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Sökning: WFRF:(Liu Tianqi)

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1.
  • Liu, Haiyang, et al. (författare)
  • A simple Schiff base as dual-responsive fluorescent sensor for bioimaging recognition of Zn2+ and Al3+ in living cells
  • 2018
  • Ingår i: Journal of materials chemistry. B. - : ROYAL SOC CHEMISTRY. - 2050-750X .- 2050-7518. ; 6:34, s. 5435-5442
  • Tidskriftsartikel (refereegranskat)abstract
    • A simple Schiff base fluorescent sensor (BDNOL) was synthesized from the reaction of picolinohydrazide and 4-(diethylamino)salicylaldehyde, and developed for selective detection of Al3+ and Zn2+. This non-fluorescent sensor displayed obvious fluorescence enhancement after binding to Al3+/Zn2+ ions with high sensitivity and selectivity, accompanied by obvious fluorescence emission enhancement (504 nm for Al3+ and 575 nm for Zn2+). The detection limits were found to be 8.30 x 10(-8) M for Al3+ and 1.24 x 10(-7) M for Zn2+. The binding mechanisms between BDNOL and Al3+/Zn2+ ions were supported by H-1 NMR and HR-MS analysis, and a density functional theory (DFT) study. The sensing behavior was also studied with molecular logic functions of OR, AND, and NOT gates. Furthermore, the fluorescent sensor was successfully used to recognize Al3+ and Zn2+ in living cells, suggesting that this simple biosensor has great potential in biological imaging applications.
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2.
  • Yang, Hao, et al. (författare)
  • Intramolecular hydroxyl nucleophilic attack pathway by a polymeric water oxidation catalyst with single cobalt sites
  • 2022
  • Ingår i: Nature Catalysis. - : Springer Nature. - 2520-1158. ; 5:5, s. 414-429
  • Tidskriftsartikel (refereegranskat)abstract
    • Exploration of efficient water oxidation catalysts (WOCs) is the primary challenge in conversion of renewable energy into fuels. Here we report a molecularly well-defined heterogeneous WOC with Aza-fused, pi-conjugated, microporous polymer (Aza-CMP) coordinated single cobalt sites (Aza-CMP-Co). The single cobalt sites in Aza-CMP-Co exhibited superior activity under alkaline and near-neutral conditions. Moreover, the molecular nature of the isolated catalytic sites makes Aza-CMP-Co a reliable model for studying the heterogeneous water oxidation mechanism. By a combination of experimental and theoretical results, a pH-dependent nucleophilic attack pathway for O-O bond formation was proposed. Under alkaline conditions, the intramolecular hydroxyl nucleophilic attack (IHNA) process with which the adjacent -OH group nucleophilically attacks Co4+=O was identified as the rate-determining step. This process leads to lower activation energy and accelerated kinetics than those of the intermolecular water nucleophilic attack (WNA) pathway. This study provides significant insights into the crucial function of electrolyte pH in water oxidation catalysis and enhancement of water oxidation activity by regulation of the IHNA pathway.
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3.
  • Yang, Hao, et al. (författare)
  • Monolithic FAPbBr3 Photoanode for Photoelectrochemical Water Oxidation with Ultralow-Onset-Potential
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Despite considerable research efforts on photoelectrochemical (PEC) water splitting over the past few decades, its practical application is still impeded by the lack of efficient, stable, and scalable photoelectrodes. Herein, we demonstrate the facile fabrication of a metal-halide perovskite-based photoanode for PEC water oxidation. A hole transport material-free and precious metal-free FAPbBr3 photovoltaic (PV) device is fabricated for the first time to examine the charge separation performance of the FAPbBr3 absorber. With a planar structure using mesoporous carbon as a hole-conducting layer, the device achieved a solar-to-electrical power conversion efficiency of 9.2% and a Voc of 1.4 V. The solar cell architecture is successfully applied to build a monolithic photoanode with the FAPbBr3 absorber, carbon/graphite conductive protection layer, and NiFe catalyst layers for direct photo-driven water oxidation. With suitable energy band alignment and minimal contact loss, the photoanode delivers an ultralow onset potential below 0 V versus a reversible hydrogen electrode and a high applied bias photon-to-current efficiency of 8.5%. Stable operation exceeding 100 h under constant solar illumination is successfully reached by the application of UV filter protection. A detailed photothermal investigation confirms that the photothermal effect can improve the overall performance of the perovskite photoanode. The results in this report are of great significance in guiding the further development of PV material-based photoelectrodes for solar fuel applications.
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4.
  • Yang, Hao, et al. (författare)
  • Monolithic FAPbBr3 photoanode for photoelectrochemical water oxidation with low onset-potential and enhanced stability
  • 2023
  • Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 14:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Despite considerable research efforts on photoelectrochemical water splitting over the past decades, practical application faces challenges by the absence of efficient, stable, and scalable photoelectrodes. Herein, we report a metal-halide perovskite-based photoanode for photoelectrochemical water oxidation. With a planar structure using mesoporous carbon as a hole-conducting layer, the precious metal-free FAPbBr3 photovoltaic device achieves 9.2% solar-to-electrical power conversion efficiency and 1.4 V open-circuit voltage. The photovoltaic architecture successfully applies to build a monolithic photoanode with the FAPbBr3 absorber, carbon/graphite conductive protection layers, and NiFe catalyst layers for water oxidation. The photoanode delivers ultralow onset potential below 0 V versus the reversible hydrogen electrode and high applied bias photon-to-current efficiency of 8.5%. Stable operation exceeding 100 h under solar illumination by applying ultraviolet-filter protection. The photothermal investigation verifies the performance boost in perovskite photoanode by photothermal effect. This study is significant in guiding the development of photovoltaic material-based photoelectrodes for solar fuel applications.
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5.
  • Biaobiao, Zhang, et al. (författare)
  • Modifying Ru-bda Backbone with Steric Hindrance and Hydrophilicity: Influence of Secondary Coordination Environments on Water-Oxidation Mechanism.
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Understanding the seven coordination and O−O coupling pathway of the distinguished Ru-bda catalysts is essential for the development of next generation efficient water-oxidation catalysts based on earth-abundant metals. This work reports the synthesis, characterization and catalytic properties of a monomeric ruthenium catalyst Ru-bnda (H2bnda = 2,2'-bi(nicotinic acid)-6,6'-dicarboxylic acid) featuring steric hindrance and enhanced hydrophilicity on the backbone. Combining experimental evidence with systematic density functional theory calculations on the Ru-bnda and related catalysts Ru-bda, Ru-pda and Ru-biqa, we emphasized that seven coordination clearly determines presence of RuV=O with high spin density on the ORuV=O atom, i.e. oxo with radical properties, which is one of the necessary conditions for reacting through the O−O coupling pathway. However, an additional factor to make the condition sufficient is the favorable intermolecular face-to-face interaction for the generation of the pre-reactive [RuV=O···O=RuV], which is significantly influenced by the secondary coordination environments. This work provides a new understanding of the structure-activity relationship of water-oxidation catalysts and their potential to adopt I2M pathway for O−O bond formation.
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6.
  • Deyev, Sergey M., et al. (författare)
  • Influence of the Position and Composition of Radiometals and Radioiodine Labels on Imaging of Epcam Expression in Prostate Cancer Model Using the DARPin Ec1
  • 2021
  • Ingår i: Cancers. - : MDPI AG. - 2072-6694. ; 13:14
  • Tidskriftsartikel (refereegranskat)abstract
    • Simple Summary Metastasis-targeting therapy might improve outcomes in oligometastatic prostate cancer. Epithelial cell adhesion molecule (EpCAM) is overexpressed in 40-60% of prostate cancer cases and might be used as a target for specific delivery of toxins and drugs. Radionuclide molecular imaging could enable non-invasive detection of EpCAM and stratification of patients for targeted therapy. Designed ankyrin repeat proteins (DARPins) are scaffold proteins, which can be selected for specific binding to different targets. The DARPin Ec1 binds strongly to EpCAM. To determine an optimal design of Ec1-based probes, we labeled Ec1 at two different positions with four different nuclides (Ga-68, In-111, Co-57 and I-125) and investigated the impact on Ec1 biodistribution. We found that the C-terminus is the best position for labeling and that In-111 and I-125 provide the best imaging contrast. This study might be helpful for scientists developing imaging probes based on scaffold proteins. The epithelial cell adhesion molecule (EpCAM) is intensively overexpressed in 40-60% of prostate cancer (PCa) cases and can be used as a target for the delivery of drugs and toxins. The designed ankyrin repeat protein (DARPin) Ec1 has a high affinity to EpCAM (68 pM) and a small size (18 kDa). Radiolabeled Ec1 might be used as a companion diagnostic for the selection of PCa patients for therapy. The study aimed to investigate the influence of radiolabel position (N- or C-terminal) and composition on the targeting and imaging properties of Ec1. Two variants, having an N- or C-terminal cysteine, were produced, site-specifically conjugated to a DOTA chelator and labeled with cobalt-57, gallium-68 or indium-111. Site-specific radioiodination was performed using ((4-hydroxyphenyl)-ethyl)maleimide (HPEM). Biodistribution of eight radiolabeled Ec1-probes was measured in nude mice bearing PCa DU145 xenografts. In all cases, positioning of a label at the C-terminus provided the best tumor-to-organ ratios. The non-residualizing [I-125]I-HPEM label provided the highest tumor-to-muscle and tumor-to-bone ratios and is more suitable for EpCAM imaging in early-stage PCa. Among the radiometals, indium-111 provided the highest tumor-to-blood, tumor-to-lung and tumor-to-liver ratios and could be used at late-stage PCa. In conclusion, label position and composition are important for the DARPin Ec1.
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7.
  • Ding, Haozhong, et al. (författare)
  • HER2-Specific Pseudomonas Exotoxin A PE25 Based Fusions : Influence of Targeting Domain on Target Binding, Toxicity, and In Vivo Biodistribution
  • 2020
  • Ingår i: Pharmaceutics. - : MDPI AG. - 1999-4923. ; 12:4
  • Tidskriftsartikel (refereegranskat)abstract
    • The human epidermal growth factor receptor 2 (HER2) is a clinically validated target for cancer therapy, and targeted therapies are often used in regimens for patients with a high HER2 expression level. Despite the success of current drugs, a number of patients succumb to their disease, which motivates development of novel drugs with other modes of action. We have previously shown that an albumin binding domain-derived affinity protein with specific affinity for HER2, ADAPT(6), can be used to deliver the highly cytotoxic protein domain PE25, a derivative of Pseudomonas exotoxin A, to HER2 overexpressing malignant cells, leading to potent and specific cell killing. In this study we expanded the investigation for an optimal targeting domain and constructed two fusion toxins where a HER2-binding affibody molecule, Z(HER2:2891), or the dual-HER2-binding hybrid Z(HER2:2891)-ADAPT(6) were used for cancer cell targeting. We found that both targeting domains conferred strong binding to HER2; both to the purified extracellular domain and to the HER2 overexpressing cell line SKOV3. This resulted in fusion toxins with high cytotoxic potency toward cell lines with high expression levels of HER2, with EC50 values between 10 and 100 pM. For extension of the plasma half-life, an albumin binding domain was also included. Intravenous injection of the fusion toxins into mice showed a profound influence of the targeting domain on biodistribution. Compared to previous results, with ADAPT(6) as targeting domain, Z(HER2:2891) gave rise to further extension of the plasma half-life and also shifted the clearance route of the fusion toxin from the liver to the kidneys. Collectively, the results show that the targeting domain has a major impact on uptake of PE25-based fusion toxins in different organs. The results also show that PE25-based fusion toxins with high affinity to HER2 do not necessarily increase the cytotoxicity beyond a certain point in affinity. In conclusion, Z(HER2:2891) has the most favorable characteristics as targeting domain for PE25.
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8.
  • Fan, Lizhou, et al. (författare)
  • Molecular Functionalization of NiO Nanocatalyst for Enhanced Water Oxidation by Electronic Structure Engineering
  • 2020
  • Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 13:22, s. 5901-5909
  • Tidskriftsartikel (refereegranskat)abstract
    • Tuning the local environment of nanomaterial-based catalysts has emerged as an effective approach to optimize their oxygen evolution reaction (OER) performance, yet the controlled electronic modulation around surface active sites remains a great challenge. Herein, directed electronic modulation of NiO nanoparticles was achieved by simple surface molecular modification with small organic molecules. By adjusting the electronic properties of modifying molecules, the local electronic structure was rationally tailored and a close electronic structure-activity relationship was discovered: the increasing electron-withdrawing modification readily decreased the electron density around surface Ni sites, accelerating the reaction kinetics and improving OER activity, and vice versa. Detailed investigation by operando Raman spectroelectrochemistry revealed that the electron-withdrawing modification facilitates the charge-transfer kinetics, stimulates the catalyst reconstruction, and promotes abundant high-valent gamma-NiOOH reactive species generation. The NiO-C(6)F(5)catalyst, with the optimized electronic environment, exhibited superior performance towards water oxidation. This work provides a well-designed and effective approach for heterogeneous catalyst fabrication under the molecular level.
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9.
  • Fan, Lizhou, et al. (författare)
  • Promoting the Fe(VI) active species generation by structural and electronic modulation of efficient iron oxide based water oxidation catalyst without Ni or Co
  • 2020
  • Ingår i: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 72
  • Tidskriftsartikel (refereegranskat)abstract
    • Fe is considered as a promising alternative for OER catalysts owing to its high natural abundance and low cost. Due to the low conductivity and sluggish catalytic kinetics, the catalytic efficiency of Fe-rich catalysts is far from less abundant Ni, Co-rich alternatives and has been hardly improved without the involvement of Ni or Co. The lower activity of Fe-rich catalysts renders the real active center of state-of-the-art NiFe, CoFe catalyst in long-term scientific debate, despite of detection of Fe-based active intermediates in these catalysts during catalytic process. In the present work, we fabricated a series of sub-5 nm Fe1-yCryOx nanocatalysts via a simple solvothermal method, achieving systematically promoted high-valent Fe(VI) species generation by structural and electronic modulation, displaying highly active OER performance without involvement of Ni or Co. Detailed investigation revealed that the high OER activity is related to the ultrasmall nanoparticle size that promotes abundant edge- and corner-site exposure at catalyst surface, which involves in OER as highly reactive site; and the incorporated Cr ions that remarkably accelerate the charge transfer kinetics, providing an effective conduit as well as suitable host for high-valent active intermediate. This work reveals the structural prerequisites for efficient Fe-rich OER catalyst fabrication, inspiring deeper understanding of the structure-activity relationship as well as OER mechanism of Fe-based catalysts.
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10.
  • Garousi, Javad, et al. (författare)
  • Experimental HER2-Targeted Therapy Using ADAPT6-ABD-mcDM1 in Mice Bearing SKOV3 Ovarian Cancer Xenografts : Efficacy and Selection of Companion Imaging Counterpart
  • 2022
  • Ingår i: Pharmaceutics. - : MDPI. - 1999-4923. ; 14:8
  • Tidskriftsartikel (refereegranskat)abstract
    • Overexpression of the human epidermal growth factor receptor 2 (HER2) in breast and gastric cancer is exploited for targeted therapy using monoclonal antibodies and antibody-drug conjugates. Small engineered scaffold proteins, such as the albumin binding domain (ABD) derived affinity proteins (ADAPTs), are a promising new format of targeting probes for development of drug conjugates with well-defined structure and tunable pharmacokinetics. Radiolabeled ADAPT6 has shown excellent tumor-targeting properties in clinical trials. Recently, we developed a drug conjugate based on the HER2-targeting ADAPT6 fused to an albumin binding domain (ABD) for increased bioavailability and conjugated to DM1 for cytotoxic action, designated as ADAPT6-ABD-mcDM1. In this study, we investigated the therapeutic efficacy of this conjugate in mice bearing HER2-expressing SKOV3 ovarian cancer xenografts. A secondary aim was to evaluate several formats of imaging probes for visualization of HER2 expression in tumors. Administration of ADAPT6-ABD-mcDM1 provided a significant delay of tumor growth and increased the median survival of the mice, in comparison with both a non-targeting homologous construct (ADAPT(Neg)-ABD-mcDM1) and the vehicle-treated groups, without inducing toxicity to liver or kidneys. Moreover, the evaluation of imaging probes showed that small scaffold proteins, such as Tc-99m(CO)(3)-ADAPT6 or the affibody molecule Tc-99m-Z(HER2:41071), are well suited as diagnostic companions for potential stratification of patients for ADAPT6-ABD-mcDM1-based therapy.
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11.
  • Huang, Tianqi, et al. (författare)
  • Failure Characterization of Discrete SiC MOSFETs under Forward Power Cycling Test
  • 2024
  • Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 17:11
  • Tidskriftsartikel (refereegranskat)abstract
    • Silicon carbide (SiC)-based metal-oxide-semiconductor field-effect transistors (MOSFETs) hold promising application prospects in future high-capacity high-power converters due to their excellent electrothermal characteristics. However, as nascent power electronic devices, their long-term operational reliability lacks sufficient field data. The power cycling test is an important experimental method to assess packaging-related reliability. In order to obtain data closest to actual working conditions, forward power cycling is utilized to carry out SiC MOSFET degradation experiments. Due to the wide bandgap characteristics of SiC MOSFETs, the short-term drift of the threshold voltage is much more serious than that of silicon (Si)-based devices. Therefore, an offline threshold voltage measurement circuit is implemented during power cycling tests to minimize errors arising from this short-term drift. Different characterizations are performed based on power cycling tests, focused on measuring the on-state resistance, thermal impedance, and threshold voltage of the devices. The findings reveal that the primary failure mode under forward power cycling tests, with a maximum junction temperature of 130 degrees C, is bond-wire degradation. Conversely, the solder layer and gate oxide exhibit minimal degradation tendencies under these conditions.
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12.
  • Kravchenko, Oleksandr, et al. (författare)
  • Improving the Stability of Ru-bda Molecular Water Oxidation Catalysts via π‑System Extension of Backbone Ligand
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Originating from natural enzymes, molecular catalysts often serve as models for studying certain catalytic processes. Despite well-established mechanisms and structure-activity relationships, molecular electrocatalysts are much less used in industry than materials. Wide application of molecular complexes is primarily limited by their insufficient stability, and many efforts are devoted to addressing this problem. Design of water oxidation catalysts experienced gradual development, associated with the gains in stability, e.g., through well-defined coordination modes, moderate flexibility, oxidatively stable and negatively charged ligands. Herein we report a simple yet effective modification of state-of-the-art Ru-bda based water oxidation catalysts. Extension of the π-system of equatorial bipyridine ligand improves electron density delocalization and stabilizes molecular orbitals with high 3d contribution, which are partly responsible for axial ligand bonding. This feature allows catalysts to reach turnover numbers up to 20000, operating for hours in pH 1 solution at concentrations lower than 5 μM.
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13.
  • Kravchenko, Oleksandr, et al. (författare)
  • Modulation of the First and Second Coordination Sphere Effects by Backbone Substitution in Ru(bda)L2 Water Oxidation Catalysts
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Active research in the field of renewable energy has provided numerous molecular water oxidation catalysts for efficient water splitting, such as Ru-bda. As the most stable and active catalysts are based on ruthenium, a larger focus is put on the understanding, which properties of the ligands can be leveraged in cheap and sustainable catalysts to compensate the drawbacks of non-noble metals. Most modifications of the bda ([2,2'-bipyridine]-6,6'-dicarboxylate) ligand do not yield in more efficient catalysts and in general constitute a complicated structure-activity relationship. Herein, we report two new modifications of bda with strong electron-donating and electron-withdrawing substituents and their implications on the intra- and intermolecular interactions.
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14.
  • Leitao, Charles Dahlsson, et al. (författare)
  • Conditionally activated affibody-based prodrug targeting EGFR demonstrates improved tumor selectivity
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Safety and efficacy of cancer-targeting treatments can be improved by conditional activation conferred by the distinct milieu of the tumour microenvironment. Proteases are intricately involved in tumorigenesis and commonly dysregulated with elevated expression and activity. Design of prodrug molecules with protease-dependent activation has the potential to increase tumor-selective targeting, while decreasing the exposure to healthy tissues, thus improving safety, allowing for administration of higher doses or use of more aggressive treatment options, leading to higher therapeutic efficacy. We have previously performed in vitro characterizations of an affibody-based prodrug approach for protease-mediated targeting of EGFR. In this study we demonstrate the potential for selective tumor-targeting and shielded uptake in healthy tissues in vivo using tumor-bearing mice for an EGFR-targeting affibody prodrug.
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15.
  • Leitao, Charles Dahlsson, 1992-, et al. (författare)
  • Conditionally activated affibody-based prodrug targeting EGFR demonstrates improved tumour selectivity
  • 2023
  • Ingår i: Journal of Controlled Release. - : Elsevier BV. - 0168-3659 .- 1873-4995. ; 357, s. 185-195
  • Tidskriftsartikel (refereegranskat)abstract
    • Safety and efficacy of cancer-targeting treatments can be improved by conditional activation enabled by the distinct milieu of the tumour microenvironment. Proteases are intricately involved in tumourigenesis and commonly dysregulated with elevated expression and activity. Design of prodrug molecules with protease -dependent activation has the potential to increase tumour-selective targeting while decreasing exposure to healthy tissues, thus improving the safety profile for patients. Higher selectivity could also allow for adminis-tration of higher doses or use of more aggressive treatment options, leading to higher therapeutic efficacy. We have previously developed an affibody-based prodrug with conditional targeting of EGFR conferred by an anti-idiotypic affibody masking domain (ZB05). We could show that binding to endogenous EGFR on cancer cells in vitro was restored following proteolytic removal of ZB05. In this study we evaluate a novel affibody-based pro -drug design, which incorporates a protease substrate sequence recognized by cancer-associated proteases and demonstrate the potential of this approach for selective tumour-targeting and shielded uptake in healthy tissues in vivo using tumour-bearing mice. This may widen the therapeutic index of cytotoxic EGFR-targeted thera-peutics by decreasing side effects, improving selectivity of drug delivery, and enabling the use of more potent cytotoxic drugs.
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16.
  • Lensink, Marc F., et al. (författare)
  • Impact of AlphaFold on structure prediction of protein complexes: The CASP15-CAPRI experiment
  • 2023
  • Ingår i: Proteins. - : WILEY. - 0887-3585 .- 1097-0134.
  • Tidskriftsartikel (refereegranskat)abstract
    • We present the results for CAPRI Round 54, the 5th joint CASP-CAPRI protein assembly prediction challenge. The Round offered 37 targets, including 14 homodimers, 3 homo-trimers, 13 heterodimers including 3 antibody-antigen complexes, and 7 large assemblies. On average similar to 70 CASP and CAPRI predictor groups, including more than 20 automatics servers, submitted models for each target. A total of 21 941 models submitted by these groups and by 15 CAPRI scorer groups were evaluated using the CAPRI model quality measures and the DockQ score consolidating these measures. The prediction performance was quantified by a weighted score based on the number of models of acceptable quality or higher submitted by each group among their five best models. Results show substantial progress achieved across a significant fraction of the 60+ participating groups. High-quality models were produced for about 40% of the targets compared to 8% two years earlier. This remarkable improvement is due to the wide use of the AlphaFold2 and AlphaFold2-Multimer software and the confidence metrics they provide. Notably, expanded sampling of candidate solutions by manipulating these deep learning inference engines, enriching multiple sequence alignments, or integration of advanced modeling tools, enabled top performing groups to exceed the performance of a standard AlphaFold2-Multimer version used as a yard stick. This notwithstanding, performance remained poor for complexes with antibodies and nanobodies, where evolutionary relationships between the binding partners are lacking, and for complexes featuring conformational flexibility, clearly indicating that the prediction of protein complexes remains a challenging problem.
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17.
  • Liu, Tianqi, et al. (författare)
  • Bioinspired Active Site with a Coordination-Adaptive Organosulfonate Ligand for Catalytic Water Oxidation at Neutral pH
  • 2023
  • Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 145:21, s. 11818-11828
  • Tidskriftsartikel (refereegranskat)abstract
    • Many enzymes use adaptive frameworks to preorganize substrates, accommodate various structural and electronic demands of intermediates, and accelerate related catalysis. Inspired by biological systems, a Ru-based molecular water oxidation catalyst containing a configurationally labile ligand [2,2′:6′,2″-terpyridine]-6,6″-disulfonate was designed to mimic enzymatic framework, in which the sulfonate coordination is highly flexible and functions as both an electron donor to stabilize high-valent Ru and a proton acceptor to accelerate water dissociation, thus boosting the catalytic water oxidation performance thermodynamically and kinetically. The combination of single-crystal X-ray analysis, various temperature NMR, electrochemical techniques, and DFT calculations was utilized to investigate the fundamental role of the self-adaptive ligand, demonstrating that the on-demand configurational changes give rise to fast catalytic kinetics with a turnover frequency (TOF) over 2000 s–1, which is compared to oxygen-evolving complex (OEC) in natural photosynthesis. 
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18.
  • Liu, Tianqi, et al. (författare)
  • Hydrophobic Interactions of Ru-bda-Type Catalysts for Promoting Water Oxidation Activity
  • 2021
  • Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029.
  • Tidskriftsartikel (refereegranskat)abstract
    • The catalytic activity of the bimolecular reaction was affected by many parameters. Although many efforts have been dedicated to investigate the influence of secondary interactions in pre-organizing catalysts, the hydrophobic effect on Ru-bda-type water oxidation catalysts remains unclear as a result of the lack of an ideal catalytic model. In this work, four catalysts 1–4 with variable hydrophobicity have been synthesized, and cerium(IV)-driven water oxidation results showed that the hydrophobic complexes 3 and 4 outperformed the hydrophilic complex 2. Steric mapping, nuclear magnetic resonance, and differential pulse voltammogram studies indicated that the increase in activity has no correlation with electronic and steric effects but has correlation with hydrophobicity. Molecular dynamics have shown that the modifications of the hydrophobicity on the axial pyridine ligands of the Ru-bda type of catalysts can improve the water oxidation catalytic activity by stabilizing the pre-reactive catalyst dimer.
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19.
  • Liu, Tianqi, et al. (författare)
  • Iron-Based Molecular Water Oxidation Catalysts : Abundant, Cheap, and Promising
  • 2019
  • Ingår i: Chemistry - An Asian Journal. - : WILEY-V C H VERLAG GMBH. - 1861-4728 .- 1861-471X. ; 14:1, s. 31-43
  • Forskningsöversikt (refereegranskat)abstract
    • An efficient and robust water oxidation catalyst based on abundant and cheap materials is the key to converting solar energy into fuels through artificial photosynthesis for the future of humans. The development of molecular water oxidation catalysts (MWOCs) is a smart way to achieve promising catalytic activity, thanks to the clear structures and catalytic mechanisms of molecular catalysts. Efficient MWOCs based on noble-metal complexes, for example, ruthenium and iridium, have been well developed over the last 30 years; however, the development of earth-abundant metal-based MWOCs is very limited and still challenging. Herein, the promising prospect of iron-based MWOCs is highlighted, with a comprehensive summary of previously reported studies and future research focus in this area.
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20.
  • Liu, Tianqi, et al. (författare)
  • Isolation and Identification of Pseudo Seven-Coordinate Ru(III) Intermediate Completing the Catalytic Cycle of Ru-bda Type of Water Oxidation Catalysts
  • 2022
  • Ingår i: CCS Chemistry. - : Chinese Chemical Society. - 2096-5745. ; 4:7, s. 2481-2490
  • Tidskriftsartikel (refereegranskat)abstract
    • Isolation of RuIII-bda (17-electron specie) complex with an aqua ligand (2-electron donor) is challenging due to violation of the 18-electron rule. Although considerable efforts have been dedicated to mechanistic studies of water oxidation by the Ru-bda family, the structure and initial formation of the RuIII-bda aqua complex are still controversial. Herein, we challenge this often overlooked step by designing a pocket-shape Ru-based complex 1. The computational studies showed that 1 possesses the crucial hydrophobicity at the RuV(O) state as well as similar probability of access of terminal O to solvent water molecules when compared with classic Ru-bda catalysts. Through characterization of single-crystal structures at the RuII and RuIII states, a pseudo seven-coordinate “ready-to-go” aqua ligand with RuIII...O distance of 3.62 Å was observed. This aqua ligand was also found to be part of a formed hydrogen-bonding network, providing a good indication of how the RuIII-OH2 complex is formed.
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21.
  • Liu, Tianqi (författare)
  • Outer Coordination Spheres Engineering of Ru-based Molecular Water Oxidation Catalysts
  • 2022
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The outer coordination sphere plays a vital role in metalloenzyme catalysis, while this principle is relatively less considered in the design of man-made molecular catalysts. This thesis investigates the role of outer coordination spheres in water oxidation by a series of ruthenium-based complexes.The first chapter presents an overview of the development of molecular water oxidation catalysts, mainly focusing on ruthenium-based complexes. Moreover, the strategies used to modulate the inner and outer coordination spheres are also summarized.The second chapter clarifies the role of electronic effects and hydrophobic interactions in Ru-bda-type catalysts. Electronic effects are found to be the less-dominating parameter for the catalytic activity and mechanism, while hydrophobic interactions play an important role in catalysis. The third chapter focuses on the switch in mechanism with Ru-pda-type catalysts through strengthening of the π-π interactions between the axial ligands.The fourth chapter discusses a crystal structure of the long-proposed pseudo-seven-coordinate RuIII-aqua complex where the aqua ligand is stabilized by the distal ligand. The obtained complex enables us to visualize how the catalyst grasps the incoming aqua ligands at the initial catalytic step. Based on this catalytic model, four catalysts with well-defined outer coordination spheres are synthesized, and the influence of hydrophilic/hydrophobic outer spheres on water oxidation is discussed in chapter five.In general, this thesis follows the transition of the outer coordination sphere engineering from coordinated ligand modifications to remote substituent modulations.
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22.
  • Liu, Tianqi, et al. (författare)
  • Promoting O–O Radical Coupling of Water Oxidation Catalyst via Secondary Interaction
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Interaction of two metal–oxyl radicals (I2M) mechanism can theoretically provide water oxidation catalysts with lower overpotentials because they avoid forming the high-energy metal-OOH intermediate. However, only two Ru-based catalytic systems have been reported involving intermolecular I2M pathway. Herein, a Ru-pda-type (pda is 1,10-phenanthroline-2,9-dicarboxylate acid) water oxidation catalyst was designed and synthesized. Through synergistic modulation of oxo spin-density and organizational entropy, mechanism switching from the water nucleophilic attack (WNA) to I2M was realized, accompanied by a rate increase of around two orders of magnitude.
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23.
  • Liu, Tianqi, et al. (författare)
  • Promoting Proton Transfer and Stabilizing Intermediates in Catalytic Water Oxidation via Hydrophobic Outer Sphere Interactions
  • 2022
  • Ingår i: Chemistry - A European Journal. - : Wiley-VCH Verlagsgesellschaft. - 0947-6539 .- 1521-3765. ; 28:24
  • Tidskriftsartikel (refereegranskat)abstract
    • The outer coordination sphere of metalloenzyme often plays an important role in its high catalytic activity, however, this principle is rarely considered in the design of man-made molecular catalysts. Herein, four Ru-bda (bda=2,2 '-bipyridine-6,6 '-dicarboxylate) based molecular water oxidation catalysts with well-defined outer spheres are designed and synthesized. Experimental and theoretical studies showed that the hydrophobic environment around the Ru center could lead to thermodynamic stabilization of the high-valent intermediates and kinetic acceleration of the proton transfer process during catalytic water oxidation. By this outer sphere stabilization, a 6-fold rate increase for water oxidation catalysis has been achieved.
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24.
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25.
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26.
  • Liu, Yongsheng, et al. (författare)
  • Comparative Preclinical Evaluation of HER2-Targeting ABD-Fused Affibody® Molecules 177Lu-ABY-271 and 177Lu-ABY-027 : Impact of DOTA Position on ABD Domain
  • 2021
  • Ingår i: Pharmaceutics. - : MDPI. - 1999-4923. ; 13:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Radiolabeled Affibody-based targeting agent 177Lu-ABY-027, a fusion of an anti-HER2 Affibody molecule with albumin binding domain (ABD) site-specifically labeled at the C-terminus, has demonstrated a promising biodistribution profile in mice; binding of the construct to albumin prevents glomerular filtration and significantly reduces renal uptake. In this study, we tested the hypothesis that site-specific positioning of the chelator at helix 1 of ABD, at a maximum distance from the albumin binding site, would further increase the strength of binding to albumin and decrease the renal uptake. The new construct, ABY-271 with DOTA conjugated at the back of ABD, has been labelled with 177Lu. Targeting properties of 177Lu-ABY-271 and 177Lu-ABY-027 were compared directly. 177Lu-ABY-271 specifically accumulated in SKOV-3 xenografts in mice. The tumor uptake of 177Lu-ABY-271 exceeded uptake in any other organ 24 h and later after injection. However, the renal uptake of 177Lu-ABY-271 was two-fold higher than the uptake of 177Lu-ABY-027. Thus, the placement of chelator on helix 1 of ABD does not provide desirable reduction of renal uptake. To conclude, minimal modification of the design of Affibody molecules has a strong effect on biodistribution, which cannot be predicted a priori. This necessitates extensive structure-properties relationship studies to find an optimal design of Affibody-based targeting agents for therapy.
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27.
  • Liu, Yongsheng, et al. (författare)
  • Experimental Therapy of HER2-Expressing Xenografts Using the Second-Generation HER2-Targeting Affibody Molecule 188Re-ZHER2:41071
  • 2022
  • Ingår i: Pharmaceutics. - : MDPI. - 1999-4923. ; 14:5
  • Tidskriftsartikel (refereegranskat)abstract
    • HER2-targeted radionuclide therapy might be helpful for the treatment of breast, gastric, and ovarian cancers which have developed resistance to antibody and antibody-drug conjugate-based therapies despite preserved high HER2-expression. Affibody molecules are small targeting proteins based on a non-immunoglobulin scaffold. The goal of this study was to test in an animal model a hypothesis that the second-generation HER2-targeting Affibody molecule 188Re-ZHER2:41071 might be useful for treatment of HER2-expressing malignant tumors. ZHER2:41071 was efficiently labeled with a beta-emitting radionuclide rhenium-188 (188Re). 188Re-ZHER2:41071 demonstrated preserved specificity and high affinity (KD = 5 ± 3 pM) of binding to HER2-expressing cells. In vivo studies demonstrated rapid washout of 188Re from kidneys. The uptake in HER2-expressing SKOV-3 xenografts was HER2-specific and significantly exceeded the renal uptake 4 h after injection and later. The median survival of mice, which were treated by three injections of 16 MBq 188Re-ZHER2:41071 was 68 days, which was significantly longer (<0.0001 in the log-rank Mantel-Cox test) than survival of mice in the control groups treated with vehicle (29 days) or unlabeled ZHER2:41071 (27.5 days). In conclusion, the experimental radionuclide therapy using 188Re-ZHER2:41071 enabled enhancement of survival of mice with human tumors without toxicity to the kidneys, which is the critical organ.
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28.
  • Liu, Yongsheng, et al. (författare)
  • Preclinical Evaluation of a New Format of Ga-68- and In-111-Labeled Affibody Molecule Z(IGF-1R:4551) for the Visualization of IGF-1R Expression in Malignant Tumors Using PET and SPECT
  • 2022
  • Ingår i: Pharmaceutics. - : MDPI AG. - 1999-4923. ; 14:7
  • Tidskriftsartikel (refereegranskat)abstract
    • The Insulin-like growth factor-1 receptor (IGF-1R) is a molecular target for several monoclonal antibodies undergoing clinical evaluation as anticancer therapeutics. The non-invasive detection of IGF-1R expression in tumors might enable stratification of patients for specific treatment and improve the outcome of both clinical trials and routine treatment. The affibody molecule Z(IGF-1R:4551) binds specifically to IGF-1R with subnanomolar affinity. The goal of this study was to evaluate the Ga-68 and In-111-labeled affibody construct NODAGA-(HE)(3)-Z(IGF-1R:4551) for the imaging of IGF-1R expression, using PET and SPECT. The labeling was efficient and provided stable coupling of both radionuclides. The two imaging probes, [Ga-68]Ga-NODAGA-(HE)(3)-Z(IGF-1R:4551) and [In-111]In-NODAGA-(HE)(3)-Z(IGF-1R:4551), demonstrated specific binding to IGF-1R-expressing human cancer cell lines in vitro and to IGF-1R-expressing xenografts in mice. Preclinical PET and SPECT/CT imaging demonstrated visualization of IGF-1R-expressing xenografts already one hour after injection. The tumor-to-blood ratios at 3 h after injection were 7.8 +/- 0.2 and 8.0 +/- 0.6 for [Ga-68]Ga-NODAGA-(HE)(3)-Z(IGF-1R:4551) and [In-111]In-NODAGA-(HE)(3)-Z(IGF-1R:4551), respectively. In conclusion, a molecular design of the Z(IGF-1R:4551) affibody molecule, including placement of a (HE)(3)-tag on the N-terminus and site-specific coupling of a NODAGA chelator on the C-terminus, provides a tracer with improved imaging properties for visualization of IGF-1R in malignant tumors, using PET and SPECT.
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29.
  • Liu, Yongsheng, et al. (författare)
  • Radionuclide Therapy of HER2-Expressing Xenografts Using [Lu-177]Lu-ABY-027 Affibody Molecule Alone and in Combination with Trastuzumab
  • 2023
  • Ingår i: Cancers. - : MDPI. - 2072-6694. ; 15:9
  • Tidskriftsartikel (refereegranskat)abstract
    • Affibody molecules are artificial proteins that can recognize cancer-related molecular abnormalities in the living body. Clinical studies demonstrated that Affibody molecules can be successfully used for radionuclide diagnostics. Targeted radionuclide therapy selectively delivers cytotoxic radionuclides to malignant tumors, thus sparing normal tissues. For radionuclide therapy, Affibody molecules were re-engineered to decrease accumulation in the kidneys. This study has demonstrated that radionuclide therapy using re-engineered Affibody molecules increases the survival of immunodeficient mice bearing human tumors. The therapy was more efficient than the treatment with a monoclonal antibody, which is currently used in clinical practice. The best results were obtained when both the antibody and radiolabeled Affibody molecules were used simultaneously. This work provides a preclinical rationale for a potentially more efficient treatment in HER2-positive cancers.ABY-027 is a scaffold-protein-based cancer-targeting agent. ABY-027 includes the second-generation Affibody molecule Z(HER2:2891), which binds to human epidermal growth factor receptor type 2 (HER2). An engineered albumin-binding domain is fused to Z(HER2:2891) to reduce renal uptake and increase bioavailability. The agent can be site-specifically labeled with a beta-emitting radionuclide Lu-177 using a DOTA chelator. The goals of this study were to test the hypotheses that a targeted radionuclide therapy using [Lu-177]Lu-ABY-027 could extend the survival of mice with HER2-expressing human xenografts and that co-treatment with [Lu-177]Lu-ABY-027 and the HER2-targeting antibody trastuzumab could enhance this effect. Balb/C nu/nu mice bearing HER2-expressing SKOV-3 xenografts were used as in vivo models. A pre-injection of trastuzumab did not reduce the uptake of [Lu-177]Lu-ABY-027 in tumors. Mice were treated with [Lu-177]Lu-ABY-027 or trastuzumab as monotherapies and a combination of these therapies. Mice treated with vehicle or unlabeled ABY-027 were used as controls. Targeted monotherapy using [Lu-177]Lu-ABY-027 improved the survival of mice and was more efficient than trastuzumab monotherapy. A combination of therapies utilizing [Lu-177]Lu-ABY-027 and trastuzumab improved the treatment outcome in comparison with monotherapies using these agents. In conclusion, [Lu-177]Lu-ABY-027 alone or in combination with trastuzumab could be a new potential agent for the treatment of HER2-expressing tumors.
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30.
  • Lundmark, Fanny, et al. (författare)
  • Reduction of renal activity retention of radiolabeled albumin binding domain-derived affinity proteins using a non-residualizing label strategy compared with a cleavable glycine-leucine-glycine-lysine-linker
  • 2024
  • Ingår i: Molecular Medicine Reports. - : Spandidos Publications. - 1791-2997 .- 1791-3004. ; 29:2
  • Tidskriftsartikel (refereegranskat)abstract
    • The feasibility of targeted imaging and therapy using radiolabeled albumin-binding domain-derived affinity proteins (ADAPTs) has been demonstrated. However, high renal uptake of radioactivity limits the maximum tolerated dose. Successful reduction of renal retention of radiolabeled Fab fragments has been demonstrated by incorporating a cleavable linker between the targeting agent and the radiometal chelator. The present study investigated if the introduction of a glycine-leucine-glycine-lysine (GLGK)-linker would reduce the kidney uptake of radiolabeled ADAPT6 and also compared it with the non-residualizing [125I]I-[(4-hydroxyphenyl)ethyl]maleimide ([125I]I-HPEM) labeling strategy. GLGK was site-specifically coupled to human epidermal growth factor receptor 2 (HER2)-targeting ADAPT6. Conjugates without the cleavable linker were used as controls and all constructs were labeled with lutetium-177 (177Lu). [125I]I-HPEM was coupled to ADAPT6 at the C-terminus. Biodistribution of all constructs was evaluated in NMRI mice 4 h after injection. Specific binding to HER2-expressing cells in vitro was demonstrated for all constructs. No significant difference in kidney uptake was observed between the [177Lu]Lu-2,2 ',2",2"'-(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrayl)tetraacetic acid-GLGK-conjugates and the controls. The renal activity of [125I]I-HPEM-ADAPT6 was significantly lower compared with all other constructs. In conclusion, the incorporation of the cleavable GLGK-linker did not result in lower renal retention. Therefore, the present study emphasized that, in order to achieve a reduction of renal retention, alternative molecular design strategies may be required for different targeting agents.
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31.
  • Oroujeni, Maryam, PhD, 1982-, et al. (författare)
  • Affibody-Mediated PNA-Based Pretargeted Cotreatment Improves Survival of Trastuzumab-Treated Mice Bearing HER2-Expressing Xenografts
  • 2022
  • Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 63:7, s. 1046-1051
  • Tidskriftsartikel (refereegranskat)abstract
    • Treatment of patients with human epidermal growth factor receptor 2 (HER2)-expressing tumors using the monoclonal antibody trastuzumab increases survival. The Affibody-based peptide nucleic acid (PNA)-mediated pretargeted radionuclide therapy has demonstrated efficacy against HER2-expressing xenografts in mice. Structural studies suggest that Affibody molecules and trastuzumab bind to different epitopes on HER2. The aim of this study was to test the hypothesis that a combination of PNA-mediated pretargeted radionuclide therapy and trastuzumab treatment of HER2-expressing xenografts can extend survival compared with monotherapies. Methods: Mutual interference of the primary pretargeting probe Z(HER2:342)-SR-HP1 and trastuzumab in binding to HER2-expressing cell lines was investigated in vitro. Experimental therapy evaluated the survival of mice bearing HER2-expressing SKOV-3 xenografts after treatment with vehicle, trastuzumab only, pretargeting using Affibody-PNA chimera Z(HER2:342)-SR-HP1 and complementary probe Lu-177-HP2, and combination of trastuzumab and pretargeting. The ethical permit limited the study to 90 d. The animals'weightsweremonitored during the study. After study termination, samples of liver and kidneys were evaluated by a veterinary pathologist for toxicity signs. Results: The presence of a large molar excess of trastuzumab had no influence on the affinity of Z(HER2:342)-SR-HP1 binding to HER2-expressing cells in vitro. The affinity of trastuzumab was not affected by a large excess of Z(HER2:342)-SR-HP1. Themedian survival of mice treated with trastuzumab (75.5 d) was significantly longer than the survival of mice treated with a vehicle (59.5 d). Median survival of mice treated with pretargeting was not reached by day 90. Six mice of 10 in this group survived, and 2 had complete remission. All mice in the combination treatment group survived, and tumors in 7 mice had disappeared at study termination. There was no significant difference between animal weights in the different treatment groups. No significant pathologic alterations were detected in livers and kidneys of treated animals. Conclusion: Treatment of mice bearing HER2-expressing xenografts with the combination of trastuzumab and Affibody-mediated PNA-based radionuclide pretargeting significantly increased survival compared with monotherapies. Cotreatment was not toxic for normal tissues.
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32.
  • Oroujeni, Maryam, PhD, 1982-, et al. (författare)
  • Evaluation of affinity matured Affibody molecules for imaging of the immune checkpoint protein B7-H3
  • 2023
  • Ingår i: Nuclear Medicine and Biology. - : Elsevier BV. - 0969-8051 .- 1872-9614. ; 124-125
  • Tidskriftsartikel (refereegranskat)abstract
    • B7-H3 (CD276), an immune checkpoint protein, is a promising molecular target for immune therapy of malignant tumours. Sufficient B7-H3 expression level is a precondition for successful therapy. Radionuclide molecular imaging is a powerful technique for visualization of expression levels of molecular targets in vivo. Use of small radiolabelled targeting proteins would enable high-contrast radionuclide imaging of molecular targets if adequate binding affinity and specificity of an imaging probe could be provided. Affibody molecules, small engineered affinity proteins based on a non-immunoglobulin scaffold, have demonstrated an appreciable potential in radionuclide imaging. Proof-of principle of radionuclide visualization of expression levels of B7-H3 in vivo was demonstrated using the [99mTc]Tc-AC12-GGGC Affibody molecule. We performed an affinity maturation of AC12, enabling selection of clones with higher affinity. Three most promising clones were expressed with a -GGGC (triglycine-cysteine) chelating sequence at the C-terminus and labelled with technetium-99m (99mTc). 99mTc-labelled conjugates bound to B7-H3-expressing cells specifically in vitro and in vivo. Biodistribution in mice bearing B7-H3-expressing SKOV-3 xenografts demonstrated improved imaging properties of the new conjugates compared with the parental variant [99mTc]Tc-AC12-GGGC. [99mTc]Tc-SYNT-179 provided the strongest improvement of tumour-to-organ ratios. Thus, affinity maturation of B7-H3 Affibody molecules could improve biodistribution and targeting properties for imaging of B7-H3-expressing tumours.
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33.
  • Oroujeni, Maryam, PhD, 1982-, et al. (författare)
  • Evaluation of an Affibody-Based Binder for Imaging of Immune Check-Point Molecule B7-H3
  • 2022
  • Ingår i: Pharmaceutics. - : MDPI. - 1999-4923. ; 14:9
  • Tidskriftsartikel (refereegranskat)abstract
    • Radionuclide molecular imaging could provide an accurate assessment of the expression of molecular targets in disseminated cancers enabling stratification of patients for specific therapies. B7-H3 (CD276) is a transmembrane protein belonging to the B7 superfamily. This protein is overexpressed in different types of human malignancies and such upregulation is generally associated with a poor clinical prognosis. In this study, targeting properties of an Affibody-based probe, AC12, containing a -GGGC amino acid sequence as a chelator (designated as AC12-GGGC) labelled with technetium-99m (Tc-99m) were evaluated for imaging of B7-H3-expressing tumours. AC12-GGGC was efficiently labelled with Tc-99m. [Tc-99m]Tc-AC12-GGGC bound specifically to B7-H3 expressing cells in vitro with affinities in nanomolar range. In mice bearing B7-H3-expressing xenografts, [Tc-99m]Tc-AC12-GGGC showed tumour uptake of 2.1 +/- 0.5 %ID/g at 2 h after injection. Its clearance from blood, normal organs and tissues was very rapid. This new targeting agent, [Tc-99m]Tc-AC12-GGGC, provided high tumour-to-blood ratio already at 2 h (8.2 +/- 1.9), which increased to 11.0 +/- 0.5 at 4 h after injection. Significantly (p < 0.05) higher tumour-to-liver and higher tumour-to-bone ratios at 2 h in comparison with 4 h after injection were observed. Thus, [Tc-99m]Tc-AC12-GGGC could be a promising candidate for further development.
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34.
  • Shen, Nannan, et al. (författare)
  • Designing Polymorphic Bi3+-Containing Ionic Liquids for Stimuli-Responsive Luminescent Materials
  • 2019
  • Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 58:12, s. 8079-8085
  • Tidskriftsartikel (refereegranskat)abstract
    • Solid-state luminescent materials that possess reversible fluorescence changes toward external multistimuli are of immense interest because of their potential applications in data storage and sensors. While the recent developments in this field are mainly focused on the pi-conjugated organic molecules. Herein two polymorphic luminescent ionic liquid (IL)-based stimuli-responsive materials were designed by the supramolecular assemblies of an organic-decorated chlorobismuthate anion and a rotationally flexible imidazolium cation, namely, alpha (1)/beta (2)-[Bmmim][BiCl4(2,2'-bpy)] (Bmmim = 1-butyl-2,3-dimethylimidazolium; 2,2'-bpy = 2,2'-bipyridine). Because of the different conformations of the n-butyl chains on the imidazolium cations, tuning of the supramolecular packing structures as well as luminescent colors for 1 and 2 was realized. Single-crystal X-ray diffraction and Hirshfeld surface analyses disclose that the poly-morphism-dependent emission may be attributed to the different weak interactions, especially to the pi-pi interactions between adjacent [BiCl4(2,2'-bpy)](-) anions in two compounds. Additionally, compound 2 could be transformed into 1 spontaneously at ambient conditions, which could be triggered by the moisture in the air. Both of the title compounds could detect NH(3 )vapor selectively through the luminescence "turn-off" method rapidly and reversibly because of the destruction of intermolecular interactions, indicating their stimuli-responsive property toward NH3.
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35.
  • Tano, Hanna, et al. (författare)
  • Comparative Evaluation of Novel Lu-177-Labeled PNA Probes for Affibody-Mediated PNA-Based Pretargeting
  • 2021
  • Ingår i: Cancers. - : MDPI AG. - 2072-6694. ; 13:3
  • Tidskriftsartikel (refereegranskat)abstract
    • Simple Summary Affibody molecules are small, engineered affinity proteins based on a nonimmunoglobulin scaffold. Affibody-based radionuclide imaging probes have demonstrated excellent tumor targeting. However, the renal clearance of affibody molecules is accompanied by high reabsorption and retention of activity in the kidney, which prevents their use for radionuclide therapy. We have previously shown the feasibility of overcoming the high renal uptake using a pretargeting approach for affibody-mediated therapy based on peptide nucleic acid (PNA) hybridization. In this study, we test the hypothesis that shortening the PNA pretargeting probes would further increase the difference between the accumulation of radiometals in tumor xenografts and in kidneys. A series of novel PNA probes has been designed and evaluated in vitro and in vivo. We have found that a variant containing 9 nucleobases enables a two-fold increase of the tumor-to-kidney dose ratio compared with a variant containing 15 nucleobases. This creates preconditions for more efficient therapy of cancer. Affibody-mediated PNA-based pretargeting is a promising approach to radionuclide therapy of HER2-expressing tumors. In this study, we test the hypothesis that shortening the PNA pretargeting probes would increase the tumor-to-kidney dose ratio. The primary probe Z(HER2:342)-SR-HP15 and the complementary secondary probes HP16, HP17, and HP18, containing 9, 12, and 15 nucleobases, respectively, and carrying a 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) chelator were designed, synthesized, characterized in vitro, and labeled with Lu-177. In vitro pretargeting was studied in HER2-expressing SKOV3 and BT474 cell lines. The biodistribution of these novel probes was evaluated in immunodeficient mice bearing SKOV3 xenografts and compared to the previously studied [Lu-177]Lu-HP2. Characterization confirmed the formation of high-affinity duplexes between HP15 and the secondary probes, with the affinity correlating with the length of the complementary PNA sequences. All the PNA-based probes were bound specifically to HER2-expressing cells in vitro. In vivo studies demonstrated HER2-specific uptake of all Lu-177-labeled probes in xenografts in a pretargeting setting. The ratio of cumulated radioactivity in the tumor to the radioactivity in kidneys was dependent on the secondary probe's size and decreased with an increased number of nucleobases. The shortest PNA probe, [Lu-177]Lu-HP16, showed the highest tumor-to-kidney ratio. [Lu-177]Lu-HP16 is the most promising secondary probe for affibody-mediated tumor pretargeting.
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36.
  • Timmer, Brian, et al. (författare)
  • Electronic Influence of the 2,2 '-Bipyridine-6,6 '-dicarboxylate Ligand in Ru-Based Molecular Water Oxidation Catalysts
  • 2021
  • Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 60:2, s. 1203-1208
  • Tidskriftsartikel (refereegranskat)abstract
    • Water provides an ideal source for the production of protons and electrons required for generation of renewable fuels. Among the most-prominent electrocatalysts capable of water oxidation at low overpotentials are Ru(bda)L-2-type catalysts. Although many studies were dedicated to the investigation of the influence of structural variations, the true implication of the bda backbone on catalysis remains mostly unclarified. In this work, we further investigated if electronic effects are contributing to catalysis by Ru(bda)(pic)(2) or if the intrinsic catalytic activity mainly originates from the structural features of the ligand. Through introduction of pyrazines in the bda backbone, forming Ru(N-1-bda)(pic)(2) and Ru(N-2-bda)(pic)(2), electronic differences were maximized while minimizing changes in the geometry and other intermolecular interactions. Through a combination of electrochemical analysis, chemical oxygen evolution, and density functional theory calculations, we reveal that the catalytic activity is unaffected by the electronic features of the backbone and that the unique bimolecular reactivity of the Ru(bda)L-2 family of catalysts thus purely depends on the spatial geometry of the ligand.
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37.
  • Timmer, Brian, et al. (författare)
  • Electronic Influence of the 2,2′-Bipyridine-6,6′-dicarboxylate Ligand in Ru-based Type Water Oxidation Catalysts
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Water provides an ideal source for the production of protons and electrons required for generation of renewable fuels. Amongst the most prominent electrocatalysts capable of water oxidation at low overpotentials are Ru(bda)L2 type catalysts. Although many studies were dedicated to investigate the influence of structural variations, the true implication of the bda-backbone on catalysis remains mostly unknown. In this work, we investigated if electronic effects are contributing to catalysis by Ru(bda)(pic)2 or if the intrinsic catalytic activity mainly originates from the structural features of the ligand. Through introduction of pyrazines in the bda-backbone, forming Ru(N1-bda)(pic)2 and Ru(N1-bda)(pic)2, electronic differences were maximized whilst minimizing changes in geometry. Through a combination of electrochemical analysis, chemical oxygen evolution and DFT calculations we reveal that the catalytic activity is largely unaffected by the electronic features of the backbone and that the unique reactivity of the Ru(bda)L2 family of catalysts thus originates purely from their spatial geometry and intermolecular interactions.
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38.
  • Timmer, Brian, et al. (författare)
  • Off-set Interactions for Low Concentration Water Splitting Catalysis with Ru(bda)L2
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Production of renewable fuels like hydrogen requires protons and electrons, which can be simultaneously generated through an ideal pathway, i.e., water oxidation. However, detailed molecular level understanding of the formation of the O-O bond is essential for achieving high efficiencies. O-O bond formation with Ru(bda)L2-type catalysts is well-known to proceed through a bimolecular reaction pathway, limiting the potential application of this catalyst at lower concentration. Herein, we report that by simple structural considerations in the axial pyridine ligands high efficiencies have been achieved with mononuclear catalysts, with TOFs as high as 449 ± 24 s-1 at high catalyst concentrations and 31 ± 3 s-1 at only 1 μM catalyst concentration. We propose that introduction of an off-set in the interaction between the two catalytic units reduces the kinetic barrier of the second-order O-O bond formation, maintaining a longer first order dependence on the catalyst. This hypothesis, combined with the previously proposed π-π interactions, further rationalizes the high activity observed for Ru(bda)(isoq)2 type catalysts and offers inspiration to overcome the limitations of 2nd order catalysis.
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39.
  • Timmer, Brian, et al. (författare)
  • Off-Set Interactions of Ruthenium–bda Type Catalysts for Promoting Water-Splitting Performance
  • 2021
  • Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 60:26, s. 14504-14511
  • Tidskriftsartikel (refereegranskat)abstract
    • O−O bond formation with Ru(bda)L2-type catalysts is well-known to proceed through a bimolecular reaction pathway, limiting the potential application of these catalysts at low concentrations. Herein, we achieved high efficiencies with mononuclear catalysts, with TOFs of 460±32 s−1 at high catalyst loading and 31±3 s−1 at only 1 μM catalyst concentration, by simple structural considerations on the axial ligands. Kinetic and DFT studies show that introduction of an off-set in the interaction between the two catalytic units reduces the kinetic barrier of the second-order O−O bond formation, maintaining high catalytic activity even at low catalyst concentrations. The results herein furthermore suggest that π–π interactions may only play a minor role in the observed catalytic activity, and that asymmetry can also rationalize high activity observed for Ru(bda)(isoq)2 type catalysts and offer inspiration to overcome the limitations of 2nd order catalysis. 
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40.
  • Vorobyeva, Anzhelika, et al. (författare)
  • Investigation of a Pharmacological Approach for Reduction of Renal Uptake of Radiolabeled ADAPT Scaffold Protein
  • 2020
  • Ingår i: Molecules. - : MDPI. - 1431-5157 .- 1420-3049. ; 25:19
  • Tidskriftsartikel (refereegranskat)abstract
    • Albumin binding domain-Derived Affinity ProTeins (ADAPTs) are small (5 kDa) engineered scaffold proteins that are promising targeting agents for radionuclide-based imaging. A recent clinical study has demonstrated that radiolabeled ADAPTs can efficiently visualize human epidermal growth factor receptor 2 (HER2) expression in breast cancer using SPECT imaging. However, the use of ADAPTs directly labeled with radiometals for targeted radionuclide therapy is limited by their high reabsorption and prolonged retention of activity in kidneys. In this study, we investigated whether a co-injection of lysine or gelofusin, commonly used for reduction of renal uptake of radiolabeled peptides in clinics, would reduce the renal uptake of [Tc-99m]Tc(CO)(3)-ADAPT6 in NMRI mice. In order to better understand the mechanism behind the reabsorption of [Tc-99m]Tc(CO)(3)-ADAPT6, we included several compounds that act on various parts of the reabsorption system in kidneys. Administration of gelofusine, lysine, probenecid, furosemide, mannitol, or colchicine did not change the uptake of [Tc-99m]Tc(CO)(3)-ADAPT6 in kidneys. Sodium maleate reduced the uptake of [Tc-99m]Tc(CO)(3)-ADAPT6 to ca. 25% of the uptake in the control, a high dose of fructose (50 mmol/kg) reduced the uptake by ca. two-fold. However, a lower dose (20 mmol/kg) had no effect. These results indicate that common clinical strategies are not effective for reduction of kidney uptake of [Tc-99m]Tc(CO)(3)-ADAPT6 and that other strategies for reduction of activity uptake or retention in kidneys should be investigated for ADAPT6.
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41.
  • Wang, Linqin, et al. (författare)
  • A crosslinked polymer as dopant-free hole-transport material for efficient n-i-p type perovskite solar cells
  • 2021
  • Ingår i: Journal of Energy Chemistry. - : Elsevier BV. - 2095-4956 .- 2096-885X. ; 55, s. 211-218
  • Tidskriftsartikel (refereegranskat)abstract
    • A new crosslinked polymer, called P65, with appropriate photo-electrochemical, opto-electronic, and thermal properties, has been designed and synthesized as an efficient, dopant-free, hole-transport material (HTM) for n-i-p type planar perovskite solar cells (PSCs). P65 is obtained from a low-cost and easily synthesized spiro[fluorene-9,9′-xanthene]-3′,6′-diol (SFX-OH)-based monomer X65 through a free-radical polymerization reaction. The combination of a three-dimensional (3D) SFX core unit, hole-transport methoxydiphenylamine group, and crosslinked polyvinyl network provides P65 with good solubility and excellent film-forming properties. By employing P65 as a dopant-free hole-transport layer in conventional n-i-p type PSCs, a power conversion efficiency (PCE) of up to 17.7% is achieved. To the best of our knowledge, this is the first time a 3D, crosslinked, polymeric dopant-free HTM has been reported for use in conventional n-i-p type PSCs. This study provides a new strategy for the future development of a 3D crosslinked polymeric dopant-free HTM with a simple synthetic route and low-cost for commercial, large-scale applications in future PSCs.
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42.
  • Xu, Tianqi, et al. (författare)
  • Epithelial cell adhesion molecule-targeting designed ankyrin repeat protein-toxin fusion Ec1-LoPE exhibits potent cytotoxic action in prostate cancer cells
  • 2022
  • Ingår i: Oncology Reports. - : Spandidos Publications. - 1021-335X .- 1791-2431. ; 47:5
  • Tidskriftsartikel (refereegranskat)abstract
    • Targeted anticancer therapeutics offer the advantage of reducing cytotoxic side effects to normal cells by directing the cytotoxic payload selectively to cancer cells. Designed ankyrin repeat proteins (DARPins) are promising non-immunoglobulin-based scaffold proteins for payload delivery to cancer-associated molecular targets. Epithelial cell adhesion molecule (EpCAM) is overexpressed in 40-60% of prostate cancers (PCs) and is associated with metastasis, increased risk of PC recurrence and resistance to treatment. Here, we investigated the use of DARPin Ec1 for targeted delivery of Pseudomonas exotoxin A variant (LoPE) with low immunogenicity and low non-specific toxicity to EpCAM-expressing prostate cancer cells. Ec1-LoPE fusion protein was radiolabeled with tricarbonyl technetium-99m and its binding specificity, binding kinetics, cellular processing, internalization and cytotoxicity were evaluated in PC-3 and DU145 cell lines. Ec1-LoPE showed EpCAM-specific binding to EpCAM-expressing prostate cancer cells. Rapid internalization mediated potent cytotoxic effect with picomolar IC50 values in both studied cell lines. Taken together, these data support further evaluation of Ec1-LoPE in a therapeutic setting in a prostate cancer model in vivo.
  •  
43.
  • Yan, Tao, et al. (författare)
  • Diet-rich in wheat bran modulates tryptophan metabolism and AhR/IL-22 signalling mediated metabolic health and gut dysbacteriosis: A novel prebiotic-like activity of wheat bran
  • 2023
  • Ingår i: Food Research International. - : Elsevier BV. - 0963-9969 .- 1873-7145. ; 163
  • Tidskriftsartikel (refereegranskat)abstract
    • Tryptophan metabolism has shown to involve in pathogenesis of various metabolic diseases. Gut microbiota-orientated diets hold great potentials to improve metabolic health via regulating tryptophan metabolism. The present study showed that the 6-week high fat diet (HFD) disturbed tryptophan metabolism accompanied with gut dysbacteriosis, also influenced the dietary tryptophan induced changes in cecum microbiome and serum metabolome in mice. The colonic expressions of aryl hydrocarbon receptor (AhR) and interleukin-22 (IL-22) were significantly reduced in mice fed on HFD. Notably, a diet- rich in wheat bran effectively inhibited transformation of tryptophan to kynurenine-pathway metabolites, while increased melatonin and microbial catabolites, i.e. indole-3-propionic acid, indole-3-acetaldehyde and 5-hydroxy-indole-3-acetic acid. Such regulatory effects were accompanied with reduced fasting glucose and total triglycerides, and promoted AhR and IL-22 levels in HFD mice. Wheat bran increased the abundance of health promoting bacteria (e.g., Akkermansia and Lactobacillus), which were significantly correlated with tryptophan derived indolic metabolites. Additionally, beneficial modulatory effects of wheat bran on indolic metabolites in associations with gut dysbacteriosis from type 2 diabetes patients were confirmed in vitro fecal fermentation experiment. Our study proves the detrimental effects of HFD induced gut dysbacteriosis on tryptophan metabolism that may influence immune modulation, and provides novel insights in the mechanisms by which wheat bran could induce health benefits.
  •  
44.
  • Yin, Wen, 1993-, et al. (författare)
  • A comparison of affibody conjugates loaded with auristatin and maytansine derived drugs
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Auristatin and maytansine-derived drugs are cytotoxic tubulin polymerization inhibitors commonly used as payloads in drug conjugates intended for targeted cancer therapy. We have previously shown that an affibody molecule ZHER2, binding to the human epidermal growth factor receptor 2 (HER2), can be site-specifically conjugated to DM1, a maytansine- derived payload, creating the potent and specific drug conjugate, ZHER2-ABD-mcDM1, where the ABD is an albumin binding domain used for in vivo half-life extension. Here, we investigated the properties of the HER2-binding affibody molecule conjugated with the two auristatin-derived payloads, monomethyl auristatin E and F (MMAE and MMAF), in comparison with the construct with DM1. We found that the drug conjugate ZHER2-ABD- mcMMAF was more potent than ZHER2-ABD-mcDM1, with IC50 values to high-HER2 expressing cell lines ranging from 0.18 to 12 nM. By contrast the IC50 values of ZHER2-ABD- mcMMAE was considerably weaker and this construct would probably benefit from a different linker connecting the drug to the affibody fusion protein. Quantification of uptake in HER2-expressing tumors and normal organs of 99m-technetium labeled drug conjugates showed that they were predominantly cleared by the kidneys, with relatively high tumor uptake, peaking at 11.1 ± 4.1 %ID/g for ZHER2-ABD-mcMMAE at 24 h post-injection, 8.5 ± 1.5 %ID/g for ZHER2-ABD-mcMMAF at 48 h post-injection, and 7.1 ± 1.8 %ID/g for ZHER2- ABD-mcDM1 at 48 h post-injection. Most normal organs, except for the kidneys, had a relatively low uptake. In conclusion, ZHER2-ABD-mcMMAF was the best performing drug conjugate with the highest potency, and lowest uptake in liver; slightly outperforming ZHER2- ABD-mcDM1.
  •  
45.
  • Yin, Wen, 1993-, et al. (författare)
  • Comparison of HER2-targeted affibody conjugates loaded with auristatin-and maytansine-derived drugs
  • 2023
  • Ingår i: Journal of Controlled Release. - : Elsevier. - 0168-3659 .- 1873-4995. ; 355, s. 515-527
  • Tidskriftsartikel (refereegranskat)abstract
    • Treatment with antibody drug conjugates targeting receptors over-expressed on cancer cells is well established for clinical use in several types of cancer, however, resistance often occurs motivating the development of novel drugs. We have recently investigated a drug conjugate consisting of an affibody molecule targeting the human epidermal growth factor receptor 2 (HER2), fused to an albumin-binding domain (ABD) for half-life extension, loaded with the cytotoxic maytansine derivative DM1. In this study, we investigated the impact of the cytotoxic payload on binding properties, cytotoxicity and biodistribution by comparing DM1 with the auristatins MMAE and MMAF, as part of the drug conjugate. All constructs had specific and high affinity binding to HER2, human and mouse albumins with values in the low- to sub-nM range. ZHER2-ABD-mcMMAF demonstrated the most potent cytotoxic effect on several HER2-over-expressing cell lines. In an experimental therapy study, the MMAFbased conjugate provided complete tumor regression in 50% of BALB/c nu/nu mice bearing HER2-overexpressing SKOV3 tumors at a 2.9 mg/kg dose, while the same dose of ZHER2-ABD-mcDM1 provided only a moderate anti-tumor effect. A comparison with the non-targeting ZTaq-ABD-mcMMAF control demonstrated HER2-targeting specificity. In conclusion, a combination of potent cytotoxicity in vitro, with minimal uptake in normal organs in vivo, and efficient delivery to tumors provided a superior anti-tumor effect of ZHER2-ABDmcMMAF, while maintaining a favorable toxicity profile with no observed adverse effects.
  •  
46.
  • Zhang, Biaobiao, et al. (författare)
  • Advancing Proton Exchange Membrane Electrolyzers with Molecular Catalysts
  • 2020
  • Ingår i: Joule. - : Elsevier BV. - 2542-4351. ; 4:7, s. 1408-1444
  • Forskningsöversikt (refereegranskat)abstract
    • Molecular catalysts possess numerous advantages over conventional heterogeneous catalysts in precise structure regulation, in-depth mechanism understanding, and efficient metal utilization. Various molecular catalysts have been reported that efficiently catalyze reactions involved in artificial photosynthesis, however, these catalysts have been rarely considered in view of practical applications. With this review, firstly we demonstrate in the introduction that molecular catalysts can bring new opportunities to proton exchange membrane (PEM) electrolyzers. In the following parts, we provide an overview of molecular catalyst modified carbon materials developed for electrochemical water oxidation, proton reduction, and CO2 reduction reactions. These materials and the involved immobilization strategies as well as characterization techniques may be directly employed in the investigations of application of molecular catalysts in PEM electrolyzers. The future scientific perspectives and challenges to advance this promising, yet underdeveloped technology for solar fuel production, integrating PEM electrolyzer with molecular-level catalysis, are discussed in the conclusions.
  •  
47.
  • Zhang, Biaobiao, et al. (författare)
  • Identifying MnVII-oxo Species during Electrochemical Water Oxidation by Manganese Oxide
  • 2018
  • Ingår i: iScience. - : Elsevier BV. - 2589-0042. ; 4, s. 144-152
  • Tidskriftsartikel (refereegranskat)abstract
    • Identifying surface active intermediate species is essential to reveal the catalytic mechanism of water oxidation by metal-oxides-based catalysts and to develop more efficient catalysts for oxygen-oxygen bond formation. Here we report, through electrochemical methods and ex situ infrared spectroscopy, the identification of a MnVII = O intermediate during catalytic water oxidation by a c-disordered δ-MnOx with an onset-potential-dependent reduction peak at 0.93 V and an infrared peak at 912 cm−1. This intermediate is proved to be highly reactive and much more oxidative than permanganate ion. Therefore, we propose a new catalytic mechanism for water oxidation catalyzed by Mn oxides, with involvement of the MnVII = O intermediate in a resting state and the MnIV−O−MnVII = O as a real active species for oxygen-oxygen bond formation. Inorganic Chemistry; Surface Science; Energy Materials; Electrocatalysis.
  •  
48.
  • Zhang, Biaobiao, et al. (författare)
  • Modifying Ru-bda Backbone with Steric Hindrance and Hydrophilicity: Influence of Secondary Coordination Environments on Water-Oxidation Mechanism
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Understanding the seven coordination and O-O coupling pathway of the distinguished Ru-bda catalysts is essential for the development of next generation efficient water-oxidation catalysts based on earth-abundant metals. This work reports the synthesis, characterization and catalytic properties of a monomeric ruthenium catalyst Ru-bnda (H2bnda = 2,2'-bi(nicotinic acid)-6,6'-dicarboxylic acid) featuring steric hindrance and enhanced hydrophilicity on the backbone. Combining experimental evidence with systematic density functional theory calculations on the Ru-bnda and related catalysts Ru-bda, Ru-pda and Ru-biqa, we emphasized that seven coordination clearly determines presence of RuV=O with high spin density on the ORuV=O atom, i.e. oxo with radical properties, which is one of the necessary conditions for reacting through the O-O coupling pathway. However, an additional factor to make the condition sufficient is the favorable intermolecular face-to-face interaction for the generation of the pre-reactive [RuV=O...O=RuV], which is significantly influenced by the secondary coordination environments. This work provides a new understanding of the structure-activity relationship of water-oxidation catalysts and their potential to adopt I2M pathway for O-O bond formation.
  •  
49.
  • Zhang, Biaobiao, et al. (författare)
  • Switching O–O bond formation mechanism between WNA and I2M pathways by modifying the Ru-bda backbone ligands of water-oxidation catalysts
  • 2021
  • Ingår i: Journal of Energy Challenges and Mechanics. - : Elsevier B.V.. - 2056-9386. ; 54, s. 815-821
  • Tidskriftsartikel (refereegranskat)abstract
    • Understanding the seven coordination and O–O coupling pathway of the distinguished Ru-bda catalysts is essential for the development of next generation efficient water-oxidation catalysts based on earth-abundant metals. This work reports the synthesis, characterization and catalytic properties of a monomeric ruthenium catalyst Ru-bnda (H2bnda = 2,2′-bi(nicotinic acid)-6,6′-dicarboxylic acid) featuring steric hindrance and enhanced hydrophilicity on the backbone. Combining experimental evidence with systematic density functional theory calculations on the Ru-bnda and related catalysts Ru-bda (H2bda = 2,2ʹ-bipyridine-6,6ʹ-dicarboxylic acid), Ru-pda (H2pda = 1,10-phenanthroline-2,9-dicarboxylic acid), and Ru-biqa (H2biqa = (1,1ʹ-biisoquinoline)-3,3ʹ-dicarboxylic acid), we emphasized that seven coordination clearly determines presence of RuV[dbnd]O with high spin density on the ORuV[dbnd]O atom, i.e. oxo with radical properties, which is one of the necessary conditions for reacting through the O–O coupling pathway. However, an additional factor to make the condition sufficient is the favorable intermolecular face-to-face interaction for the generation of the pre-reactive [RuV[dbnd]O···O[dbnd]RuV], which may be significantly influenced by the secondary coordination environments. This work provides a new understanding of the structure–activity relationship of water-oxidation catalysts and their potential to adopt I2M pathway for O–O bond formation.
  •  
50.
  • Zhou, Shengyang, et al. (författare)
  • Electrochemical Doping and Structural Modulation of Conductive Metal‐Organic Frameworks
  • 2024
  • Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 63:14
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study, we introduce an electrochemical doping strategy aimed at manipulating the structure and composition of electrically conductive metal-organic frameworks (c-MOFs). Our methodology is exemplified through a representative c-MOF, Ni3(HITP)2 (HITP=2, 3, 6, 7, 10, 11-hexaiminotriphenylene), synthesized into porous thin films supported by nanocellulose. While the c-MOF exhibits characteristic capacitive behavior in neutral electrolyte; it manifests redox behaviors in both acidic and alkaline electrolytes. Evidence indicates that the organic ligands within c-MOF undergo oxidation (p-doping) and reduction (n-doping) when exposed to specific electrochemical potentials in acidic and alkaline electrolyte, respectively. Interestingly, the p-doping process proves reversible, with the c-MOF structure remaining stable across cyclic p-doping/de-doping. In contrast, the n-doping is irreversible, leading to the gradual decomposition of the framework into inorganic species over a few cycles. Drawing on these findings, we showcase the versatile electrochemical applications of c-MOFs and their derived composites, encompassing electrochemical energy storage, electrocatalysis, and ultrafast actuation. This study provides profound insights into the doping of c-MOFs, offering a new avenue for modulating their chemical and electronic structure, thereby broadening their potential for diverse electrochemical applications.
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