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Non-blinking semiconductor nanocrystals (2009)

X. Wang ; X. Ren ; K. Kahen ; [et al.]

Nature Publishing Group (NPG)

In: Nature. 459(7247): 686-9. doi: 10.1038/nature08072.

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Publication Date: 2009-05-12

Description: The photoluminescence from a variety of individual molecules and nanometre-sized crystallites is defined by large intensity fluctuations, known as 'blinking', whereby their photoluminescence turns 'on' and 'off' intermittently, even under continuous photoexcitation. For semiconductor nanocrystals, it was originally proposed that these 'off' periods corresponded to a nanocrystal with an extra charge. A charged nanocrystal could have its photoluminescence temporarily quenched owing to the high efficiency of non-radiative (for example, Auger) recombination processes between the extra charge and a subsequently excited electron-hole pair; photoluminescence would resume only after the nanocrystal becomes neutralized again. Despite over a decade of research, completely non-blinking nanocrystals have not been synthesized and an understanding of the blinking phenomenon remains elusive. Here we report ternary core/shell CdZnSe/ZnSe semiconductor nanocrystals that individually exhibit continuous, non-blinking photoluminescence. Unexpectedly, these nanocrystals strongly photoluminesce despite being charged, as indicated by a multi-peaked photoluminescence spectral shape and short lifetime. To model the unusual photoluminescence properties of the CdZnSe/ZnSe nanocrystals, we softened the abrupt confinement potential of a typical core/shell nanocrystal, suggesting that the structure is a radially graded alloy of CdZnSe into ZnSe. As photoluminescence blinking severely limits the usefulness of nanocrystals in applications requiring a continuous output of single photons, these non-blinking nanocrystals may enable substantial advances in fields ranging from single-molecule biological labelling to low-threshold lasers.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wang, Xiaoyong -- Ren, Xiaofan -- Kahen, Keith -- Hahn, Megan A -- Rajeswaran, Manju -- Maccagnano-Zacher, Sara -- Silcox, John -- Cragg, George E -- Efros, Alexander L -- Krauss, Todd D -- England -- Nature. 2009 Jun 4;459(7247):686-9. doi: 10.1038/nature08072.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of Rochester, Rochester, New York 14627, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19430463" target="_blank"〉PubMed〈/a〉

Print ISSN: 0028-0836

Electronic ISSN: 1476-4687

Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics

Published by Nature Publishing Group (NPG)

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Small molecule inhibition of the KRAS-PDEdelta interaction impairs oncogenic KRAS signalling (2013)

G. Zimmermann ; B. Papke ; S. Ismail ; [et al.]

Nature Publishing Group (NPG)

In: Nature. 497(7451): 638-42. doi: 10.1038/nature12205.

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Publication Date: 2013-05-24

Description: The KRAS oncogene product is considered a major target in anticancer drug discovery. However, direct interference with KRAS signalling has not yet led to clinically useful drugs. Correct localization and signalling by farnesylated KRAS is regulated by the prenyl-binding protein PDEdelta, which sustains the spatial organization of KRAS by facilitating its diffusion in the cytoplasm. Here we report that interfering with binding of mammalian PDEdelta to KRAS by means of small molecules provides a novel opportunity to suppress oncogenic RAS signalling by altering its localization to endomembranes. Biochemical screening and subsequent structure-based hit optimization yielded inhibitors of the KRAS-PDEdelta interaction that selectively bind to the prenyl-binding pocket of PDEdelta with nanomolar affinity, inhibit oncogenic RAS signalling and suppress in vitro and in vivo proliferation of human pancreatic ductal adenocarcinoma cells that are dependent on oncogenic KRAS. Our findings may inspire novel drug discovery efforts aimed at the development of drugs targeting oncogenic RAS.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Zimmermann, Gunther -- Papke, Bjorn -- Ismail, Shehab -- Vartak, Nachiket -- Chandra, Anchal -- Hoffmann, Maike -- Hahn, Stephan A -- Triola, Gemma -- Wittinghofer, Alfred -- Bastiaens, Philippe I H -- Waldmann, Herbert -- England -- Nature. 2013 May 30;497(7451):638-42. doi: 10.1038/nature12205. Epub 2013 May 22.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemical Biology, Max Planck Institute of Molecular Physiology, D-44227 Dortmund, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23698361" target="_blank"〉PubMed〈/a〉

Keywords: Adenocarcinoma/drug therapy/genetics/metabolism ; Animals ; Benzimidazoles/*chemistry/metabolism/*pharmacology/therapeutic use ; Binding Sites ; Carcinoma, Pancreatic Ductal/drug therapy/genetics/metabolism ; Cell Line ; Cell Line, Tumor ; Cell Proliferation/drug effects ; Cyclic Nucleotide Phosphodiesterases, Type 6/antagonists & ; inhibitors/chemistry/*metabolism ; Dogs ; Humans ; Hydrogen Bonding ; MAP Kinase Signaling System/drug effects ; Mice ; Mice, Nude ; Mitogen-Activated Protein Kinases/metabolism ; Models, Molecular ; Molecular Conformation ; Neoplasm Transplantation ; Oncogene Protein p21(ras)/*antagonists & inhibitors/genetics/*metabolism ; Protein Binding/drug effects ; Signal Transduction/*drug effects

Print ISSN: 0028-0836

Electronic ISSN: 1476-4687

Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics