeta.

Tyrosine kinases have been strongly implicated as therapeutic targets that influence the angiogenic process in growing tumors. In this study, we revealed that TKI-31 is a potent broad spectrum tyrosine kinase inhibitor, which inhibits vascular endothelial growth factor receptor 2 (VEGFR2), platelet-derived growth factor receptor beta (PDGFRbeta) and also inhibits kinases of other class, such as c-Kit and c-Src on molecular base, but showed no activity against vascular endothelial growth factor receptor 1 (VEGFR1) and epidermal growth factor receptor (EGFR). TKI-31 inhibits VEGF-induced phosphorylation of VEGFR2 in endothelial cells as well as PDGF(BB)-induced phosphorylation in fibroblast cells, and leading to the inhibition of down-stream signaling triggered by these receptors such as PI3K/Akt/mTOR, MAPK42/44(ERK) and paxillin. TKI-31 also inhibited VEGF-induced endothelial cells proliferation, migration and their differentiation into capillary-like tube formation. Its anti-angiogenic property was further confirmed by the inhibition of neovascularization on CAM, in vivo. These results collectively highlight the therapeutic potential of this compound for the treatment of solid tumors and other diseases where angiogenesis plays an important role.

Role of 18F-FDG PET/CT in detecting pelvic lymph-node metastases in patients with early-stage uterine cervical cancer: comparison with MRI findings.

OBJECTIVE: This study aimed to investigate the applied value of F-fluoro-2-dexoxyglucose (F-FDG) PET/computed tomography (CT) and MRI in detecting lymph-node metastasis in early-stage cervical cancer. MATERIALS AND METHODS: A retrospective study was performed on 87 early-stage cervical cancer patients evaluated with PET/CT and pelvic MRI before surgery. Histopathological evaluation of lymph nodes served as the diagnostic standard. F-FDG PET/CT and MRI images were analyzed and correlated with histopathological findings. RESULTS: The overall node-based sensitivity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET/CT were 91% (61/67), 78.2% (61/78), 99.4% (1079/1085), and 98% (1140/1163), respectively, which were higher than the corresponding values of MRI, at 37.3% (25/67), 61% (25/41), 96.3% (1080/1122), and 95% (1105/1163) (P<0.034). The difference in diagnostic efficacy for identifying node-based metastases between PET/CT and MRI was significant (PET/CT vs. MRI, 0.719 vs. 0.587, P=0.017). Meanwhile, the overall patient-based sensitivity, PPV, NPV, and accuracy of PET/CT were 100% (34/34), 87.2% (34/39), 100% (48/48), and 94.3% (82/87), respectively, whereas the corresponding MRI values were 44% (15/34), 65% (15/23),74% (45/61), and 69% (60/87) (P<0.04). The difference in diagnostic efficacy for identifying patient-based metastases between PET/CT and MRI was significant (PET/CT vs. MRI, 0.974 vs. 0.705, P<0.001). CONCLUSION: PET/CT has been proven to be valuable in detecting lymph-node metastases. Compared with MRI, PET/CT has higher sensitivity, PPV, NPV, and accuracy in patients with early-stage cervical cancer for detecting lymphatic metastases.