New heteroscorpionate and macrocyclic ligands, related metal complexes and novel Gold nanoparticles: synthesis, structure analysis and biological studies

The synthesis, the structural and the biological analysis of a series of new macrocyclic, heteroscorpionate ligands and related copper complexes are reported in the first two parts of this PhD thesis. In the third part the study of the internalization processes of new gold nanoparticles in the HeLa cells were showed. In the first part the coordination environment and the stability behavior of the new macrocyclic ligands 1,10-dithia-4,7-diazacyclododecane-3,8-dicarboxylic acid (NEC-SE), 1,10-dithia-4,7-diazacyclotridecane-3,8-dicarboxylic acid (NEC-SP), 1,10-dithia-4,7-diazacyclotetradecane-3,8-dicarboxylic acid (NEC-SB), 4-methyl-1,7-ditihia-4,10,13-triazacyclopentadecane-9,14-dicarboxylic acid (NEC-SN-Me) and of the corresponding Cu(II) complexes were investigated both in the solid state and in aqueous solution. The Cu2+ complexation constants for NEC-SE were determined in aqueous solution. The behavior of the copper complexes in presence of the strong copper chelating bioagent human serum albumin was also examined, to gain information on the stability of these compounds in biological fluids. The corresponding 64Cu(II) labeled complexes were produced in major98% radiochemical purity in collaboration with Prof. J. S. Lewis (Memorial Sloan-Kettering Cancer Center, NY). Rats were injected with complexes and were euthanized at 1, 4 and 24 h. All three complexes were cleared from the blood over the first hour following injection but there was poor clearance of this activity over 24 h. In the second section the syntheses by direct coupling of preformed side chain acid and amine components of new nitroimidazole and glucosamine conjugated heteroscorpionate ligands, namely 2,2-bis(3,5-dimethyl-1H-pyrazol-1-yl)-N-(2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethyl)acetamide (LMN) and 1,3,4,6-tetra-O-acetyl-2-{[bis(3,5-dimethyl-1H-pyrazol-1-yl)acetyl]amino}-2-deoxy-b-D-glucopyranose (LDAC), respectively, were reported. The related copper(II) complexes {[(LMN)2Cu]Cl2} and {[(LDAC)2Cu]Cl2} were prepared from the reaction of CuCl2*2H2O with LMN or LDAC in methanol solution. XAS and EXAFS were used to determine the local environment of the two copper(II) complexes. The new copper(II) complexes and the uncoordinated ligands were evaluated for their cytotoxic activity towards a panel of several human tumour cell lines. The results indicated that both copper(II) complexes show similar spectra of cytotoxicity and very low resistance factors (RF minus 2) against C13* ovarian cancer cells which have acquired resistance to cisplatin. In the last part only partial results were reported because the study is still in progress. This part of PhD work was carried out in collaboration with the research groups of Prof. Stellacci in the Department of Materials Science and Engineering, Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne, Switzerland, during my abroad 6 months stage. The synthesis of a series of mixed-ligand gold nanoparticle (NPs) obtained varying the lengths of both the hydrophobic and hydrophilic ligand length were carried out. The synthesized NPs were studied using 1H-NMR (first and before the decomposition with potassium cyanide), TEM and GC-MS analysis. The NPs with a size between 4 and 10 nm were recovered using the fractionation by centrifugation, which is a technique that uses the principle that larger particles sediment faster than smaller ones. Confocal laser scanning microscopy (CLSM) and flow cytometry (FCM) were used to explore how the temperature of the system, the size of NPs and their shell composition affect the internalization processes in the analyzed cell.