Konjugate aus Übergangsmetallverbindungen und Biomolekülen als Bausteine für Biosensoren mit spektroskopischer und elektrochemischer Detektion

Meine Gruppe nutzt die besonderen spektroskopischen und chemischen Eigenschaften von Übergangsmetallverbindungen für die Detektion und Modifizierung von Biomolekülen wie bioaktiven Peptiden und DNA-Analoga. Anwendungen unserer Biokonjugate umfassen die med. Diagnostik und DNA-Analytik, insbesondere auf sog. DNA Chips. Die folgenden Detektionsmethoden sind besonders auf Metallkomplexe zugeschnitten: • Optische Spektroskopie (incl. Fluoreszenzspektroskopie) • Infrarot-Spektroskopie (u. a. als Carbonyl Metallo Immuno Assay CMIA) • Elektrochemische Detektion Von diesen ist die elektrochemische Detektion besonders für das moderne high-throughput Screening mithilfe von Biochips geeignet und stellt naturgemäß einen Schwerpunkt unserer Arbeiten dar, da eine Vielzahl von Metallkomplexen in einem geeigneten Potentialbereich reversibel oxdierbar bzw. reduzierbar ist. Die experimentelle Herausforderung liegt darin, luft- und wasserstabile Metallkomplexe mit geeigneten Eigenschaften zu identifizieren und milde, biokompatible Methoden für die Synthese der Biokonjugate mit diesen Metallkomplexen zu entwickeln. Offensichtlich können nur solche synthetischen Methoden verwendet werden, die mit den diversen funktionellen Gruppen in Biomolekülen (Amine, Amide, Alkohole, Thiole, etc.) kompatibel sind. Auf dem Poster präsentieren wir neue synthetische Methoden für die Markierung von Biomolekülen mit Übergangsmetallverbindungen, die in meiner Gruppe entwickelt wurden, sowie die Charakterisierung der Konjugate an ausgewählten Beispielen. In einem weiteren Projekt untersuchen wir Metallkomplexe von PNA (Peptide Nucleic Acid) auf ihre mögliche Verwendung in Biosensoren. PNA wurde 1991 von Nielsen und Buchardt entwickelt und ist ein DNA-Analogon mit ausgezeichneten Eigenschaften für Anwendungen in der Molekularbiologie und Biotechnologie. Die Wechselwirkung eines PNA-Ruthenium-Konjugates 2 mit komplementärer DNA und PNA wurde mittels UV-Schmelztemperatur und CD-Spektroskopie untersucht

Iridium(I) Compounds as Prospective Anticancer Agents: Solution Chemistry, Antiproliferative Profiles and Protein Interactions for a Series of Iridium(I) N-Heterocyclic Carbene Complexes

Aseries of structurally related mono-and bis-NHC–iridium(I) (NHC:N-heterocyclic carbene) complexeshave been investigatedfor their suitability as potential anti-cancer drugs.Their spectral behaviour in aqueous buffersunder physiologic al-like conditions and their cytotoxicityagainstthe cancercell lines MCF-7 and HT-29are reported.Notably,almostall complexes exhibit significant cytotoxic ef-fects towards both cancer cell lines. In general,the cationicbis-carbene complex es show higherstabilityand greater an-ticanceractivity than their neutral mono-carbene analogueswith IC50valuesinthe high nanomolar range.Furthermore,to gain initialmechanistic insight, the interactions of theseiridium(I)–NHC complexes with two model proteins,namelylysozyme and cytochrome c, were exploredbyHR-ESI-MSanalyses. The different protein metalation patternsofthecomplexes can be roughlyclassified into two distinctgroups. Those interactions give us afirst idea about the pos-sible mechanism of action of this class of compounds. Over-all, our findings show that iridium(I)–NHC complexesrepre-sent very interesting candidates forfurther development asnew metal-based anticancer drugs

Metal and Substituent Influence on the Cytostatic Activity of Cationic Bis‐cyclometallated Iridium and Rhodium Complexes with Substituted 1,10‐Phenanthrolines as Ancillary Ligands

Synthesis and characterization of the new cyclometalated complex salts [Rh(ptpy)2(5.6‐dimethyl‐1,10‐phenanthroline)]PF6 (1a) [Rh(ptpy)2(2.9‐dimethyl‐4.7‐diphenyl‐1,10‐ phenanthroline)]PF6 (2a), [Rh(ptpy)2(5‐amino‐1,10‐phenanthroline)] PF6 (3a), and [M(ptpy)2 (pyrazino‐[2.3‐f]‐1,10‐phenanthroline)]PF6 (M = Rh, 4a; M = Ir, 4b), (ptpy = 2‐(p‐tolyl)pyridinato) are described. The molecular structures of compounds 1b and 4a in the solid state were determined by single‐crystal X‐ray diffraction. All these compounds and their already known Iridium counterparts 1b – 3b display significant cytotoxicity against human cancer cell lines MCF‐7 (human breast adenocarcinoma) and HT‐29 (colon adenocarcinoma) with IC50 values in the low micromolar range

Ru(ii)-Peptide bioconjugates with the cppH linker (cppH = 2-(2'-pyridyl)pyrimidine-4-carboxylic acid): synthesis, structural characterization, and different stereochemical features between organic and aqueous solvents

Three new Ru(ii) bioconjugates with the C-terminal hexapeptide sequence of neurotensin, RRPYIL, namely trans,cis-RuCl2(CO)2(cppH-RRPYIL-\u3baNp) (7), [Ru([9]aneS3)(cppH-RRPYIL-\u3baNp)(PTA)](Cl)2 (8), and [Ru([9]aneS3)Cl(cppH-RRPYIL-\u3baNp)]Cl (11), where cppH is the asymmetric linker 2-(2'-pyridyl)pyrimidine-4-carboxylic acid, were prepared in pure form and structurally characterized in solution. The cppH linker is capable of forming stereoisomers (i.e. linkage isomers), depending on whether the nitrogen atom ortho (No) or para (Np) to the carboxylate on C4 in the pyrimidine ring binds the metal ion. Thus, one of the aims of this work was to obtain pairs of stereoisomeric conjugates and investigate their biological (anticancer, antibacterial) activity. A thorough NMR characterization clearly indicated that in all cases exclusively Np conjugates were obtained in pure form. In addition, the NMR studies showed that, whereas in DMSO-d6 each conjugate exists as a single species, in D2O two (7) or even three if not four (8 and 11) very similar stable species form (each one corresponding to an individual compound). Similar results were observed for the cppH-RRPYIL ligand alone. Overall, the NMR findings are consistent with the occurrence of a strong intramolecular stacking interaction between the phenol ring of tyrosine and the pyridyl ring of cppH. Such stacking interactions between aromatic rings are expected to be stronger in water. This interaction leads to two stereoisomeric species in the free cppH-RRPYIL ligand and in the bioconjugate 7, and is somehow modulated by the less symmetrical Ru coordination environments in 8 and 11, affording three to four very similar species

Cytotoxic Activities of Bis-cyclometalated M(III) Complexes (M=Rh, Ir) Containing 5-substituted 1,10-Phenanthroline or 4,4'-substituted 2,2'-Bipyridine Ligands

The synthesis and characterization of eight new bis-cyclometalated compounds [M(ptpy)(2)(NN)]PF6 (ptpy=2-(p-tolyl)pyridinato;NN=5-chloro-1,10-phenanthroline: M=Rh, 1;M=Ir, 2);NN=5-methyl-1,10-phenanthroline: M=Rh, 3;M=Ir, 4;NN=4,4'-diphenyl-2,2'-bipyridine: M=Rh, 5;M=Ir, 6;NN=4,4'-diamino-2,2'-bipyridine: M=Rh, 7;M=Ir, 8) are described. All compounds were characterized by spectroscopic means. Additionally, the molecular structures of compounds 4, 5, 6, and 8 in the crystal were determined by single-crystal X-ray diffraction studies. To explore the cytotoxic properties of all new eight compounds, colorimetric assays (MTT assay) against prominent cancer cell lines, MCF-7 and HT-29, were performed. The determined IC50 values are in the low micromolar range, between 1.3-5.6 mu M. The most effective compounds are 1 and 2 with 5-chloro-substituted phenanthroline ligands, whereas the diamino-substituted bipyridine ligands (5 and 6) are the least cytotoxic compounds. The tested complexes showed a significant increase in cytotoxicity, up to 25-fold increase in MCF-7 cancer cells, and up to 60-fold increase in the HT-29 cell line compared to the established anticancer compound cisplatin under identical conditions

Bis‐cyclometalated Rhodium and Iridium Chloride Complexes Yield Different Products Upon Reaction With 9,10‐Diaminophenanthrene

The reaction of 9.10‐diaminophenanthrene with [{Rh(μ‐Cl)(ptpy)2}2] yields – quite unexpected – the new cyclometalated complex salts [Rh(ptpy)2(9,10‐diiminophenanthrene)]PF6 (1), whereas with the corresponding dinuclear iridium compound the “usual” [Ir(ptpy)2(9,10‐diaminophenanthrene)]PF6 (2) is obtained. The molecular structure of compound 1 was confirmed by single‐crystal X‐ray diffraction. 1 crystallized in the monoclinic space group P21/n as a dichloromethane solvate. Both compounds display significant cytotoxicity against human cancer cell lines with the IC50 values in the low micromolar range

Cytotoxic Activities of Bis-cyclometalated Iridium(III) Complexes Containing Chloro-substituted kappa N-2-terpyridines

The synthesis and characterization of two new bis-cyclometalated compounds [Ir(ptpy)(2)(kappa N-2-terpy-C6H4Cl-p)]PF6 [terpy-C6H4Cl-p=4'-(4-chlorophenyl)-2,2':6',2''-terpyridine, (1)], and [Ir(ptpy)(2)(kappa N-2-terpy-Cl)]PF6 [terpy-Cl=4'-chloro-2,2':6',2''-terpyridine, (2);ptpy=2-(p-tolyl)pyridinato)] are described. The molecular structures of compounds 1 and 2 in the crystal were determined by single-crystal X-ray diffraction. 1 crystallized from dichloromethane/methanol/iso-hexane in the monoclinic space group P2/(n) and 2 from the same mixture of solvents in the triclinic space group P(-)1. Photophysical investigations on 1 and 2 revealed broad unstructured luminescence in the red spectral region with the emission maxima in dichloromethane at 620 and 630 nm respectively. To explore cytotoxic properties of compounds 1 and 2, a colorimetric assay (MTT assay) against prominent cancer cell lines, MCF-7 and HT-29, was performed. The determined IC50 values are in the low micromolar range (2-3 mu M). In comparison to cisplatin, the tested complexes 1 and 2 exhibit up to >20-fold (MCF-7) and >40-fold (HT-29) increase in biological activity

Cytotoxicity studies of water soluble coordination compounds with a [Mo 2 O 2 S 2 ] 2+ core

Post-print (lokagerð höfundar)Selected molybdenum sulfur compounds with the formulas (M)[Mo2O2S4L] where (Et4N)2(1), L = S42 −, (Et4N)(2), L = Cp, (3), L = DMF, K(5), L = serine, M = Et4N+, K+, Na+ and [Mo2O2S2L2] where Na2(4), L = cysteine, and (6), L = threonine, were prepared and subjected to cytotoxicity studies in vitro. The results were analyzed to rank the compounds according to their relative cytotoxicity and to correlate the observed toxicity to specific composition. The results guide future efforts to synthesize highly water soluble, non-toxic, compounds. Strong correlation was observed between toxicity and cation selection, as well as selection of biocompatible ligands combined with alkali metal salts. The most toxic compound analyzed showed about 50 times less cytotoxicity than the cisplatin reference compound in HT-29 cells. Preliminary results from in vivo data agree with the ranking obtained in vitro.JMG thanks for support by a STSM Grant by COST Action CM1105. Icelandic Centre for Research (Rannís) is thanked for financial support (grant 140945-052).Peer reviewe

Elucidation of Plasma-induced Chemical Modifications on Glutathione and Glutathione Disulphide

Cold atmospheric pressure plasmas are gaining increased interest in the medical sector and clinical trials to treat skin diseases are underway. Plasmas are capable of producing several reactive oxygen and nitrogen species (RONS). However, there are open questions how plasma-generated RONS interact on a molecular level in a biological environment, e.g. cells or cell components. The redox pair glutathione (GSH) and glutathione disulphide (GSSG) forms the most important redox buffer in organisms responsible for detoxification of intracellular reactive species. We apply Raman spectroscopy, mass spectrometry, and molecular dynamics simulations to identify the time-dependent chemical modifications on GSH and GSSG that are caused by dielectric barrier discharge under ambient conditions. We find GSSG, S-oxidised glutathione species, and S-nitrosoglutathione as oxidation products with the latter two being the final products, while glutathione sulphenic acid, glutathione sulphinic acid, and GSSG are rather reaction intermediates. Experiments using stabilized pH conditions revealed the same main oxidation products as were found in unbuffered solution, indicating that the dominant oxidative or nitrosative reactions are not influenced by acidic pH. For more complex systems these results indicate that too long treatment times can cause difficult-to-handle modifications to the cellular redox buffer which can impair proper cellular function