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Bao, Kai

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Bao, Kai
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Now showing 1 - 6 of 6
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    Bioimaging of botulinum toxin and hyaluronate hydrogels using zwitterionic near-infrared fluorophores
    (BioMed Central, 2017) Kim, Ki Su; Kim, Yun Seop; Bao, Kai; Wada, Hideyuki; Choi, Hak Soo; Hahn, Sei Kwang
    Background: The injection of botulinum toxin (BTX) to reduce facial wrinkles is one of the most frequently performed plastic surgery procedures. The biocompatible hydrogels are injected with BTX for effective tissue augmentation. However, it is difficult to determine the interval of injection for effective tissue augmentation. Method BTX and hyaluronate (HA) hydrogels were labeled with zwitterionic (ZW) near-infrared (NIR) fluorophores and visualized for 3 weeks after injection to BALB/c nude mice. Results: BTX-ZW conjugates and diaminohexane (DAH)-HA-ZW hydrogels were successfully prepared by the conventional EDC/NHS chemistry. Using the NIR fluorescence imaging, we confirmed that approximately 10% of BTX-ZW conjugates and 50% of DAH-HA-ZW hydrogels remained 3 weeks post-injection. Conclusion: This bioimaging technique using invisible NIR fluorescence light can be exploited for various biomedical applications.
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    Synthesis and bioevaluation of N,4-diaryl-1,3-thiazole-2-amines as tubulin inhibitors with potent antiproliferative activity
    (Public Library of Science, 2017) Sun, Maolin; Xu, Qile; Xu, Jingwen; Wu, Yue; Wang, Yueting; Zuo, Daiying; Guan, Qi; Bao, Kai; Wang, Jian; Wu, Yingliang; Zhang, Weige
    A series of N,4-diaryl-1,3-thiazole-2-amines containing three aromatic rings with an amino linker were designed and synthesized as tubulin inhibitors and evaluated for their antiproliferative activity in three human cancer cell lines. Most of the target compounds displayed moderate antiproliferative activity, and N-(2,4-dimethoxyphenyl)-4-(4-methoxyphenyl)-1,3-thiazol-2-amine (10s) was determined to be the most potent compound. Tubulin polymerization and immunostaining experiments revealed that 10s potently inhibited tubulin polymerization and disrupted tubulin microtubule dynamics in a manner similar to CA-4. Moreover, 10s effectively induced SGC-7901 cell cycle arrest at the G2/M phase in both concentration- and time-dependent manners. The molecular docking results revealed that 10s could bind to the colchicine binding site of tubulin.
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    Activated carbon for aerobic oxidation: Benign approach toward 2-benzoylbenzimidazoles and 2-benzoylbenzoxazoles synthesis
    (Nature Publishing Group, 2015) Bao, Kai; Li, Fuqing; Liu, Hanjing; Wang, Zhiwei; Shen, Qirong; Wang, Jian; Zhang, Weige
    A general strategy involving a novel and highly efficient aerobic benzylic oxidation promoted by cheap, reusable activated carbon in water is developed. Application of this method has been demonstrated in the benign synthesis of bioactive 2-benzoylbenzimidazoles and 2-benzoylbenzoxazoles derivatives. Furthermore, the activated carbon catalyst could be recovered and reused at least three times without significantly losing its activity. Preliminary research suggests that the oxidation mechanism may involve intermediate hydroperoxidation and that a portion of the final carbonyl product is obtained through a secondary benzylic alcohol intermediate. Finally, theoretical calculations reveal that the oxidation yield is closely associated with the electric density at the benzylic position of the substrate.
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    Ultrasound-promoted two-step synthesis of 3-arylselenylindoles and 3-arylthioindoles as novel combretastatin A-4 analogues
    (Nature Publishing Group, 2016) Wen, Zhiyong; Li, Xiaona; Zuo, Daiying; Lang, Binyue; Wu, Yang; Jiang, Mingyang; Ma, Huizhuo; Bao, Kai; Wu, Yingliang; Zhang, Weige
    A series of 3-(3′-hydroxy-4′-methoxyphenyl)selenyl-5,6,7-trimethoxy-1H-indoles and 3-(3′-hydroxy-4′-methoxyphenyl)thio-5,6,7-trimethoxy-1H-indoles were obtained as a new class of combretastatin A-4 (CA-4) analogues via a convenient ultrasound (US)-assisted two-step process involving 3-selenenylation/sulfenylation followed by O-deallylation. With the assistance of US irradiation, both the reaction rates and yields of selenenylation, sulfenylation and O-deallylation could be significantly improved. A comparison of the reaction rates of O-deallylation and ester reduction demonstrated that O-deallylation was more sensitive to US irradiation. Finally, these products were evaluated for their antiproliferative activities, and most of them showed moderate to potent activities against three human cancer cell lines in vitro.
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    Charge and Hydrophobicity Effects of NIR Fluorophores on Bone-Specific Imaging
    (Ivyspring International Publisher, 2015) Bao, Kai; Nasr, Khaled A.; Hyun, Hoon; Lee, Jeong Heon; Gravier, Julien; Gibbs, Summer L.; Choi, Hak Soo
    Recent advances in near-infrared (NIR) fluorescence imaging enabled real-time intraoperative detection of bone metastases, bone growth, and tissue microcalcification. Pamidronate (PAM) has been widely used for this purpose because of its high binding affinity toward bone and remarkable therapeutic effects. Herein we describe the development of a series of PAM-conjugated NIR fluorophores that varied in net charges and hydrophobicity, and compared their bone targeting efficiency, biodistribution, and blood clearance. Since the targeting moiety, PAM, is highly negatively charged but small, the overall in vivo bone targeting and biodistribution were mediated by the physicochemical properties of conjugated fluorophores.
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    Screening of Small Molecule Microarrays for Ligands Targeted to the Extracellular Epitopes of Living Cells
    (2015) Lee, Jeong Heon; Bao, Kai; Frangioni, John; Choi, Hak Soo
    The screening of living cells using high-throughput microarrays is technically challenging. Great care must be taken in the chemical presentation of potential ligands and the number of collisions that cells make with them. To overcome these issues, we have developed a glass slide-based microarray system to discover small molecule ligands that preferentially bind to one cell type over another, including when the cells differ by only a single receptor. Chemical spots of 300 ± 10 μm in diameter are conjugated covalently to glass slides using an arraying robot, and novel near-infrared fluorophores with peak emission at 700 nm and 800 nm are used to label two different cell types. By carefully optimizing incubation conditions, including cell density, motion, kinetics, detection, etc. we demonstrate that cell-ligand binding occurs, and that the number of cells bound per chemical spot correlates with ligand affinity and specificity. This screening system lays the foundation for high-throughput discovery of novel ligands to the cell surface.