Ricerc@Sapienza

To study the formation and characterize the structure of mixed complexes of oppositely charged block copolymers and surfactants are of great significance for practical applications, e.g., in drug carrier formulations that are based on electrostatically assisted assembly. In this context, biocompatible block copolymers and biosurfactants (like bile salts) are particularly interesting.

In this study we have explored by means of polarizable molecular dynamics simulations and small-angle X-ray diffraction, a subset of liquids belonging to the following three different classes of compounds: pentyl ammonium nitrate, 1-pentanol and 1-pentanoic acid. The presence of a low-Q peak in the X-ray spectra of the liquids provides evidence that a long alkyl chain is connected to the polar moiety and it is sufficient to establish nanodomain segregation in the liquid.

Anthracyclines self-assemble in water into dimers. In the presence of sufficiently high salt (NaCl) concentrations, solutions of the antibiotic doxorubicin, but not those of the closely related molecules daunomycin and epirubicin, turn into gels barely compatible with the presence of small oligomers. The use of spectroscopic, scattering, imaging and computational techniques, allowed light to be shed on the self-assembly process that triggered doxorubicin gelification.

Fungal laccases have great potential as biocatalysts oxidizing a variety of aromatic compounds using oxygen as co-substrate. Here, the crystal structure of 7D5 laccase (PDB 6H5Y), developed in Saccharomyces cerevisiae and overproduced in Aspergillus oryzae, is compared with that of the wild type produced by basidiomycete PM1 (Coriolopsis sp.), PDB 5ANH. SAXS showed both enzymes form monomers in solution, 7D5 laccase with a more oblate geometric structure due to heavier and more heterogeneous glycosylation.

The protein Human Serum Albumin (HSA) is known to undergo conformational transitions towards partially unfolded forms triggered by acidification below pH 4.5. The extent of Fatty Acids (FA) binding has been thought to have an impact on the conformational equilibrium between the native and acid forms and to be a possible explanation for the observation of more than one band in early electrophoretic migration experiments at pH 4.

Within the homologous series of amphiphilic peptides AnK, both A8K and A10K self-assemble in water to form twisted-ribbon fibrils with lengths around 100 nm [1]. The structure of the fibrils can be described in terms of twisted -sheets extending in the direction of the fibril, laminated to give a constant cross section of 4 nm by 8 nm.

Knowing the ability of water and bile salts to promote the reverse wormlike micelle growth in lecithin/water or lecithin/bile salt mixtures in oil, this work was aimed at elucidating the association properties of the three solutes lecithin, water and the bile salt (BS) sodium deoxycholate in cyclohexane. By systematically changing the fraction of the two additives (i.e.: water and BS) we could identify a region at low additive/lecithin molar ratios where stable wormlike micelle dispersions were formed.

Background: Phosphodiesterases (PDEs) are a superfamily of evolutionary conserved cyclic nucleotides (cAMP/cGMP) hydrolysing enzymes, components of transduction pathways regulating crucial aspects of cell life. PDE5, one of these families, is the molecular target of several drugs used to treat erectile dysfunction and pulmonary hypertension. Despite its medical relevance, PDE5 macromolecular structure has only been solved for the isolated regulatory and catalytic domains.

Span-20 non-ionic surfactant vesicles (niosomes), designed for future applications in brain drug delivery through intranasal route, are prepared and coated with chitosan glutamate, a mucoadhesive agent specifically proposed for brain delivery and for an optimal interaction with nasal mucin, with the aim to promote the vesicles residence time in the nasal cavity. The understanding of the interaction between chitosan coated niosomes with mucin is of great relevance as it can influence their in vivo distribution and physiological behaviour.