Innovative synthesis of nanostructured composite materials by a spray-freeze drying process: Efficient catalysts and photocatalysts preparation

The spray-freeze-drying (SFD) approach was successfully applied for the preparation of nanostructured porous mixed oxides with high surface area. The preparation of different composite materials and the encapsulation of metal nanoparticles in inorganic matrix was easily obtained using this interesting technique. In particular, TiO2-SiO2 mixed-oxides were produced at different compositions using the colloidal heterocoagulation of very stable sols, associated with SFD. Moreover, its versatility allowed the incorporation of metal. This synthetic approach led to the preparation of porous micro-granules characterised by a high homogeneity in the phase distribution. The prepared materials were active and selective in the reduction of 5-hydroxymethyl-2-furfural (HMF) to 2,5-bishydroxymethylfuran (BHMF) and in the photodegradation of rhodamine B (RhB), used as a as a stain model. These encouraging results pave the way for the use of this method for the homogeneous embedding of different typologies of catalytic active phases (metal nanoparticles, inorganic complexes, enzyme) into any kind of support (inorganic, organic, polymeric) minimizing the possibility of phase separation on a molecular scale, as also demonstrated for drugs

Cationic liposomes formulated with DMPC and a gemini surfactant traverse the cell membrane without causing a significant bio-damage

Cationic liposomes have been intensively studied both in basic and applied research because of their promising potential as non-viral molecular vehicles. This work was aimed to gain more information on the interactions between the plasmamembrane and liposomes formed by a natural phospholipid and a cationic surfactant of the gemini family. The present work was conducted with the synergistic use of diverse experimental approaches: electro-rotation measurements, atomic force microscopy, ζ-potential measurements, laser scanning confocal microscopy and biomolecular/cellular techniques. Electro-rotation measurements pointed out that the interaction of cationic liposomes with the cell membrane alters significantly its dielectric and geometric parameters. This alteration, being accompanied by significant changes of the membrane surface roughness as measured by atomic force microscopy, suggests that the interaction with the liposomes causes locally substantial modifications to the structure and morphology of the cell membrane. However, the results of electrophoretic mobility (ζ-potential) experiments show that upon the interaction the electric charge exposed on the cell surface does not vary significantly, pointing out that the simple adhesion on the cell surface of the cationic liposomes or their fusion with the membrane is to be ruled out. As a matter of fact, confocal microscopy images directly demonstrated the penetration of the liposomes inside the cell and their diffusion within the cytoplasm. Electro-rotation experiments performed in the presence of endocytosis inhibitors suggest that the internalization is mediated by, at least, one specific pathway. Noteworthy, the liposome uptake by the cell does not cause a significant biological damage. © 2014 Elsevier B.V

Nanoparticles and molecular delivery system for nutraceuticals bioavailability

This contribution discusses methods for transferring exogenous materials and drugs, particularly, into biological tissues. The focus is on matrices such as micelles, vesicles, and oil-based dispersions as well as carbon nanotubes. An ensemble of physical forces takes a fundamental role in drug dispersion and includes van der Waals (vdW), steric (ST), double layer, (DL), osmotic (OS), etc. Combination of these forces is responsible for drug uptake in matrices and for their release in tissues. Uptake of exogenous either macro- or small molecules into cargo particles and their transfer to recipient cells is the result of complex processes, concomitant to drug partition among supramolecular aggregates and the bulk. Similar conclusions apply to drug release, mostly as to the kinetic features are concerned; therefore, adsorption of nutraceuticals and release within target organs are particularly relevant. These complex features can be accounted for on thermodynamic grounds and expressed as the combination of different forces. In what follows some details on the energies to be considered are outlined. These include terms controlling the fate of transfectants. We will consider first the forces responsible for the formation of such supramolecular entities on physicochemical grounds and the drug uptake; finally, we will review the actual possibility of transfecting cargo-mediated aggregates of nanoparticle/drug complexes to cells or tissues of interest and their bioactivity upon release within the cell matrix