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  1. Article ; Online: Hydrogen evolution catalysis by terminal molybdenum-oxo complexes

    Pinky Yadav / Izana Nigel-Etinger / Amit Kumar / Amir Mizrahi / Atif Mahammed / Natalia Fridman / Sophia Lipstman / Israel Goldberg / Zeev Gross

    iScience, Vol 24, Iss 8, Pp 102924- (2021)

    2021  

    Abstract: Summary: Stable complexes with terminal triply bound metal-oxygen bonds are usually not considered as valuable catalysts for the hydrogen evolution reaction (HER). We now report the preparation of three conceptually different (oxo)molybdenum(V) corroles ... ...

    Abstract Summary: Stable complexes with terminal triply bound metal-oxygen bonds are usually not considered as valuable catalysts for the hydrogen evolution reaction (HER). We now report the preparation of three conceptually different (oxo)molybdenum(V) corroles for testing if proton-assisted 2-electron reduction will lead to hyper-reactive molybdenum(III) capable of converting protons to hydrogen gas. The upto 670 mV differences in the [(oxo)Mo(IV)]-/[(oxo)Mo(III)]−2 redox potentials of the dissolved complexes came into effect by the catalytic onset potential for proton reduction thereby, significantly earlier than their reduction process in the absence of acids, but the two more promising complexes were not stable at practical conditions. Under heterogeneous conditions, the smallest and most electron-withdrawing catalyst did excel by all relevant criteria, including a 97% Faradaic efficiency for catalyzing HER from acidic water. This suggests complexes based on molybdenum, the only sustainable heavy transition metal, as catalysts for other yet unexplored green-energy-relevant processes.
    Keywords Chemistry ; Inorganic chemistry ; Molecular inorganic chemistry ; Chemical reaction ; Catalysis ; Science ; Q
    Subject code 540
    Language English
    Publishing date 2021-08-01T00:00:00Z
    Publisher Elsevier
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Ultrafast Dynamics of Sb-Corroles

    Clark Zahn / Till Stensitzki / Mario Gerecke / Alexander Berg / Atif Mahammed / Zeev Gross / Karsten Heyne

    Molecules, Vol 22, Iss 7, p

    A Combined Vis-Pump Supercontinuum Probe and Broadband Fluorescence Up-Conversion Study

    2017  Volume 1174

    Abstract: Corroles are a developing class of tetrapyrrole-based molecules with significant chemical potential and relatively unexplored photophysical properties. We combined femtosecond broadband fluorescence up-conversion and fs broadband Vis-pump Vis-probe ... ...

    Abstract Corroles are a developing class of tetrapyrrole-based molecules with significant chemical potential and relatively unexplored photophysical properties. We combined femtosecond broadband fluorescence up-conversion and fs broadband Vis-pump Vis-probe spectroscopy to comprehensively characterize the photoreaction of 5,10,15-tris-pentafluorophenyl-corrolato-antimony(V)-trans-difluoride (Sb-tpfc-F2). Upon fs Soret band excitation at ~400 nm, the energy relaxed almost completely to Q band electronic excited states with a time constant of 500 ± 100 fs; this is evident from the decay of Soret band fluorescence at around 430 nm and the rise time of Q band fluorescence, as well as from Q band stimulated emission signals at 600 and 650 nm with the same time constant. Relaxation processes on a time scale of 10 and 20 ps were observed in the fluorescence and absorption signals. Triplet formation showed a time constant of 400 ps, with an intersystem crossing yield from the Q band to the triplet manifold of between 95% and 99%. This efficient triplet formation is due to the spin-orbit coupling of the antimony ion.
    Keywords photoreaction ; triplet formation ; femtosecond spectroscopy ; fluorescence up-conversion ; corrole dynamics ; tetrapyrrole ; ultrafast relaxation ; intersystem crossing ; Organic chemistry ; QD241-441
    Subject code 530
    Language English
    Publishing date 2017-07-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Development of Singlet Oxygen Luminescence Kinetics during the Photodynamic Inactivation of Green Algae

    Tobias Bornhütter / Judith Pohl / Christian Fischer / Irena Saltsman / Atif Mahammed / Zeev Gross / Beate Röder

    Molecules, Vol 21, Iss 4, p

    2016  Volume 485

    Abstract: Recent studies show the feasibility of photodynamic inactivation of green algae as a vital step towards an effective photodynamic suppression of biofilms by using functionalized surfaces. The investigation of the intrinsic mechanisms of photodynamic ... ...

    Abstract Recent studies show the feasibility of photodynamic inactivation of green algae as a vital step towards an effective photodynamic suppression of biofilms by using functionalized surfaces. The investigation of the intrinsic mechanisms of photodynamic inactivation in green algae represents the next step in order to determine optimization parameters. The observation of singlet oxygen luminescence kinetics proved to be a very effective approach towards understanding mechanisms on a cellular level. In this study, the first two-dimensional measurement of singlet oxygen kinetics in phototrophic microorganisms on surfaces during photodynamic inactivation is presented. We established a system of reproducible algae samples on surfaces, incubated with two different cationic, antimicrobial potent photosensitizers. Fluorescence microscopy images indicate that one photosensitizer localizes inside the green algae while the other accumulates along the outer algae cell wall. A newly developed setup allows for the measurement of singlet oxygen luminescence on the green algae sample surfaces over several days. The kinetics of the singlet oxygen luminescence of both photosensitizers show different developments and a distinct change over time, corresponding with the differences in their localization as well as their photosensitization potential. While the complexity of the signal reveals a challenge for the future, this study incontrovertibly marks a crucial, inevitable step in the investigation of photodynamic inactivation of biofilms: it shows the feasibility of using the singlet oxygen luminescence kinetics to investigate photodynamic effects on surfaces and thus opens a field for numerous investigations.
    Keywords singlet oxygen ; photodynamic inactivation ; phototoxicity ; biofilms ; corroles ; Organic chemistry ; QD241-441
    Subject code 660
    Language English
    Publishing date 2016-04-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article ; Online: Cell-Penetrating Protein/Corrole Nanoparticles

    Matan Soll / Tridib K. Goswami / Qiu-Cheng Chen / Irena Saltsman / Ruijie D. Teo / Mona Shahgholi / Punnajit Lim / Angel J. Di Bilio / Sarah Cohen / John Termini / Harry B. Gray / Zeev Gross

    Scientific Reports, Vol 9, Iss 1, Pp 1-

    2019  Volume 11

    Abstract: Abstract Recent work has highlighted the potential of metallocorroles as versatile platforms for the development of drugs and imaging agents, since the bioavailability, physicochemical properties and therapeutic activity can be dramatically altered by ... ...

    Abstract Abstract Recent work has highlighted the potential of metallocorroles as versatile platforms for the development of drugs and imaging agents, since the bioavailability, physicochemical properties and therapeutic activity can be dramatically altered by metal ion substitution and/or functional group replacement. Significant advances in cancer treatment and imaging have been reported based on work with a water-soluble bis-sulfonated gallium corrole in both cellular and rodent-based models. We now show that cytotoxicities increase in the order Ga < Fe < Al < Mn < Sb < Au for bis-sulfonated corroles; and, importantly, that they correlate with metallocorrole affinities for very low density lipoprotein (VLDL), the main carrier of lipophilic drugs. As chemotherapeutic potential is predicted to be enhanced by increased lipophilicity, we have developed a novel method for the preparation of cell-penetrating lipophilic metallocorrole/serum-protein nanoparticles (NPs). Cryo-TEM revealed an average core metallocorrole particle size of 32 nm, with protein tendrils extending from the core (conjugate size is ~100 nm). Optical imaging of DU-145 prostate cancer cells treated with corrole NPs (≤100 nM) revealed fast cellular uptake, very slow release, and distribution into the endoplasmic reticulum (ER) and lysosomes. The physical properties of corrole NPs prepared in combination with transferrin and albumin were alike, but the former were internalized to a greater extent by the transferrin-receptor-rich DU-145 cells. Our method of preparation of corrole/protein NPs may be generalizable to many bioactive hydrophobic molecules to enhance their bioavailability and target affinity.
    Keywords Medicine ; R ; Science ; Q
    Subject code 500
    Language English
    Publishing date 2019-02-01T00:00:00Z
    Publisher Nature Publishing Group
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article: Singlet oxygen luminescence kinetics under PDI relevant conditions of pathogenic dermatophytes and molds

    Bornhütter, Tobias / Atif Mahammed / Beate Röder / Georg Däschlein / Irena Saltsman / Nedaa Shamali / Zeev Gross

    Journal of photochemistry and photobiology. 2018 Jan., v. 178

    2018  

    Abstract: A treatment of onychomycosis using the photodynamic effect would be a favorable alternative to currently used antimycotic drugs. This study should be considered as a first step towards development and control of an efficient photodynamic inactivation of ... ...

    Abstract A treatment of onychomycosis using the photodynamic effect would be a favorable alternative to currently used antimycotic drugs. This study should be considered as a first step towards development and control of an efficient photodynamic inactivation of onychomycosis causative pathogens. Here, we evaluate the usage of time-resolved 2D singlet oxygen luminescence detection in combination with 2D fluorescence scanning as a tool to understand the behavior of the photosensitizer when applied to fungi on Petri dishes. To investigate the interaction of photosensitizer with fungi in various concentrations and in different stages of live, a photodynamic inactivation was avoided by keeping the samples in darkness. Scans of singlet oxygen luminescence and photosensitizer fluorescence were performed over a period of 24days. Two different photosensitizer, a cationic porphyrin and cationic corrole and two fungi strains, the dermatophyte Trichophyton rubrum and the mold Scopulariopsis brevicaulis, were investigated in this study. The two-dimensional correlation of photosensitizer fluorescence and singlet oxygen luminescence revealed differences in the diffusion of both photosensitizer. Even though the singlet oxygen luminescence was quenched with increasing growth of fungi, it was found that the kinetics of singlet oxygen luminescence could be detected on Petri dishes for both photosensitizers and both fungi strains for up to seven days.
    Keywords fluorescence ; keratinophilic fungi ; photosensitizing agents ; porphyrins ; Scopulariopsis ; singlet oxygen ; Trichophyton rubrum
    Language English
    Dates of publication 2018-01
    Size p. 606-613.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 623022-2
    ISSN 1873-2682 ; 1011-1344
    ISSN (online) 1873-2682
    ISSN 1011-1344
    DOI 10.1016/j.jphotobiol.2017.12.015
    Database NAL-Catalogue (AGRICOLA)

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  6. Article: Photodynamic inactivation of mold fungi spores by newly developed charged corroles

    Preuß, Annegret / Irena Saltsman / Atif Mahammed / Michael Pfitzner / Israel Goldberg / Zeev Gross / Beate Röder

    Journal of Photochemistry & Photobiology, B: Biology. 2014 Apr. 05, v. 133

    2014  

    Abstract: The photodynamic effect, originally used in photodynamic therapy (PDT) for the treatment of different diseases, e.g. of cancer, has recently been introduced for the inactivation of bacteria. Mold fungi, which provoke health problems like allergies and ... ...

    Abstract The photodynamic effect, originally used in photodynamic therapy (PDT) for the treatment of different diseases, e.g. of cancer, has recently been introduced for the inactivation of bacteria. Mold fungi, which provoke health problems like allergies and diseases of the respiratory tract, are even more resistant and their biology is also very different. This study presents the development of four new photosensitizers, which, in combination with low doses of white light, inhibit the germination of mold fungi spores. Two of them even cause lethal damage to the conidia (spores) which are responsible for the spreading of mold fungi. The photoactivity of the newly synthesized corroles was obtained by their application on three different mold fungi: Aspergillus niger, Cladosporium cladosporoides, and Penicillium purpurgenum. To distinguish between inactivation of germination and permanent damage, the fungi were first incubated under illumination for examination of photosensitizer-induced growth inhibition and then left in darkness to test the survival of the conidia. None of the compounds displayed dark toxicity, but all of them attenuated or prevented germination when exposed to light, and the positively charged complexes induced a complete damage of the conidia.
    Keywords Aspergillus niger ; Cladosporium ; Penicillium ; bacteria ; conidia ; fungi ; germination ; growth retardation ; hypersensitivity ; lighting ; neoplasms ; photosensitizing agents ; respiratory tract diseases ; therapeutics ; toxicity ; white light
    Language English
    Dates of publication 2014-0405
    Size p. 39-46.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 623022-2
    ISSN 1873-2682 ; 1011-1344
    ISSN (online) 1873-2682
    ISSN 1011-1344
    DOI 10.1016/j.jphotobiol.2014.02.013
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  7. Article: A corrole nanobiologic elicits tissue-activated MRI contrast enhancement and tumor-targeted toxicity

    Sims, Jessica D / Ahmed Ibrahim / Chris Hanson / Eduardo Marban / Felix Alonso-Valenteen / Gevorg Karapetyan / Harry B. Gray / Ira Harutyunyan / Jae Youn Hwang / Jan Michael Taguiam / Karn Sorasaenee / Lali K. Medina-Kauwe / Rex Moats / Richard Polo / Shawn Wagner / Zeev Gross

    Journal of Controlled Release. 2015 Nov. 10, v. 217

    2015  

    Abstract: Water-soluble corroles with inherent fluorescence can form stable self-assemblies with tumor-targeted cell penetration proteins, and have been explored as agents for optical imaging and photosensitization of tumors in pre-clinical studies. However, the ... ...

    Abstract Water-soluble corroles with inherent fluorescence can form stable self-assemblies with tumor-targeted cell penetration proteins, and have been explored as agents for optical imaging and photosensitization of tumors in pre-clinical studies. However, the limited tissue-depth of excitation wavelengths limits their clinical applicability. To examine their utility in more clinically-relevant imaging and therapeutic modalities, here we have explored the use of corroles as contrast enhancing agents for magnetic resonance imaging (MRI), and evaluated their potential for tumor-selective delivery when encapsulated by a tumor-targeted polypeptide. We have found that a manganese-metallated corrole exhibits significant T1 relaxation shortening and MRI contrast enhancement that is blocked by particle formation in solution but yields considerable MRI contrast after tissue uptake. Cell entry but not low pH enables this. Additionally, the corrole elicited tumor-toxicity through the loss of mitochondrial membrane potential and cytoskeletal breakdown when delivered by the targeted polypeptide. The protein–corrole particle (which we call HerMn) exhibited improved therapeutic efficacy compared to current targeted therapies used in the clinic. Taken together with its tumor-preferential biodistribution, our findings indicate that HerMn can facilitate tumor-targeted toxicity after systemic delivery and tumor-selective MR imaging activatable by internalization.
    Keywords cytoskeleton ; fluorescence ; image analysis ; magnetic resonance imaging ; membrane potential ; mitochondrial membrane ; neoplasms ; pH ; photosensitivity ; polypeptides ; proteins ; toxicity ; wavelengths
    Language English
    Dates of publication 2015-1110
    Size p. 92-101.
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 632533-6
    ISSN 1873-4995 ; 0168-3659
    ISSN (online) 1873-4995
    ISSN 0168-3659
    DOI 10.1016/j.jconrel.2015.08.046
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