A DNA-transfection protocol has been developed that makes use of thiourea non-cationic synthetic lipid, N-[1,3-bis(carbamothioylamino)propan-2-yl]-2-(dialkycarbamoylmethoxy)acetamide. It was found that these new compounds could be formulated without helper lipid and that the N-decanoyl and N-lauryl derivatives transfected B16 cells in the presence of serum with an efficiency at the same level as cationic lipids, under identical conditions. In vivo transfection using intratumoral injection was also investigated. It was found that compounds 18c and 19 showed an efficiency of the same magnitude as naked DNA and cationic lipid.

Ultracentrifugated compact polyelectrolyte complexes (uCoPECs) represent a new class of materials that are obtained by ultracentrifugation of solutions of polyanion/polycation complexes in the presence of salt. In the present study, two polysaccharides, chitosan and alginate, were used to form such complexes, thus providing a solid material uniquely composed of polysaccharides. The conditions for obtaining the uCoPEC material were optimized: the optimal salt concentration and polysaccharide concentrations were assessed, and the ultracentrifugation speed proved to be a key parameter to obtain compact and homogeneous materials. The Young's modulus, E, of the material was of the order of 12 MPa, which is the highest E value measured for a uCoPEC. The material contained nanometer-sized crystals of chitosan as indicated by X-ray diffraction. Most strikingly, this material proves to be totally cell-and bacteria-resistant. Immunological tests show that this uCoPEC does not induce any proinflammatory response. This makes it a suitable candidate for the development of biocompatible and antifouling biomaterials composed only of polysaccharides.