Publications of Pierre Colson
Bookmark and Share    
See detailElaboration of Magnetic Nanodots by Nanosphere Lithography : a Computerized Method for Order Quantification
Colson, Pierre ULg; Cloots, Rudi ULg; Henrist, Catherine ULg

Conference (2008, December 01)

Nanosphere lithography (NSL) is an ideal inexpensive fabrication tool for producing regular, nearly homogenous arrays of nanoparticules with different sizes. There are many different methods for the ... [more ▼]

Nanosphere lithography (NSL) is an ideal inexpensive fabrication tool for producing regular, nearly homogenous arrays of nanoparticules with different sizes. There are many different methods for the fabrication of the latex monolayer based on electrophoresis, the controlled evaporation of a solvent from the suspension containing latex particles, spincoating etc… We focused our work on this last method. The main problem with formation of 2D latex monolayers is that there are always a high number of different structural defects such as: point defects (vacancies), line defects (dislocations) and also many disordered areas. The influence of the different spincoating parameters on the amount of defects was determined by image analysis of SEM micrographies from the different samples. FePt and Co films were deposited onto quartz substrates through the polystryrene monolayers by magnetron sputtering. The nanopsheres were removed by sonication in toluene. Post-deposition annealing treatment was performed under reductive atmosphere for the FePt nanodots in order to transform the as-deposited chemically disoredered face-centered cubic (fcc) structure into the chemically ordered face-centered tetragonal (fct) phase (L10-phase). DRX , SEM and MFM analysis were performed on the different samples. [less ▲]

Detailed reference viewed: 38 (3 ULg)
Full Text
See detailCovalent binding of antitumor benzoacronycines to double-stranded DNA induces helix opening and the formation of single-stranded DNA: Unique consequences of a novel DNA-bonding mechanism
David-Cordonnier, MH; Laine, W; Lansiaux, A et al

in Molecular Cancer Therapeutics (2005), 4(1), 71-80

The majority of DNA-binding small molecules known thus far stabilize duplex DNA against heat denaturation. A high, drug-induced increase in the melting temperature (T-m) of DNA is generally viewed as a ... [more ▼]

The majority of DNA-binding small molecules known thus far stabilize duplex DNA against heat denaturation. A high, drug-induced increase in the melting temperature (T-m) of DNA is generally viewed as a good criterion to select DNA ligands and is a common feature of several anticancer drugs such as intercalators (e.g., anthracyclines) and alkylators (e.g., ecteinascidin 743). The reverse situation (destabilization of DNA to facilitate its denaturation) may be an attractive option for the identification of therapeutic agents acting on the DNA structure. We have identified the tumor-active benzoacronycine derivative S23906-1 [(+/-)-cis-1, 2-diacetoxy-6-methoxy-3,3,14-trimethyl 1,2,3,14-tetrahydro-7H-benzo[b]pyrano[3,2]acridin-7- one] as a potent DNA alkylating agent endowed with a helicase-like activity. Using complementary molecular approaches, we show that covalent binding to DNA of the diacetate compound S23906-1 and its monoacetate analogue S28687-1 induces a marked destabilization of the double helix with the formation of alkylated ssDNA. The DNA-bonding properties and effects on DNA structure of a series of benzoacronycine derivatives, including the dicarbamate analogue S29385-1, were studied using complementary biochemical (electromobility shift assay, nuclease S1 mapping) and spectroscopic (fluorescence and T-m measurements) approaches. Alkylation of guanines in DNA by S28687-1 leads to a local denaturation of DNA, which becomes susceptible to cleavage by nuclease S1 and significantly decreases the T-m of DNA. The drug also directly alkylates single-strand DNA, but mass spectrometry experiments indicate that guanines in duplexes are largely preferred over single-stranded structures. This molecular study expands the repertoire of DNA-binding mechanisms and provides a new dimension for DNA recognition by small molecules. [less ▲]

Detailed reference viewed: 52 (16 ULg)