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  • 1
    Online Resource
    Online Resource
    Transient Ru-methyl formate intermediates generated with bifunctional transfer hydrogenation catalysts
    Proceedings of the National Academy of Sciences ; 2012
    In:  Proceedings of the National Academy of Sciences Vol. 109, No. 7 ( 2012-02-14), p. 2246-2250
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 109, No. 7 ( 2012-02-14), p. 2246-2250
    Abstract: Desorption electrospray ionization (DESI) coupled to high-resolution Orbitrap mass spectrometry (MS) was used to study the reactivity of a (β-amino alcohol)(arene)RuCl transfer hydrogenation catalytic precursor in methanol (CH 3 OH). By placing [( p -cymene)RuCl 2 ] 2 on a surface and spraying a solution of β-amino alcohol in methanol, two unique transient intermediates having lifetimes in the submillisecond to millisecond range were detected. These intermediates were identified as Ru (II) and Ru (IV) complexes incorporating methyl formate (HCOOCH 3 ). The Ru (IV) intermediate is not observed when the DESI spray solution is sparged with Ar gas, indicating that O 2 dissolved in the solvent is necessary for oxidizing Ru (II) to Ru (IV). These proposed intermediates are supported by high-resolution and high mass accuracy measurements and by comparing experimental to calculated isotope profiles. Additionally, analyzing the bulk reaction mixture using gas chromatography-MS and nuclear magnetic resonance spectroscopy confirms the formation of HCOOCH 3 . These results represent an example that species generated from the (β-amino alcohol)(arene)RuCl (II) catalytic precursor can selectively oxidize CH 3 OH to HCOOCH 3 . This observation leads us to propose a pathway that can compete with the hydrogen transfer catalytic cycle. Although bifunctional hydrogen transfer with Ru catalysts has been well-studied, the ability of DESI to intercept intermediates formed in the first few milliseconds of a chemical reaction allowed identification of previously unrecognized intermediates and reaction pathways in this catalytic system.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1118934109
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2012
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  • 2
    Online Resource
    Online Resource
    Spontaneous generation of hydrogen peroxide from aqueous microdroplets
    Proceedings of the National Academy of Sciences ; 2019
    In:  Proceedings of the National Academy of Sciences Vol. 116, No. 39 ( 2019-09-24), p. 19294-19298
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 116, No. 39 ( 2019-09-24), p. 19294-19298
    Abstract: We show H 2 O 2 is spontaneously produced from pure water by atomizing bulk water into microdroplets (1 μm to 20 µm in diameter). Production of H 2 O 2 , as assayed by H 2 O 2 -sensitve fluorescence dye peroxyfluor-1, increased with decreasing microdroplet size. Cleavage of 4-carboxyphenylboronic acid and conversion of phenylboronic acid to phenols in microdroplets further confirmed the generation of H 2 O 2 . The generated H 2 O 2 concentration was ∼30 µM (∼1 part per million) as determined by titration with potassium titanium oxalate. Changing the spray gas to O 2 or bubbling O 2 decreased the yield of H 2 O 2 in microdroplets, indicating that pure water microdroplets directly generate H 2 O 2 without help from O 2 either in air surrounding the droplet or dissolved in water. We consider various possible mechanisms for H 2 O 2 formation and report a number of different experiments exploring this issue. We suggest that hydroxyl radical (OH) recombination is the most likely source, in which OH is generated by loss of an electron from OH − at or near the surface of the water microdroplet. This catalyst-free and voltage-free H 2 O 2 production method provides innovative opportunities for green production of hydrogen peroxide.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1911883116
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2019
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
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  • 3
    Online Resource
    Online Resource
    Charge-altering releasable transporters (CARTs) for the delivery and release of mRNA in living animals
    Proceedings of the National Academy of Sciences ; 2017
    In:  Proceedings of the National Academy of Sciences Vol. 114, No. 4 ( 2017-01-24)
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 114, No. 4 ( 2017-01-24)
    Abstract: Functional delivery of mRNA to tissues in the body is key to implementing fundamentally new and potentially transformative strategies for vaccination, protein replacement therapy, and genome editing, collectively affecting approaches for the prevention, detection, and treatment of disease. Broadly applicable tools for the efficient delivery of mRNA into cultured cells would advance many areas of research, and effective and safe in vivo mRNA delivery could fundamentally transform clinical practice. Here we report the step-economical synthesis and evaluation of a tunable and effective class of synthetic biodegradable materials: charge-altering releasable transporters (CARTs) for mRNA delivery into cells. CARTs are structurally unique and operate through an unprecedented mechanism, serving initially as oligo(α-amino ester) cations that complex, protect, and deliver mRNA and then change physical properties through a degradative, charge-neutralizing intramolecular rearrangement, leading to intracellular release of functional mRNA and highly efficient protein translation. With demonstrated utility in both cultured cells and animals, this mRNA delivery technology should be broadly applicable to numerous research and therapeutic applications.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1614193114
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2017
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
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  • 4
    Online Resource
    Online Resource
    Designed guanidinium-rich amphipathic oligocarbonate molecular transporters complex, deliver and release siRNA in cells
    Proceedings of the National Academy of Sciences ; 2012
    In:  Proceedings of the National Academy of Sciences Vol. 109, No. 33 ( 2012-08-14), p. 13171-13176
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 109, No. 33 ( 2012-08-14), p. 13171-13176
    Abstract: The polyanionic nature of oligonucleotides and their enzymatic degradation present challenges for the use of siRNA in research and therapy; among the most notable of these is clinically relevant delivery into cells. To address this problem, we designed and synthesized the first members of a new class of guanidinium-rich amphipathic oligocarbonates that noncovalently complex, deliver, and release siRNA in cells, resulting in robust knockdown of target protein synthesis in vitro as determined using a dual-reporter system. The organocatalytic oligomerization used to synthesize these co-oligomers is step-economical and broadly tunable, affording an exceptionally quick strategy to explore chemical space for optimal siRNA delivery in varied applications. The speed and versatility of this approach and the biodegradability of the designed agents make this an attractive strategy for biological tool development, imaging, diagnostics, and therapeutic applications.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1211361109
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2012
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 5
    Online Resource
    Online Resource
    mRNA vaccination with charge-altering releasable transporters elicits human T cell responses and cures established tumors in mice
    Proceedings of the National Academy of Sciences ; 2018
    In:  Proceedings of the National Academy of Sciences Vol. 115, No. 39 ( 2018-09-25)
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 115, No. 39 ( 2018-09-25)
    Abstract: In vivo delivery of antigen-encoding mRNA is a promising approach to personalized cancer treatment. The therapeutic efficacy of mRNA vaccines is contingent on safe and efficient gene delivery, biological stability of the mRNA, and the immunological properties of the vaccine. Here we describe the development and evaluation of a versatile and highly efficient mRNA vaccine-delivery system that employs charge-altering releasable transporters (CARTs) to deliver antigen-coding mRNA to antigen-presenting cells (APCs). We demonstrate in human peripheral blood mononuclear cells that CART vaccines can activate a robust antigen-specific immune response against mRNA-encoded viral epitopes. In an established mouse model, we demonstrate that CARTs preferentially target professional APCs in secondary lymphoid organs upon i.v. injections and target local APCs upon s.c. injection. Finally, we show that CARTs coformulated with mRNA and a Toll-like receptor ligand simultaneously transfect and activate target cells to generate an immune response that can treat and cure mice with large, established tumors.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1810002115
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2018
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 6
    Online Resource
    Online Resource
    Enhanced mRNA delivery into lymphocytes enabled by lipid-varied libraries of charge-altering releasable transporters
    Proceedings of the National Academy of Sciences ; 2018
    In:  Proceedings of the National Academy of Sciences Vol. 115, No. 26 ( 2018-06-26)
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 115, No. 26 ( 2018-06-26)
    Abstract: We report a strategy for generating a combinatorial library of oligonucleotide transporters with varied lipid domains and their use in the efficient transfection of lymphocytes with mRNA in vitro and in vivo. This library is based on amphiphilic charge-altering releasable transporters (CARTs) that contain a lipophilic block functionalized with various side-chain lipids and a polycationic α-amino ester mRNA-binding block that undergoes rearrangement to neutral small molecules, resulting in mRNA release. We show that certain binary mixtures of these lipid-varied CARTs provide up to a ninefold enhancement in mRNA translation in lymphocytes in vitro relative to either a single-lipid CART component alone or the commercial reagent Lipofectamine 2000, corresponding to a striking increase in percent transfection from 9–12% to 80%. Informed by the results with binary mixtures, we further show that CARTs consisting of optimized ratios of the two lead lipids incorporated into a single hybrid-lipid transporter molecule maintain the same delivery efficacy as the noncovalent mixture of two CARTs. The lead lipid CART mixtures and hybrid-lipid CARTs show enhanced lymphocyte transfection in primary T cells and in vivo in mice. This combinatorial approach for rapidly screening mRNA delivery vectors has provided lipid-varied CART mixtures and hybrid-lipid CARTs that exhibit significant improvement in mRNA delivery to lymphocytes, a finding of potentially broad value in research and clinical applications.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1805358115
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2018
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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  • 7
    Online Resource
    Online Resource
    Condensing water vapor to droplets generates hydrogen peroxide
    Proceedings of the National Academy of Sciences ; 2020
    In:  Proceedings of the National Academy of Sciences Vol. 117, No. 49 ( 2020-12-08), p. 30934-30941
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 117, No. 49 ( 2020-12-08), p. 30934-30941
    Abstract: It was previously shown [J. K. Lee et al. , Proc. Natl. Acad. Sci. U.S.A ., 116, 19294–19298 (2019)] that hydrogen peroxide (H 2 O 2 ) is spontaneously produced in micrometer-sized water droplets (microdroplets), which are generated by atomizing bulk water using nebulization without the application of an external electric field. Here we report that H 2 O 2 is spontaneously produced in water microdroplets formed by dropwise condensation of water vapor on low-temperature substrates. Because peroxide formation is induced by a strong electric field formed at the water–air interface of microdroplets, no catalysts or external electrical bias, as well as precursor chemicals, are necessary. Time-course observations of the H 2 O 2 production in condensate microdroplets showed that H 2 O 2 was generated from microdroplets with sizes typically less than ∼10 µm. The spontaneous production of H 2 O 2 was commonly observed on various different substrates, including silicon, plastic, glass, and metal. Studies with substrates with different surface conditions showed that the nucleation and the growth processes of condensate water microdroplets govern H 2 O 2 generation. We also found that the H 2 O 2 production yield strongly depends on environmental conditions, including relative humidity and substrate temperature. These results show that the production of H 2 O 2 occurs in water microdroplets formed by not only atomizing bulk water but also condensing water vapor, suggesting that spontaneous water oxidation to form H 2 O 2 from water microdroplets is a general phenomenon. These findings provide innovative opportunities for green chemistry at heterogeneous interfaces, self-cleaning of surfaces, and safe and effective disinfection. They also may have important implications for prebiotic chemistry.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.2020158117
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2020
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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