Analysis of 4-dimethylaminopyridine (DMAP)-gold nanoparticles behaviour in solution and of their interaction with calf thymus DNA and living cells

4-(Dimethylamino)pyridine-coated gold nanoparticles (DMAP-Au NPs) were synthesized, characterised and their interaction with DNA and living cells was analysed. Concerning the interaction of the DMAP-Au NPs with DNA, absorbance titrations indicate that a non-covalent interaction between DNA and the external surface of the NPs does take place. The binding constant was evaluated to be (2.8 ± 0.8) × 10⁵ M⁻¹. Exposure of cultured cells to NPs revealed a dose-dependent effect on cell proliferation which was increased or reduced in dependence of DMAP-Au NPs concentrations. Subcellular localisation by transmission electron microscopy showed mitochondrial and nuclear localisations of NPs, thus suggesting their direct involvement in the mitochondrial alterations observed and a possible direct interaction with cell DNA. These findings clearly indicate that DMAP-Au NPs can strongly interact with living cells and confirm the importance of systematic evaluations of NPs properties, also in the perspective of their arising diagnostic and therapeutic applications.     

Influence of processing method and components molecular structure on the phase behaviour of polyethylenes/dye blends

The phase dispersion of terthiophene alkyl derivatives on different polyethylene matrices was investigated. The PE affinity toward dichroic dyes with different structure, the effect of blending process and the influence of a polyolefinic compatibilizer on the homogeneity of host-guest blends were comparatively investigated by calorimetry, DSC and SEM analyses. For these purposes, polyethylenes with different molecular weights and densities and EVAc were used as host matrices. The polymeric compatibilizer was prepared by radical functionalization of a commercial low density polyethylene. The dichroic nature of the guest phase allowed to perform UV-Vis measurements in polarized light on oriented blend film samples. The dyes affinity toward PE is one of the key factor in obtaining oriented polyolefinic films with high optical performances for several applications.     

Molecularly controlled blending of metals and organic metals with polyolefins for the preparation of materials with modulated optical properties

In this paper, after revisiting previous data on terthiophene molecules, several attempts are described to use metal containing species such as nanoclusters and molecular complexes as dispersed chromophores in the same ethylene polymer matrix in order to extend an approach to new classes of molecules and improve some specific optical responses including fluorescence dichroism and behaviour as linear optical polarizers is evaluated. Comparison with typical linear polarizers from the same polymer and terthiophenes of innovative gold clusters is discussed as well as transition metal complexes.