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Cheng G.,University of Hong Kong | Cheng G.,Jilin University | Cheng G.,HKU Shenzhen Institute of Research and Innovation | Chan K.T.,University of Hong Kong | And 3 more authors.
Advanced Materials | Year: 2014

Gold(III) complexes supported by C-deprotonated fluorene-C^N^C ligands having high emission quantum yield up to 0.61 and long-lived emissive excited states are used as yellow emitters in color tunable PLEDs and OLEDs. High EQEs of 13.16% and 22.02% are achieved in the best PLED and OLED, respectively. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Lok C.-N.,University of Hong Kong | Zou T.,University of Hong Kong | Zhang J.-J.,University of Hong Kong | Lin I.W.-S.,University of Hong Kong | And 2 more authors.
Advanced Materials | Year: 2014

The therapeutic applications of many anticancer or antimicrobial metal complexes often suffer from low solubility and low stability in physiological conditions or from drug resistance. To circumvent these problems, nanoparticle systems that allow controlled release and specific accumulation in the targeted disease tissue are of advantage for efficient treatment with minimal toxicity. The focus of this Research News is metal-based nanomaterials comprising anticancer gold(III)/platinum(II) complexes or antimicrobial silver, highlighting the controlled-release properties of self-assembled metal systems. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Xiao X.-S.,University of Hong Kong | Lu W.,South University of Science and Technology of China | Che C.-M.,University of Hong Kong | Che C.-M.,HKU Shenzhen Institute of Research and Innovation
Chemical Science | Year: 2014

A new class of dinuclear cyclometalated platinum(ii) complexes with [PtII(C^N^N)CNR]+ (HC^N^N = 6-phenyl-2,2′-bipyridyl, CNR = 2,6-dimethylphenyl isocyanide) motifs covalently connected by oligo(oxyethylene) chains form luminescent lyotropic chromonic liquid crystals or hydrogels in aqueous dispersions with intra- and intermolecular Pt⋯Pt and π-π interactions as the driving force. Their solution behaviour is modulated by the length of the oligo(oxyethylene) chain connecting the two cyclometalated platinum(ii) motifs. One of the dinuclear Pt(ii) complexes with a long oligo(oxyethylene) bridge and which does not display intramolecular Pt⋯Pt and π-π interactions can act as an effective 'gelling stimulus' for mononuclear [PtII(C^N^N)CNR]+ complexes in aqueous solutions, resulting in the formation of a nematic hydrogel that is persistent and displays red photoluminescence. This journal is © the Partner Organisations 2014.


Zou T.,University of Hong Kong | Lok C.-N.,University of Hong Kong | Fung Y.M.E.,University of Hong Kong | Che C.-M.,University of Hong Kong | Che C.-M.,HKU Shenzhen Institute of Research and Innovation
Chemical Communications | Year: 2013

A panel of luminescent platinum(ii) complexes containing bidentate N-heterocyclic carbene ligands selectively localize to the endoplasmic reticulum (ER) domain, induce ER stress and cell apoptosis. Some of them show potent photo-toxicity to cancer cells. © 2013 The Royal Society of Chemistry.


Zou T.,University of Hong Kong | Lum C.T.,University of Hong Kong | Lok C.-N.,University of Hong Kong | To W.-P.,University of Hong Kong | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2014

In the design of anticancer gold(I) complexes with high in vivo efficacy, tuning the thiol reactivity to achieve stability towards blood thiols yet maintaining the thiol reactivity to target cellular thioredoxin reductase (TrxR) is of pivotal importance. Herein we describe a dinuclear gold(I) complex (1-PF6) utilizing a bridging bis(N-heterocyclic carbene) ligand to attain thiol stability and a diphosphine ligand to keep appropriate thiol reactivity. Complex 1-PF6 displays a favorable stability that allows it to inhibit TrxR activity without being attacked by blood thiols. In vivo studies reveal that 1-PF6 significantly inhibits tumor growth in mice bearing HeLa xenograft and mice bearing highly aggressive mouse B16-F10 melanoma. It inhibits angiogenesis in tumor models and inhibits sphere formation of cancer stem cells in vitro. Toxicology studies indicate that 1-PF 6 does not show systemic anaphylaxis on guinea pigs and localized irritation on rabbits. It′s in the blood: A binuclear gold(I) complex 1-PF6 is stable towards blood thiols and is a tight-binding inhibitor of thioredoxin reductase (TrxR). In vivo antitumor studies show 81-% inhibition of tumor growth in mice with HeLa xenografts and 62-% inhibition of highly aggressive mouse B16-F10 melanoma. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Lai W.-F.,University of Hong Kong | Shum H.C.,University of Hong Kong | Shum H.C.,HKU Shenzhen Institute of Research and Innovation
Nanoscale | Year: 2016

Proteins have emerged as an important class of therapeutic agents due to their high specificity in their physiological actions. Over the years, diverse protein carriers have been developed; however, some concerns, such as the relatively low loading efficiency and release sustainability, have limited the efficiency of protein delivery. This study reports the use of hydrogel nanoparticles based on a novel copolymer, poly(ethylenimine)-graft-polysorbate (PEIP), as effective protein carriers. The copolymer is fabricated by grafting poly(ethylenimine) (PEI) with polysorbate 20 using carbonyldiimidazole chemistry. Its cytotoxicity is much lower than that of unmodified PEI in RGC5 and HEK293 cells. In comparison with nanoparticles formed by unmodified PEI, our nanoparticles are not only more efficient in cellular internalization, as indicated by the 5- to 6-fold reduction in the time they take to cause 90% of cells to exhibit intracellular fluorescence, but also give a protein loading efficiency as high as 70-90%. These, together with the salt-responsiveness of the nanoparticles in protein release and the retention of the activity of the loaded protein, suggest that PEIP and its hydrogel nanoparticles warrant further development as protein carriers for therapeutic applications. © 2016 The Royal Society of Chemistry.


Chan K.-H.,HKU Shenzhen Institute of Research and Innovation | Guan X.,University of Hong Kong | Lo V.K.-Y.,HKU Shenzhen Institute of Research and Innovation | Che C.-M.,HKU Shenzhen Institute of Research and Innovation
Angewandte Chemie - International Edition | Year: 2014

Bis(NHC)ruthenium(II)-porphyrin complexes were designed, synthesized, and characterized. Owing to the strong donor strength of axial NHC ligands in stabilizing the trans Mï£CRR′/Mï£NR moiety, these complexes showed unprecedently high catalytic activity towards alkene cyclopropanation, carbene C-H, N-H, S-H, and O-H insertion, alkene aziridination, and nitrene C-H insertion with turnover frequencies up to 1950 min-1. The use of chiral [Ru(D4-Por)(BIMe)2] (1 g) as a catalyst led to highly enantioselective carbene/nitrene transfer and insertion reactions with up to 98 % ee. Carbene modification of the N terminus of peptides at 37 °C was possible. DFT calculations revealed that the trans axial NHC ligand facilitates the decomposition of diazo compounds by stabilizing the metal-carbene reaction intermediate. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


To W.-P.,University of Hong Kong | Chan K.T.,University of Hong Kong | Tong G.S.M.,University of Hong Kong | Ma C.,University of Hong Kong | And 5 more authors.
Angewandte Chemie - International Edition | Year: 2013

Photochemistry: A series of emissive gold(III) complexes with fluorene-containing cyclometalating ligands exhibits strong phosphorescence and long-lived excited states with emission quantum yields and lifetimes up to 58 % and 305 μs, respectively. These complexes can sensitize energy up-conversion of 9,10-diphenylanthracene (DPA; see picture) and display rich two-photon absorption properties (TPA; TTA=triplet-triplet annihilation). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


To W.-P.,University of Hong Kong | Liu Y.,University of Hong Kong | Lau T.-C.,City University of Hong Kong | Che C.-M.,University of Hong Kong | Che C.-M.,HKU Shenzhen Institute of Research and Innovation
Chemistry - A European Journal | Year: 2013

A series of palladium(II)-porphyrin complexes that display dual emissions with lifetimes up to 437μs have been synthesized. Among the four complexes, PdF20TPP is an efficient and robust catalyst for photoinduced oxidative C-H functionalization by using oxygen as terminal oxidant. α-Functionalized tertiary amines were obtained in good to excellent yields by light irradiation (λ>400nm) of a mixture of PdF20TPP, tertiary amine, and nucleophile (cyanide, nitromethane, dimethyl malonate, diethyl phosphite, and acetone) under aerobic conditions. Four examples of intramolecular cyclized amine compounds could be similarly prepared. Comparison of the UV-visible absorption spectra before and after the photochemical reaction revealed that PdF20TPP was highly robust (>95 % recovery). The practical application of PdF20TPP has been revealed by the photochemical reactions performed by using a low catalyst loading (0.01mol %) and on a 10mmol scale. The PdF20TPP catalyst could sensitize photoinduced oxidation of sulfides to sulfoxides in excellent yields. Mechanistic studies revealed that the photocatalysis proceeded by singlet-oxygen oxidation. Long-lived excited states! A series of palladium(II)-porphyrin complexes have been synthesized and found to display long-lived excited states with lifetimes up to 437μs (see scheme). Among these complexes, PdF 20TPP is an efficient and robust catalyst for a broad array of photoinduced oxidative C-H functionalization reactions. PtF20TPP= platinum(II) meso-tetrakis(2,3,4,5,6-pentafluorophenyl)porphyrin. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Zou T.,University of Hong Kong | Zou T.,HKU Shenzhen Institute of Research and Innovation | Lum C.T.,University of Hong Kong | Lok C.-N.,University of Hong Kong | And 3 more authors.
Chemical Society Reviews | Year: 2015

Gold complexes have recently gained increasing attention in the design of new metal-based anticancer therapeutics. Gold(iii) complexes are generally reactive/unstable under physiological conditions via intracellular redox reactions, and the intracellular AuIII to AuI reduction reaction has recently been "traced" by the introduction of appropriate fluorescent ligands. Similar to most Au(i) complexes, Au(iii) complexes can inhibit the activities of thiol-containing enzymes, including thioredoxin reductase, via ligand exchange reactions to form Au-S(Se) bonds. Nonetheless, there are examples of physiologically stable Au(iii) and Au(i) complexes, such as [Au(TPP)]Cl (H2TPP = 5,10,15,20-tetraphenylporphyrin) and [Au(dppe)2]Cl (dppe = 1,2-bis(diphenylphosphanyl)ethane), which are known to display highly potent in vitro and in vivo anticancer activities. In this review, we summarize our current understanding of anticancer gold complexes, including their mechanisms of action and the approaches adopted to improve their anticancer efficiency. Some recent examples of gold anticancer chemotherapeutics are highlighted. © The Royal Society of Chemistry 2015.

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