Gold nanoclusters prepared with a controlled amount of Ag exhibit intense fluorescence with a quantum yield of ~16% and a "quasi-monoexponential" long lifetime of >200 ns. Characterization of the luminescent probes indicates high photostability and easy detection in cells. Additionally, fluorescence enhancement in the presence of proteins was found.

The van der Waals molecule NaAr has been prepared in a supersonic expansion of sodium vapor plus a few percent argon in a helium carrier gas. The fluorescence excitation spectrum of the X2Σ+→A2Π optical transition has been analyzed and the vibrational and rotational spectroscopic constants have been derived from this analysis. The ground state interatomic potential implied by these parameters is consistent with that measured or calculated by other workers. The observed Λ-doubling of the A2Π state suggests that the coupling between the A2Π and B2Σ states may be stronger than would be expected from previous calculations. The magnitude and sign of the dependence of the fine-structure splitting of the A2Π state on vibrational quantum number suggests that the van der Waals bond produces an observable perturbation of the core electrons of the sodium atom.

Cationic polyrotaxanes, obtained by temperature activated threading of cationic cyclodextrin derivatives onto water soluble cationic polymers (ionenes), form metastable nanometric polyplexes with pDNA and combinations of siRNA with pDNA.Because of their low toxicity, the polyrotaxane polyplexes constitute a very interesting system for the transfection of polynucleotides into mammalian cells. The complexation of Cy3-labeled siRNA within the polyplexes was demonstrated by fluorescence correlation spectroscopy. The uptake of the polyplexes (red) was imaged by confocal fluorescence microscopy using the A549 cell line as a model (blue: nuclei, green: membranes). The results prove the potential of polyrotaxanes for further investigations involving knocking down genes of therapeutic interest.

Starch was oxidized with TEMPO for the synthesis of water-soluble copolymers of glucuronic acid and glucose. The carboxylate groups of these copolymers were conjugated with pteroic acid as cell-specific ligand for targeting to cancer cells. Stable spherical nanoparticles (NPs) were formulated mixing aqueous solutions of the anionic copolymers and of a cationic thioether of b-cyclodextrin (b-CD). Particle size distributions of NPs were investigated with DLS as the function of the charge ratio of the constituents. The smallest and most uniform particles with a diameter of about 130 nm were generated at a charge ratio of anion/cation close to 1, preferably 1.2. Stabilities and particle size distributions of these starch NPs were very satisfactory. The starch/b-CD NPs could be loaded with hydrophobic guest molecules like 1,4-dihydroxyanthraquinone (DHA), which served as a model for the important class of anthracycline antibiotics used in cancer therapy.

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