51
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Lee PK, Liu HW, Yiu SM, Louie MW, Lo KKW. Luminescent cyclometallated iridium(III) bis(quinolylbenzaldehyde) diimine complexes--synthesis, photophysics, electrochemistry, protein cross-linking properties, cytotoxicity and cellular uptake. Dalton Trans 2010; 40:2180-9. [PMID: 20717588 DOI: 10.1039/c0dt00501k] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Four new luminescent cyclometallated iridium(III) bis(quinolylbenzaldehyde) diimine complexes [Ir(qba)(2)(N⁁N)](PF(6)) (Hqba = 4-(2-quinolyl)benzaldehyde, N⁁N = 2,2'-bipyridine, bpy (1); 1,10-phenanthroline, phen (2); 3,4,7,8-tetramethyl-1,10-phenanthroline, Me(4)-phen (3); 4,7-diphenyl-1,10-phenanthroline, Ph(2)-phen (4)) have been synthesised and characterised, and their electronic absorption, emission and electrochemical properties investigated. The X-ray crystal structures of complexes 1 and 2 have been determined. Upon irradiation, complexes 1-4 exhibited intense and long-lived orange-yellow emission in fluid solutions at 298 K and in alcohol glass at 77 K. The emission has been assigned to a triplet intra-ligand ((3)IL) excited state associated with the qba ligand, probably with mixing of some triplet metal-to-ligand charge-transfer ((3)MLCT) (dπ(Ir) →π*(qba)) character. Reductive amination reactions of complexes 1-4 with the protein bovine serum albumin (BSA) afforded the bioconjugates 1-BSA-4-BSA, respectively. Upon photoexcitation, these bioconjugates displayed intense and long-lived (3)MLCT (dπ(Ir) →π*(N⁁C)) emission in aqueous buffer at 298 K. The cross-linked nature of the Ir-BSA bioconjugates has been verified by SDS-PAGE. Additionally, the cytotoxicity of the complexes towards human cervix epithelioid carcinoma (HeLa) cells has been examined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assays, and the cellular uptake of complex 4 has been investigated by laser-scanning confocal microscopy and flow cytometry.
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Affiliation(s)
- Pui-Kei Lee
- Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong, People's Republic of China
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52
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Keyes TE, Forster RJ, Blackledge C. Time resolved spectroscopy of inorganic complexes. SPECTROSCOPIC PROPERTIES OF INORGANIC AND ORGANOMETALLIC COMPOUNDS 2010. [DOI: 10.1039/9781849730853-00211] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Time resolved spectroscopy has revolutionised our understanding of photochemical and photophysical reactions of inorganic complexes. In this review, we briefly describe the most common time resolved optical spectroscopic methods applied to inorganic complexes and outline some examples and highlights from the recent literature. The review is not intended to be exhaustive, but highlights key recent papers from coordination chemistry, supramolecular chemistry, carbonyl chemistry and bioinorganic chemistry, as well as, recent insights from ultrafast spectroscopy into the photophysics of important prototypes such as [Ru(bpy)3]2+ and [Cu(dmp)2]+. A brief perspective is then presented which discusses areas where time resolved spectroscopy of inorganic complexes could play a particularly important role in the next few years.
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Affiliation(s)
- Tia E. Keyes
- National Biophotonics and Imaging Platform School of Chemical Sciences, Dublin City University Glasnevin, Dublin 7 Ireland
| | - Robert J. Forster
- National Biophotonics and Imaging Platform School of Chemical Sciences, Dublin City University Glasnevin, Dublin 7 Ireland
| | - Charles Blackledge
- National Biophotonics and Imaging Platform School of Chemical Sciences, Dublin City University Glasnevin, Dublin 7 Ireland
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53
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Li SY, Liu HW, Zhang K, Lo KW. Modification of Luminescent Iridium(III) Polypyridine Complexes with Discrete Poly(ethylene glycol) (PEG) Pendants: Synthesis, Emissive Behavior, Intracellular Uptake, and PEGylation Properties. Chemistry 2010; 16:8329-39. [DOI: 10.1002/chem.201000474] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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54
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Zhang KY, Liu HW, Fong TTH, Chen XG, Lo KKW. Luminescent Dendritic Cyclometalated Iridium(III) Polypyridine Complexes: Synthesis, Emission Behavior, and Biological Properties. Inorg Chem 2010; 49:5432-43. [DOI: 10.1021/ic902443e] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Kenneth Yin Zhang
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
| | - Hua-Wei Liu
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
| | - Tommy Tsz-Him Fong
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
| | - Xian-Guang Chen
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
| | - Kenneth Kam-Wing Lo
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, People’s Republic of China
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55
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Puckett CA, Barton JK. Targeting a ruthenium complex to the nucleus with short peptides. Bioorg Med Chem 2010; 18:3564-9. [PMID: 20430627 DOI: 10.1016/j.bmc.2010.03.081] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 03/18/2010] [Accepted: 03/23/2010] [Indexed: 11/24/2022]
Abstract
In an effort to develop octahedral metal complexes as chemotherapeutic and diagnostic agents targeted to DNA, it is critical to optimize the properties of their cellular uptake. Appending d-octaarginine has been found to improve both the uptake and nuclear localization efficiency of these complexes, but the increased positive charge interferes with selective DNA binding and hence activity. Herein, we evaluate the nuclear entry of a series of luminescent ruthenium peptide conjugates of shorter sequence and lower charge. As is the case for the d-octaarginine conjugate (Ru-D-R8), the tetrapeptide RrRK (where r=d-arginine) facilitates nuclear localization of the ruthenium complex above a threshold concentration, though the threshold is higher for this conjugate (Ru-RrRK) than for Ru-D-R8. Furthermore, appended fluorescein, which lowers the threshold concentration for Ru-D-R8, does not improve nuclear entry of Ru-RrRK, indicating that fluorescein conjugation is not a general strategy for modulating the distribution of cell-penetrating peptides. Similarly, the concentration required for nuclear entry of Ru-RrRK is much higher than has been reported for a thiazole orange RrRK conjugate, demonstrating the influence of payload on the efficiency of uptake and localization of cell-penetrating peptides.
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Affiliation(s)
- Cindy A Puckett
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, United States
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56
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Affiliation(s)
- Ulrich Schatzschneider
- Lehrstuhl für Anorganische Chemie I – Bioanorganische Chemie and Research Department Interfacial Systems Chemistry (RD IFSC), Ruhr‐Universität Bochum NC 3/74, Universitätsstr. 150, 44801 Bochum, Germany, Fax: +49‐234‐32‐14378
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57
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Holzhauser C, Berndl S, Menacher F, Breunig M, Göpferich A, Wagenknecht HA. Synthesis and Optical Properties of Cyanine Dyes as Fluorescent DNA Base Substitutions for Live Cell Imaging. European J Org Chem 2010. [DOI: 10.1002/ejoc.200901423] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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58
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Abstract
Transition metal complexes offer great potential as diagnostic and therapeutic agents, and a growing number of biological applications have been explored. To be effective, these complexes must reach their intended target inside the cell. Here we review the cellular accumulation of metal complexes, including their uptake, localization, and efflux. Metal complexes are taken up inside cells through various mechanisms, including passive diffusion and entry through organic and metal transporters. Emphasis is placed on the methods used to examine cellular accumulation, to identify the mechanism(s) of uptake, and to monitor possible efflux. Conjugation strategies that have been employed to improve the cellular uptake characteristics of metal complexes are also described.
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Affiliation(s)
- Cindy A. Puckett
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Russell J. Ernst
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Jacqueline K. Barton
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125
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59
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Zhang KY, Li SPY, Zhu N, Or IWS, Cheung MSH, Lam YW, Lo KKW. Structure, Photophysical and Electrochemical Properties, Biomolecular Interactions, and Intracellular Uptake of Luminescent Cyclometalated Iridium(III) Dipyridoquinoxaline Complexes. Inorg Chem 2010; 49:2530-40. [DOI: 10.1021/ic902465b] [Citation(s) in RCA: 133] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Kenneth Yin Zhang
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P.R. China
| | - Steve Po-Yam Li
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P.R. China
| | - Nianyong Zhu
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P.R. China
| | - Iyana Wai-Shan Or
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P.R. China
| | - Maggie Shau-Ha Cheung
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P.R. China
| | - Yun-Wah Lam
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P.R. China
| | - Kenneth Kam-Wing Lo
- Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, P.R. China
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60
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Assunta Girasolo M, Rubino S, Portanova P, Calvaruso G, Ruisi G, Stocco G. New organotin(IV) complexes with l-Arginine, Nα-t-Boc-l-Arginine and l-Alanyl-l-Arginine: Synthesis, structural investigations and cytotoxic activity. J Organomet Chem 2010. [DOI: 10.1016/j.jorganchem.2009.11.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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61
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Gill MR, Garcia-Lara J, Foster SJ, Smythe C, Battaglia G, Thomas JA. A ruthenium(II) polypyridyl complex for direct imaging of DNA structure in living cells. Nat Chem 2009; 1:662-7. [PMID: 21378959 DOI: 10.1038/nchem.406] [Citation(s) in RCA: 387] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Accepted: 09/10/2009] [Indexed: 12/13/2022]
Abstract
In the search for new biological imaging agents, metal coordination compounds able to emit from triplet metal-to-ligand charge transfer (MLCT) states offer many advantages as luminescent probes of DNA structure. However, poor cellular uptake restricts their use in live cells. Here, we present a dinuclear ruthenium(II) polypyridyl system that works as a multifunctional biological imaging agent staining the DNA of eukaryotic and prokaryotic cells for both luminescence and transition electron microscopy. This MLCT 'light switch' complex directly images nuclear DNA of living cells without requiring prior membrane permeabilization. Furthermore, inhibition and transmission electron microscopy studies show this to be via a non-endocytotic, but temperature-dependent, mechanism of cellular uptake in MCF-7 cells, and confocal microscopy reveals multiple emission peaks that function as markers for cellular DNA structure.
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Affiliation(s)
- Martin R Gill
- Department of Chemistry, University of Sheffield, Sheffield, UK
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62
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Haas KL, Franz KJ. Application of metal coordination chemistry to explore and manipulate cell biology. Chem Rev 2009; 109:4921-60. [PMID: 19715312 PMCID: PMC2761982 DOI: 10.1021/cr900134a] [Citation(s) in RCA: 611] [Impact Index Per Article: 40.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Kathryn L Haas
- Department of Chemistry, Duke University, 124 Science Drive, Durham, North Carolina 27708-0346, USA
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63
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Puckett CA, Barton JK. Fluorescein redirects a ruthenium-octaarginine conjugate to the nucleus. J Am Chem Soc 2009; 131:8738-9. [PMID: 19505141 DOI: 10.1021/ja9025165] [Citation(s) in RCA: 218] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The cellular uptake and localization of a Ru-octaarginine conjugate with and without an appended fluorescein are compared. The inherent luminescence of the Ru(II) dipyridophenazine complex allows observation of its uptake without the addition of a fluorophore. Ru-octaarginine-fluorescein stains the cytosol, nuclei, and nucleoli of HeLa cells under conditions where the Ru-octaarginine conjugate without fluorescein shows only punctate cytoplasmic labeling. At higher concentrations, however, Ru-octaarginine without the fluorescein tag does exhibit cytoplasmic, nuclear, and nucleolar staining. Attaching fluorescein to Ru-octaarginine lowers the threshold concentration required for diffuse cytoplasmic labeling and nuclear entry. Hence, the localization of the fluorophore-bound peptide cannot serve as a proxy for that of the free peptide.
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Affiliation(s)
- Cindy A Puckett
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
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64
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Zeglis BM, Pierre VC, Kaiser JT, Barton JK. A bulky rhodium complex bound to an adenosine-adenosine DNA mismatch: general architecture of the metalloinsertion binding mode. Biochemistry 2009; 48:4247-53. [PMID: 19374348 DOI: 10.1021/bi900194e] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Two crystal structures of Delta-Rh(bpy)(2)(chrysi)(3+) (chrysi is 5,6-chrysenequinone diimine) bound to the oligonucleotide duplex 5'-CGGAAATTACCG-3' containing two adenosine-adenosine mismatches (italics) through metalloinsertion were determined. Diffraction quality crystals with two different space groups (P3(2)21 and P4(3)2(1)2) were obtained under very similar crystallization conditions. In both structures, the bulky rhodium complex inserts into the two mismatched sites from the minor groove side, ejecting the mismatched bases into the major groove. The conformational changes are localized to the mismatched site; the metal complex replaces the mismatched base pair without an increase in base pair rise. The expansive metal complex is accommodated in the duplex by a slight opening in the phosphodiester backbone; all sugars retain a C2'-endo puckering, and flanking base pairs neither stretch nor shear. The structures differ, however, in that in one of the structures, an additional metal complex is bound by intercalation from the major groove at the central 5'-AT-3' step. We conclude that this additional metal complex is intercalated into this central step because of crystal packing forces. The structures described here of Delta-Rh(bpy)(2)(chrysi)(3+) bound to thermodynamically destabilized AA mismatches share critical features with binding by metalloinsertion in two other oligonucleotides containing different single-base mismatches. These results underscore the generality of metalloinsertion as a new mode of noncovalent binding by small molecules with a DNA duplex.
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Affiliation(s)
- Brian M Zeglis
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
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65
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Lim MH, Song H, Olmon ED, Dervan EE, Barton JK. Sensitivity of Ru(bpy)2dppz2+ luminescence to DNA defects. Inorg Chem 2009; 48:5392-7. [PMID: 19453124 PMCID: PMC2747521 DOI: 10.1021/ic900407n] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The luminescent characteristics of Ru(bpy)(2)dppz(2+) (dppz = dipyrido[3,2-a:2',3'-c]phenazine), a DNA light switch, were investigated in the presence of oligonucleotides containing single base mismatches or an abasic site. In water, the ruthenium luminescence is quenched, but, bound to well matched duplex DNA, the Ru complex luminesces. Here we show that with DNAs containing a defect, rac-, Delta-, and Lambda-Ru(bpy)(2)dppz(2+) exhibit significant luminescent enhancements above that with well matched DNA. In the presence of a single base mismatch, large luminescent enhancements are evident for the Delta-Ru isomer; the Lambda-isomer shows particularly high luminescence bound to an oligonucleotide containing an abasic site. Similar increases are not evident with two common DNA-binding organic fluorophores, ethidium bromide and TO-PRO-3. Titrations with hairpin oligonucleotides containing a variable mismatch site show correlation between the level of luminescent enhancement and the thermodynamic destabilization associated with the mismatch. This correlation is reminiscent of that found earlier for a bulky rhodium complex that binds mismatched DNA sites through metalloinsertion, where the complex binds the DNA from the minor groove side, ejecting the mismatched bases into the major groove. Differential quenching studies with minor and major groove quenchers and time-resolved emission studies support this metalloinsertion mode for the dppz complex at the defect site. Certainly these data underscore the utility of Ru(bpy)(2)dppz(2+) as a sensitive luminescent reporter of DNA and its defects.
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Affiliation(s)
| | - Hang Song
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, 91125
| | - Eric D. Olmon
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, 91125
| | - Elizabeth E. Dervan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, 91125
| | - Jacqueline K. Barton
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, 91125
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66
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Berndl S, Wagenknecht HA. Fluorescent color readout of DNA hybridization with thiazole orange as an artificial DNA base. Angew Chem Int Ed Engl 2009; 48:2418-21. [PMID: 19229903 DOI: 10.1002/anie.200805981] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A fluorescent chameleon: A single thiazole orange (TO) dye, when used as an artificial DNA base shows the typical green emission, whereas the interstrand TO dimer exhibits an orange excimer-type emission inside duplex DNA (see picture).
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Affiliation(s)
- Sina Berndl
- Institute for Organic Chemistry, University of Regensburg, 93040 Regensburg, Germany
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67
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Ernst RJ, Song H, Barton JK. DNA mismatch binding and antiproliferative activity of rhodium metalloinsertors. J Am Chem Soc 2009; 131:2359-66. [PMID: 19175313 DOI: 10.1021/ja8081044] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Deficiencies in mismatch repair (MMR) are associated with carcinogenesis. Rhodium metalloinsertors bind to DNA base mismatches with high specificity and inhibit cellular proliferation preferentially in MMR-deficient cells versus MMR-proficient cells. A family of chrysenequinone diimine complexes of rhodium with varying ancillary ligands that serve as DNA metalloinsertors has been synthesized, and both DNA mismatch binding affinities and antiproliferative activities against the human colorectal carcinoma cell lines HCT116N and HCT116O, an isogenic model system for MMR deficiency, have been determined. DNA photocleavage experiments reveal that all complexes bind to the mismatch sites with high specificities; DNA binding affinities to oligonucleotides containing single base CA and CC mismatches, obtained through photocleavage titration or competition, vary from 10(4) to 10(8) M(-1) for the series of complexes. Significantly, binding affinities are found to be inversely related to ancillary ligand size and directly related to differential inhibition of the HCT116 cell lines. The observed trend in binding affinity is consistent with the metalloinsertion mode where the complex binds from the minor groove with ejection of mismatched base pairs. The correlation between binding affinity and targeting of the MMR-deficient cell line suggests that rhodium metalloinsertors exert their selective biological effects on MMR-deficient cells through mismatch binding in vivo.
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Affiliation(s)
- Russell J Ernst
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA
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68
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Noor F, Kinscherf R, Bonaterra GA, Walczak S, Wölfl S, Metzler-Nolte N. Enhanced cellular uptake and cytotoxicity studies of organometallic bioconjugates of the NLS peptide in Hep G2 cells. Chembiochem 2009; 10:493-502. [PMID: 19115329 DOI: 10.1002/cbic.200800469] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
SPACE INVADERS: Organometallic fragments such as the ferrocenyl group (shown in red in the picture) help to enhance cellular entry of NLS peptides. Eventually, these nontoxic conjugates find their way to the cellular nucleus as shown by fluorescence microscopy studies in this work. Intracellular delivery to biomolecular targets is still a major challenge in molecular and cell biology. We recently found that attaching an organometallic group, namely the cobaltocenium cation, to the SV 40 large T antigen nuclear localisation signal (NLS) greatly enhances cellular uptake of the conjugate (Noor et al., Angew. Chem. Int. Ed. 2005, 45, 2429). In addition, nuclear localisation of the conjugate was observed. In this work, we present a thorough investigation of this novel cellular delivery system with respect to the nature of the metal complex and the peptide sequence. A number of ferrocene ((Fe(II)), neutral metal complex) and cobaltocenium ((Co(III)), cationic metal complex) bioconjugates with both the NLS wild-type sequence PKKKRKV and a scrambled sequence (NLS(scr), KKVKPKR) were prepared by solid-phase peptide synthesis (SPPS). Cellular and nuclear uptake of these bioconjugates was studied by fluorescence microscopy on living Hep G2 cells. In addition, cytotoxicity screening on the conjugates was carried out, as the toxic effects of several simple metallocenes have been noted previously. Rapid cellular uptake as well as nuclear localisation was observed for the metal-NLS conjugates, but not for any dipeptide controls, the metal-NLS(scr) conjugates or any metal-free conjugates. It thus appears that the presence of a metallocene, but not its charge, and the correct NLS sequence is essential for cellular uptake. Fluorescence microscopy co-localisation studies did not reveal a significant endosomal entrapment of the conjugates. The metallocene not only provides a hydrophobic handle for membrane translocation but also facilitates the localisation and distribution of the conjugate in the cytoplasm. The NLS peptide on the other hand is responsible for the nuclear localisation of the bioconjugate. Finally, none of the conjugates were found to be toxic up to the highest concentrations that was tested (1 mM) against the Hep G2 cells that were used in this study. In conclusion, this work supports metallocene-NLS bioconjugates, in particular with the very robust cobaltocenium group, as a simple but potent, nontoxic system for cellular uptake and nuclear delivery. Concurrently, our finding is relevant to the still-unresolved question of cytotoxicity of metallocenes because it excludes binding and/or damage to the DNA as a mechanism of metallocene cytotoxicity. This finding is confirmed by a combined yeast cytotoxicity/genotoxicity assay, which also shows very little toxic effects for all organometal-NLS conjugates that were tested.
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Affiliation(s)
- Fozia Noor
- Department of Biochemical Engineering, University of Saarland, Saarbrücken, Germany
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69
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Fluoreszenz-Farbwechsel bei der DNA-Hybridisierung mit Thiazolorange als artifizieller DNA-Base. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200805981] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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70
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Yang P, De Cian A, Teulade-Fichou MP, Mergny JL, Monchaud D. Engineering Bisquinolinium/Thiazole Orange Conjugates for Fluorescent Sensing of G-Quadruplex DNA. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200805613] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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71
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Yang P, De Cian A, Teulade-Fichou MP, Mergny JL, Monchaud D. Engineering Bisquinolinium/Thiazole Orange Conjugates for Fluorescent Sensing of G-Quadruplex DNA. Angew Chem Int Ed Engl 2009; 48:2188-91. [DOI: 10.1002/anie.200805613] [Citation(s) in RCA: 143] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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72
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Microwave-assisted solid-phase synthesis, cellular uptake, and cytotoxicity studies of cymantrene–peptide bioconjugates. J Organomet Chem 2009. [DOI: 10.1016/j.jorganchem.2008.07.031] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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73
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Harrison RJE. Confocal Microscopy: Exploring the Cellular Uptake and Intracellular Distribution of Fluorescent Metal-Based Drugs. Aust J Chem 2009. [DOI: 10.1071/ch08117] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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74
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N′Dongo HWP, Neundorf I, Merz K, Schatzschneider U. Synthesis, characterization, X-ray crystallography, and cytotoxicity of a cymantrene keto carboxylic acid for IR labelling of bioactive peptides on a solid support. J Inorg Biochem 2008; 102:2114-9. [DOI: 10.1016/j.jinorgbio.2008.07.019] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2008] [Revised: 07/30/2008] [Accepted: 07/31/2008] [Indexed: 11/15/2022]
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75
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Neugebauer U, Pellegrin Y, Devocelle M, Forster RJ, Signac W, Moran N, Keyes TE. Ruthenium polypyridyl peptide conjugates: membrane permeable probes for cellular imaging. Chem Commun (Camb) 2008:5307-9. [PMID: 18985192 DOI: 10.1039/b810403d] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Two novel polyarginine labelled ruthenium polypyridyl dyes are reported, one conjugated to five, (Ru-Ahx-R5), and one to eight arginine residues, (Ru-Ahx-R8); both complexes exhibit long-lived, intense, and oxygen-sensitive luminescence; (Ru-R8) is passively, efficiently and very rapidly transported across the cell membrane into the cytoplasm without requirement for its permeablisation.
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Affiliation(s)
- Ute Neugebauer
- The Biomedical Diagnostics Institute, Dublin City University, Dublin 9, Ireland
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Menacher F, Rubner M, Berndl S, Wagenknecht HA. Thiazole orange and Cy3: improvement of fluorescent DNA probes with use of short range electron transfer. J Org Chem 2008; 73:4263-6. [PMID: 18442293 DOI: 10.1021/jo8004793] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Thiazole orange was synthetically incorporated into oligonucleotides by using the corresponding phosphoramidite as the building block for automated DNA synthesis. Due to the covalent fixation of the TO dye as a DNA base surrogate, the TO-modified oligonucleotides do not exhibit a significant increase of fluorescence upon hybridization with the counterstrand. However, if 5-nitroindole (NI) is present as a second artificial DNA base (two base pairs away from the TO dye) a fluorescence increase upon DNA hybridization can be observed. That suggests that a short-range photoinduced electron transfer causes the fluorescence quenching in the single strand. The latter result represents a concept that can be transferred to the commercially available Cy3 label. It enables the Cy3 fluorophore to display the DNA hybridization by a fluorescence increase that is normally not observed with this dye.
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Affiliation(s)
- Florian Menacher
- University of Regensburg, Institute for Organic Chemistry, Universitätsstrasse 31, Regensburg, Germany
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77
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Elias B, Creely C, Doorley GW, Feeney MM, Moucheron C, Kirsch-DeMesmaeker A, Dyer J, Grills DC, George MW, Matousek P, Parker AW, Towrie M, Kelly JM. Photooxidation of guanine by a ruthenium dipyridophenazine complex intercalated in a double-stranded polynucleotide monitored directly by picosecond visible and infrared transient absorption spectroscopy. Chemistry 2008; 14:369-75. [PMID: 17886324 DOI: 10.1002/chem.200700564] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Transient species formed by photoexcitation (400 nm) of [Ru(dppz)(tap)2]2+ (1) (dppz = dipyrido[3,2-a:2',3'-c]phenazine; tap=1,4,5,8-tetraazaphenanthrene) in aqueous solution and when intercalated into a double-stranded synthetic polynucleotide, [poly(dG-dC)]2, have been observed on a picosecond timescale by both visible transient absorption (allowing monitoring of the metal complex intermediates) and transient infrared (IR) absorption spectroscopy (allowing direct study of the DNA nucleobases). By contrast with its behavior when free in aqueous solution, excitation of 1 when bound to [poly(dG-dC)]2 causes a strong increase in absorbance at 515 nm due to formation of the reduced complex [Ru(dppz)(tap)2]+ (rate constant=(2.0+/-0.2) x 10(9) s(-1)). The subsequent reformation of 1 proceeds with a rate constant of (1.1+/-0.2) x 10(8) s(-1). When the process is carried out in D2O, the rates of formation and removal of [Ru(dppz)(tap)2]+ are reduced (rate constants (1.5+/-0.3) x 10(9) and (0.7+/-0.2) x 10(8) s(-1) respectively) consistent with proton-coupled electron transfer processes. Picosecond transient IR measurements in the 1540-1720 cm(-1) region in D2O solution confirm that the reduction of 1 intercalated into [poly(dG-dC)]2 is accompanied by bleaching of IR ground-state bands of guanine (1690 cm(-1)) and cytosine (1656 cm(-1)), each with similar rate constants.
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Affiliation(s)
- Benjamin Elias
- Service de Chimie Organique et Photochimie, CP 160/08, Université Libre de Bruxelles, 50 Avenue F.D. Roosevelt, 1050 Bruxelles, Belgium
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78
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Farrer NJ, Sadler PJ. Photochemotherapy: Targeted Activation of Metal Anticancer Complexes. Aust J Chem 2008. [DOI: 10.1071/ch08088] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The present article highlights recent findings in the field of photoactivation of anticancer metal complexes. Developments of some photoactivatable Rh-, Pt-, and Fe-based complexes are discussed and their mechanisms of anticancer action are outlined. Features required for the successful design of photoactive drugs are considered, in particular methods for improving the targeting and selectivity of such complexes through techniques such as conjugate delivery and multiphoton absorption.
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79
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Abstract
Since the elucidation of the structure of double helical DNA, the construction of small molecules that recognize and react at specific DNA sites has been an area of considerable interest. In particular, the study of transition metal complexes that bind DNA with specificity has been a burgeoning field. This growth has been due in large part to the useful properties of metal complexes, which possess a wide array of photophysical attributes and allow for the modular assembly of an ensemble of recognition elements. Here we review recent experiments in our laboratory aimed at the design and study of octahedral metal complexes that bind DNA non-covalently and target reactions to specific sites. Emphasis is placed both on the variety of methods employed to confer site-specificity and upon the many applications for these complexes. Particular attention is given to the family of complexes recently designed that target single base mismatches in duplex DNA through metallo-insertion.
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Affiliation(s)
- Brian M. Zeglis
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena CA 91125 USA Fax: 626-577-4976; Tel: 626-395-6075; E-mail:
| | - Valerie C. Pierre
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena CA 91125 USA Fax: 626-577-4976; Tel: 626-395-6075; E-mail:
| | - Jacqueline K. Barton
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena CA 91125 USA Fax: 626-577-4976; Tel: 626-395-6075; E-mail:
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80
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Cordier C, Pierre VC, Barton JK. Insertion of a bulky rhodium complex into a DNA cytosine-cytosine mismatch: an NMR solution study. J Am Chem Soc 2007; 129:12287-95. [PMID: 17877349 PMCID: PMC2748819 DOI: 10.1021/ja0739436] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The bulky octahedral complex Rh(bpy)2chrysi3+ (chrysi = 5,6-chrysenequinonediimine) binds single-base mismatches in a DNA duplex with micromolar binding affinities and high selectivity. Here we present an NMR solution study to characterize the binding mode of this bulky metal complex with its target CC mismatch in the oligonucleotide duplex (5'-CGGACTCCG-3')2. Both NOESY and COSY studies indicate that Rh(bpy)2chrysi3+ inserts deeply in the DNA at the mismatch site via the minor groove and with ejection of both destabilized cytosines into the opposite major groove. The insertion only minimally distorts the conformation of the oligonucleotide local to the binding site. Both flanking, well-matched base pairs remain tightly hydrogen-bonded to each other, and 2D DQF-COSY experiments indicate that all sugars maintain their original C2'-endo conformation. Remarkably, 31P NMR reveals that opening of the phosphate angles from a BI to a BII conformation is sufficient for insertion of the bulky metal complex. These results corroborate those obtained crystallographically and, importantly, provide structural evidence for this specific insertion mode in solution.
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81
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Zeglis BM, Barton JK. DNA base mismatch detection with bulky rhodium intercalators: synthesis and applications. Nat Protoc 2007; 2:357-71. [PMID: 17406597 PMCID: PMC2754800 DOI: 10.1038/nprot.2007.22] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This protocol describes the syntheses and applications of two metallointercalators, Rh(bpy)2(chrysi)3+ and Rh(bpy)2(phzi)3+, that target single base mismatches in DNA. The complexes bind mismatched DNA sites specifically and, upon photoactivation, promote strand scission neighboring the mismatch. Owing to their high specificity and sequence context independence, targeting mismatches with these complexes offers an attractive alternative to current mismatch- and SNP-detection methodologies. This protocol also describes the synthesis of these complexes and their use in marking mismatched sites. Irradiation of 32P-labeled duplex DNA with either intercalator followed by denaturing PAGE allows the detection of mismatches in oligonucleotides. The protocol also outlines a method for efficient detection of single nucleotide polymorphisms (SNPs) in larger genes or plasmids. Pooled genes are denatured and re-annealed to form heteroduplexes; they are then incubated with either complex, irradiated and analyzed using capillary electrophoresis to probe for mismatches (SNP sites). The synthesis of the metallointercalators requires approximately 5-7 d. The mismatch- and SNP-detection experiments each require approximately 3 d.
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82
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Patel LN, Zaro JL, Shen WC. Cell Penetrating Peptides: Intracellular Pathways and Pharmaceutical Perspectives. Pharm Res 2007; 24:1977-92. [PMID: 17443399 DOI: 10.1007/s11095-007-9303-7] [Citation(s) in RCA: 299] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Accepted: 03/20/2007] [Indexed: 12/19/2022]
Abstract
Cell penetrating peptides, generally categorized as amphipathic or cationic depending on their sequence, are increasingly drawing attention as a non-invasive delivery technology for macromolecules. Delivery of a diverse set of cargo in terms of size and nature ranging from small molecules to particulate cargo has been attempted using different types of cell penetrating peptides (CPPs) in vitro and in vivo. However, the internalization mechanism of CPPs is an unresolved issue to date, with dramatic changes in view regarding the involvement of endocytosis as a pathway of internalization. A key reason for the lack of consensus on the mechanism can be attributed to the methodology in deciphering the internalization mechanism. In this review, we highlight some of the methodology concerns, focus more on the internalization pathway and also provide a novel perspective about the intracellular processing of CPPs, which is a crucial aspect to consider when selecting a cell penetrating peptide as a drug delivery system. In addition, recent applications of cell penetrating peptides for the delivery of small molecules, peptides, proteins, oligonucleotides, nanoparticles and liposomes have been reviewed.
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Affiliation(s)
- Leena N Patel
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, California 90089, USA
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