Browsing by Author "Michael P. Coogan"

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Cytotoxic activity, cell imaging and photocleavage of DNA induced by a Pt(ii) cyclophane bearing 1,2 diamino ethane as a terminal ligand
(2011) Niraj Kumari; Brajesh Kumar Maurya; Raj Kumar Koiri; Surendra Kumar Trigun; Srikrishna Saripella; Michael P. Coogan; Lallan Mishra
A Pt II complex [{Pt(en)L} 2]·4PF 6 (Ptcyp) (LH 2 = N,N′-bis(salicylidene)-p-phenylenediamine, en = 1,2-diamino ethane) shows high cytotoxicity against HeLa cells (IC 50 - 11.5 μM) and against Dalton's lymphoma (DL) cells (IC 50 - 0.65 nM); UV-vis titration of Ptcyp with calf thymus DNA (CT-DNA) demonstrated its DNA binding, which could be further quantified by competitive fluorescence titration of DNA, Ptcyp and ethidium bromide. Circular dichroism studies suggest that Ptcyp interacts with CT-DNA by intercalation in an aqueous medium containing a minimum amount of DMSO. Agarose gel electrophoresis showed that Ptcyp is able to convert a supercoiled pBR322 plasmid DNA into a nicked circular DNA in DMSO, but to a much lower extent in an aqueous medium. However, with UV irradiation, Ptcyp is able to cause concentration-dependent nicking of supercoiled DNA in an aqueous medium. These findings indicate the DNA binding and UV exposure-dependent DNA cleavage properties of Ptcyp. Cell imaging studies using the HeLa cell line carried out in the presence of Ptcyp represent one of the first examples of Pt complexes applied as fluorophores in cell imaging and strongly support its interaction with DNA. © 2011 The Royal Society of Chemistry.
The importance of cellular localisation of probes: Synthesis, photophysical properties, DNA interactions and cellular imaging properties of rhenium dppz complexes with known cellular localisation vectors
(Royal Society of Chemistry, 2012) Flora L. Thorp-Greenwood; Michael P. Coogan; Lallan Mishra; Niraj Kumari; Geeta Rai; Srikrishna Saripella
The synthesis, photophysical properties, DNA binding, DNA cleavage and cellular imaging behaviour of a range of complexes of the type [Re(CO) 3(dppz)(PyR)]+ are reported, where PyR represents a range of substituted pyridines which have previously been studied for cellular localisation of related complexes. Confocal imaging experiments confirm that the complexes retain the variety of cellular localisation behaviour associated with the PyR units in other complexes, and suggest applications as probes for oligonucleotides in specific cellular compartments (e.g. mitochondrial DNA). This study illustrates the importance of considering cellular localisation as a prime consideration in the design of probes for in vivo application. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.