Assessing the interactions between a single dendrimer and (bio)surfaces using AFM

International audienc

Sol/Gel and Isotropic/nematic transitions in aqueous suspensions of natural nontronite clay. Influence of particle anisotropy. Part 1. Features of the I/N transition

The phase behavior of a natural nontronite clay was studied for size-selected particles by combining osmotic pressure measurements, visual observations under polarized light, and rheological experiments. In parallel, the positional and orientational correlations of the particles were analyzed by small-angle X-ray scattering. Aqueous suspensions of nontronite exhibit a true isotropic/nematic (I/N) transition that occurs before the sol/gel transition, for ionic strengths below 10(-3) M/L. In this region of the phase diagrams, the system appears to be purely repulsive. The I/N transition shifts toward lower volume fractions for increasing particle anisotropy, and its position in the phase diagram agrees well with the theoretical predictions for platelets. SAXS measurements reveal the presence of characteristic interparticular distances in the isotropic, nematic, and gel phases. The swelling law (separation distance vs swelling law) exhibits two regimes. For high volume fractions, the swelling law is one-dimensional as in layered systems and reveals the presence of isolated platelets. At lower volume fraction, distances scale as phi(-1/3), indicating isotropic volumic swelling. Finally, the experimental osmotic pressure curves can be satisfactorily reproduced by considering the interparticle distances between two charged planes whose effective charge is around 10% of the structural charge

Nanoparticle (NP) interactions with (bio)surfaces probed by single-NP force spectroscopy

International audienc

Adsorption of polyamine on clay minerals

International audienc

Silencing of the <em>miR-17~92</em> Cluster Family Inhibits Medulloblastoma Progression

Medulloblastoma (MB), originating in the cerebellum, is the most common malignant brain tumor in children. MB consists of four major groups where constitutive activation of the Sonic Hedgehog (SHH) signaling pathway is a hallmark of one group. Mouse and human SHH MBs exhibit increased expression of microRNAs encoded by the miR-17~92 and miR-106b~25 clusters compared to granule progenitors and post-mitotic granule neurons. Here, we assessed the therapeutic potential of 8-mer seed-targeting LNA-modified antimiR oligonucleotides, termed tiny LNAs, that inhibit microRNA seed families expressed by miR-17~92 and miR-106b~25 in two mouse models of SHH MB. We found that tumor cells (MB cells) passively took up 8-mer LNA-antimiRs, and specifically inhibited targeted microRNA seed-sharing family members. Inhibition of miR-17 and miR-19a seed families by antimiR-17 and antimiR-19, respectively, resulted in diminished tumor cell proliferation in vitro. Treatment of mice with systemic delivery of antimiR-17 and antimiR-19 reduced tumor growth in flank and brain allografts in vivo and prolonged the survival of mice with intracranial transplants, suggesting that inhibition of the miR-17~92 cluster family by 8-mer LNA-antimiRs might be considered for the treatment of SHH MBs